From pfperry at melbpc.org.au  Tue Dec  1 00:27:36 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Tue, 1 Dec 1998 10:27:36 +1100 (EST)
Subject: Oscilloscope books
Message-ID: <1.5.4.16.19970224145652.364f28ec@popa.melbpc.org.au>

At 01:33 PM 30/11/98 -0500, Thomas Hudson  wrote:
>
>I just purchased and oscilloscope and was wondering if anyone can
>suggest good books on using scopes. 

I can't really recommend any that I have.
The best stuff i have seen is in R.A.Pease's "Troubleshooting Analog
Circuits". If you are going to use your scope for anything analog,
you have to have this book anyway.
It's got a very favourable review at Amazon, BTW. ;-)

paul perry melbourne australia




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From mike at p-w-m.demon.co.uk  Tue Dec  1 02:04:35 1998
From: mike at p-w-m.demon.co.uk (Michael Rogers)
Date: Tue, 1 Dec 1998 01:04:35 +0000
Subject: MN3005, MN3007 BBD.. anyone built one?
In-Reply-To: <199811301435.PAA06039@window.intermetall.de>
Message-ID: <3JwXQLAjC0Y2Ewnz@p-w-m.demon.co.uk>

>>I've built the delay based on Electronotes using the MN3005. It pretty
>>much works as advertised, though I find it to be rather noisey - I'm
not
>>using any companding around it or anything. You also can start hearing
>>the clock feedthrough at anything longer than 100ms of delay time. I
did
>>add VC feedback and VC mixing of wet and dry signal using an SSM2024
for
>>the VCAs. 

Sorry if this is off-topic, but I've been trying to repair a DOD digital
delay for the last few weeks, and I was puzzling over what the NE570N
compander was doing there. Is it normal to compress the signal before it
goes through the delay stage? Also, this pedal has infinite repeat.
Would the feedback signal be compressed and expanded on every repeat? I
ask because the infinite repeat sound quality is very good, and I had
enough trouble believing it was being resampled on every repeat, without
being expanded and compressed as well...


Michael Rogers



From budweiser at ozemail.com.au  Tue Dec  1 02:48:00 1998
From: budweiser at ozemail.com.au (Benjamin  Woenig)
Date: Tue, 1 Dec 1998 12:18:00 +1030
Subject: MXR envelope follower..?how works?
Message-ID: <004e01be1ccc$a2aceae0$78a66ccb@ppp.ozemail.com.au>



>
>>Well, there is only *1* female electronics engineering student out
>>of 150 at The Levels, UniSA..... its a shame really :(
>
>-well, there are almost ten in my class of 50 or so EEs at UCSD, so maybe
>all is not lost.. i'm not sure any of them are quite wife material though
:]


Thats the same situation :) All the goodlooking girls dropped out :(
Maybe i should have done nursing.....


<bUd>




From mamundso at mr.net  Tue Dec  1 03:17:42 1998
From: mamundso at mr.net (Mark Amundson)
Date: Mon, 30 Nov 1998 18:17:42 -0800
Subject: Pre-amp input Zin
References: <199811301756.LAA28430@keen.austin.ibm.com>
Message-ID: <366351C6.3AC@mr.net>

R.G. Keen wrote:
> 
> The recording engineer is right. Almost all guitar amps are over 470K
> Zin, as a result of the treble loss from pickups when driving low
> impedance loads.

And actually, one meg-ohm is the prefered input impedance for electric
guitars and basses.

Mark Amundson,



From theremin1 at worldnet.att.net  Tue Dec  1 04:05:35 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 30 Nov 1998 19:05:35 -0800
Subject: Solus Troubleshooting Results
Message-ID: <002f01be1cd7$77fa6ec0$fd43440c@hpcustomer>

I was wondering if the resistors were PTC thermistors to act as
self-regulating heaters for the '3086 arrays, or if they were used
as compensating circuit elements. Odd that all the arrays went bad.

Re: IC removal.  Sounds like you did okay getting the old arrays out.
One product that helps for one or two-sided boards with sufficiently
large holes is a product called "Soder Wick."  It is a fine mesh copper
braid that is held over the joint and then heated.  Capillary action soaks
up the solder.  Radio Shack sells it, as do most mail order houses,
in little 5 foot spools.  You can also buy it in bulk rolls of 250 or 500
feet,
depending on the gauge.  (Besides desoldering, I use the stuff for bus
bars on perfboard with great results.)

Here's another good technique:  Once you pull the component lead out
of the hole, remaining solder can be blown out using a foot or so of medium
gauge tubing and your lungs.  Minimal expense, there!

Of course, the best method for desoldering is a vacuum desoldering machine,
but the good ones cost a bundle, and require a lot of maintenance.

-Art


-----Original Message-----
From: Chris & Ann MacDonald <cmacdon at ix.netcom.com>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Sunday, November 29, 1998 3:30 PM
Subject: Solus Troubleshooting Results


>I finally had time this weekend to take apart a broken ARP Solus I
>bought recently.
>
>Initially I could get no sound at all out of it.  There is an external
>audio input, so I plugged a signal into that and found that most of the
>synth was working (VCF, ADSR, LFO, keyboard), only the oscillators
>appeared to be dead.
>
>By staring at my fuzzy schematic and comparing it to the circuit board,
>I figured out that each Solus oscillator (there are two) is based around
>a CA3086.  I decided to try to replace them since I wasn't getting
>anywhere otherwise.
>
>What a pain it was to remove the old chips!  There was a tempco resistor
>glued to the top of each chip which I tried to carefully pry off.  The
>chips were not socketed and removing a soldered-in IC didn't look like
>much fun.  In the end I had to cut the old chips off pin by pin, remove
>the pins, and then use a solder sucker to clean the PCB holes.  Are
>there any tools or tricks for doing this more easily?  I decided to use
>sockets for the new chips to prevent possible damage to the board if
>another replacement became necessary later.
>
>After replacing the CA3086 the oscillators began to oscillate - but at a
>maximum frequency of around 2 hz!  This stumped me for a while until I
>thought to check the tempco resistors.  They were dead (open circuit).
>Are tempco resistors more fragile than ordinary ones?  I wasn't
>expecting a problem with them, thinking that they were as rugged as
>regular resistors.  Anyway, I replaced them temporarily with standard
>1.8k resistors and the oscillators started working properly.
>
>The only problem left was that one oscillator had a bad square wave
>shape.  I discovered that the TL082 chip in that part of the circuit was
>too hot to touch so I figured it needed replacing.  That fixed it, next
>time I'll check for hot components first!
>
>-Chris MacDonald




From theremin1 at worldnet.att.net  Tue Dec  1 04:24:26 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 30 Nov 1998 19:24:26 -0800
Subject: Solus Troubleshooting Results
Message-ID: <005001be1cda$1af0f5c0$fd43440c@hpcustomer>


Roman wrote:

BTW sockets are not recommended for analog circuits - contacts may
get lousy after some time.

I write:

I've used thousands of DIP IC sockets without any problem; some of them in
analog electronics equipment now over 20 years old.  The important thing is
to use good quality ones, such as machined-pin sockets with gold plated
contacts, from a reputable manufacturer such as Augat or Andon.  Avoid
cheap sockets with one stamped, tin plated contact per pin.

-Art




From theremin1 at worldnet.att.net  Tue Dec  1 04:42:30 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 30 Nov 1998 19:42:30 -0800
Subject: Oscilloscope books
Message-ID: <005c01be1cdc$a04657e0$fd43440c@hpcustomer>

It's very basic, but you might enjoy:
http://hem2.passagen.se/sm0vpo/scope/osc-0.htm
on Harry Lythall's page.

This only addresses the plain vanilla old-fashioned
analog scopes. (Nothing wrong with them!) 

-Art

-----Original Message-----
From: Thomas Hudson <thudson at cygnus.com>
To: Synth DIY <synth-diy at mailhost.bpa.nl>
Date: Monday, November 30, 1998 1:09 PM
Subject: Oscilloscope books


>
>I just purchased and oscilloscope and was wondering if anyone can
>suggest good books on using scopes. Amazon list tons of mostly out
>of print books, does anyone have a favorite? The only book reviewed
>was _Complete Book of Oscilloscopes_, and it was given a pretty
>bad review.
>
>Thanks in advance,
>Thomas - staring at wonderful waveforms...
>
>
>




From thelab at sprint.ca  Tue Dec  1 04:43:38 1998
From: thelab at sprint.ca (|||| Philip Pilgrim ||||)
Date: Mon, 30 Nov 1998 23:43:38 -0400
Subject: MXR envelope follower..?how works?
References: <004e01be1ccc$a2aceae0$78a66ccb@ppp.ozemail.com.au>
Message-ID: <366365EA.709C@sprint.ca>

Benjamin Woenig wrote:

> Thats the same situation :) All the goodlooking girls dropped out :(
> Maybe i should have done nursing.....


Hey watch star trek to see the future :)

Philip

-- 
Philip Pilgrim               The Lab
5 Evan's Drive               synth mods, software development
Hammond's Plains             digital audio recording/mastering
Nova Scotia, Canada          music architecture/construction
B4B 1M8
(902) 835-7844

           Home of NovaMod, UP and Microwave tools

           web page: http://www.robotnik.com/the_lab
           email:    mailto:thelab at sprint.ca



From theremin1 at worldnet.att.net  Tue Dec  1 06:02:12 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 30 Nov 1998 21:02:12 -0800
Subject: leaving
Message-ID: <002d01be1ce7$c2dae0e0$d1764e0c@hpcustomer>

Well, this list server is tooooo screwed up to deal with.  
Tooooo may bounced messages; a real MESS.

Nice knowing you all.

L8TR,

Art




From inman at interpath.com  Tue Dec  1 06:07:26 1998
From: inman at interpath.com (inman at interpath.com)
Date: Mon, 30 Nov 1998 21:07:26 -0800
Subject: DCO's, Anti-Aliasing, and Filters
Message-ID: <3663798E.73C0@interpath.com>

I just read in Nuts and Volts about MAXIM's new filters:  5TH-ORDER 
FILTER ("5th-order lowpass, switched-capacitor Butterworth and Bessel 
filters available in 8-pin mMAX and DIP packages," MAXIM web page) and an 
8TH-ORDER ELLIPTIC, LOWPASS SWITCHED-CAPACITOR FILTERS ("...provide corner
frequencies from 1Hz to 10kHz and draw supply currents of only 2mA, making
them well suited for low-power anti-aliasing and post-DAC filtering 
applications," MAXIM web page).  Be a bit careful before you begin to design 
with some of the 8TH-ORDER stuff in the spec sheets; only the 7400 is ready. 
The others are future products (a fine print truth pointed out in the 
promotional stuff).  The cool thing about the 8TH order filters is that
they will run off of a capacitor OR a clock (input clock / 100).  If you
are designing a microchip that is already sending out a square wave, why
not send a second one out to the MAXIM filter?  For that matter, why not 
vary the speed of the microchip output to vary the cutoff frequency of
the filter and create a sweeping filter?  Or, if you don't want to program
a PIC, etc..., why not use a 555 to control the cutoff, instead of a control 
voltage?  You could even use the control voltage input on the 555 to 
vary the speed of the 555 and use that to vary the filter cutoff.

The best part:  8TH ORDER FILTER $2.00 US.

Although ads can be very misleading sometimes, it sure does sound as if
this little chip would reduce a tremendous amount of undesired alias
waveforms caused by imprecise timing of the period of square waves or
A/D coversion of phase accumulator waveforms.  At a decent price.

Any thoughts from DSP folks with the brains to do the math?

Spec sheets and some promotional material may be found at their web site.

http://www.maxim-ic.com/NewProd.htm


Elliot  "Probably Re-inventing the Wheel, but Having Fun Imagining
	No One Has Ever Seen a Rock Roll"



From inman at interpath.com  Tue Dec  1 06:16:01 1998
From: inman at interpath.com (inman at interpath.com)
Date: Mon, 30 Nov 1998 21:16:01 -0800
Subject: Mellotron Lovers Unite!
Message-ID: <36637B91.533A@interpath.com>

Mellotrons must be in the air.  

(Or is that the sound of two clouds kissing?)

Keyboard magazine's January 1998 issue has (p. 12 top left corner if you 
read your copy standing at the magazine rack) a brief list of hints on
how to make samples sound more like a Mellotron, a kind of by-ear 
reverse-engineering.  See "Instant Mellotron" (check out the itsy bitsy
Mark Vail credit at the bottom).

This may or may not be posted on their website:

http://www.keyboardmag.com


Elliot in the Land of Coincidence



From bjacquot at CALAMITY.WYOMING.COM  Tue Dec  1 06:31:46 1998
From: bjacquot at CALAMITY.WYOMING.COM (Byron Jacquot)
Date: Mon, 30 Nov 1998 22:31:46 -0700
Subject: TB303 quickie question and EG findings...
Message-ID: <1.5.4.32.19981201053146.009bcc30@mailhost.wyoming.com>

>I am wondering why the TB's accent control signal is controlled by the
>slide control. The accent logic signal comes from the output of a D-type
>flip flop, the rising edge triggered CLK is the slide control (high to
>slide), and the DATA IN is coming off the control board. Anyone know why
>there should be a d-type there??

>From what I can tell, it was done in order to conserve lines from the
processor.    The line being used to clock the flip flop (IC 9, the basis of
an R2R Digital to analog converter), and also switch on the slide circuit.

I've never analyzed a 303 using a scope, but here my guess what happens:

If a note is to be triggered, but without slide, the clock line will pulse
high for a very short moment, then go low again very quickly.  The data will
hit the flip-flop and generate the proper CV voltage.  The slide circuit
will be switched in for a breif moment, but switched right back out, so the
CV may have a tiny portamento, but probably not enough for us to hear.

For a slid note, the clock line will go high, clock in the note bits on its
rising edge, then stay high, leaving the portamento cap in the circuit,
inducing glide.

Incidentally, the same clock line also latches the accent information to IC13.

It's actually a pretty ingenious way to conserve processor lines.  If you
have lines to spare, you might make things a bit more flexible by using more
lines and handling things in software...or stick with the classic!


Byron




From inman at interpath.com  Tue Dec  1 07:43:23 1998
From: inman at interpath.com (inman at interpath.com)
Date: Mon, 30 Nov 1998 22:43:23 -0800
Subject: Mellotron Lovers Unite!
Message-ID: <3663900B.52A1@interpath.com>

Mellotrons must be in the air.

(Or is that the sound of two clouds kissing?)

Keyboard magazine's January 1998 issue has (p. 12 top left corner if you
read your copy standing at the magazine rack) a brief list of hints on
how to make samples sound more like a Mellotron, a kind of by-ear
reverse-engineering.  See "Instant Mellotron" (check out the itsy bitsy
Mark Vail credit at the bottom).

This may or may not be posted on their website:

http://www.keyboardmag.com


Elliot in the Land of Coincidence



From inman at interpath.com  Tue Dec  1 07:48:58 1998
From: inman at interpath.com (inman at interpath.com)
Date: Mon, 30 Nov 1998 22:48:58 -0800
Subject: DCO's, Anti-aliasing, and a New IC Filter
Message-ID: <3663915A.36D0@interpath.com>

I just read in Nuts and Volts about MAXIM's new filters:  5TH-ORDER
FILTERS ("5th-order lowpass, switched-capacitor Butterworth and Bessel
filters available in 8-pin mMAX and DIP packages," MAXIM web page) and 
8TH-ORDER ELLIPTIC, LOWPASS SWITCHED-CAPACITOR FILTERS ("...provide corner
frequencies from 1Hz to 10kHz and draw supply currents of only 2mA, making
them well suited for low-power anti-aliasing and post-DAC filtering
applications," MAXIM web page).  Be a bit careful before you begin to design
with some of the 8TH-ORDER stuff in the spec sheets; only the 7400 is ready.
The others are future products -- a fine print truth pointed out in the
promotional .pdf.  The cool thing about the 8TH order filters is that
they will run off of a capacitor OR a clock (input clock / 100).  If you
are designing a microchip that is already sending out a square wave, why
not send a second one out to the MAXIM filter?  For that matter, why not
vary the speed of the microchip output to vary the cutoff frequency of
the filter and create a sweeping filter?  Or, if you don't want to program
a PIC, etc..., why not use a 555 to control the cutoff, instead of a control
voltage?  You could even use the control voltage input on the 555 to
vary the speed of the 555 and use that to vary the filter cutoff.

The best part:  8TH ORDER FILTER $2.00 US.

Although ads can be very misleading sometimes, it sure does sound as if
this little chip would reduce a tremendous amount of undesired alias
waveforms caused by imprecise timing of the period of square waves or
A/D coversion of phase accumulator waveforms.  At a decent price.

Any thoughts from DSP folks with the brains to do the math?

Spec sheets and some promotional material may be found at their web site.

http://www.maxim-ic.com/NewProd.htm


Elliot  "Probably Re-inventing the Wheel, but Having Fun Imagining
        No One Has Ever Seen a Rock Roll"



From martin.czech at intermetall.de  Tue Dec  1 09:33:14 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Tue, 1 Dec 1998 09:33:14 +0100 (MET)
Subject: Echolette, Binson EchoRec
Message-ID: <199812010833.JAA12278@window.intermetall.de>

> >It is said, that Edge (U2 gitarist) uses such an old delay, or even an
> >echolette magneto-mechanical delay for his typical delay based rythm
> >playing, you know what I mean. He is driving his sound eng. mad, because
> >it is so noisy, but no way, he claims it has a specific sound as the
> >echo fades away, and also if overdriven....
> 
> Finally, a memtion of the magnetic-mechanical echo machines. To make a long
> story short, I'm looking for one for two years now.
> 
> Does anyone: 1) have one for sale - any condidtion or 2) have
> service/theory documentation or 3) know of a source for replacement parts?
> 
> I've a friend in town with one each Echorec and Echolette; both need
> repairs sorely. Like, what to use for the (metal?) tape??? 
> 
> Thanks,
> 
> 
When I was young (;->) i bought a little book "Electronic Effects
for musicians", you know this 2 transistor circuits, LC-Filter bongos
etc. Very disappointing.  Today it looks abit differnt, why not use these
bongos as low fi percussion, why not build the simple Leslie-Rotor, and
there is a instruction for doing an echolette, too. Simply a aluminum
disk, 5mm thick, diameter, say 10cm.  Now, slay a cassette and glue the
tape to the disk edge, of course the ends not with 90 degrees angle but
45 degrees, to avoid pops or klicks. This is an awfull job to do, and you
need the right glue that doesn't dissolve the tape. You need a motor,
some tape recorder heads (replacement parts) and preamp electronics
(I think National have some app notes about that). And a motor. That's it.

I have no experience with tape technology, ie. hf erease, bias and all
this stuff, so I never tryed this.

If you want, I could dig this book out , and scan the interesting parts.


m.c.




From debus at cityweb.de  Tue Dec  1 09:33:33 1998
From: debus at cityweb.de (Ingo Debus)
Date: Tue, 01 Dec 1998 09:33:33 +0100
Subject: ODP: Solus Troubleshooting Results
References: <2BF6F749A4A3D11185AD00A0C94CF67A4D67A9@demon>
Message-ID: <3663A9DC.206E@cityweb.de>

Roman Sowa wrote:
> 
> Why didn't you use solder sucker before cutting and removing IC leads?
> Usualy I have no problem desoldering ICs with solder sucker
> even from double sided boards.

Depends on the quality of the PCB. The PCB in the DX7 cartridge is
excellent: I replaced the EPROM in it again and again (no place for a
socket) and never damaged the PCB. On other PCBs the traces often get
loose when an IC is desoldered.

Ingo




From zzynt at swipnet.se  Tue Dec  1 10:00:24 1998
From: zzynt at swipnet.se (BJ)
Date: Tue, 01 Dec 1998 01:00:24 -0800
Subject: MN3005, MN3007 BBD.. anyone built one?
References: <199811301435.PAA06039@window.intermetall.de>
Message-ID: <3663B028.679F@swipnet.se>

Martin Czech wrote:
> 
> > I've built the delay based on Electronotes using the MN3005. It pretty
> > much works as advertised, though I find it to be rather noisey - I'm not
> > using any companding around it or anything. You also can start hearing
> > the clock feedthrough at anything longer than 100ms of delay time. I did
> > add VC feedback and VC mixing of wet and dry signal using an SSM2024 for
> > the VCAs.
> >
> Well, these are the shortcommings of BBD designs, noise and feedthrough.
> You have to decide if it's really worth the pain, in terms of sound.

I agree into that, but realy, the use for a BBD is not as a delay line
but morefor phasing, chorus,flanger.In that konfiguration they are quite
nice!

I have a old boss hi range phaser/flanger and this one is a joy to use,
dead silent because its not working!!!!       Ooohaa ha ha ha!.......   

No realy, it vas a joke,it is dead silent in the noise department for
shure.

BJ 
[who is conteplating as a alcoholic muslim praying to budda in the belif
of jesus!!]



From cmacdon at ix.netcom.com  Tue Dec  1 12:16:54 1998
From: cmacdon at ix.netcom.com (Chris & Ann MacDonald)
Date: Tue, 01 Dec 1998 03:16:54 -0800
Subject: Solus Troubleshooting Results
References: <002f01be1cd7$77fa6ec0$fd43440c@hpcustomer>
Message-ID: <3663D026.1621@ix.netcom.com>

Arthur Harrison wrote:
> I was wondering if the resistors were PTC thermistors to act as
> self-regulating heaters for the '3086 arrays, or if they were used
> as compensating circuit elements.

In the Solus the tempco resistors appear to be used as part of a voltage
divider connected to the CV input of each oscillator.

> Here's another good technique:  Once you pull the component lead out
> of the hole, remaining solder can be blown out using a foot or so of medium
> gauge tubing and your lungs.  Minimal expense, there!

I'll have to try that next time, accidentally inhaling might be bad
though!  :-) 

Thanks,

-Chris M.



From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 12:22:09 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 12:22:09 +0100 
Subject: AW: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F738A7@nbgm336a.nbgm.siemens.de>

	> I agree into that, but realy, the use for a BBD is not as a delay
line
	> but morefor phasing, chorus,flanger.In that konfiguration they are
quite
	> nice!

You should hear the Dynacord SRS-56.
It's a BBD-based stereo delay, don't remember the exact delay
time, but I guess it's like 300ms x 2, all done with BBD. Haven't
counted how many, but must be 10+ BBD chips in there.
This box is so *excellent* that I have it directly in the mix all the time.
I have (almost) a dozen other delays, BBD, tape, PCM, delta
modulation, but nothing comes close to the SRS. It's rather
quiet, too - no magic, just a few NE570 chips for noise reduction.

JH.



From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 12:30:24 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 12:30:24 +0100 
Subject: AW: Solus Troubleshooting Results
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F738CB@nbgm336a.nbgm.siemens.de>

	>Here's another good technique:  Once you pull the component lead
out
	>of the hole, remaining solder can be blown out using a foot or so
of medium
	>gauge tubing and your lungs.  Minimal expense, there!

Reversing the procedure would give the word "solder sucking"
a whole new meaning (;->)

Sorry, couldn't resist ...

JH.




From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 12:41:42 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 12:41:42 +0100 
Subject: AW: leaving
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F738FC@nbgm336a.nbgm.siemens.de>

	>Yesterday, I sent two messages to the list.  Before they posted, I
	>received undeliverable messages from mailhost.  So, I sent both
	>again, thinking I had made an error in the e-mail address.  
	>Then, this morning, all four messages posted, and I received 
	>two more mail messages telling me neither mail message had 
	>been received.  This time, I can read the actual messages 
	>and know the "undeliverable" messages are untrue.  
	>
	>My sincerest apologies to all bothered by this error.  I do
	>not know where the error lies, but I now know not to trust
	>the "undeliverable" messages and will wait and wonder a
	>day or two for a post.
	>
	>Arthur Harrison wrote:
	>> 
	>> Well, this list server is tooooo screwed up to deal with.
	>> Tooooo may bounced messages; a real MESS.

I got several of these error messages, too.
It does not mean that it is rejected by the whole mailing
list - it only means that there is *one* person who is
subscribed, but whose email adress does not work.
No need to send the message again.

JH.




From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 12:44:52 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 12:44:52 +0100 
Subject: Synthesizer von Gestern mellotron again
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F73905@nbgm336a.nbgm.siemens.de>

just wanted to add that I have checked the CD
this morning. The sleeve text clearly says that
the samples are transposed. And listening to
the track, I still think that every note has the same
attack as the other ones.

JH.



From Colin.Fraser at scottishpower.plc.uk  Tue Dec  1 13:42:37 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Tue, 1 Dec 1998 12:42:37 -0000 
Subject: leaving
Message-ID: <BA865FF10473D211BC6F00805F0D8307027386@catsprntp01.scottishpower.plc.uk>

> -----Original Message-----
> From: Haible Juergen [mailto:Juergen.Haible at nbgm.siemens.de]
> Sent: 01 December 1998 11:42
> To: Arthur Harrison; inman at interpath.com
> Cc: DIY
> Subject: AW: leaving
> 
> 
> I got several of these error messages, too.
> It does not mean that it is rejected by the whole mailing
> list - it only means that there is *one* person who is
> subscribed, but whose email adress does not work.
> No need to send the message again.

It could be worse - I sent a mail to another list recently and lost count of
the undeliverable messages, and they kept coming for 3 or 4 days...

Who is the list admin for synth-diy anyway ?

Colin f
 



From mark at spooky-solutions.co.uk  Tue Dec  1 14:16:06 1998
From: mark at spooky-solutions.co.uk (Mark E. Havard-Brown)
Date: Tue, 1 Dec 1998 13:16:06 -0000
Subject: Circuit Designers and Simulators
Message-ID: <01be1d2c$c10eed20$LocalHost@spookymb>

I am looking at the present crop of circuit designers/simulators for designing synths and logic circuits and I read in Electronics World (here in the UK) that the 'best', (for want of a better word) is Proteus from Labcenter Electronics. Not having any experience of using these packages; does anyone out there use this piece of software, or can point me at another recommendation. No doubt that this subject has already been covered in this list, but hey, I'm relatively new to all this.

By the way thanks for all of those (too numerous to mention) who replied to my diode problem. One of the replies recommend purchasing "The Art of Electronics", which I did and am working my way through it at this moment.
 
Cheers,


Mark.
 

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From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 14:26:01 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 14:26:01 +0100 
Subject: AW: Re: [AH] Regelwerk
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F73AFE@nbgm336a.nbgm.siemens.de>

> > I've just taken delivery of a Doepfer Regelwerk, and it is a great
 >> controller. 8 CV & gate outs!
 >> The one thing that bothers me is that if you connect more than one synth
to
> > a CV-out, the voltage drops and the synths cannot be tuned.
> > Does anyone else have this problem?
> > 
> Anyone who did this would have this problem ;-)

You only have this problem when the outputs are either
cheap, badly designed, or simply not intended for
precise V/Oct CV's. (I don't know the circuit of the Regelwerk,
so this is not meant as an offense. I'm trying to give a few
helpful hints *in case* that there is a problem with voltage
droop - for this unit, or for similar output stages. Wheather there is such 
a problem with the Regelwerk or not I don't know.)
 
> Any synth's CV input is a current drain; the higher the current drain,
> the more the voltage seen at each synth's CV in will sag.
>
> To solve this you can build a simple circuit based around an Op-Amp
buffer.
> I went off to search the net for such a thing, but came up blank -- anyone
> else got a good circuit reference on line?  Radio Shack has an Op-Amp
>cookbook
> that should get you going.

As someone said before, such a buffer should probably have been built into 
the box in the first place.
Admitted, these buffers are a little tricky. It looks easy at the first
glance:
An opamp buffer has such a low impedance that you can connect more
synths that you probably have, without any noticeable voltage droop.
But then there is a problem with capacitance: If you connect a long shielded
cable, the buffer will oscillate, and be worthless. You will run into the
same problem if you build an external buffer, btw. (But then it's *your*
problem,
not the manufacturer's anymore (;->) )
The cheap solution to avoid oscillation is simply adding a resistor at the
opamp output. This works fine if you don't need precision, or if you
re-calculate
(or simply trim) the gain of your output so that it compensates the voltage
droop
for one single load. I do this on all non-precision outputs - but if you use
it
for tuned 1V/Oct connections, it's bad design.

There are several ways to avoid these problems:
(1) You can use special opamps that are designed to drive capacitive loads.
(Check the data sheets !) These will work without the resistor. Problem:
They are a little more expensive than some other opamps, and some of
them are rather slow (slew rate!), so you might run into troubles if you
want to make audio rate FM from the same output. (This might apply
to an external buffer, not so much to the regelwerk, I guess.)
(2) You can build a special circuit that uses a resistor, too, but this time
it's
*inside* the opamp's feedback loop, so that the voltage droop is
automatically
compensated. The opamp needs a second (capacitive) feedback path then,
to ensure stability. Calculating the components is tricky. But you can get
around
if you use a prooven design with a certain opamp type and the fitting R and
C
values. I think there are examples of this on the Rane site.
(3) If you use some slow opamps (caveat see (1)) it might even work without
the capacitor. I have seen LM324's with 330R resistors (inside the feedback
loop !)
in some Serge designs, if memory serves. Don't know it still works on long
shielded cables, though. 

It's not a question of "designing around physics", as someone posted. It's
part of the price you pay when you buy low budged gear. You don't see things
like this from the outside, nor does it usually appear in the specs. But it
can make a difference.

JH.



From pfperry at melbpc.org.au  Tue Dec  1 14:29:22 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Wed, 2 Dec 1998 00:29:22 +1100 (EST)
Subject: Solus Troubleshooting Results
Message-ID: <1.5.4.16.19970225045836.379f2a34@popa.melbpc.org.au>


>Arthur Harrison wrote:

>> Here's another good technique:  Once you pull the component lead out
>> of the hole, remaining solder can be blown out using a foot or so of medium
>> gauge tubing and your lungs.  Minimal expense, there!

Doesn't seem to work for me, with plated-thru holes.
maybe I just don't have enough puff left.
I'll try again tomorrow with a wider tube and a little nozzle on it.
Maybe I need one of those foot pumps from the air mattress..

paul perry melbourne australia




From pfperry at melbpc.org.au  Tue Dec  1 14:47:43 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Wed, 2 Dec 1998 00:47:43 +1100 (EST)
Subject: Echolette, Binson EchoRec
Message-ID: <1.5.4.16.19970225051657.379f5f68@popa.melbpc.org.au>

At 09:33 AM 1/12/98 +0100, Martin Czech  wrote:

>there is a instruction for doing an echolette, too. Simply a aluminum
>disk, 5mm thick, diameter, say 10cm.  Now, slay a cassette and glue the
>tape to the disk edge, 

if anyone is crazy enough to do this, perhaps a horizontal drum would be 
better than a disk. And, you could make a stereo one more easily.

For the REALLY crazed, perhaps we could use wax as the recording material.
Or however those Morley electrostatic echo drums work..

Speaking of 'novelty electronic music' ckts, I saw one once that 
consisted of three multivibrator transistor pairs, running at different
frequencies and coupled together. Anyone built it & how did it sound?

paul perry melbourne australia




From inman at interpath.com  Tue Dec  1 15:08:45 1998
From: inman at interpath.com (inman at interpath.com)
Date: Tue, 01 Dec 1998 06:08:45 -0800
Subject: leaving
References: <002d01be1ce7$c2dae0e0$d1764e0c@hpcustomer>
Message-ID: <3663F86D.4EE2@interpath.com>

Yesterday, I sent two messages to the list.  Before they posted, I
received undeliverable messages from mailhost.  So, I sent both
again, thinking I had made an error in the e-mail address.  
Then, this morning, all four messages posted, and I received 
two more mail messages telling me neither mail message had 
been received.  This time, I can read the actual messages 
and know the "undeliverable" messages are untrue.  

My sincerest apologies to all bothered by this error.  I do
not know where the error lies, but I now know not to trust
the "undeliverable" messages and will wait and wonder a
day or two for a post.

Arthur Harrison wrote:
> 
> Well, this list server is tooooo screwed up to deal with.
> Tooooo may bounced messages; a real MESS.



From thelab at sprint.ca  Tue Dec  1 15:49:13 1998
From: thelab at sprint.ca (Philip)
Date: Tue, 01 Dec 1998 11:49:13 -0300
Subject: AW: leaving
References: <1BF5E20E0C4DD111BBAB00805FE2D582F738FC@nbgm336a.nbgm.siemens.de>
Message-ID: <366401E9.DD6@sprint.ca>

How about we move the list to listone.com? I recently set up two mailing
lists there for free. It is fairly fast, easy to manage and free.

Philip
-- 
Philip Pilgrim                  The Lab Audio Works
5 Evan's Drive                  - Analog/Digital Recording/Processing
Hammonds Plains                 - Computer/Synth Interfacing
Nova Scotia, Canada             - Hardware/Software Development
B4B 1M8

Phone     +1.902.835.7844
Email      mailto:thelab at sprint.ca

Web Page: http://www.robotnik.com/the_lab



From b.layer at vikingelectronics.com  Tue Dec  1 16:35:06 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 01 Dec 1998 09:35:06 -0600
Subject: Solus Troubleshooting Results
In-Reply-To: <005001be1cda$1af0f5c0$fd43440c@hpcustomer>
Message-ID: <3.0.6.32.19981201093506.007d2390@192.168.210.18>

hey,

>I've used thousands of DIP IC sockets without any problem; some of them in
>analog electronics equipment now over 20 years old.  The important thing is
>to use good quality ones, such as machined-pin sockets with gold plated
>contacts, from a reputable manufacturer such as Augat or Andon.  Avoid
>cheap sockets with one stamped, tin plated contact per pin.

Machined GOOD. Stamped BAD. Universal rule it seems?





From Juergen.Haible at nbgm.siemens.de  Tue Dec  1 16:38:33 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 1 Dec 1998 16:38:33 +0100 
Subject: AW: Echolette, Binson EchoRec
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F73DBF@nbgm336a.nbgm.siemens.de>


	>>there is a instruction for doing an echolette, too. Simply a
aluminum
	>>disk, 5mm thick, diameter, say 10cm.  Now, slay a cassette and
glue the
	<>tape to the disk edge, 
	>
	>if anyone is crazy enough to do this, perhaps a horizontal drum
would be 
	>better than a disk. And, you could make a stereo one more easily.

I remember this book - the idea of gluing a tape to a disc or drum
was that you could use standard tape heads, but they would not have
to touch the tape - there would be a tiny gap. No tape wear.
I wonder how good the bearings for such a rotating disc have to
be, in order to have a constant gap. Hard to imagine that it could work
at all, for a "mechano-phobe" like me, but that doesn't mean anything.

I also remember someone who suggested to use an old (vinyl) record
player for this.

How is it done in that famous Binson Echorec ? How thin is the gap
between head and the magnetic surface ?

Anybody experimented with writing analogue signals to a Floppy disc ??

(just brainstorming)

JH.



From bluebear at enterprise.net  Tue Dec  1 17:57:53 1998
From: bluebear at enterprise.net (Jeremy Brookes)
Date: Tue, 1 Dec 1998 16:57:53 -0000
Subject: Echolette, Binson EchoRec
Message-ID: <007501be1d4c$8fcab8a0$01010101@aardvark>

>>there is a instruction for doing an echolette, too. Simply a aluminum
>>disk, 5mm thick, diameter, say 10cm.  Now, slay a cassette and glue the
>>tape to the disk edge,
>
>if anyone is crazy enough to do this, perhaps a horizontal drum would be
>better than a disk. And, you could make a stereo one more easily.

Or maybe you could just use a cassette hacked so the tape is in a constant
loop inside with separate record and playback heads - hmmm... hasn't this
already been done?

How much head gap can be tolerated between the tape head and the drum/disk?


Did I hear in here about someone considering hacking a hard drive for
similar purposes? I'd guess at hard drive speeds you'd get sub-ms delays
though :-)

>Speaking of 'novelty electronic music' ckts, I saw one once that
>consisted of three multivibrator transistor pairs, running at different
>frequencies and coupled together. Anyone built it & how did it sound?

I remember this circuit from many years ago and have also lost the circuit.
I remember the article said that it was very sensitive to set up and the
chance of getting a sound that you'd previously liked was almost
impossible - you could never set the controls to *exactly* the same position
and repeat the sound. It almost sounded like chaos theory before I'd ever
heard of it.







From adrian at internode.com.au  Tue Dec  1 18:13:05 1998
From: adrian at internode.com.au (Adrian Corston)
Date: Tue, 1 Dec 98 11:13:05 CST
Subject: MXR envelope follower..?how works?
In-Reply-To: <199811302034.MAA18879@smtp.ucsd.edu>; from "Ethan Duni" at Nov 30, 98 12:34:33 pm
Message-ID: <199812010043.LAA28915@wraith.internode.com.au>

Ethan Duni types:
>>Well, there is only *1* female electronics engineering student out
>>of 150 at The Levels, UniSA..... its a shame really :(
>
>-well, there are almost ten in my class of 50 or so EEs at UCSD, so maybe
>all is not lost.. i'm not sure any of them are quite wife material though :]

My girlfriend is a computer systems engineering student, and she's
definitely wife material (mind you, the definition of 'wife material'
varies widely from person to person!)

Her course isn't focussed on electronics, but there is a fair number
of electronics-related subjects, and we supplement this by building
electronic music projects on the weekends together ;-)

-- 
Adrian Corston
Internet Engineer
Internode Professional Access



From synth1 at airmail.net  Tue Dec  1 18:22:12 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Tue, 1 Dec 1998 11:22:12 -0600
Subject: Paul's Goodie Box Auction #2 has begun!!
Message-ID: <000301be1d4f$39ba86e0$9c4bb2cc@paults>

Need to thin the herd in the random parts department again!!

Here's the drill: I'm tossing 100's (I mean 100's!!) of random parts and ICs
into a large box.
Highest bid gets it. Bids start at $20. This will cover postage anywhere in
the world.

These are not necessarily CEM parts!!! (I promise at least 1 in there,
BTW! ) Rather, these are
all new parts, never used, that are over-runs from glorious projects of
years gone by.

There are DIPS, SMT, all sorts of stuff. John Barlow in Calif. got the last
box and he found an
old brass doorstop in there! (That was his fault: he made a related
comment!) I may toss in a few CDs
as well (gifts from well-meaning sisters).

So, I want this box out of here ASAP. Send those bids in!!!

Paul Schreiber





From dbalvage at ptdcs2.ra.intel.com  Tue Dec  1 18:59:27 1998
From: dbalvage at ptdcs2.ra.intel.com (Duane R Balvage)
Date: Tue, 01 Dec 1998 09:59:27 -0800
Subject: Echolette, Binson EchoRec
References: <007501be1d4c$8fcab8a0$01010101@aardvark>
Message-ID: <36642E7F.167E@ptdcs2.intel.com>

Hi All -
> >Speaking of 'novelty electronic music' ckts, I saw one once that
> >consisted of three multivibrator transistor pairs, running at different
> >frequencies and coupled together. Anyone built it & how did it sound?
> 

   What do you mean by "coupled together"? You mean each one's frequency
directly

   affects the next one's frequency, and the next one, and looped back
to the first?

   That makes my head hurt. %^P It's kind of like time travel, where
everything 

   affects everything else...  Still, I like the idea. (even if it does
cause migraines...)

> I remember this circuit from many years ago and have also lost the circuit.
> I remember the article said that it was very sensitive to set up and the
> chance of getting a sound that you'd previously liked was almost
> impossible - you could never set the controls to *exactly* the same position
> and repeat the sound.

  That makes sense, since miniscule changes are "propagated & amplified"
around the

  feedback loop... this thing has got to be TOTALLY unstable! How cool!

> It almost sounded like chaos theory before I'd ever
> heard of it.

  Yeah, i'd say so... sounds totally unpredictable. Guess it's time to
try and build

  something like this... wonder if you could use 555 multivibrators
instead of 

  the regular "transistor" multi's..?

  Let's get those ideas flowing!

					- Duane "Migraine" Balvage


-- 
   "That boy's got a mouth like a cannon ... Always shootin' it off..."
                                
                             - Foghorn Leghorn
                      ________________________________
                     / o o oo              o ooo o   /\
       -------------/ ////  Duane R. Balvage   //// / /---------
                   /    _________________________  / /
                  / // / // /// // /// // /// / / / /
                 /___ //////////////////////////_/ /
                 \____\________________________\_\/

                     Intel Corporation, RA1-303
                   Portland Technology Development
       =========================================================

              Phone: (503) 613-8055    FAX: (503) 613-8261
                   E-Mail: dbalvage at ptdcs2.intel.com



From cmacdon at ix.netcom.com  Tue Dec  1 20:28:05 1998
From: cmacdon at ix.netcom.com (Chris & Ann MacDonald)
Date: Tue, 01 Dec 1998 11:28:05 -0800
Subject: tempco question
Message-ID: <36644345.29AE@ix.netcom.com>

This might be a long shot but does anybody recall what the ppm
specification is for the old KRL 1.87k tempco resistor that was used in
ARP products?  I'm going to try to order replacements from KRL. (I have
tried asking KRL themselves but the salesperson wasn't sure, they don't
make the exact part anymore apparently).

Thanks,

Chris M.



From sky36919 at skynet.be  Tue Dec  1 20:35:18 1998
From: sky36919 at skynet.be (Hugo Haesaert)
Date: Tue, 1 Dec 1998 21:35:18 +0200
Subject: Solus Troubleshooting Results
In-Reply-To: <3663D026.1621@ix.netcom.com>
Message-ID: <199812012035.VAA25094@papagena.skynet.be>

Hi Chris and All !

To clear holes that are closed up with solder, on single side that 
is, a cheap trick that i've used a lot is just to stick a sharpened 
pencil in the heated solder .  Also works with a steel point .  And 
most useful on those pesky solder eyes .  Molten solder won't stick 
to graphite or steel .  Care should always be taken not to overcook 
the pads, lest they detatch themselves from the substrate .

That Radio Shack device, the desoldering iron with the rubber bulb is 
cheap and cheerful, works well, but gets very hot as it's not temp 
regulated :  pad lifting !  It's also easy to burn oneself, been 
there :)

Also, don't forget that drops of molten solder give deep burns when 
they hit the skin .  Tube blowers, take care :)

Happy desoldering :)


Keep 'em oscillating :)


Hugo
=



From sky36919 at skynet.be  Tue Dec  1 20:35:18 1998
From: sky36919 at skynet.be (Hugo Haesaert)
Date: Tue, 1 Dec 1998 21:35:18 +0200
Subject: Solus Troubleshooting Results
In-Reply-To: <3.0.6.32.19981201093506.007d2390@192.168.210.18>
References: <005001be1cda$1af0f5c0$fd43440c@hpcustomer>
Message-ID: <199812012035.VAA25043@papagena.skynet.be>

Hi Art, Bill and All !

Always made sure i had reasonable quality twin contact sockets, can't 
recall having problems .  Stayed away from those real cheap single 
contact ones though .  Even those molex "contacts by the yard" are 
not too bad (twins) .  Climatic conditions may play a larger role in 
this matter than i have experienced . YMMMV :)

For roadworthy constructins i would now go for turned 4 contact pins, 
but nowadays they are widely available and more affordable than 
yesteryear :)

As the saying goes :  you get what you pay for :)


Keep 'em oscillating :)


Hugo
=

BTW :  Art, i do not experience bounced messages from this list, 
something else must be amiss .  Hope you can get things cleared up 
soon .




From oakley at techrepairs.freeserve.co.uk  Tue Dec  1 20:41:18 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Tue, 1 Dec 1998 19:41:18 -0000
Subject: TB303 quickie question and EG findings...
Message-ID: <000301be1d62$ac9b1e00$f031883e@default>

Hi,

I am wondering why the TB's accent control signal is controlled by the
slide control. The accent logic signal comes from the output of a D-type
flip flop, the rising edge triggered CLK is the slide control (high to
slide), and the DATA IN is coming off the control board. Anyone know why
there should be a d-type there??

The TB's EG is very interesting. The output to the VCF is the usual
exponential fall, but the odd thing is if the gate arrives before the
cap is discharged the output rises higher than before. If multiple gates
trigger the EG the output CV can be very big. mmm... there really is
more to this beast than I first thought. I like it.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From Hess.Hodge at Colorado.EDU  Tue Dec  1 22:28:17 1998
From: Hess.Hodge at Colorado.EDU (Hess Hodge)
Date: Tue, 1 Dec 1998 14:28:17 -0700 (MST)
Subject: SCI Pro-One midi kit
Message-ID: <Pine.GSO.3.95.981201142526.24430A-100000@rintintin.Colorado.EDU>

Hello,
Has anyone here installed the midi kit for the Pro-One from Wine Country?
Do you like the results.  Is it worth the $299?  Am I better off with the
cheaper Kenton pro-solo external?

any info appreciated!
hess

-/\= Hess M. Hodge
~/\  hess.hodge at colorado.edu
(/\) http://rtt.colorado.edu/~hodge





From DCMagnuson at aol.com  Tue Dec  1 23:02:54 1998
From: DCMagnuson at aol.com (DCMagnuson at aol.com)
Date: Tue, 1 Dec 1998 17:02:54 EST
Subject: Echolette, Binson EchoRec
Message-ID: <ef19d12b.3664678e@aol.com>

In a message dated 12/1/98 5:46:50 AM Eastern Standard Time,
martin.czech at intermetall.de writes:

> there is a instruction for doing an echolette, too. Simply a aluminum
>  disk, 5mm thick, diameter, say 10cm.  Now, slay a cassette and glue the
>  tape to the disk edge, of course the ends not with 90 degrees angle but
>  45 degrees, to avoid pops or klicks. This is an awfull job to do, and you
>  need the right glue that doesn't dissolve the tape. You need a motor,
>  some tape recorder heads (replacement parts) and preamp electronics
>  (I think National have some app notes about that). And a motor. That's it.
>  
>  I have no experience with tape technology, ie. hf erease, bias and all
>  this stuff, so I never tryed this.
>  
>  If you want, I could dig this book out , and scan the interesting parts.
>  

There's a series of books by Graf and Sheets called "Encyclopedia of
Electronic Circuits"... There's 6 or more volumes, and I don't remember which
volume had the info, but I recall seeing schematics for tape play and record
preamps in one of them.   If anyone is interested in info or the schematics,
let me know and look for them.  

Likewise, if you want exactly which volume the schemo's are in, let me know
and I'll dig the books out of storage.

Dave Magnuson
Independent Music Site
http://members.aol.com/dcmagnuson



From magnus at analogue.org  Tue Dec  1 23:31:47 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Tue, 01 Dec 1998 23:31:47 +0100
Subject: VCOs and sawtooth frequency doubler
Message-ID: <199812012231.XAA24685@piraya.electrum.kth.se>

Hi!

Some time ago there where talk about high speed VCOs etc. I proposed a
cursuit that would double the frequency of a sawtooth. As one can
figure out, this solution has its pros and cons. However, for thus
that would like to test it I made a schematic available at:

http://www.it.kth.se/~e93_mda/synths/schematics/

Oh, I haven't built it, so there is a bogus factor.

Happy hacking.

Cheers,
Magnus



From amr at gpu.srv.ualberta.ca  Wed Dec  2 01:37:11 1998
From: amr at gpu.srv.ualberta.ca (adam)
Date: Tue, 1 Dec 1998 17:37:11 -0700 (MST)
Subject: my troubles with resonance on the cem 3378
Message-ID: <Pine.A41.3.96.981201170850.80774C-100000@gpu5.srv.ualberta.ca>

hi.

  i'm still working on my filter box.  it is a manually controlled (pots
controlling freq and reso) lpf built around the cem3378.  originally i had
some trouble with the powersupply, but with the help you all sent i figured
it out.
(i needed -5v,+5v,+12v.  So, first i followed paul s.' advice and
bought a nice supply, then i built my own circuit to convert a 12v wallwart
into the required voltages using a 7905 and some caps, thanks john b.)

now my problem is this resonance thing. with 5v going to the reso CV, the
filter has a very subtle resonance (not at all squealchy).  i have followed
paul s.'(the cem guy) instructions on hooking up manual control. but i
cannot get it to work.
(i don't think it is the chip.  i have four and the same occurs with
all of them)

has anyone had this problem?

alternatively, would it be possible for me to built my own resonance
circuit?(with op amps?) [i need a resoLPF for a music project i'm working
on, and would like to juryrig this thing, even if i have to sacrifice
signal-to-noise.  after newyear i will try to get the built-in reso
working.}

thanks in advance for the help,
adam.




From ka4hjh at gte.net  Wed Dec  2 03:06:57 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Tue, 1 Dec 1998 21:06:57 -0500
Subject: Echolette, Binson EchoRec
In-Reply-To: <007501be1d4c$8fcab8a0$01010101@aardvark>
Message-ID: <v04011700b28a4ecf853e@[208.252.40.47]>

>Did I hear in here about someone considering hacking a hard drive for
>similar purposes? I'd guess at hard drive speeds you'd get sub-ms delays
>though :-)

You could still get fairly long delays if you had a larger platter. 5' or
10' in diameter might be a good start. And you wouldn't have to worry too
much about runout in the bearings--half a gallon of mercury should smooth
things out. The only real technical challenge is that the media and heads
are for digital recording, but if you like the sound of non-linear
recording who cares? Maybe you could even hook it up to some serial
converters and have a variable speed analog/digital delay. Be a bitch to
take on tour, but it would help to keep the bus from slewing around and
causing motion sickness if you kept it running all the time.

Terry Bowman, KA4HJH
"The Mac Doctor"



From amr at gpu.srv.ualberta.ca  Wed Dec  2 03:28:10 1998
From: amr at gpu.srv.ualberta.ca (adam)
Date: Tue, 1 Dec 1998 19:28:10 -0700 (MST)
Subject: my troubles with resonance on the cem 3378 
Message-ID: <Pine.A41.3.96.981201192748.68134A-100000@gpu5.srv.ualberta.ca>


  i'm still working on my filter box.  it is a manually controlled (pots
controlling freq and reso) lpf built around the cem3378.  originally i had
some trouble with the powersupply, but with the help you all sent i figured
it out.
(i needed -5v,+5v,+12v.  So, first i followed paul s.' advice and
bought a nice supply, then i built my own circuit to convert a 12v wallwart
into the required voltages using a 7905 and some caps, thanks john b.)

now my problem is this resonance thing. with 5v going to the reso CV, the
filter has a very subtle resonance (not at all squealchy).  i have followed
paul s.'(the cem guy) instructions on hooking up manual control. but i
cannot get it to work.
(i don't think it is the chip.  i have four and the same occurs with
all of them)

has anyone had this problem?

alternatively, would it be possible for me to built my own resonance
circuit?(with op amps?) [i need a resoLPF for a music project i'm working
on, and would like to juryrig this thing, even if i have to sacrifice
signal-to-noise.  after newyear i will try to get the built-in reso
working.}

thanks in advance for the help,
adam.





From theremin1 at worldnet.att.net  Wed Dec  2 03:33:10 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 1 Dec 1998 18:33:10 -0800
Subject: Sockets (was:: Solus Troubleshooting Results)
Message-ID: <000c01be1d9c$1bb06000$4641440c@hpcustomer>

JH wrote:

There are a few ICs that should *never* be used in sockets,
though. LM339 is one example. (Unless you have a
hysteresis on each comparator)

I write:

I don't understand this.  If the dv/dt is sufficiently high and the
reference
input is stable and of low impedance, these comparators seem to
work fine in sockets, without hysteresis.

-Art






From wils0450 at itlabs.umn.edu  Wed Dec  2 03:57:26 1998
From: wils0450 at itlabs.umn.edu (Rocket queen)
Date: Tue, 1 Dec 1998 20:57:26 -0600 (CST)
Subject: drum machines and ID's
Message-ID: <Pine.GSO.4.05.9812012051530.7184-100000@boris.itlabs.umn.edu>

I am looking at pickin up a Boss DR110. It has zero sync options and I am
lookin to modify this once I get it. I have no idea how to do this, and
was hoping someone could point me in the right direction. Also, the hats
just produce an audible "click." What might be causing the trouble there?
Nothing more humbling than not knowing a darn thing about what you want to
do.
 
            <<< << The obvious solution is to kill you all >> >>>




From theremin1 at worldnet.att.net  Wed Dec  2 04:22:32 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 1 Dec 1998 19:22:32 -0800
Subject: Solus Troubleshooting Results
Message-ID: <003501be1da3$018dd660$4641440c@hpcustomer>

Hugo,

You echo my sentiments re: sockets.  I had just posted
a (lengthy!) comment on this subject, and _then_ I saw
your post.

Re:  list problems.  Thanks to everyone who offered comments
and suggestions.  I guess I'll hang on for a while (:

My request for unsubscribing didn't work, anyway!

-Art


-----Original Message-----
From: Hugo Haesaert <sky36919 at skynet.be>
To: Arthur Harrison <theremin1 at worldnet.att.net>; Bill Layer
<b.layer at vikingelectronics.com>
Cc: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 01, 1998 12:35 PM
Subject: Re: Solus Troubleshooting Results


Hi Art, Bill and All !

Always made sure i had reasonable quality twin contact sockets, can't
recall having problems .  Stayed away from those real cheap single
contact ones though .  Even those molex "contacts by the yard" are
not too bad (twins) .  Climatic conditions may play a larger role in
this matter than i have experienced . YMMMV :)

For roadworthy constructins i would now go for turned 4 contact pins,
but nowadays they are widely available and more affordable than
yesteryear :)

As the saying goes :  you get what you pay for :)


Keep 'em oscillating :)


Hugo
=

BTW :  Art, i do not experience bounced messages from this list,
something else must be amiss .  Hope you can get things cleared up
soon .





From cmacdon at ix.netcom.com  Wed Dec  2 04:53:54 1998
From: cmacdon at ix.netcom.com (Chris & Ann MacDonald)
Date: Tue, 01 Dec 1998 19:53:54 -0800
Subject: MN3005, MN3007 BBD.. anyone built one?
References: <3JwXQLAjC0Y2Ewnz@p-w-m.demon.co.uk>
Message-ID: <3664B9D2.3BBA@ix.netcom.com>

> I was puzzling over what the NE570N
> compander was doing there. Is it normal 
> to compress the signal before it
> goes through the delay stage?

Compression at input followed by expansion at output is a noise
reduction technique.  Here's my non-technical understanding of this
process: Basically you compress the signal before it enters a device
which introduces noise (like a delay line), then expand the signal after
it leaves the device.  This (ideally) causes no change in the desired
signal, but the noise which was introduced while the signal was
compressed will become proportionally quieter to the desired signal
after expansion.

-Chris M.



From JWBarlow at aol.com  Wed Dec  2 05:36:47 1998
From: JWBarlow at aol.com (JWBarlow at aol.com)
Date: Tue, 1 Dec 1998 23:36:47 EST
Subject: Paul's Goodie Box Auction #2 has begun!!
Message-ID: <c02834fd.3664c3df@aol.com>

Paul!

When I said "so your cleaning out your garage eh?" I meant it in a good way!
Everybody likes a clean garage don't they?

BTW I'm willing to trade a "beautiful" door stop for say a dusty old ladder
filter!
Any takers?

In a message dated 12/1/98 9:37:24 AM, synth1 at airmail.net wrote:

>John Barlow in Calif. got the last
>
>box and he found an
>
>old brass doorstop in there! (That was his fault: he made a related
>
>comment!) 



From cyborg0 at GlobalEyes.net  Wed Dec  2 06:48:01 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Tue, 01 Dec 1998 23:48:01 -0600
Subject: drum machines and ID's
References: <Pine.GSO.4.05.9812012051530.7184-100000@boris.itlabs.umn.edu>
Message-ID: <3664D491.98924386@globaleyes.net>

Rocket queen wrote:
> 
> I am looking at pickin up a Boss DR110. It has zero sync options and I am
> lookin to modify this once I get it. I have no idea how to do this, and
> was hoping someone could point me in the right direction. Also, the hats
> just produce an audible "click." What might be causing the trouble there?
> Nothing more humbling than not knowing a darn thing about what you want to
> do.
> 
>             <<< << The obvious solution is to kill you all >> >>>

Well, basically, you need to poke around inside with an o-scope while it
is playing and find the line that changes its pulse times when you
change the tempo. OR, you could find out what the tempo knob is doing to
the processor to change the tempo. 

With either of these found, you could conceivably figure out what its
looking for as far as a sync signal ie, what sync value 24ppq, 4ppq,
etc.

so.. Find the internal sync signal.. thats 90% of your work..
good luck..

To stop the click, you could use a simple passive lowpass filter... a
resistor and a cap to ground would do it..

Rob



From zzynt at swipnet.se  Wed Dec  2 07:38:15 1998
From: zzynt at swipnet.se (BJ)
Date: Tue, 01 Dec 1998 22:38:15 -0800
Subject: Zyclus sequensers??
References: <1BF5E20E0C4DD111BBAB00805FE2D582F73AFE@nbgm336a.nbgm.siemens.de>
Message-ID: <3664E057.4326@swipnet.se>

Hi folks!
There was a performance sequenser named Zyclus,
does any one have any info about this sequenser.
One user who still uses it is Vangelis as far as i know!

Who made it,teck spec wanted, anyone, pleeease!!

BJ



From wils0450 at itlabs.umn.edu  Wed Dec  2 07:48:01 1998
From: wils0450 at itlabs.umn.edu (Rocket queen)
Date: Wed, 2 Dec 1998 00:48:01 -0600 (CST)
Subject: drum machines & ID's
Message-ID: <Pine.GSO.4.05.9812020046050.23950-100000@beluga.itlabs.umn.edu>

Someone sent me an URl with the schematics and the mod, Thanks!
Now the click problem, I should be aliitle clearer on this. When
triggered, it doesn't make any sound but a click. No hat/cymbal, just
clickety-click-click. What would be a likely couse ofr this sort of thing?

            <<< << The obvious solution is to kill you all >> >>>




From martin.czech at intermetall.de  Wed Dec  2 08:58:05 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 2 Dec 1998 08:58:05 +0100 (MET)
Subject: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <199812020758.IAA20477@window.intermetall.de>

> > I was puzzling over what the NE570N
> > compander was doing there. Is it normal 
> > to compress the signal before it
> > goes through the delay stage?
> 
> Compression at input followed by expansion at output is a noise
> reduction technique.  Here's my non-technical understanding of this
> process: Basically you compress the signal before it enters a device
> which introduces noise (like a delay line), then expand the signal after
> it leaves the device.  This (ideally) causes no change in the desired
> signal, but the noise which was introduced while the signal was
> compressed will become proportionally quieter to the desired signal
> after expansion.
> 

The infinite delay is not practical realizeable without a kind of
compression. You could dial the feddback only close to infinity, on one
side the signal would slowly fade, on the other it wold rise and rise,
until total distortion/and or oscillation. I think it needs a jard limiter
before the delay to get a real infinite delay without this problems.

m.c.




From bluebear at enterprise.net  Wed Dec  2 11:50:02 1998
From: bluebear at enterprise.net (Jeremy Brookes)
Date: Wed, 2 Dec 1998 10:50:02 -0000
Subject: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <00bf01be1de2$32d81930$01010101@aardvark>

>> I was puzzling over what the NE570N
>> compander was doing there. Is it normal
>> to compress the signal before it
>> goes through the delay stage?
>
>Compression at input followed by expansion at output is a noise
>reduction technique.  Here's my non-technical understanding of this
>process: Basically you compress the signal before it enters a device
>which introduces noise (like a delay line), then expand the signal after
>it leaves the device.  This (ideally) causes no change in the desired
>signal, but the noise which was introduced while the signal was
>compressed will become proportionally quieter to the desired signal
>after expansion.


Hmmm... I remember hearing something slightly different though it was
applied to digital delay and hence sampling.

What the compressing does is effectively give you a non-linear quantisation
interval so you get much finer resolution for low level signals round about
the zero volts point, with much bigger steps at the peaks of big signals.
Expansion on the output reverses the effect. What I think this means is that
low level signal suffer from less quantisation noise at the expense of the
noise being present in a high level signal. But then the high level signal
would mask the noise anyway. I think I remember this from an article for
building an 8-bit sampler with 12-bit apparent resolution to interface to a
Sinclair ZX Spectrum! (Wasn't that a Timex T1000 or something in the US?)





From bluebear at enterprise.net  Wed Dec  2 11:53:33 1998
From: bluebear at enterprise.net (Jeremy Brookes)
Date: Wed, 2 Dec 1998 10:53:33 -0000
Subject: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <00c001be1de2$343c1600$01010101@aardvark>

>> > I was puzzling over what the NE570N
>> > compander was doing there. Is it normal
>> > to compress the signal before it
>> > goes through the delay stage?
>>
>> Compression at input followed by expansion at output is a noise
>> reduction technique.  Here's my non-technical understanding of this
>> process: Basically you compress the signal before it enters a device
>> which introduces noise (like a delay line), then expand the signal after
>> it leaves the device.  This (ideally) causes no change in the desired
>> signal, but the noise which was introduced while the signal was
>> compressed will become proportionally quieter to the desired signal
>> after expansion.
>>
>
>The infinite delay is not practical realizeable without a kind of
>compression. You could dial the feddback only close to infinity, on one
>side the signal would slowly fade, on the other it wold rise and rise,
>until total distortion/and or oscillation. I think it needs a jard limiter
>before the delay to get a real infinite delay without this problems.


The infinite repeat was from Michael Rogers who was referring to a DOD
digital delay pedal. Being digital I guess it would be quite easy for the
feedback to be in the digital domain, whereas the compressing and expansion
only apply to the analogue input and output, not the feedback loop. Or I
might be wrong :)





From Juergen.Haible at nbgm.siemens.de  Wed Dec  2 13:03:43 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 2 Dec 1998 13:03:43 +0100 
Subject: AW: Sockets (was:: Solus Troubleshooting Results)
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F9CDB8@nbgm336a.nbgm.siemens.de>

	>JH wrote:
	>
	>There are a few ICs that should *never* be used in sockets,
	>though. LM339 is one example. (Unless you have a
	>hysteresis on each comparator)
	>
	>I write:
	>
	>I don't understand this.  If the dv/dt is sufficiently high and the
	>reference
	>input is stable and of low impedance, these comparators seem to
	>work fine in sockets, without hysteresis.
	>
	>-Art

There's a remark about that in the data sheet. Sure, there are applications
where it will work in a socket. Problems occur when your input signals
have high impedance. Using a socket increases stray capacitance,
and feedback from the output is likely. So I retract the "never". It's good
to be careful, though. 

JH.






From rsowa at WizjaTV.pl  Wed Dec  2 13:05:40 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Wed, 2 Dec 1998 13:05:40 +0100 
Subject: Mellotron question.
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67B9@demon>

forgive my stupid question, but...
what makes mellotron so great sounding?
is it some circuitry, or the speakers, or something else?
It is a bunch of tape players after all...
or as we would say today - a sampler with too much memory.
What were original sounds recorded on mellotron tapes?
string ensemble and choirs?

Roman

> Oryginalna wiadomo??-----
> Od:	Ingo Debus [SMTP:debus at cityweb.de]
> Wys?ano:	30 listopada 1998 10:17
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	Re: AW: AW: Mellotron/sample/wave type question.
> 
> Haible Juergen wrote:
> > I never listened to a solo mellotron, it was always in a mix (;->).
> 
> I played one once, but that was more than 15 years ago, and I never
> could do a dierct compare between a real Mellotron and Mellotron
> samples. 
> 
> > I cannot imagine how you would play things like King Crimson's
> > "In the Wake Of Poseidon" or Genesis' "Watcher Of The Skies"
> > with a multisample and no one notice it. You're not done with
> > a separate sample for each note; you will need separate samples
> [...]
> 
> Sure. It's certainly not a good idea to expect a perfect emulation of
> any instrument from a sampler. But Mellotron samples can sound very
> expressive anyway, even if it doesn't sound like a real Mellotron at
> all. I use them quite often.
> 
> Ingo
> 



From Juergen.Haible at nbgm.siemens.de  Wed Dec  2 13:10:10 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 2 Dec 1998 13:10:10 +0100 
Subject: AW: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F9CDC9@nbgm336a.nbgm.siemens.de>

	>The infinite delay is not practical realizeable without a kind of
	>compression. You could dial the feddback only close to infinity, on
one
	>side the signal would slowly fade, on the other it wold rise and
rise,
	>until total distortion/and or oscillation. I think it needs a jard
limiter
	>before the delay to get a real infinite delay without this
problems.

In case we're speaking of a digital delay, the switch often does
bypass the ADC / DAC and feeds the digital output into the 
loop again.
Works badly on the few PCM delays I have (there's always
a glitch), but used to work fine on the Delta Delay (you only
switch one tiny bit of an oversampled signal).

JH.



From martin.czech at intermetall.de  Wed Dec  2 13:16:28 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 2 Dec 1998 13:16:28 +0100 (MET)
Subject: AW: MN3005, MN3007 BBD.. anyone built one?
Message-ID: <199812021216.NAA21274@window.intermetall.de>

> 	>The infinite delay is not practical realizeable without a kind of
> 	>compression. You could dial the feddback only close to infinity, on
> one
> 	>side the signal would slowly fade, on the other it wold rise and
> rise,
> 	>until total distortion/and or oscillation. I think it needs a jard
> limiter
> 	>before the delay to get a real infinite delay without this
> problems.
> 
> In case we're speaking of a digital delay, the switch often does
> bypass the ADC / DAC and feeds the digital output into the 
> loop again.
> Works badly on the few PCM delays I have (there's always
> a glitch), but used to work fine on the Delta Delay (you only
> switch one tiny bit of an oversampled signal).
> 

Well ,that's too easy, I thought inifite means infinite decay time AND
ability to add input signals as well...  In this case you nead a hard
limiter, be it digital or analog.  I think this would be an nice effect,
if you stop playing, it repeats forever, and if you play a new (pattern)
it would superseed the old, the more new stuff comes in the more the
old stuff fades away.

The LXP5 I have can do this with a reverb algorithm...
Of course there are many diffuse echoes in this case...

m.c.




From rsowa at WizjaTV.pl  Wed Dec  2 13:19:45 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Wed, 2 Dec 1998 13:19:45 +0100 
Subject: ODP: DCO's, Anti-Aliasing, and Filters
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67BA@demon>

Post filtering has nothing to do with aliasing originated at phase
accumulator
waveforms. You can only filter DAC result which is already "infected".
Since you have sigma-delta DACs with filters onboard, there's no need for
additional filters.

Aliasing comes from reading sample faster than it was recorded
(i.e. for playing it at higher pitch)

But hey! those are not so bad filters for other purposes.
At this price...

Roman

> -----Oryginalna wiadomo??-----
> Od:	inman at interpath.com [SMTP:inman at interpath.com]
> Wys?ano:	1 grudnia 1998 06:07
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	DCO's, Anti-Aliasing, and Filters
> 
> I just read in Nuts and Volts about MAXIM's new filters:  5TH-ORDER 
> FILTER ("5th-order lowpass, switched-capacitor Butterworth and Bessel 
> filters available in 8-pin mMAX and DIP packages," MAXIM web page)
> 
> The best part:  8TH ORDER FILTER $2.00 US.
> 
> Although ads can be very misleading sometimes, it sure does sound as if
> this little chip would reduce a tremendous amount of undesired alias
> waveforms caused by imprecise timing of the period of square waves or
> A/D coversion of phase accumulator waveforms.  At a decent price.
> 
> 



From pab210 at is8.nyu.edu  Wed Dec  2 15:04:22 1998
From: pab210 at is8.nyu.edu (Plinio Andres Barraza)
Date: Wed, 2 Dec 1998 09:04:22 -0500 (EST)
Subject: Lockin Amplifyer
Message-ID: <Pine.OSF.3.95.981202085818.13932A-100000@is8.nyu.edu>


Hi All:

I was reading about lock in amplifyers yesterday and wondered if these
could be useful for a synth DYI stuff.  Is it basically a filter (and an
amplifyer)?

...just daydreamming aloud


Plinio




From Juergen.Haible at nbgm.siemens.de  Wed Dec  2 15:26:27 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 2 Dec 1998 15:26:27 +0100 
Subject: AW: Mellotron question.
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582F9D088@nbgm336a.nbgm.siemens.de>


	>what makes mellotron so great sounding?

Its imperfections. Really.
When mellotrons were the only way to play sampled sounds
on the stage, people were happy to have "real" sounds,
and either ignored, or more often complained about, the
severe imperfections, like pitch instability, every note sounding
different than the other, tuning going flat when several notes
were played at once, the limited duration of tapes (no loops ...),
and so on. If we can believe certain documents from that area,
people *cursed* their mellotrons for that.
Klaus Schulze complained that he had to use two mellotrons
and a pedal to crossfade between them, in order to produce
its long sustained choirs on "X". 
Robert Fripp pointedly said "tuning a mellotron is not."
There's a famous King Crimson live recording where the mellotron
broke down in the middle of a breathtaking performance.
You would be able to tell a mellotron sound from an original 
(or sampled) sound from a distance - because of its typical
imperfections.

The point is, people start to love what they grow familiar with.
(At least there is the potential to do so.) We learned to appreciate
distorted guitar sounds, hammond organs (which were imperfect
simulations of pipe organs - and Hammond spent a lot of effort
to get rid of the key click ...) - and some of us learned to love
mellotron sounds.

Thinking of it, from a modern point of view, it's no mystery that
we tend to love instruments that have character, rather than being
perfect. (Isn't it the same thing with people, too ?)

I have to add that loving a certain sound is not the same as loving
the instrument. From what I've heard, I doubt I would like to have
a mellotron in my house. (I even hesitate with a Hammond.)
So: still dreaming of a good emulation. And still in doubt if a
goud emulation would be possible with today's technology
(and my limited budget).

	JH.



From martin.czech at intermetall.de  Wed Dec  2 15:30:28 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 2 Dec 1998 15:30:28 +0100 (MET)
Subject: Mellotron question.
Message-ID: <199812021430.PAA21638@window.intermetall.de>


> forgive my stupid question, but...
> what makes mellotron so great sounding?
> is it some circuitry, or the speakers, or something else?
> It is a bunch of tape players after all...
> or as we would say today - a sampler with too much memory.

As far as I understand it is

a) nonstable rotation in case of key press (brake effect),
   later models have servo control, but this will also take
   some time to stabilize rotation speed.
   The more keys are pressed, the more "pitch envelope".

b) limited bandwidth

c) tape and preamp noise

d) no loops, ie. no sampler looping effect. The tapes
   are not endless, when the key is released the tape zippes
   back into the container. There is a maximum sound
   length.

e) key pressure modulates head/tape distance, thereby volume
   and maybe frequency filtering

f) tape/head/preamp distortion.

> What were original sounds recorded on mellotron tapes?
> string ensemble and choirs?

I think the standard set was flute, strings, choir...
BUT most artistst ordered custom tapes, with all kinds
of stuff, percusion , what you like.
This is a sound feature that cannot be emulatet, if you don't
have the original tapes, even if you buy a mellotron.

m.c.




From wils0450 at itlabs.umn.edu  Wed Dec  2 17:03:23 1998
From: wils0450 at itlabs.umn.edu (Rocket queen)
Date: Wed, 2 Dec 1998 10:03:23 -0600 (CST)
Subject: Syrupy goo(was Re: AW: Mellotron question.)
In-Reply-To: <1BF5E20E0C4DD111BBAB00805FE2D582F9D088@nbgm336a.nbgm.siemens.de>
Message-ID: <Pine.GSO.4.05.9812020937480.6191-100000@batman.itlabs.umn.edu>

To paraphrase HJ, 
> 
> Its imperfections. Really.
> The point is, people start to love what they grow familiar with.
> (At least there is the potential to do so.) We learned to appreciate
> distorted guitar sounds, hammond organs (which were imperfect
> simulations of pipe organs - and Hammond spent a lot of effort
> to get rid of the key click ...) - and some of us learned to love
> mellotron sounds.
> Thinking of it, from a modern point of view, it's no mystery that
> we tend to love instruments that have character, rather than being
> perfect. (Isn't it the same thing with people, too ?)
Absolutely. I probably wouldn't own a MC-202 (Roland) if wasnt for Paul
Berkin. Most people hate the interface, which through Paul's tutelage, I
feel I have mastered in a way that enhances the over all quality of sounds
that come out of it. Thus, the one thing people complain about the most,
is the one thing I feel makes this instrument unique and a joy to work
with. 
Same with the TR-606, cheesey sounds in a cute silver box. Why do I love
it? Acid Music, baby. The early 90's and late 80's were dominated by this
little toy in the midwest. It's tinny hi-hats will be a favorite of mine
forever. Ditto for the DR-110, although that is a holdover from my youth
in Canada.
Now that I am starting to build and modify my own equipment, I see big
things for my little battery operated fun-boxes (all of the above run on a
few C-cells). I dare to dream of a personalized 606 with a kickk drum that
has some real decay to it, a patchable 202 and a110 that will sync to
anything !! 
 > (and my limited budget).
Yes, they were all dirt cheap.
            <<< << The obvious solution is to kill you all >> >>>




From mark at spooky-solutions.co.uk  Wed Dec  2 20:09:16 1998
From: mark at spooky-solutions.co.uk (Mark E. Havard-Brown)
Date: Wed, 2 Dec 1998 19:09:16 -0000
Subject: Oscilloscopes
Message-ID: <01be1e27$41750b20$0100007f@spookymb>

I am looking at purchasing an oscilloscope and have found a supplier selling Philips PM3217 for what appears to be a good price. Does anyone have any experience of this make/type/offering?


Cheers,


Mark.
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From james at newd.demon.co.uk  Wed Dec  2 20:41:32 1998
From: james at newd.demon.co.uk (James Jackson)
Date: Wed, 02 Dec 1998 19:41:32 +0000
Subject: Simple Midi Controller
Message-ID: <1.5.4.32.19981202194132.0066646c@pop3.demon.co.uk>

>Does anyone have a schematic for a simple midi controller? I will need

>parameters for 4 octaves of kbd control, pitch bend, modulation,and

>midi channel assign. Thanks in advance. Lew  

I designed something similar to what you want. I have the scematic somewhere
for it. It is based around a PIC16C84, so you need access to a programmer (I
built mine for ?2 :-) ) but that allows you to make changes to the programme
as the evice evolves! A PIC is the easiest way of doing it, as otherwise you
have to make logic to genarate the timing and the serial messages. The
timing has quite a large window, as it is wondow based!, but it would
require a LOT of logic. As you want pitch bant and modulation, it would
probably be best to design it around a PIC16C74, as this has eight A/D
converters built in that you could use for the analogue input. It also has
an onboard UART, which you could configure for MIDI communication. Whilsh
only having 33 I/O lines, you could multiplex the keyboard to allow fot the
four octaves.

Hope this helps,
James.
-------------------------------------------------------------------------------
James Jackson - A Minefield Of Information

Who ever knew a 14 year old could program and make
electronic stuff??
-------------------------------------------------------------------------------




From b.layer at vikingelectronics.com  Wed Dec  2 20:42:06 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Wed, 02 Dec 1998 13:42:06 -0600
Subject: Mellotron question.
Message-ID: <3.0.6.32.19981202134206.007d15c0@192.168.210.18>

Hey,

Have any of us read the Mellotron section in Mark Vail's book? He's
actually right on with his functional descriptions. The tapes are not so
much 'rewound' as they are 'restrung'. 

The loops themselves run down through the cabinet, stretching nearly to the
bottom. Vail also gives info on a chap in the UK who is the world
specialist for the various Mellotron models, and can supply tape sets.

I wonder if there is a yodeling tape? Think about it...

 
=======================================================================
This message and any attachments to it are subject to copying and are 
sent solely for the personal amusement the sender.  It may include 
information which is technically wrong and exempt from disclosure. If 
you receive this communication in any way, please ignore us immediately.
========================================================================




From jmik at rci.rutgers.edu  Wed Dec  2 21:02:06 1998
From: jmik at rci.rutgers.edu (Joe Miklojcik)
Date: Wed, 02 Dec 1998 15:02:06 -0500
Subject: [Digital_Hell] DX-7 Noise
References: <ISSMTP.1.3(1).19981202101914.4294030311C@Corp.wdc.com>
Message-ID: <36659CBD.818CA9B@rci.rutgers.edu>

I too read this article in MIX, and thought the same thing about my TX81Z.  I
went out and obtained service manuals, and it looks like the the D/A is
fairly well cordoned off from the rest of the system.  Sadly, I'm a software
guy, so I can't go any further with this mod.  I just don't know enough.  I'd
really like to hook up with an engineer who could try this, and I'd be more
than happy to risk sacrificing my TX81Z to the cause.  Also, if someone could
help me figure out how to use an eprom burner to up and download the ROM ...
I'm totally willing to share all of my results.

Barry L Klein wrote:

> This may be what is needed, as I tried replacing the opamps in my DX7 with
> 5534 or whatever series parts and the effort was not worth it.   I think a
> better D/A with a less glitchy circuit would work.  Anyone have a junk DX7
> to try this on?  I don't want to accidentally trash mine.
> Barry
>
> ----------
> From:   Aaron Anderson
> Sent:   Tuesday, December 01, 1998 10:43 PM
> To:     David Evans; David Shipman
> Cc:     digitalhell at resrocket.com
> Subject:        Re: [Digital_Hell] DX-7 Noise
>
> At 10:25 PM -0500 12/1/1998, David Evans wrote:
>
> i was reading in Mix a couple weeks ago about some places that do
> reasonably cheap gear mods.. things like add better converters to
> lxp-1/5s... perhaps it would be a trivial mod to clean up the dx-7's
> output
> stage..




From mike at p-w-m.demon.co.uk  Wed Dec  2 21:22:48 1998
From: mike at p-w-m.demon.co.uk (Michael Rogers)
Date: Wed, 2 Dec 1998 20:22:48 +0000
Subject: Digital delay (was MN3005, MN3007)
In-Reply-To: <00c001be1de2$343c1600$01010101@aardvark>
Message-ID: <xXf2nAAYGaZ2EwPl@p-w-m.demon.co.uk>

Jeremy Brookes <bluebear at enterprise.net> wrote:
>>The infinite delay is not practical realizeable without a kind of
>>compression. You could dial the feddback only close to infinity, on one
>>side the signal would slowly fade, on the other it wold rise and rise,
>>until total distortion/and or oscillation. I think it needs a jard limiter
>>before the delay to get a real infinite delay without this problems.
>
>
>The infinite repeat was from Michael Rogers who was referring to a DOD
>digital delay pedal. Being digital I guess it would be quite easy for the
>feedback to be in the digital domain, whereas the compressing and expansion
>only apply to the analogue input and output, not the feedback loop. Or I
>might be wrong :)

The NE570 only affecting the input and output of the delay section would
suit me fine... in fact it might mean I only have one component to
replace. However I'm hoping the feedback loop is analogue, otherwise the
block diagram I've been drawing in my head is totally screwed. What
puzzles me is, if all the feedback and input mixing goes on in the
digital domain what is the pedal doing with five dual op amps (plus
compander and various other chips)?

Michael Rogers




From mike at p-w-m.demon.co.uk  Wed Dec  2 21:46:57 1998
From: mike at p-w-m.demon.co.uk (Michael Rogers)
Date: Wed, 2 Dec 1998 20:46:57 +0000
Subject: AW: MN3005, MN3007 BBD.. anyone built one?
In-Reply-To: <199812021216.NAA21274@window.intermetall.de>
Message-ID: <rH5wDFABdaZ2Ewsl@p-w-m.demon.co.uk>

Martin Czech <martin.czech at intermetall.de> wrote:
>> In case we're speaking of a digital delay, the switch often does
>> bypass the ADC / DAC and feeds the digital output into the 
>> loop again.
>> Works badly on the few PCM delays I have (there's always
>> a glitch), but used to work fine on the Delta Delay (you only
>> switch one tiny bit of an oversampled signal).
>> 
>
>Well ,that's too easy, I thought inifite means infinite decay time AND
>ability to add input signals as well...  In this case you nead a hard
>limiter, be it digital or analog.  I think this would be an nice effect,
>if you stop playing, it repeats forever, and if you play a new (pattern)
>it would superseed the old, the more new stuff comes in the more the
>old stuff fades away.

It *was* a nice effect :(

This is why I had imagined the feedback loop coming out of the DAC and
being mixed with the new input signal (with the input being mixed at a
level proportionate to its volume so that a quiet input didn't reduce
the volume of the feedback loop), before being returned to the ADC. 
At the risk of sounding stupid (too late!), which of the following
"mystery parts" would you use to make the limiter circuit?

NE570 compander (btw is this dual channel like the NE571?)
2 voltage comparators
CD4066 quad bilateral switch
M74HC75
Various op amps unaccounted for...

Sorry to bother you all with these questions... let me know if it's off-
topic.


 - Michael Rogers



From debus at cityweb.de  Wed Dec  2 21:53:43 1998
From: debus at cityweb.de (Ingo Debus)
Date: Wed, 02 Dec 1998 21:53:43 +0100
Subject: Mellotron question.
References: <2BF6F749A4A3D11185AD00A0C94CF67A4D67B9@demon>
Message-ID: <3665A8D4.2CAA@cityweb.de>

Roman Sowa wrote:
> 
> forgive my stupid question, but...
> what makes mellotron so great sounding?

This question isn't stupid at all.. it is one of the three most
interesting questions in musical electronics (the other two are: "what
makes a Hammond organ so great sounding?" and "what makes a Minimoog so
great sounding?").

> What were original sounds recorded on mellotron tapes?
> string ensemble and choirs?

There also were orchestra, sax, flute, oboe....

and Juergen Haible wrote:

>Its imperfections. Really.

But that's not all. When using Mellotron samples with a sampler and most
of the imperfections are no longer there, there's still a lot of magic
in the sound. Mellotron string samples are completely different from any
other string samples. The same with wind instrument sounds. Maybe they
did more effort when recording the instruments back then than today. I
don't know.

Ingo





From harv23 at leland.Stanford.EDU  Wed Dec  2 23:38:33 1998
From: harv23 at leland.Stanford.EDU (Harvey Devoe Thornburg)
Date: Wed, 2 Dec 1998 14:38:33 -0800 (PST)
Subject: Digital delay (was MN3005, MN3007)
In-Reply-To: <xXf2nAAYGaZ2EwPl@p-w-m.demon.co.uk> from "Michael Rogers" at Dec 2, 98 08:22:48 pm
Message-ID: <199812022238.OAA22265@epic5.Stanford.EDU>

> 
> Jeremy Brookes <bluebear at enterprise.net> wrote:
> >>The infinite delay is not practical realizeable without a kind of
> >>compression. You could dial the feddback only close to infinity, on one
> >>side the signal would slowly fade, on the other it wold rise and rise,
> >>until total distortion/and or oscillation. I think it needs a jard limiter
> >>before the delay to get a real infinite delay without this problems.
> >

I think your limiter is more or less a degenerate case of a compressor 
with infinitely fast response times. As such, it has the most tendency to
distort the output.  As long as the compressor's time constant is on 
the order of the delay period there should be no problems using a
compressor.  I have gotten very convincing Roland space-echo sounds 
with a compressor and high-pass EQ in the feedback path.

> >
> >The infinite repeat was from Michael Rogers who was referring to a DOD
> >digital delay pedal. Being digital I guess it would be quite easy for the
> >feedback to be in the digital domain, whereas the compressing and expansion
> >only apply to the analogue input and output, not the feedback loop. Or I
> >might be wrong :)
>

If audible distortion is what you want, then I'd think you'd want the
feedback compression in the analog path; if you do this digitally, 
you'll have to upsample by quite a bit to avoid aliasing.  This 
problem is worsened with a highpass filter in feedback.  If the compressor
has slower time constants then I've found no problem with doing 
feedback digitally.  The modulation of the feedback signal is not 
enough to generate aliasing.  Plus, there are the advantages of
digital control.

--Harvey




From jlarryh at iquest.net  Thu Dec  3 01:42:20 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Wed, 2 Dec 1998 18:42:20 -0600
Subject: DCO's, Anti-Aliasing, and Filters
Message-ID: <199812022337.AAA26436@mailhost.bpa.nl>

> From: Roman Sowa <rsowa at WizjaTV.pl>
> To: synth-diy at mailhost.bpa.nl
> Subject: ODP: DCO's, Anti-Aliasing, and Filters
> Date: Wednesday, December 02, 1998 6:19 AM
>
> Aliasing comes from reading sample faster than it was recorded
> (i.e. for playing it at higher pitch)

Doesn't that come from playing the sample slower for a lower pitch?
Larry Hendry



From theremin1 at worldnet.att.net  Thu Dec  3 04:07:39 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 2 Dec 1998 19:07:39 -0800
Subject: Sockets (was:: Solus Troubleshooting Results)
Message-ID: <000c01be1e6a$1c9efa20$f3754e0c@hpcustomer>

Yup, I'll agree with that.  Those problems get especially
severe with some high speed comparators.  Of those, I
especially like the  Maxim MAX912 and MAX913 parts,
since they behave well without hysteresis.  Maxim, BTW,
never has obsoleted a single one of their thousands of ICs,
and has pledged never to do so.  (More than can be said
for many IC manufacturers!)

-----Original Message-----
From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
To: DIY <synth-diy at mailhost.bpa.nl>; Arthur Harrison
<theremin1 at worldnet.att.net>
Date: Wednesday, December 02, 1998 4:03 AM
Subject: AW: Sockets (was:: Solus Troubleshooting Results)


> >JH wrote:
> >
> >There are a few ICs that should *never* be used in sockets,
> >though. LM339 is one example. (Unless you have a
> >hysteresis on each comparator)
> >
> >I write:
> >
> >I don't understand this.  If the dv/dt is sufficiently high and the
> >reference
> >input is stable and of low impedance, these comparators seem to
> >work fine in sockets, without hysteresis.
> >
> >-Art
>
>There's a remark about that in the data sheet. Sure, there are applications
>where it will work in a socket. Problems occur when your input signals
>have high impedance. Using a socket increases stray capacitance,
>and feedback from the output is likely. So I retract the "never". It's good
>to be careful, though.
>
>JH.
>
>
>
>




From gur-m at internet-zahav.net  Thu Dec  3 04:08:05 1998
From: gur-m at internet-zahav.net (Gur Milstein)
Date: Thu, 03 Dec 1998 04:08:05
Subject: electronics workbench
Message-ID: <3.0.2.16.19981203040805.295f150a@mail.internet-zahav.net>

hi guy's.
do any body know frome where i can down load the "electronics workbench"
softwere ?
a demo can allso be good ,and what are the system requerments to run this
softwere ?
allso do any body know a softwere a  like that can run on win 3.1 486 ?

thanx a lot
Gur Milstein



From digiboy at erols.com  Thu Dec  3 07:12:14 1998
From: digiboy at erols.com (mike(digiboy))
Date: Thu, 3 Dec 1998 01:12:14 -0500
Subject: WTB: EML 400/401/416 sequencer
Message-ID: <l03130302b28bdc3a7e5e@[207.172.80.240]>


Looking for an EML 400/401/416 sequencer with full 32 stage panel ( two 16
stage sets ). Hot to trot,   cash ready!



Mike Berman
digiboy at erols.com







From tpaddock at seanet.com  Thu Dec  3 09:12:18 1998
From: tpaddock at seanet.com (Toby Paddock)
Date: Thu, 3 Dec 1998 00:12:18 -0800
Subject: [S-DIY] Re: Mellotron question.
Message-ID: <01BE1E51.9CEB4080@v22.dialup.seanet.com>

Bill Layer said:
>I wonder if there is a yodeling tape? Think about it...

Mmmm... OK.
Seems like I remember years ago seeing Focus on TV.
Yodeling... 
and a Mellotron... 
but not a yodeling Mellotron, I guess.

Sorry, I know this doesn't add anything useful.

--Toby




From rsowa at WizjaTV.pl  Thu Dec  3 10:13:57 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Thu, 3 Dec 1998 10:13:57 +0100 
Subject: ODP: DCO's, Anti-Aliasing, and Filters
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67C0@demon>

I didn't express myself clearly.
By reading sample faster I ment reading not every sample
at constant sampling frequency, which gives higher pitch.
It causes aliasing, although not always noticable, but we were
arguing about it a while ago...

Reading say, 256 sample waveform at variable sampling frequency
and hooking up 1/50 frequency corner SC filter clocked
with e.g. 16x wavetable address clock - yes, now I see it.

But then you need very high speed VCO for driving this.

Roman

> -----Oryginalna wiadomo??-----
> Od:	J. Larry Hendry [SMTP:jlarryh at iquest.net]
> Wys?ano:	3 grudnia 1998 01:42
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	Re: DCO's, Anti-Aliasing, and Filters
> 
> > From: Roman Sowa <rsowa at WizjaTV.pl>
> > Aliasing comes from reading sample faster than it was recorded
> > (i.e. for playing it at higher pitch)
> 
> Doesn't that come from playing the sample slower for a lower pitch?
> Larry Hendry



From MHELIN at tne01.ntc.nokia.com  Thu Dec  3 10:19:44 1998
From: MHELIN at tne01.ntc.nokia.com (Mikko Helin)
Date: Thu, 3 Dec 1998 11:19:44 +0200
Subject: Simple Midi Controller
Message-ID: <981203111944.49c2b64c@tnclus.ntc.nokia.com>

PIC 16F84 (newer version of 16C84 with 64 bytes of RAM) is indeed nice,
and the programmer for it is easy to build also. But for
MIDI kbd, pitch bend and controller input you don't want to use
it to emulate UART (there's no inbuilt so you got to do
it with timing loops). It's better to use external UART like
MAX3100, which has serial interface (good for PICs, as they don't
have too many input/output ports). Maxim has also many 8-channel
ADC's (10-16 bit) with serial output available, as well as DAC's which you
could use for CV generation for analog synths.

Another good choice for microcontroller could be Atmel's 89S2051,
which has inbuilt UART, and is Intel 8051 compatible (without
external data bus interface), 20-pin device (PIC is 18 pin).
I have an extra (musical) keyboard without MIDI, and one future
project is to midify it using AT89S2051.

Now, if somebody has reached this line before pressing delete button,
I'd like to introduce him/her the Scenix SX-18/SX-28 PIC16C5x compatible
(almost) processors with upto 100 Mhz/ 100 MIPS operation and
low price (around $5 or litle bit more). See www.scenix.com,
they even specially mention in datasheets that these devices 
could be used in musical synthesis applications!


-Mikko



>Does anyone have a schematic for a simple midi controller? I will need

>parameters for 4 octaves of kbd control, pitch bend, modulation,and

>midi channel assign. Thanks in advance. Lew =20

I designed something similar to what you want. I have the scematic somewh=
ere
for it. It is based around a PIC16C84, so you need access to a programmer=
 (I
built mine for =A32 :-) ) but that allows you to make changes to the prog=
ramme
as the evice evolves! A PIC is the easiest way of doing it, as otherwise =
you
have to make logic to genarate the timing and the serial messages. The
timing has quite a large window, as it is wondow based!, but it would
require a LOT of logic. As you want pitch bant and modulation, it would
probably be best to design it around a PIC16C74, as this has eight A/D
converters built in that you could use for the analogue input. It also ha=
s
an onboard UART, which you could configure for MIDI communication. Whilsh
only having 33 I/O lines, you could multiplex the keyboard to allow fot t=
he
four octaves.

Hope this helps,
James.
-------------------------------------------------------------------------=
------
James Jackson - A Minefield Of Information

Who ever knew a 14 year old could program and make
electronic stuff??
-------------------------------------------------------------------------=
------




From pfperry at melbpc.org.au  Thu Dec  3 13:20:58 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Thu, 3 Dec 1998 23:20:58 +1100 (EST)
Subject: [Digital_Hell] DX-7 Noise
Message-ID: <1.5.4.16.19970227035009.36a723dc@popa.melbpc.org.au>

I *think* Robin 'devilfish' Whittle used to do low-noise fixes on the DX7
(I know he did for the early Roland midi module).

paul perry melb aust




From boldman at interplanet.it  Thu Dec  3 15:04:57 1998
From: boldman at interplanet.it (riccardo)
Date: Thu, 3 Dec 1998 15:04:57 +0100
Subject: mellotron source
Message-ID: <l03102801b28c46ee595a@[192.106.97.204]>

Hi everybody,
may be this has already been written, but there is a good CD ROM called
Mike Pinter's mellotron which covers all classic mellotronic (from
chamberlin to
mellotron 4 tracks) sounds.
There are no loops and the samples cover each key (of mellos or
chamberlins) sampled for the famous 8 seconds.

I have three mellotrons (a 400 a 400s and a novatron 400) and I find quite
satisfactory the quality of the samples and the entire "philosophy" of the
CD ROM. There should also be another CD but I cannot tell anything about it.

In any case the samples reproduce many goodies and odds of the old beast,
some scratches all over, the famous emotional pitch and the difference
between adiacent keys.
One of the main difference between the samples and the original is that
samples always sound the same, the original not always sounds (the very
drastic cases).

By the way it is true that key strucking weght means a lot, also heads
alignement is very important, never tried to put a head between two tracks?

Tapes rewinding is faster than you could imagine, but don't try to play
fast trills or it'll become a thrill.

getting too stupid, must go.......

ciao
riccardo






From inman at interpath.com  Thu Dec  3 15:07:31 1998
From: inman at interpath.com (inman at interpath.com)
Date: Thu, 03 Dec 1998 06:07:31 -0800
Subject: DCO's, Anti-Aliasing, and Filters
References: <199812022337.AAA26436@mailhost.bpa.nl>
Message-ID: <36669B23.65A9@interpath.com>

Roman Sowa wrote:
> > Aliasing comes from reading sample faster than it was recorded
> > (i.e. for playing it at higher pitch)

Larry Hendry wrote: 
> Doesn't that come from playing the sample slower for a lower pitch?
> Larry Hendry

I ask:

In Hal Chamberlin's "Musical Applications of Microprocessors,"
he talks about alias distortion as a result of direct synthesis 
of waveforms (p. 423) before discussing aliasing as a result of
table lookup methods in which samples are read at different 
speeds.  Is it possible that the kind of direct synthesis 
"aliasing" that Chamberlin was talking about is no longer a 
common usage of the word "aliasing" because his book was last 
updated in 1985 and microprocessors are so much faster now and 
new DAC's for converting signals are so much better that such 
aliasing is generally not a problem?  Except perhaps to us
re-inventers trying to do it with a 2K PIC...
  
The idea that aliasing could be produced by direct computation
of waveforms (and not just a DAT machine reading in and
replaying signals that we didn't know were there or want) was
new to me, until a couple of recent posts on digital waveforms.
I had also never considered that one could produce aliasing 
just by outputting a digital square wave with positive and 
negative output intervals that are not consistent across musical 
notes -- until some recent posts on DCO's drew that to my attention.  
If you cannot time the positive and negative pulses to parallel 
perfection, you will create additional (possibly random or
unpleasant) harmonics, which I believe the writer was calling
"aliasing."  Is it is or is it ain't?

Any corrections to these thoughts are more than welcome.

Elliot "choosing embarassment over ignorance any day of the week"



From Juergen.Haible at nbgm.siemens.de  Thu Dec  3 15:11:53 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 3 Dec 1998 15:11:53 +0100 
Subject: AW: [Digital_Hell] DX-7 Noise
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582FC3668@nbgm336a.nbgm.siemens.de>

	>I *think* Robin 'devilfish' Whittle used to do low-noise fixes on
the DX7
	>(I know he did for the early Roland midi module).

This is just from memory (as so often):
 I think I remember the headphone amp of the DX-7 was quite noisy,
but not the normal audio path. You could trim the (compound) DAC
of the Mk1 DX7 for minimum noise of the D/A conversion, but the
whole FM algorithm would still produce more noise than the audio
path (except the HP amp).
The later models (Mk 2, TX-802 and even the models that combined
FM and ROMpler) had better DACs, but still suffered from the noisy
digital implementation. Only important for dark sounds, and not *that*
bad really - but I doubt that replacing opamps would help much.

Yamaha aparently have still put quite some remarkable analogue
stuff into the DX-7: I still remember my surprise when I found the
opto electronic VCA for the volume pedal !

JH.



From pjson at pacbell.net  Thu Dec  3 15:56:44 1998
From: pjson at pacbell.net (Kirke Sonnichsen)
Date: Thu, 3 Dec 1998 06:56:44 -0800
Subject: mellotron source
Message-ID: <v02130500b28c5620389a@[206.170.3.50]>

I would second this with one caveat: all the samples are 22.05kHz!

- Kirke
(fine and mello)


>Hi everybody,
>may be this has already been written, but there is a good CD ROM called
>Mike Pinter's mellotron which covers all classic mellotronic (from
>chamberlin to
>mellotron 4 tracks) sounds.
>There are no loops and the samples cover each key (of mellos or
>chamberlins) sampled for the famous 8 seconds.
>
>I have three mellotrons (a 400 a 400s and a novatron 400) and I find quite
>satisfactory the quality of the samples and the entire "philosophy" of the
>CD ROM. There should also be another CD but I cannot tell anything about it.
>
>In any case the samples reproduce many goodies and odds of the old beast,
>some scratches all over, the famous emotional pitch and the difference
>between adiacent keys.
>One of the main difference between the samples and the original is that
>samples always sound the same, the original not always sounds (the very
>drastic cases).
>
>By the way it is true that key strucking weght means a lot, also heads
>alignement is very important, never tried to put a head between two tracks?
>
>Tapes rewinding is faster than you could imagine, but don't try to play
>fast trills or it'll become a thrill.
>
>getting too stupid, must go.......
>
>ciao
>riccardo





From cyborg0 at GlobalEyes.net  Thu Dec  3 16:13:10 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Thu, 03 Dec 1998 09:13:10 -0600
Subject: DCO's, Anti-Aliasing, and Filters
References: <199812022337.AAA26436@mailhost.bpa.nl> <36669B23.65A9@interpath.com>
Message-ID: <3666AA86.6F0D157E@globaleyes.net>

ANY and ALL digital signals have aliasing...There is no way around it.
This is because between the samples, or dots that represent the
waveform, ANYTHING can happen, and we would never know about it from the
digital recording. This is really where aliasing occurs. Its about the
space between the dots.

We say that this is a straight line, but more often, it is not. The
natural curve of the original analog signal is gone.

The best way to describe aliasing is to think of what aliasing means in
dictionary terms:something is acting or taking on the characteristic of
something else.

In our terms, it means that there is insufficient numerical frequency to
accurately represent all the harmonic characteristics of our original
information. 

So, what happens is that we have a recorded signal that has all the
elements to represent a harmonic below the information. Like not having
enough dots when playing connect the dots.. If you dont have enough dots
to accurately represent your image, you could think that a picture of a
cow was a teacup.. This is in essence what aliasing is.
In the picture example, the dots are represented in x and y, whereas in
our example, they are represented by y vs. time.

So, from what I have seen, all anti-aliasing filters do is limit
bandwidth. The anti-aliasing filter is a bandpass filter with a steep
rolloff after the upper and lower limits of our hearing (10hz to 25khz)
that makes the aliasing inaudible, or at least lessened..
But, if you did not record with sufficient sampling rate essentially you
are just going to make muddy semi-sinusoidal noise. Try it sometime..
I hope this helps anyone who was lost in the shuffle of the discussion.

Rob

Anyone who is interested, correct me if I have made a mistake. :)



From synth1 at airmail.net  Thu Dec  3 16:31:36 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Thu, 3 Dec 1998 09:31:36 -0600
Subject: TEMPCOs have been ordered
Message-ID: <000801be1ed2$045fb860$500442ce@paults>

The 1K tempcos are shipping to me this Friday, and orders will trickle out
(I have 31 orders!)
starting Tuesday of next week.

Paul Schreiber





From johns at oei.com  Thu Dec  3 17:37:32 1998
From: johns at oei.com (John Speth)
Date: Thu, 3 Dec 1998 08:37:32 -0800
Subject: DCO's, Anti-Aliasing, and Filters
In-Reply-To: <3666AA86.6F0D157E@globaleyes.net>
Message-ID: <000301be1edb$3993a100$2c15d7d0@johns.oei.com>

> So, from what I have seen, all anti-aliasing filters do is limit
> bandwidth. The anti-aliasing filter is a bandpass filter with a steep
> rolloff after the upper and lower limits of our hearing (10hz to 25khz)
> that makes the aliasing inaudible, or at least lessened..

I'd like to add one more point: In addition to bandwidth limiting the signal
to be sampled (using a steep filter) you are, therefore, certainly required
to sample the signal at at least twice the filter cutoff frequency.  Failing
to do this will result in the *alias* frequencies being heard when the
sample is played back.

> But, if you did not record with sufficient sampling rate essentially you
> are just going to make muddy semi-sinusoidal noise. Try it sometime..
> I hope this helps anyone who was lost in the shuffle of the discussion.

You can learn alot about this by breadboarding an analog delay line with a
variable clock that drives the BBD at audio rates.  Then fiddle around and
listen to what happens as you vary the clock rate.

John Speth
Object Engineering, Inc
mailto:johns at oei.com





From chris at scp.de  Thu Dec  3 17:45:40 1998
From: chris at scp.de (Christian Hofmann)
Date: Thu, 3 Dec 1998 17:45:40 +0100
Subject: mellotron source
In-Reply-To: <v02130500b28c5620389a@[206.170.3.50]>
References: <v02130500b28c5620389a@[206.170.3.50]>
Message-ID: <199812031645.RAA13419@dilbert.scp.de>

On Thu, 3 Dec 1998 06:56:44 -0800
pjson at pacbell.net (Kirke Sonnichsen) wrote:

> I would second this with one caveat: all the samples are 22.05kHz!
> 
> - Kirke
> (fine and mello)
> 
> 
> >Hi everybody,
> >may be this has already been written, but there is a good CD ROM called
> >Mike Pinter's mellotron which covers all classic mellotronic (from
> >chamberlin to
> >mellotron 4 tracks) sounds.
> >There are no loops and the samples cover each key (of mellos or
> >chamberlins) sampled for the famous 8 seconds.

Hi,
now that's not such a bad thing with tron samples. I don't think there's
much above 10 kHz anyway, and I found out that those samples I have can
be made a bit more authentic by applying a LP filter. Strange, but maybe
it's because the sampled mellotron was in better shape than those being
played in the 70s...

cu
Christian

P.S.: Can someone tell me where I can get that Mike Pinder CD,
preferably in Europe or even in Germany?




From jocke at netcontrol.fi  Thu Dec  3 18:00:13 1998
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Thu, 3 Dec 1998 19:00:13 +0200 (EET)
Subject: Mellotron question.
In-Reply-To: <3665A8D4.2CAA@cityweb.de>
Message-ID: <Pine.LNX.3.96.981203185630.6801A-100000@alf.netcontrol.fi>

Ingo wrote:

> When using Mellotron samples with a sampler and most of the
> imperfections are no longer there, there's still a lot of magic
> in the sound.

There are several sources of imperfection in the Mellotron sound
-- those that arise in the playback process, and those that are
in the recordings themselves.

IMO, a lot of the "magic" is in the latter category. There's so
much natural movement, or animation, in those sounds because the
recordings were performed by humans, not a synthesis algorithm.
Each recording constantly evolves throughout the eight-second
duration -- there's always slight variation in pitch, tone, volume,
etc, which is why Mellotron sounds often benefit from a slight
amount of room ambience or reverb to bring out the richness.

> Mellotron string samples are completely different from any
> other string samples. The same with wind instrument sounds. Maybe
> they did more effort when recording the instruments back then than
> today.

I think the opposite is true -- they didn't make much effort in
matching adjacent recordings so that the notes in a chord would
sound reasonably similar. Also, the relative tuning of notes is
often rather sloppy, all of which adds character. After all, the
Mellotron was originally meant to be no more than a home entertainment
keyboard.

As Riccardo and others have pointed out, there are several Mellotron
sample CDs available. The Mike Pinder CD-ROM is very good -- it has
a very comprehensive selection of sounds -- from the classic flutes,
strings and choirs, to the hilarious rhythm accompaniments of the
Mellotron Mk II. They've also programmed alternative patches which
fix the tuning imperfections of the original recordings, but
personally I prefer the raw, unfixed ones.

An other CD worth checking out is Propeller Island's "Legendary M400",
which has somewhat brighter samples (recorded at 44.1 as opposed to
22.05kHz), but made from a M400 with rather worn tapes. Still good
because of the extra brightness.

Some related links:

http://www.mellotron.com
http://www.geocities.com/SunsetStrip/Studio/7846/mtron.html
http://www.ilio.com/propeller/m400/index.html


cheers,

-joachim





From Juergen.Haible at nbgm.siemens.de  Thu Dec  3 18:19:52 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 3 Dec 1998 18:19:52 +0100 
Subject: AW: DCO's, Anti-Aliasing, and Filters
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582FC3984@nbgm336a.nbgm.siemens.de>

	> ANY and ALL digital signals have aliasing...There is no way around
it.

Not quite. If you have sampled a band limited analogue signal
at a sample rate larger than twice its bandwidth, you have
no aliasing. 

	>This is because between the samples, or dots that represent the
	>waveform, ANYTHING can happen, and we would never know about it
from the
	>digital recording. 

We can know, if we have a *little* extra information: that the original
signal was properly band limited, and where the band is located
in relation to the sampling frequency. (The second one is just
a theoretical problem, as we can asume the audio was in the
base band, and not, say, between 1Mhz and 1.005 Mhz.)

	>We say that this is a straight line, but more often, it is not. 

Actually, it is *never*. If it were, it would not be band limited.
Theory says that if the original signal was band limited, you
can interpolate between the points with a sin(x) / x function
(not straight lines), and get the original signal without error.
(Speaking of time discretisation, not the error you get from
limited level, i.e. number of bits, resolution.)

	> The
	>natural curve of the original analog signal is gone.

It's perfectly restored when you use the interpolation described
above.
In the frequency domain, that means a brickwall
low pass filter. Sure, there is no such filter in the real world,
but there is no limit approximating it, either. (other than a 
certain time delay thru the filter)

 The trick is that 3 pieces of information work together:
(1) The discrete points
(2) the "agreement" that the signal was properly band limited
(3) the agreement that the base band is used
These 3 things *together* will restore the full information.

When you receive the digital signal (i.e. only the "dots"), you
will asume that the sender has "agreed" to point (2) and (3),
because it would not have been reasonable to sample at
that specific rate otherwise. But you cannot tell *if* sampling
was done "reasonable", i.e. in conformance with Nyquist's
theorem. So you just do the obvious: Apply your sin(x) / x
interpolation (low pass filter). If sampling was ok, you can
restore the original signal (given your filter is a good enough
approximation). If it was not, you have aliasing.

	>So, what happens is that we have a recorded signal that has all the
	>elements to represent a harmonic below the information. Like not
having
	>enough dots when playing connect the dots.. If you dont have enough
dots
	>to accurately represent your image, you could think that a picture
of a
	>cow was a teacup.. This is in essence what aliasing is.

Nice description. While it does not apply to the simple sample
and playback operation, it can surely happen when you start
to process this once sampled signal, transpose it, resample it,
and what else they are doing in those hideous contraptions.  

JH.




From simon at dynamite.com.au  Thu Dec  3 20:55:14 1998
From: simon at dynamite.com.au (Simon)
Date: Fri, 4 Dec 1998 05:55:14 +1000
Subject: 808/909 DIY Kick Drums?
Message-ID: <l03130300b28c9c09e8a1@[203.23.182.6]>

A friend showed me a small DIY project that was a box with 808 and 909 Kick
Drums, it had a few different tuning knobs for the 808 and 909 Kicks. It
was triggered by either CV or MIDI, I'm not sure.

Can someone point me in the direction of DIY 808 and 909 Kick Drum
schematics (and maybe other drums like snare, hh), so I can try it myself?

Thanks
Simon
Canberra
AUSTRALIA





From aschrock at cs.brandeis.edu  Thu Dec  3 20:58:18 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Thu, 3 Dec 1998 14:58:18 -0500 (EST)
Subject: Shielding material
In-Reply-To: <1BF5E20E0C4DD111BBAB00805FE2D582FC3984@nbgm336a.nbgm.siemens.de>
Message-ID: <Pine.LNX.3.96.981203145129.13238A-100000@circe.cs.brandeis.edu>

Hi all, 

I'm looking for some simple, flat yet thin and pliable conductive material
to use for shielding and ground planes to decrease noise and other
interference. Sorta that cardboard-with-tin-foil-on-the-other-side deal...
Actually preferably conductive on one side, non- on the other. Any ideas?
Should be cheap and available from digikey/mouser/other large supplier in
the US. 

thanks, 
Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|




From gt7276a at prism.gatech.edu  Thu Dec  3 21:09:21 1998
From: gt7276a at prism.gatech.edu (Brian Towles)
Date: Thu, 03 Dec 1998 15:09:21 -0500
Subject: DCO's, Anti-Aliasing, and Filters
References: <199812022337.AAA26436@mailhost.bpa.nl> <36669B23.65A9@interpath.com> <3666AA86.6F0D157E@globaleyes.net>
Message-ID: <3666EFF1.768FFF22@prism.gatech.edu>

I been reading this thread for a while, but now I'm moved to words ... ;)

Rob wrote:

> ANY and ALL digital signals have aliasing...There is no way around it.
> This is because between the samples, or dots that represent the
> waveform, ANYTHING can happen, and we would never know about it from the
> digital recording. This is really where aliasing occurs. Its about the
> space between the dots.
>
> We say that this is a straight line, but more often, it is not. The
> natural curve of the original analog signal is gone.
>
> The best way to describe aliasing is to think of what aliasing means in
> dictionary terms:something is acting or taking on the characteristic of
> something else.
>
> In our terms, it means that there is insufficient numerical frequency to
> accurately represent all the harmonic characteristics of our original
> information.

This is _not_ strictly true ... however, you are stepping into the realm of
fourier transforms and mathematical representations of signals.  Most
DIYer's probably have little practical need for what's mathematically going
on here, but it's not bad to know :)  When you mention the straight-line
interpolation of the output signal, you're sighting a problem with the
reconstruction of a signal.  As long as the original sample met the Nyquist
condition ( fmax <= 2*fsample ) and if you ignore the effects of quantizing
the signal level, the digital representation stores _all_ of the signal's
information.  So, a discrete set of points can accurately represent an
analog signal.  However, the problems arise when the signal must be
recovered.  Theory tells us that an ideal low-pass filter can perform this
operation, but realizing this filter is impossible.  So, people make
approximations with high-order filters ....

> So, what happens is that we have a recorded signal that has all the
> elements to represent a harmonic below the information. Like not having
> enough dots when playing connect the dots.. If you dont have enough dots
> to accurately represent your image, you could think that a picture of a
> cow was a teacup.. This is in essence what aliasing is.
> In the picture example, the dots are represented in x and y, whereas in
> our example, they are represented by y vs. time.
>
> So, from what I have seen, all anti-aliasing filters do is limit
> bandwidth. The anti-aliasing filter is a bandpass filter with a steep
> rolloff after the upper and lower limits of our hearing (10hz to 25khz)
> that makes the aliasing inaudible, or at least lessened..
> But, if you did not record with sufficient sampling rate essentially you
> are just going to make muddy semi-sinusoidal noise. Try it sometime..
> I hope this helps anyone who was lost in the shuffle of the discussion.

These bandpass filters you mention are just a practical implementation of
the ideal filters I mentioned earlier.  Also, the linear approximation you
noted relates to using a first-order filter on the DAC output.
Higher-order filters give better and better approximations. So, now I
finally come to the two possible definitions of aliasing:

1. When you sample a signal whose frequency content is greater than half of
your sampling frequency, aliasing occurs ( this is Nyquist stuff ).  No
matter what ADC and DAC techniques you use, the signal is inaccurate and
cannot be perfectly reconstructed - I'd call this aliasing.

2. If you perfectly sample a signal, but use an approximate filter after
the DAC, some extra frequency information will be passed through the filter
- I wouldn't call this aliasing.

There exist more problems when you begin to consider the quantization
effects of ADC and DAC, but we'll let that go ...

Hope that helps and if I'm wrong, shoot me down! ;)

Brian





From pab210 at is8.nyu.edu  Thu Dec  3 21:26:55 1998
From: pab210 at is8.nyu.edu (Plinio Andres Barraza)
Date: Thu, 3 Dec 1998 15:26:55 -0500 (EST)
Subject: Glossary?
In-Reply-To: <000301be1edb$3993a100$2c15d7d0@johns.oei.com>
Message-ID: <Pine.OSF.3.95.981203143457.15127A-100000@is8.nyu.edu>



Hi all, 

Does anyone know where I might find (perhaps on the web) a glossary of
acronyms comonly used in electronics?  I've figured out lots of the
easy ones, but I still don't know what BBD stands for, for example.

Also, regarding intellectual propety, is it illegal to scan something out
of an encyclopedia to post on the web?  There is an interesting entry
about analog computers (a little over three pages long) in McGraw-Hill's
Concise Encyclopedia of Science and Technology.  It seems me (with my
limited understanding of electronics) that it goes into considerable
depth, and I know (having followed a recent thread on this subject)
that some of you may be interested.  It even has a few paragraphs
describing hybrid computers.

Any responses welcome, thanks.

Plinio





From jeffry at aracnet.net  Thu Dec  3 22:07:37 1998
From: jeffry at aracnet.net (Jeffry James)
Date: Thu, 3 Dec 1998 21:07:37 GMT
Subject: Simple Midi Controller
Message-ID: <199812032107.VAA15466@trapdoor.aracnet.net>

I have also already built a (not so simple) midi keyboard controller, based
on the Z180.  Therefore I have a circuit plus the kbd and 8 channel A/D code
drivers, etc.  Since my circuit can provide for any sized
(velocity-switching) keyboard and user interface, it's a more costly
solution than using a PIC for something simpler.  I also have (a few)
left-over keyboards, to anyone who may be interested at www.aracnet.net/~jeffry.

>
>
>Does anyone have a schematic for a simple midi controller? I will need
>parameters for 4 octaves of kbd control, pitch bend, modulation,and
>midi channel assign. Thanks in advance. Lew =20




From magnus at analogue.org  Thu Dec  3 22:24:17 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Thu, 03 Dec 1998 22:24:17 +0100
Subject: AW: [Digital_Hell] DX-7 Noise
In-Reply-To: Your message of "Thu, 3 Dec 1998 15:11:53 +0100 "
References: <1BF5E20E0C4DD111BBAB00805FE2D582FC3668@nbgm336a.nbgm.siemens.de>
Message-ID: <199812032124.WAA26998@piraya.electrum.kth.se>

>>>>> "HJ" == Haible Juergen <Juergen.Haible at nbgm.siemens.de> writes:

 HJ> Yamaha aparently have still put quite some remarkable analogue
 HJ> stuff into the DX-7: I still remember my surprise when I found the
 HJ> opto electronic VCA for the volume pedal !

Old habits never dies ;)

Cheers,
Magnus



From a-davidh at microsoft.com  Thu Dec  3 23:34:17 1998
From: a-davidh at microsoft.com (David Halliday (Volt Computer))
Date: Thu, 3 Dec 1998 14:34:17 -0800 
Subject: Shielding material
Message-ID: <C35556591D34D111BB5600805F1961B90BBEAE24@RED-MSG-47>

Three less-than-perfect things come to mind:

Check electronic surplus houses in your area for scrap pieces of flexible PC
board.  Locally, I have found large sheets of the stuff for under $5 each -
cut with shears and glue in place.  Major advantage is that you can solder
to it.

Go to a commercial HVAC supplier ( Heating Ventilation and Air Conditioning
).  There is a super strong aluminum adhesive tape sold for sealing
ductwork.  It is also pure aluminum with no plastic covering ( as some
cheaper tapes have ).  You can screw it to a wooden case or metal chassis
with a lockwasher and connect your wire to that.

Get some cardboard, some 3M spray adhesive ( type 77 comes to mind ) and
some aluminum foil.  The 3M adhesive is expensive but very very good and
will hold the foil to the cardboard without coming off... ever...    use
lots of it and spray it in a well ventilated area over a large spread of
newspaper.  Don't want it in your lungs or on your floor...

-----Original Message-----
From: Andrew Schrock [mailto:aschrock at cs.brandeis.edu]
Sent: Thursday, December 03, 1998 11:58 AM
To: DIY
Subject: Shielding material


Hi all, 

I'm looking for some simple, flat yet thin and pliable conductive material
to use for shielding and ground planes to decrease noise and other
interference. Sorta that cardboard-with-tin-foil-on-the-other-side deal...
Actually preferably conductive on one side, non- on the other. Any ideas?
Should be cheap and available from digikey/mouser/other large supplier in
the US. 

thanks, 
Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|



From cyborg0 at GlobalEyes.net  Thu Dec  3 23:41:08 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Thu, 03 Dec 1998 16:41:08 -0600
Subject: DCO's, Anti-Aliasing, and Filters
References: <199812022337.AAA26436@mailhost.bpa.nl> <36669B23.65A9@interpath.com> <3666AA86.6F0D157E@globaleyes.net> <3666EFF1.768FFF22@prism.gatech.edu>
Message-ID: <36671384.A4AFB69D@globaleyes.net>

Brian Towles wrote:
> 
> I been reading this thread for a while, but now I'm moved to words ... ;)
> 
> Rob wrote:
> 
> > ANY and ALL digital signals have aliasing...There is no way around it.
> > This is because between the samples, or dots that represent the
> > waveform, ANYTHING can happen, and we would never know about it from the
> > digital recording. This is really where aliasing occurs. Its about the
> > space between the dots.
> >
> > We say that this is a straight line, but more often, it is not. The
> > natural curve of the original analog signal is gone.
> >
Mind you, I ignored the nyquist theorem on purpose when coming up with
this analogy.. because it gives you more of a baseline to go off of and
doesnt lead you into the false thinking that the Nyquist theory will
ALWAYS work, because sometimes it doesnt... For tech types, this can be
learned the hard way.. like I learned, which gave me to forget about the
Nyquist theory, cuz sometimes things work the way they are supposed to,
and sometimes they don't, no matter how closely they follow theory..
Rob



From keen at austin.ibm.com  Fri Dec  4 00:14:11 1998
From: keen at austin.ibm.com (R.G. Keen)
Date: Thu, 03 Dec 98 17:14:11 -0600
Subject: Shielding material 
In-Reply-To: (Your message of Thu, 03 Dec 98 14:58:18 -0500.)
             <Pine.LNX.3.96.981203145129.13238A-100000@circe.cs.brandeis.edu>
Message-ID: <199812032314.RAA25894@keen.austin.ibm.com>

>I'm looking for some simple, flat yet thin and pliable conductive 
>material to use for shielding and ground planes to decrease noise 
>and other interference. Sorta that cardboard-with-tin-foil-on-the-
>other-side deal...
>Actually preferably conductive on one side, non- on the other. Any 
>ideas? Should be cheap and available from digikey/mouser/other 
>large supplier in the US. 

The devil makes me ask - why don't you just spray some 3M "77" 
spray adhesive onto your favorite cardboard and use a brayer to roll
down some aluminum foil? It doesn't get much cheaper and more available
than that.




From cmacdon at ix.netcom.com  Fri Dec  4 01:32:20 1998
From: cmacdon at ix.netcom.com (Chris MacDonald)
Date: Thu, 03 Dec 1998 16:32:20 -0800
Subject: New modules done
Message-ID: <36672D94.25629688@ix.netcom.com>

After a long hiatus due to an extremely busy period at my work, I have
finally finished two more modules in my system.  They are a dual ADSR
and a dual analog multiplier.  The ADSR is my own design although I
borrowed liberally from several other circuits.  The multiplier is based
on the AD633 chip and was quite simple to put together.  I've posted
some pictures and a schematic if anyone is interested:
http://www.evenfall.com/diy/

-Chris M.




From jhaible at primus-online.de  Fri Dec  4 03:22:10 1998
From: jhaible at primus-online.de (jhaible)
Date: Fri, 4 Dec 1998 03:22:10 +0100
Subject: AW: [Digital_Hell] DX-7 Noise
Message-ID: <19981204022147.23796.qmail@nuernberg2.pop.metronet.de>


> Now, really the TG77 are wery silent indeed the thing that makes the
> noise in
> the TG77 are the reverb,delay DSP IC.So i cant agree onto your statement
> about
> that the "digital implementation" are noisy.

Hmm, I didn't mean the TG77 does only produce noisy sounds. 
I was speaking of the FM part (without running it thru filters
etc.) I once planned to buy one, but I didn't because I got
the impression that the FM part wasn't that different from
the TX-802, for example.

JH.



From idreamin3d at toad.net  Fri Dec  4 04:55:04 1998
From: idreamin3d at toad.net (I Dream In 3D)
Date: Thu, 03 Dec 1998 22:55:04 -0500
Subject: VEMA Online Auction
Message-ID: <3.0.1.32.19981203225504.006c9d50@toad.net>


I won a synth on the VEMA online auction (UK) and now I am having trouble
shipping it to the US.  And, I've lost the contact information to the
people who run VEMA.  Does anyone have the URL to their website?

idreamin3d at toad.net




From harv23 at leland.Stanford.EDU  Fri Dec  4 07:43:29 1998
From: harv23 at leland.Stanford.EDU (Harvey Devoe Thornburg)
Date: Thu, 3 Dec 1998 22:43:29 -0800 (PST)
Subject: ODP: DCO's, Anti-Aliasing, and Filters
In-Reply-To: <2BF6F749A4A3D11185AD00A0C94CF67A4D67C0@demon> from "Roman Sowa" at Dec 3, 98 10:13:57 am
Message-ID: <199812040643.WAA21773@amy7.Stanford.EDU>

> 
> I didn't express myself clearly.
> By reading sample faster I ment reading not every sample
> at constant sampling frequency, which gives higher pitch.
> It causes aliasing, although not always noticable, but we were
> arguing about it a while ago...
> 
> Reading say, 256 sample waveform at variable sampling frequency
> and hooking up 1/50 frequency corner SC filter clocked
> with e.g. 16x wavetable address clock - yes, now I see it.
>

Hmm... There may still be confusion here the way you've stated things,
although it might just be my confusion.  Anyway, if you are reading
the wavetable using a true analog variable clock, you will not get 
aliasing in the way I had described, and almost never in a way that's
perceptible. Just make sure there are an integer number of samples per
period of the waveform.  Then aliases fall upon existing harmonics,
minimizing audible distortion.  If you want to maintain an odd
harmonic structure (like a square wave), then the number of 
samples/period needs to be even.  Otherwise you'd get some even 
harmonics.  You can think of these as due to aliasing, OR a slight 
duty cycle error (both interpretations are correct).

When you run everything at a common sampling rate and change the pitch 
continuously using DSP (by this I mean sample rate conversion), there's no
way to maintain integer relationships.  Then you need to implement an 
antialiasing filter, equivalent to sinc interpolation.

In summary, the effect of aliasing depends on your implementation.
So -- what exactly is your implementation?

--Harvey




From martin.czech at intermetall.de  Fri Dec  4 08:45:00 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Fri, 4 Dec 1998 08:45:00 +0100 (MET)
Subject: DCO's, Anti-Aliasing, and Filters
Message-ID: <199812040745.IAA02137@window.intermetall.de>

> ANY and ALL digital signals have aliasing...There is no way around it.
> This is because between the samples, or dots that represent the
> waveform, ANYTHING can happen, and we would never know about it from the
> digital recording. This is really where aliasing occurs. Its about the
> space between the dots.
> 

SNIPPED

Very good description.

I just want to add that some proposals to this and related threads
included sample rate conversion also, this is a related matter.

Eg.  the front end of a system runs with Fs 30 Hz, and the back end
with 50 Hz sample rate (low figures, so I can calculate it in my head)
or vice versa.  First you would go to an intermediate rate 300 Hz,
the smallest integer multiple of both. Ie. every 10th (30 Hz) or 6th
(50 Hz) sample has a real value, the others are zero. Then this would be
lowpass filtered so that the Nyquist constraint is kept for the wanted
output rate. This lowpass filtering will fill the zero samples with
interpolation information.  Then you would keep only  every 10th or 6th
sample and throw the others away. I think this is the only way for high
quality sample rate conversion, ie. using an intermediate rate that is
the smallest integer multiple of both rates.

What does this mean for the usuall 44100 to 48000 Hz conversion?
Intermediate rate of 7,056,000 Hz !  Now I know why the high quality
sample rate conversion algos need so long! There are faster algos that
need less computation time, but they sound not that clean.

Or am I completely wrong? Is there a clean method that avoids these
extreme high intermediate rates ?

m.c.







From martin.czech at intermetall.de  Fri Dec  4 09:07:03 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Fri, 4 Dec 1998 09:07:03 +0100 (MET)
Subject: AW: [Digital_Hell] DX-7 Noise
Message-ID: <199812040807.JAA02193@window.intermetall.de>


> Hmm, I didn't mean the TG77 does only produce noisy sounds. 
> I was speaking of the FM part (without running it thru filters
> etc.) I once planned to buy one, but I didn't because I got
> the impression that the FM part wasn't that different from
> the TX-802, for example.
> 
Well, a lot of modulation amount can lead to problems with
aliasing, I think Fs  is 96 kHz, but "FM" sidebands don't
care about that...

Another example of alias in a completely digital system.

If you stay away from this with proper level scaling, it should be no
problem. The sound should be very clean, cool as ice...
OTOH some effect sounds use heavy aliasing, or
you can add some dirt via aliasing...

I think the "FM" section differs from the 802, because it is possible to 
use the PCM section as modulator input...

The PCM samples are crap, I wish one could download other
samples, but this is only possible in the SY99,
and these are getting dirt cheap on thes used gear market...

I think the 802 has no PCM, so it can't have this option.

m.c.




From martin.czech at intermetall.de  Fri Dec  4 09:26:46 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Fri, 4 Dec 1998 09:26:46 +0100 (MET)
Subject: Maxim (was: Sockets)
Message-ID: <199812040826.JAA02262@window.intermetall.de>

SNIPPED

> I worry, to, about the Exar XR-2206 function generator IC, a
> single source item.  Exar claims that it is their "biggest selling"
> IC, but I don't trust that it will last forever.  Another worry is the
> CA3096 transistor array, which seems to just barely hold on
> from the old RCA days.  But it is now a Harris part, and I wouldn't
> trust them to keep anything that doesn't make huge profits.
> 
> -Art  
> 

Some people on this list believe in using "standard parts", whatever
the definition for this may be.

And with some reason.

But there is no way to decide, if e.g. a 741 or a 3080 will be still
available during the lifetime of our instruments.  Using CEM stuff is
a risc, SSM may be less, if you have a second source even lesser, but
there is no reason to refuse designs with scarce parts, if they make
good use on unique properties, I think.

m.c.




From beszedes at cc.u-szeged.hu  Fri Dec  4 10:03:54 1998
From: beszedes at cc.u-szeged.hu (Beszedes Arpad)
Date: Fri, 04 Dec 1998 10:03:54 +0100
Subject: DCO's, Anti-Aliasing, and Filters
References: <199812022337.AAA26436@mailhost.bpa.nl> <36669B23.65A9@interpath.com> <3666AA86.6F0D157E@globaleyes.net>
Message-ID: <3667A57A.79596A71@cc.u-szeged.hu>

Hi!

Rob wrote:
> 
> ANY and ALL digital signals have aliasing...There is no way around it.
> This is because between the samples, or dots that represent the
> waveform, ANYTHING can happen, and we would never know about it from the
> digital recording. This is really where aliasing occurs. Its about the
> space between the dots.
> 
> We say that this is a straight line, but more often, it is not. The
> natural curve of the original analog signal is gone.
> 

One way to improve this is the following technique which is used in
software (or even some hardware) wavetable synthesis: you do not
determine the actual output voltage based only on the two surrounding
samples (i.e. a straight line, which is actually a 1st order (linear)
interpolation), but you take into account >2 of the surrounding samples
(say 4), and this is in mathematical terms called an nth order
polynomial interpolation. Of course the accurate reproduction would
require all of the samples (which are sampled on the Nyquist frequency,
i.e. 2x the highest harmonic in the input analog signal), but this is
based on the calculation of the DFT (Discrete Fourier Transform) of the
input samples, so it's interesting only in mathamatical theory.


> The best way to describe aliasing is to think of what aliasing means in
> dictionary terms:something is acting or taking on the characteristic of
> something else.
> 
> In our terms, it means that there is insufficient numerical frequency to
> accurately represent all the harmonic characteristics of our original
> information.
> 
> So, what happens is that we have a recorded signal that has all the
> elements to represent a harmonic below the information. Like not having
> enough dots when playing connect the dots.. If you dont have enough dots
> to accurately represent your image, you could think that a picture of a
> cow was a teacup.. This is in essence what aliasing is.
> In the picture example, the dots are represented in x and y, whereas in
> our example, they are represented by y vs. time.
> 
> So, from what I have seen, all anti-aliasing filters do is limit
> bandwidth. The anti-aliasing filter is a bandpass filter with a steep
> rolloff after the upper and lower limits of our hearing (10hz to 25khz)
> that makes the aliasing inaudible, or at least lessened..
> But, if you did not record with sufficient sampling rate essentially you
> are just going to make muddy semi-sinusoidal noise. Try it sometime..
> I hope this helps anyone who was lost in the shuffle of the discussion.
> 
> Rob
> 
> Anyone who is interested, correct me if I have made a mistake. :)

-- 
***********************************************
*  Arpad Beszedes                             *
*                                             *
*  Research Group on Artificial Intelligence  *
*  Hungarian Academy of Sciences              *
*  Attila Jozsef University, Szeged, Hungary  *
*  e-mail: beszedes at cc.u-szeged.hu            *
*  tel.: (+36) 62/45-41-45                    *
***********************************************



From rsowa at WizjaTV.pl  Fri Dec  4 10:06:48 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Fri, 4 Dec 1998 10:06:48 +0100 
Subject: ODP: Shielding material
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67C3@demon>

I saw copper adhesive tape and also other kinds in ELFA catalog
try http://www.elfa.se

Roman

> -----Oryginalna wiadomo??-----
> Od:	Andrew Schrock [SMTP:aschrock at cs.brandeis.edu]
> Wys?ano:	3 grudnia 1998 20:58
> Do:	DIY
> Temat:	Shielding material
> 
> Hi all, 
> 
> I'm looking for some simple, flat yet thin and pliable conductive material
> to use for shielding and ground planes to decrease noise and other
> interference. Sorta that cardboard-with-tin-foil-on-the-other-side deal...
> Actually preferably conductive on one side, non- on the other. Any ideas?
> Should be cheap and available from digikey/mouser/other large supplier in
> the US. 
> 
> thanks, 
> Andrew
> 
> | Andrew Schrock							|
> | Network Programmer, Synthesizer and electronic music enthusiast	|
> | aschrock at cs.brandeis.edu						|



From zzynt at swipnet.se  Fri Dec  4 10:19:18 1998
From: zzynt at swipnet.se (BJ)
Date: Fri, 04 Dec 1998 01:19:18 -0800
Subject: AW: [Digital_Hell] DX-7 Noise
References: <1BF5E20E0C4DD111BBAB00805FE2D582FC3668@nbgm336a.nbgm.siemens.de>
Message-ID: <3667A915.50FA@swipnet.se>

Haible Juergen wrote:

> This is just from memory (as so often):
>  I think I remember the headphone amp of the DX-7 was quite noisy,
> but not the normal audio path. You could trim the (compound) DAC
> of the Mk1 DX7 for minimum noise of the D/A conversion, but the
> whole FM algorithm would still produce more noise than the audio
> path (except the HP amp).
> The later models (Mk 2, TX-802 and even the models that combined
> FM and ROMpler) had better DACs, but still suffered from the noisy
> digital implementation.

Well, not the TG77 that i have since 1990, its dead silent!
because it dont work!!..... Oha ha ha ha, this dead silent thing again
dude! :)

Now, really the TG77 are wery silent indeed the thing that makes the
noise in
the TG77 are the reverb,delay DSP IC.So i cant agree onto your statement
about
that the "digital implementation" are noisy.

In my opinion the TG77 are wery clean in its sound.
there is one thing thats make noise and thats the LCD driver oscillator,
wery anoying at least it was, because i have lifted of the coil of the
PCB
and drouvned the whole coil and PCB in silicone, and now its "dead
silent"!

> Yamaha aparently have still put quite some remarkable analogue
> stuff into the DX-7: I still remember my surprise when I found the
> opto electronic VCA for the volume pedal !

Well, thats "wery retro" so to say but
wasn't the DX7 released in 1982 or something?

BJ



From rsowa at WizjaTV.pl  Fri Dec  4 10:51:11 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Fri, 4 Dec 1998 10:51:11 +0100 
Subject: ODP: DCO's, Anti-Aliasing, and Filters
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67C6@demon>

There are chips which do that.
And they use simplified method. I read about it a while ago but
cannot remember it now. The basic concept is like you described
but in reality it gets more simple

Those chips can resample in 2:1 to 1:2 sample frequency relations
and I saw some posts to this list about projects done with them.
and they are about 30$

Roman

> -----Oryginalna wiadomo??-----
> Od:	Martin Czech [SMTP:martin.czech at intermetall.de]
> Wys?ano:	4 grudnia 1998 08:45
> Do:	inman at interpath.com; cyborg0 at GlobalEyes.net
> DW:	synth-diy at mailhost.bpa.nl
> Temat:	Re: DCO's, Anti-Aliasing, and Filters
> 
> Eg.  the front end of a system runs with Fs 30 Hz, and the back end
> with 50 Hz sample rate (low figures, so I can calculate it in my head)
> or vice versa.  First you would go to an intermediate rate 300 Hz,
> the smallest integer multiple of both. Ie. every 10th (30 Hz) or 6th
> (50 Hz) sample has a real value, the others are zero. Then this would be
> lowpass filtered so that the Nyquist constraint is kept for the wanted
> output rate. This lowpass filtering will fill the zero samples with
> interpolation information.  Then you would keep only  every 10th or 6th
> sample and throw the others away. I think this is the only way for high
> quality sample rate conversion, ie. using an intermediate rate that is
> the smallest integer multiple of both rates.
> 
> What does this mean for the usuall 44100 to 48000 Hz conversion?
> Intermediate rate of 7,056,000 Hz !  Now I know why the high quality
> sample rate conversion algos need so long! There are faster algos that
> need less computation time, but they sound not that clean.
> 
> Or am I completely wrong? Is there a clean method that avoids these
> extreme high intermediate rates ?
> 
> m.c.
> 
> 
> 



From theremin1 at worldnet.att.net  Fri Dec  4 11:23:19 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 4 Dec 1998 02:23:19 -0800
Subject: Maxim (was: Sockets)
Message-ID: <001701be1f70$1e038d20$c6754e0c@hpcustomer>

Yes, I was speaking to one of the Maxim salespeople the other 
day, complaining that most of their new offerings were only 
available in surface-mount packages.  (Fine for cell phones 
and such, but miserable for routine breadboarding!)  

He pointed out that none of their products that come in 
DIP packages will ever be obsoleted, so even if the newest 
technology isn't offered in DIPs, at least the old stuff won't 
disappear.

Maxim has seen unbelievable growth and stability in the last 
decade, so perhaps their promise of non-obsolescence may
actually be good for another ten or twenty years.

I worry, to, about the Exar XR-2206 function generator IC, a
single source item.  Exar claims that it is their "biggest selling"
IC, but I don't trust that it will last forever.  Another worry is the
CA3096 transistor array, which seems to just barely hold on
from the old RCA days.  But it is now a Harris part, and I wouldn't
trust them to keep anything that doesn't make huge profits.

-Art  



-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
To: Arthur Harrison <theremin1 at worldnet.att.net>
Date: Thursday, December 03, 1998 3:31 AM
Subject: Re: Sockets (was:: Solus Troubleshooting Results)


>At 07:07 PM 2/12/98 -0800, you wrote:
> Maxim, BTW,
>>never has obsoleted a single one of their thousands of ICs,
>>and has pledged never to do so.  
>
>wow, i didn't know that!
>(I had to do a major redesign when motorola droped the MC41495)
>and I worry every day abt the SSm octal sample/hold..
>
>paul perry melb aust
>>
>>
>
>




From pfperry at melbpc.org.au  Fri Dec  4 12:37:10 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Fri, 4 Dec 1998 22:37:10 +1100 (EST)
Subject: Shielding material
Message-ID: <1.5.4.16.19970228030621.37c7ae38@popa.melbpc.org.au>

I havn't tried it for this aplication, but aluminium foil (heavyish) is
available
adhesive backed. (in aust, it comes from JacPaper). You just peel off the
backing,
it is FIERCE sticking, I use it for serial number plates (just emboss the foil
before you stick it on).

paul perry Frostwave P/l melbourne Australia




From Juergen.Haible at nbgm.siemens.de  Fri Dec  4 12:56:05 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Fri, 4 Dec 1998 12:56:05 +0100 
Subject: AW: AW: [Digital_Hell] DX-7 Noise
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582FC4080@nbgm336a.nbgm.siemens.de>

	> HJ> Yamaha aparently have still put quite some remarkable analogue
	> HJ> stuff into the DX-7: I still remember my surprise when I found
the
	> HJ> opto electronic VCA for the volume pedal !
	>
	>Old habits never dies ;)

You can even buy opto electronic stereo volume pedals 
from Yamaha today. I have two of them, and they are very
nice and quiet.

JH.




From Juergen.Haible at nbgm.siemens.de  Fri Dec  4 13:03:05 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Fri, 4 Dec 1998 13:03:05 +0100 
Subject: AW: AW: [Digital_Hell] DX-7 Noise
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582FC40B9@nbgm336a.nbgm.siemens.de>

	>Well, a lot of modulation amount can lead to problems with
	>aliasing, I think Fs  is 96 kHz, but "FM" sidebands don't
	>care about that...
	>
	>Another example of alias in a completely digital system.
	>
	>If you stay away from this with proper level scaling, it should be
no
	>problem. The sound should be very clean, cool as ice...
	>OTOH some effect sounds use heavy aliasing, or
	>you can add some dirt via aliasing...

The sounds I was after were mellow Rhodes and Wurlie
sounds - most probably not high modulation index.

	>I think the "FM" section differs from the 802, because it is
possible to 
	>use the PCM section as modulator input...

Did they build a new chipset for the SY / TG series ?
If so, did they increase the word length, compared to
the DX / TX series ?

	JH.




From pfperry at melbpc.org.au  Fri Dec  4 13:06:24 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Fri, 4 Dec 1998 23:06:24 +1100 (EST)
Subject: Maxim (was: Sockets)
Message-ID: <1.5.4.16.19970228033536.36cf2bd2@popa.melbpc.org.au>

If you use parts that are in 'lots' of other things, then
there will always be a few for the individual constructor.
For a manufacturer, the problem is entirely different.

I notice some people (like Aries) are making surface mount 
carrier boards with dip pins around them. If anyone sees a cheap 
source of these, let us know. Mouser has them at $5 or so.
(and for a mere $86, a universal zif soic to dip adaptor,
which I must admit would be handy for prototyping!)

paul perry Frostwave P/l Melbounre Australia




From theremin1 at worldnet.att.net  Fri Dec  4 13:25:40 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 4 Dec 1998 04:25:40 -0800
Subject: Maxim (was: Sockets)
Message-ID: <002501be1f81$350ae020$c6754e0c@hpcustomer>


-----Original Message-----
From: Martin Czech <martin.czech at intermetall.de>
To: theremin1 at worldnet.att.net <theremin1 at worldnet.att.net>
Cc: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Friday, December 04, 1998 12:27 AM
Subject: Re: Maxim (was: Sockets)


>SNIPPED
>
>> I worry, to, about the Exar XR-2206 function generator IC, a
>> single source item.  Exar claims that it is their "biggest selling"
>> IC, but I don't trust that it will last forever.  Another worry is the
>> CA3096 transistor array, which seems to just barely hold on
>> from the old RCA days.  But it is now a Harris part, and I wouldn't
>> trust them to keep anything that doesn't make huge profits.
>> 
>> -Art  
>> 
>
>Some people on this list believe in using "standard parts", whatever
>the definition for this may be.
>
>And with some reason.
>
>But there is no way to decide, if e.g. a 741 or a 3080 will be still
>available during the lifetime of our instruments.  Using CEM stuff is
>a risc, SSM may be less, if you have a second source even lesser, but
>there is no reason to refuse designs with scarce parts, if they make
>good use on unique properties, I think.
>
>m.c.
>

Oh yes, I totally agree, especially when you consider what you'd 
have to do to make a octal SH from op amps and fet switches!

The Exar part I mentioned, for example, has a benefit in that it 
can be used as a VCO (albeit a rather non-linear one) and a 
VCA with about 55dB of dynamic range.  This part, therefore, 
is great for "synthetic" theremins.  The alternative is a VCO made 
of an LF353, a LM311, a CD4066, a CA3096 for the sine shaper, 
and two LM13600s, one for a tracking VCF to clean up the sine and 
the other for the VCA.  Lotsa parts!

-Art





From jorgen.bergfors at idg.se  Fri Dec  4 14:16:00 1998
From: jorgen.bergfors at idg.se (jorgen.bergfors at idg.se)
Date: Fri, 4 Dec 1998 14:16:00 +0100
Subject: Maxim (was: Sockets)
Message-ID: <TFSWENOZ@idg.se>

I use a carrier that has pins both top and bottom. The bottom pins goes in a normal IC socket and the top pins goes into a very small board that I have etched. The board is the same size as the carrier, which in turn is the same size as the IC socket. The small board has the copper on the upside, so it can easily be soldered to the top pins on the carrier.On the small board one or several surface mount parts can be soldered. I have used this for a dual transistor and a tempco resistor, all on an 8 pin carrier. The resulting module can be inserted and swapped like an ordinary IC. The carriers cost $1 each for quantities of ten.

/Jorgen





MIME:pfperry at melbpc.org.au on 98-12-04 14:05:16
To:  synth-diy at mailhost.bpa.nl @ SMTP cc:  (bcc: Jorgen Bergfors/IDGSE)
Subject: Re: Maxim (was: Sockets) 

If you use parts that are in 'lots' of other things, then
there will always be a few for the individual constructor.
For a manufacturer, the problem is entirely different.

I notice some people (like Aries) are making surface mount carrier boards with dip pins around them. If anyone sees a cheap source of these, let us know. Mouser has them at $5 or so.
(and for a mere $86, a universal zif soic to dip adaptor,
which I must admit would be handy for prototyping!)

paul perry Frostwave P/l Melbounre Australia










From synth1 at airmail.net  Fri Dec  4 14:36:32 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Fri, 4 Dec 1998 07:36:32 -0600
Subject: Maxim (was: Sockets)
Message-ID: <007501be1f8b$1b794480$770b42ce@paults>

If you stay away from the 3310, 3340, and 3360 I don't consider CEM DIY
projects
a risk: I have over 1000 of each chip just sitting here.

Paul Schreiber
Synthesis Technology





From clark at andrews.edu  Fri Dec  4 16:07:50 1998
From: clark at andrews.edu (Tony Clark)
Date: Fri, 4 Dec 1998 10:07:50 -0500 (EST)
Subject: need Taurus schematics (fwd)
Message-ID: <Pine.SOL.3.91.981204100644.12873A-100000@edmund.cs.andrews.edu>

   Hi guys,

   Just got this in the mailbox, so I thought I'd pass it on.  If anyone 
can help him out, I'm sure he'd appreciate it.

   Thanks,

   Tony

------------------------------------,----------------------------------
I can't drive (my Moog) 55!         |     The E-Music DIY Archive
------------------------------------|  
Tony Clark -- clark at andrews.edu     | aupe.phys.andrews.edu/diy_archive
http://aupe.phys.andrews.edu/~clark |     Contributions welcomed!
------------------------------------'----------------------------------

---------- Forwarded message ----------
Date: Thu, 3 Dec 1998 22:49:55 -0600
From: MoniDanAlex <insomnie at mtl.paradiso.net>
To: "'clark at andrews.edu'" <clark at andrews.edu>
Subject: need chematics

hello,
I have a Taurus by Moog but it doesn't work correctly,and nobody could fix it.
They need the schemat or the manuel service to repair it.

coold you send it to me, or tell me where i can find it please.

you can reach me at my E.mail:  insomnie at mtl.paradiso.net
                               or by faxe: (514) 365 8099       at Montr?al Canada
thank for your help.
	
	Daniel Jacazio




From Aranakin at aol.com  Fri Dec  4 18:36:33 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Fri, 4 Dec 1998 12:36:33 EST
Subject: does any one have...?
Message-ID: <5bd1b0c0.36681da1@aol.com>

tom g's email address?
his tomg at vivid.net does not work for some reason...
thanks anthony



From vco at mindspring.com  Fri Dec  4 18:51:35 1998
From: vco at mindspring.com (tomg)
Date: Fri, 04 Dec 1998 12:51:35 -0500
Subject: Mad Mouse Update
Message-ID: <yam7642.1780.119073448@mail.mindspring.com>

I built the Mad Mouse last weekend. I have spent the last few
days tweeking this and that and it's finally ready. I'll 
complete the pages over this weekend and finish posting it Monday.

The Mad Mouse is a micro version of a standard normalized synth.

2 - VCOs 2-LM13600s - VCO-5a type
1 - VCF  LM13600    - ms20 lowpass type
2 - VCAs LM13600    - one for output and one for LFO mod
2 - ADs  LM556/TLO74
1 - LFO  TLO74


The idea  for the MM was to build a cheep small simple synth for
beginner DIYers. It's very small the board is 6x4" the case is 
7 1/4 x 4 1/4. It's also cheep under $45. However small and 
cheep do not equal a beginners project, it's still seems a little
too complicated. I have been talking with a local PCB maker
about doing the board, I would have to charge $25-30 but I may 
do it anyway. 

If you want to look at it I posted some pics. More on Monday.

http://www.mindspring.com/~vco/madm/temp.html

-tg









From harv23 at leland.Stanford.EDU  Fri Dec  4 20:04:51 1998
From: harv23 at leland.Stanford.EDU (Harvey Devoe Thornburg)
Date: Fri, 4 Dec 1998 11:04:51 -0800 (PST)
Subject: DCO's, Anti-Aliasing, and Filters
In-Reply-To: <199812040745.IAA02137@window.intermetall.de> from "Martin Czech" at Dec 4, 98 08:45:00 am
Message-ID: <199812041904.LAA23731@amy7.Stanford.EDU>

Martin Czech writes:

> What does this mean for the usuall 44100 to 48000 Hz conversion?
> Intermediate rate of 7,056,000 Hz !  Now I know why the high quality
> sample rate conversion algos need so long! There are faster algos that
> need less computation time, but they sound not that clean.
> 
> Or am I completely wrong? Is there a clean method that avoids these
> extreme high intermediate rates ?
> 

Yes. For example,  think of what goes on when you do filtering then 
downsampling.  Suppose your filter is a simple "moving average" filter
eg. you average 10 samples then downsample by 10.  By "downsample" I 
mean tossing out the 9 intermediate samples.  You can either
slide the averaging window one sample at a time, then toss out the 9
intermediate samples, *or* you can move the window 10 samples at a time,
getting the same result with 1/10 the computations.  The latter 
corresponds to filtering at the lower sampling rate.  

The same thing goes for upsampling then interpolation.  Instead of 
taking a bunch of samples, inserting 9 zeros inbetween, then averaging
the results by a filter whose window moves by 1 sample, you can 
get the same results just by hopping the window in 10-sample blocks
and averaging. Again, the goal is to filter (eg. interpolate) at the *lower* 
sampling rate!

Now, a moving-average filter, or a box filter, is rather poor for 
antialiasing. To get a better filter you also need filter longer than 
10 samples. A generalization of this approach for longer filters
is known as "polyphase network". IMHO, the clearest explanation of the 
polyphase network is explained in Vaidynathan, _Multirate Systems and 
Filter Banks_ (ch. 4 I believe is devoted to polyphase network and 
sample rate conversion).  

Now, what needs to be done for fixed sample rate conversion?
The diagram as you have explained is Upsample->Filter->Filter->Downsample.
Again, by "upsample" I mean inserting zeros and by "downsample"
tossing out samples.  The first Filter corresponds to interpolation; 
the second to antialiasing.  As these are ideal lowpass filters,
you can replace their combination with the one with the lower cutoff 
frequency, leaving Upsample->Filter->Downsample.

Now you can probably see what is done.  The Filter need not be computed
at the 7,056,000 Hz sample rate.  You can choose to compute the
polyphase network at 44100 or 48000 Hz.  In fact, the intermediate sample
rate is never used.  If you're worried that you still need to 
output the samples at the 7.1MHz rate, this step can be eliminated also
(Vaidyanathan shows how).  What you get is the remarkable 
fact that the computation time of "ideal" sample rate conversion 
is independent of the least common multiple of the sampling rates!

For variable sample rate conversion, such as transposing a sample up and
down, the conversion factor is probably irrational.  The idea is similar,
though, and here the technique is called "bandlimited interpolation" or
"sinc interpolation" because the filter is a sin(x)/x function.  The
classic paper on this is Smith and Gossett, "A flexible sampling-rate
conversion method", Proc. ICASSP, 1984.  An updated, online manuscript 
called "Bandlimited Interpolation, Introduction and Algorithm" by Smith
can be found: http://www-ccrma.stanford.edu/~jos/src/src.htm.

Anyway, the theory is moderately complicated, but this is what makes
high-end samplers work so well.  I think the Emu samplers have always used
this technique.  Most lower end stuff (especially drum machines) uses 
linear or cubic (Hermite) interpolation.  This gives adequate results
when converting to a higher sampling rate.  But they *almost always* mess
up when doing the downconversion.  The reason is that since the filter's
cutoff should be the *minimum* of the Nyquist frequencies for the two
rates, you must "stretch out" the interpolation function by a factor
equal to the original sampling rate divided by the lower sampling rate. 

--Harvey 







> m.c.
> 
> 
> 
> 
> 




From WeAreAs1 at aol.com  Fri Dec  4 20:15:30 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Fri, 4 Dec 1998 14:15:30 EST
Subject: AW: AW: [Digital_Hell] DX-7 Noise
Message-ID: <2d103544.366834d2@aol.com>

Juergen Haible asked:

<<Did they build a new chipset for the SY / TG series ?
If so, did they increase the word length, compared to
the DX / TX series ?  >>

The original DX7, TX7, and TX816 all had 12-bit DAC's.  The subsequent models
(DX7-II, DX7s, and TX802) had 16-bit DAC's.  I imagine that they also had
larger word lengths to take advantage of the larger DAC's.  They certainly are
cleaner and less distorted sounding than the original units, especially on
sounds with low modulation indexes (mellow sine-like sounds, etc.)

The later models in the series (SY77, SY99, TG77) also were 16-bit.

In case you guys haven't yet heard, Yamaha has two new FM instruments coming
out at this time.  One of them is the FS1r, which appears to be a kind of
combination of FM and additive technologies (imagine a cross between a highly
expanded type of Yamaha FM and a Kawai K5000, probably with multimode digital
filters and lots of built-in effects).  I don't know if it has any PCM
partials as part of the sound.  The other new instrument is an expansion board
that can be put into some of their current models (such as the MU100R and the
SW1000G).  It is a full-featured FM sound module that has a new expanded type
of FM, but is fully compatible with old DX/TX/SY sysex data.  Of course, the
FM sounds from this card can also be routed through the (quite substantial)
internal effects in these units.  I think this card will be about $300.00 US.

Michael Bacich



From WeAreAs1 at aol.com  Fri Dec  4 21:24:06 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Fri, 4 Dec 1998 15:24:06 EST
Subject: AW: AW: [Digital_Hell] DX-7 Noise
Message-ID: <cf23a1cb.366844e6@aol.com>


In a message dated 12/4/98 11:22:58 AM, you wrote:

<<Juergen Haible asked:

<<Did they build a new chipset for the SY / TG series ?
If so, did they increase the word length, compared to
the DX / TX series ?  >>>>

Oh yeah, I forgot to mention this - There were completely new tone generation
chipsets for each of the three series of Yamaha six-operator FM instruments
(series 1: DX7, TX7, TX816; series 2: DX7II, DX7s, TX802; series 3: sy77,
SY99, TG77).

There were also several different chipsets made for their various four-
operator FM instruments (TX81z, DX100, FB-01, etc)

Michael Bacich



From cyborg0 at GlobalEyes.net  Fri Dec  4 21:51:16 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Fri, 04 Dec 1998 14:51:16 -0600
Subject: Shielding material
References: <1.5.4.16.19970228030621.37c7ae38@popa.melbpc.org.au>
Message-ID: <36684B44.83EA7006@globaleyes.net>

Paul Perry wrote:
> 
> I havn't tried it for this aplication, but aluminium foil (heavyish) is
> available
> adhesive backed. (in aust, it comes from JacPaper). You just peel off the
> backing,
> it is FIERCE sticking, I use it for serial number plates (just emboss the foil
> before you stick it on).
> 
> paul perry Frostwave P/l melbourne Australia

They have copper stuff just like this.. And, yes, it IS scary.. I got
some on my skin and regretted it.. You can get it from newark too.. in
different thicknesses and such.
rob



From DCMagnuson at aol.com  Fri Dec  4 23:02:51 1998
From: DCMagnuson at aol.com (DCMagnuson at aol.com)
Date: Fri, 4 Dec 1998 17:02:51 EST
Subject: Shielding material
Message-ID: <57d08d5f.36685c0b@aol.com>

In a message dated 12/4/98 8:40:22 AM Eastern Standard Time,
pfperry at melbpc.org.au writes:

> I havn't tried it for this aplication, but aluminium foil (heavyish) is
>  available
>  adhesive backed. (in aust, it comes from JacPaper). You just peel off the
>  backing,
>  it is FIERCE sticking, I use it for serial number plates (just emboss the 
> foil
>  before you stick it on).
>  

If anyone in the US needs this foil tape, and can't find it, email me.  I
install ductwork for a living, and can get rolls of it (3" wide by 100ft, I
believe).  I'd prefer not to ship overseas, but I can send people a roll at my
cost plus shipping.   This is industrial grade stuff, a little thicker than
the typical home depot stuff.

Dave Magnuson
Independent Music Site
http://members.aol.com/dcmagnuson
 



From theremin1 at worldnet.att.net  Sat Dec  5 07:26:33 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 4 Dec 1998 22:26:33 -0800
Subject: Maxim (was: Sockets)
Message-ID: <001a01be2018$34f79fa0$31794e0c@hpcustomer>

$5 is about as cheap as I've seen for those adapters.  
It is a shame, though, to have to spend that much money 
to mount a $3 op amp!  Not to mention the microscope 
some of nearly-blind folks need just to tell where the leads 
are on those tiny packages!

-Art


-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Friday, December 04, 1998 6:27 AM
Subject: Re: Maxim (was: Sockets)


>If you use parts that are in 'lots' of other things, then
>there will always be a few for the individual constructor.
>For a manufacturer, the problem is entirely different.
>
>I notice some people (like Aries) are making surface mount 
>carrier boards with dip pins around them. If anyone sees a cheap 
>source of these, let us know. Mouser has them at $5 or so.
>(and for a mere $86, a universal zif soic to dip adaptor,
>which I must admit would be handy for prototyping!)
>
>paul perry Frostwave P/l Melbounre Australia
>
>




From zzynt at swipnet.se  Sat Dec  5 07:52:45 1998
From: zzynt at swipnet.se (BJ)
Date: Fri, 04 Dec 1998 22:52:45 -0800
Subject: AW: DX-7 Noise
References: <199812040807.JAA02193@window.intermetall.de>
Message-ID: <3668D83D.C6B@swipnet.se>

Martin Czech wrote:
> 
> > Hmm, I didn't mean the TG77 does only produce noisy sounds.
> > I was speaking of the FM part (without running it thru filters
> > etc.) I once planned to buy one, but I didn't because I got
> > the impression that the FM part wasn't that different from
> > the TX-802, for example.
> >
> Well, a lot of modulation amount can lead to problems with
> aliasing, I think Fs  is 96 kHz, but "FM" sidebands don't
> care about that...
> 
> Another example of alias in a completely digital system.
> 
> If you stay away from this with proper level scaling, it should be no
> problem. The sound should be very clean, cool as ice...
> OTOH some effect sounds use heavy aliasing, or
> you can add some dirt via aliasing...

I agre with Martin here because the way to use the FM synthesis in a
DX/TG 
is to do some level scaling to actually reduce the modulators amplitude
in
to the carriers.This is a important issue to get clean sounds out of any
FM machine, applying this to the K2000 to makes cleaner and nicer
sounds. 
 
> I think the "FM" section differs from the 802, because it is possible to
> use the PCM section as modulator input...

And other nice things is: 12 separate outputs, loopable ENV's 
several gaussian noise generators,(noo need to use sampled noise)  
2 LFO's 45 algos,16 waveforms on each oscillator, carrier as modulator,
setting the phase on each osc's,etc. Programmable algos' and feedback
routings
its wery easy to do 6 sawtooth osc's just using the programable feedback
routing,
not available on any other FM from Yamaha other then the TG77/Sy99.  

> The PCM samples are crap, I wish one could download other
> samples, but this is only possible in the SY99,
> and these are getting dirt cheap on thes used gear market...

yes ,the PCM samples is crap particullary the percussion are just waste
of
RAM space, actually i was into the same ideas as Barry Klein (hello
Barry :))
some years ago, was into his Korg W-station to replace the internal PCM
samples
with some better ones, i did some design around this but i newer come to
shot so to say, the main reason was i needed a software that could
record
sample editing and saving the samples into a Mot S19 or Intel hex format
so it was possible to program the PROM in a eprom programmer.(This was
in 1991).

Infact there was someone or some company who had done this, i saw a
addvert
in some magazine for just this thing and they sold even the prom's
with different samples setts, but it was expencive as i can recall it. 

Hmm,It may bee the same company who made the card programmer to the 
roland D50 and the Korg M1, and if that's soo then its a german
company?? 

BJ



From zzynt at swipnet.se  Sat Dec  5 07:53:40 1998
From: zzynt at swipnet.se (BJ)
Date: Fri, 04 Dec 1998 22:53:40 -0800
Subject: AW: [Digital_Hell] DX-7 Noise
References: <19981204022147.23796.qmail@nuernberg2.pop.metronet.de>
Message-ID: <3668D874.53BA@swipnet.se>

jhaible wrote:
> 
> > Now, really the TG77 are wery silent indeed the thing that makes the
> > noise in
> > the TG77 are the reverb,delay DSP IC.So i cant agree onto your statement
> > about
> > that the "digital implementation" are noisy.
> 
> Hmm, I didn't mean the TG77 does only produce noisy sounds.
> I was speaking of the FM part (without running it thru filters
> etc.) I once planned to buy one, but I didn't because I got
> the impression that the FM part wasn't that different from
> the TX-802, for example.

Well, thats what i did belive you was saying, and still i dont agree
into this because the FM  part is dead silent.Actually the TGG77/99
is wery different from the TX802, different FM ASIC, different DACs
different FM implementation of the FM synthesis.Dont forget that
the TX802 is in fact one generation older then the DX7II and the DX7IIFD
machines, you can definitively hear the difference between those DX FM
generation the DX7FD are slightely less noisier then the TX802.

There are differences between the first generation of Dx7 to
10 bit DAC, 12 bit DAC, 14 bit ,16 bit DAC's was used between the
models.
(she's a model and are looking good, deooo, de, deo ,deoo , deoo de
deooooow!)

Newertheless, i think you shall go out and buy your self a TG77
its dead cheap these days, here i often se them at 3500skr=777DM
some times even cheaper.And then you buy the RP from us so you can
build your self a custom Remote Programmer(RP for short) for the TG77 
using its 128 pot AD channels and 32 buttoms.(when its get finished)

Regards
BJ



From zzynt at swipnet.se  Sat Dec  5 08:24:10 1998
From: zzynt at swipnet.se (BJ)
Date: Fri, 04 Dec 1998 23:24:10 -0800
Subject: AW: AW: [Digital_Hell] DX-7 Noise
References: <cf23a1cb.366844e6@aol.com>
Message-ID: <3668DF9A.4EB6@swipnet.se>

WeAreAs1 at aol.com wrote:
> 
> In a message dated 12/4/98 11:22:58 AM, you wrote:
> 
> <<Juergen Haible asked:
> 
> <<Did they build a new chipset for the SY / TG series ?
> If so, did they increase the word length, compared to
> the DX / TX series ?  >>>>
> 
> Oh yeah, I forgot to mention this - There were completely new tone generation
> chipsets for each of the three series of Yamaha six-operator FM instruments
> (series 1: DX7, TX7, TX816; series 2: DX7II, DX7s, TX802; series 3: sy77,
> SY99, TG77).
> 
> There were also several different chipsets made for their various four-
> operator FM instruments (TX81z, DX100, FB-01, etc)

Hmm,I had a TX81Z for may years and it vas wery nice too, but it was
some what
noisy because of the low resolution on the DAC and it did not have full
multitimb.
The later DX11 had much better spec's.

The DX11 was wey nice and usefull to be a simple 4 oP FM  machine.

BJ



From rsowa at WizjaTV.pl  Sat Dec  5 13:13:02 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Sat, 5 Dec 1998 13:13:02 +0100 
Subject: ODP: Maxim (was: Sockets)
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67D2@demon>

Did anybody consider making this?

I do my PCBs in a "PCB-factory" because it's cheap and easy.
I think such carrier board would cost less than $1 together with pins
in not so big quantities.

Roman

> -----Oryginalna wiadomo??-----
> Od:	Paul Perry [SMTP:pfperry at melbpc.org.au]
> Wys?ano:	4 grudnia 1998 13:06
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	Re: Maxim (was: Sockets)
> 
> I notice some people (like Aries) are making surface mount 
> carrier boards with dip pins around them. If anyone sees a cheap 
> source of these, let us know. Mouser has them at $5 or so.
> (and for a mere $86, a universal zif soic to dip adaptor,
> which I must admit would be handy for prototyping!)
> 
> paul perry Frostwave P/l Melbounre Australia



From rsowa at WizjaTV.pl  Sat Dec  5 13:17:14 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Sat, 5 Dec 1998 13:17:14 +0100 
Subject: ODP: DCO's, Anti-Aliasing, and Filters
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D67D3@demon>

I didn't want to start this aliasing thing again.
this whole thing made me sick of DSPs, wavetables and so on.
I'll stick to analog for a while

BTW if anyone recalls my posts about SSM2164 VCO, get ready
for results. It's almost done. And not only that - VC ADDSR too.

Roman

	-----Oryginalna wiadomo??-----
	Od:	Harvey Devoe Thornburg [SMTP:harv23 at leland.Stanford.EDU]
	Wys?ano:	4 grudnia 1998 07:43
	Do:	rsowa at WizjaTV.pl
	DW:	synth-diy at mailhost.bpa.nl
	Temat:	Re: ODP: DCO's, Anti-Aliasing, and Filters


	When you run everything at a common sampling rate and change the
pitch 
	continuously using DSP (by this I mean sample rate conversion),
there's no
	way to maintain integer relationships.  Then you need to implement
an 
	antialiasing filter, equivalent to sinc interpolation.

	In summary, the effect of aliasing depends on your implementation.
	So -- what exactly is your implementation?

	--Harvey




From cyborg0 at GlobalEyes.net  Sat Dec  5 19:52:05 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sat, 05 Dec 1998 12:52:05 -0600
Subject: gate time inversion
References: <2BF6F749A4A3D11185AD00A0C94CF67A4D67D3@demon>
Message-ID: <366980D5.CA1FAE99@globaleyes.net>

Ok, I am trying to modify my 777 (303-like clone with sequencer).
I have figured out a way to invert the accent (all accented notes become
unaccented, unaccented become accented).. It was a pure success and it
is great to be able to change the feel of a sequence with just a flip of
a toggle..

But, my most daunting task is ahead: I have been trying to make an
invert switch for the glide function..So far, I have figured out how to
make the glide circuit charge up to the CV value by taking the 5 volt
signal off of the accent output.
Where I am currently having a problem is with the gate time.
When the glide is on a note, it leaves BOTH the slide circuit on AND the
gate signal on..This makes the slide audible, otherwise the slide is
pretty much inaudible because the gate turns off before the slide is
completed... It is actually a pretty cool effect to just hear the slide
just begin then cut off, but I want it to be able to also leave the gate
on..

So, anyone have any ideas? I need to make the short gates long and the
long gates short...
How could you do this with the least amount of circuitry?

Rob



From jhaible at primus-online.de  Sat Dec  5 22:31:01 1998
From: jhaible at primus-online.de (jhaible)
Date: Sat, 5 Dec 1998 22:31:01 +0100
Subject: AW: [Digital_Hell] DX-7 Noise
Message-ID: <19981205213234.322.qmail@nuernberg2.pop.metronet.de>

BJ wrote:

> Well, thats what i did belive you was saying, and still i dont agree
> into this because the FM  part is dead silent.Actually the TGG77/99
> is wery different from the TX802, different FM ASIC, different DACs
> different FM implementation of the FM synthesis.Dont forget that
> the TX802 is in fact one generation older then the DX7II and the DX7IIFD
> machines, you can definitively hear the difference between those DX FM
> generation the DX7FD are slightely less noisier then the TX802.
> 
> There are differences between the first generation of Dx7 to
> 10 bit DAC, 12 bit DAC, 14 bit ,16 bit DAC's was used between the
> models.
> (she's a model and are looking good, deooo, de, deo ,deoo , deoo de
> deooooow!)
> 
> Newertheless, i think you shall go out and buy your self a TG77
> its dead cheap these days, here i often se them at 3500skr=777DM
> some times even cheaper.And then you buy the RP from us so you can
> build your self a custom Remote Programmer(RP for short) for the TG77 
> using its 128 pot AD channels and 32 buttoms.(when its get finished)

Michael Bacich wrote:

>Oh yeah, I forgot to mention this - There were completely new tone
generation
>chipsets for each of the three series of Yamaha six-operator FM
instruments
>(series 1: DX7, TX7, TX816; series 2: DX7II, DX7s, TX802; series 3: sy77,
>SY99, TG77).

Ok, I am ready to believe every word you say, as my own "experience" with
the SY / TG synths is next to zero. What I heard when I considered
upgrading
to a SY77 may as well just have been badly programmed sounds. I was 
disappointed, and that stopped me from doing any further invertigations.
(Which might have been an error.)

Having sad that, now to a more precise question.

I'm aware that the *output* resolution (i.e. DAC) was increased from
earlier
to later models. (Btw, 10 bit for DX-7 Mk 1, does that mean 8-bit DAC chip 
+ 2 extra bits, or 10-bit DAC + 2 extra bits = 12 bits ?)
That's why I programmed as few dynamics as possible into the level of the
*carrier* for many sounds. That, and carefully adjusting the trimmer for
the
"extra bits" helped a lot to make sounds cleaner. Later models (even the
TX-802) would surely be more tolerant about carrier level dynamics.

But even then, there was the noise from *modulation* the carrier. As this
is just phase modulation, it would't affect the output amplitude (of the
carrier), and thus wouldn't change the amount of quantisation by the DAC.
But the mere phase modulation process introduced some extra noise,
so I came to believe that this was due to a limed resolution of the 
*modulation process*. Maybe adress length of the sine tables, or whatever.
never dug deeper into that.
So for me the big question is: Did they increase this *internal* resolution
from the DX to the SY / TG models ??

I really don't know, and I may be on the wrong track here, too, but now I'd
like to know.

JH.







From jhaible at primus-online.de  Sun Dec  6 00:01:29 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 6 Dec 1998 00:01:29 +0100
Subject: More stuff on the 303...
Message-ID: <19981205230421.1722.qmail@nuernberg2.pop.metronet.de>


> All the Japanese parts are fairly easy to get hold of, once you know
> where to look. My thanks to all who helped me in this. The SC1583 is
> actually very cheap. 75p compared to 3UKP for the SSM2210. 

I just bought 50 pieces of SC1583 for less than DM 1,- a piece.
You can never kow ... 
I also got a few of these BA-forgot-the-numer VCA chips that were 
recently mentioned - no time to test them yet, though.
This Japanese stuff seems to be quite handy, once you've overcome
the initial shyness. I really love the SIL (rather than DIL) packages,
too. Easier to layout or veroboard.
Do you know a few good standard opamps in SIL package? 
The bad thing of my source of Jap stuff (Reichelt Elektronik) is
that they have no description whatsoever, just "Japan Transistor"
or "Japan IC" and the part number.
Are there even *data sheets* out there, in the web ??

JH.



From oakley at techrepairs.freeserve.co.uk  Sun Dec  6 21:44:36 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sun, 6 Dec 1998 20:44:36 -0000
Subject: More stuff on the 303...
Message-ID: <001f01be2159$a4909fa0$c227883e@default>

Hi,

Well I have built my first TB, at least the analogue bit anyhow. Some
more musings from me about the circuit. I have already established that
the VCO waveform is very dependent on the selection of the saw buffer
FET. Roland do indeed have preselected SK30s to choose from. However,
Roland have plenty of these (but not at the moment in the UK, because I
bought them all, ha ha) I had five other more common types of fet and
they just didn't give the output I wanted.

The filter resonance is not only dependent on the res pot, but also on
the actual value of the 5V3 power supply. If it is only a little higher,
the gain of the diff amp becomes large enough to cause the filter to
self oscillate with the res pot fully clockwise. The 5V3 is set up to
feed the dac, and hence to give 1v/oct, so I suppose most 303s will have
fairly similar power supplies.

The mixer is greatly affected by output load. When loaded with a 22k
input impedance from my bench amp, it clips on negative swings, and the
positive is affected in an unusual way. This generates some nice
distortion. This may well be a cause of that TB sound. However, the
amount of distortion is dependent on the level of signal from the volume
pot. I am experimenting with additional overdrive circuitry to enhance
the sound. But I can't decide whether to put it before the VCA or after
it. The more I look at the waveforms, the less I am convinced that the
BA662 actually affects the sound... but more tests have yet to be done.
I could really do with a distortion meter or a DSO.

All the Japanese parts are fairly easy to get hold of, once you know
where to look. My thanks to all who helped me in this. The SC1583 is
actually very cheap. 75p compared to 3UKP for the SSM2210. I havn't
tried the CA3046 yet.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From synth1 at airmail.net  Mon Dec  7 03:22:16 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Sun, 6 Dec 1998 20:22:16 -0600
Subject: New MOTM modules pictures & tempco last call!
Message-ID: <001301be2188$68b65040$2d1388cf@paults>

Please visit

www.synthtech.com/news

for new photos on the MOTM-940 Patch Panel and MOTM-700 Dual VC 2:1 Mux.

Also, if you still want to order 1K +3500ppm tempcos, you MUST have the
order to
me by 5PM Wednesday.

Paul Schreiber
Synthesis Technology





From wils0450 at itlabs.umn.edu  Mon Dec  7 07:14:55 1998
From: wils0450 at itlabs.umn.edu (Rocket Queen)
Date: Mon, 7 Dec 1998 00:14:55 -0600 (CST)
Subject: book recomendations
Message-ID: <Pine.GSO.4.05.9812070009350.25300-100000@boris.itlabs.umn.edu>

I am sure you guys are sick of this question by now, but my filing/data
managment skills are poor, so any messages I saw earlier are lost. This is
my first time asking this question though, :) I also went looking for some
textbook from Farnell (not sure on that). I could not find it on ant of
the sites I was directed too. Tell me if I'm stupid and they are just
hidden somewhere. 
 		I am already aware of the following...


Digital Projects for Musicians~Craig Anderton
http://www.amazon.com
Electronic Projects for Musicians~Craig Anderton
http://www.paia.com
Electronic Music Circuits~Barry Klien
http://www.amazon.com (out of print)
Build a Better Music Synthesizer~Thomas Henry
http://www.amazon.com (out of print)
The Art of Linear Electronics~John Linsley Hood
Cmos Cookbook; Donald E. Lancaster, Don Lancaster   http://www.amazon.com
Design With Operational Amplifiers and Analog Integrated Circuits
(Electronics and Vlsi Circuits)~Sergio Franco
http://www.amazon.com
Ttl Cookbook~Don Lancaster
http://www.amazon.com

Thanks for any help you can throw my way - 


            <<< << The obvious solution is to kill you all >> >>>





From costello at seanet.com  Mon Dec  7 09:16:57 1998
From: costello at seanet.com (Sean Costello)
Date: Mon, 07 Dec 1998 00:16:57 -0800
Subject: book recomendations
References: <Pine.GSO.4.05.9812070009350.25300-100000@boris.itlabs.umn.edu>
Message-ID: <366B8EF9.D7377F5E@seanet.com>

Rocket Queen wrote:
> 
> I am sure you guys are sick of this question by now, but my filing/data
> managment skills are poor, so any messages I saw earlier are lost. This is
> my first time asking this question though, :) I also went looking for some
> textbook from Farnell (not sure on that). I could not find it on ant of
> the sites I was directed too. Tell me if I'm stupid and they are just
> hidden somewhere.

> Electronic Music Circuits~Barry Klien
> http://www.amazon.com (out of print)

A reprint is available directly from Barry Klein
(Barry.L.Klein at wdc.com). Very nice book.

> Build a Better Music Synthesizer~Thomas Henry
> http://www.amazon.com (out of print)

Many of these circuits are also available in "Electronic Music Circuits:
The Reprints," available direct from Tom Henry at
http://prairie.lakes.com/~map. Get it now, though, as it probably won't
be reprinted.  Mostly CEM and SSM stuff.
 
Another EXCELLENT book is "Musical Applications of Microprocessors" by
Hal Chamberlin. Despite its name, it covers analog synth circuits in a
fair amount of detail.  Also great coverage of digital synthesis
techniques.  Out of print, but shows up a fair amount.  I saw a copy at
Powell's Technical Bookstore in Portland, OR last weekend, and was
tempted to buy it, even though I have a copy (it's such a great find). 
Be sure to get the 2nd edition.  According to the PAiA home page, Hal
Chamberlin sells photocopy versions of this book for $30, and can be
contacted at halc at ycrdi.com.

I'd also recommend getting the Preferred Circuits Collection from
Electronotes.  Bernie Hutchins is cranky and seems to dislike anyone who
would want to buy this from him or use his old circuits in general, but
Electronotes is chock full of great circuits, and the PCC has the best.
Go to Tom Henry's page, and follow the links.  Bernie DOES deliver his
orders, although it may take a while.

Another great book is "Computer Music," by Charles Dodge and Thomas
Jerse. Maybe not relevant to this list, but I've been getting the
coolest sounds out of Csound...let's just say that a reversed bell
sound, where each partial is ring modulated by an independent source of
low frequency noise, is a beautiful thing to hear (tonight, I made a few
changes, so that the base source is a timpani).  Dodge & Jerse has been
invaluable - probably the best textbook for sitting down and learning
computer music techniques.

Sean Costello



From qfulsom at usa.net  Mon Dec  7 09:20:03 1998
From: qfulsom at usa.net (Quint)
Date: Mon, 7 Dec 1998 02:20:03 -0600
Subject: Roland BA662 data
Message-ID: <001d01be21ba$64f0f820$b5a85380@s8p8t9>

Funny I had noticed the same thing.  I'll bet they were allowed to refab them after x number of years.  They are exactly the same it would appear with the differences of the 1st 4 pins being varied.  ALL the same i/o is there.  I am definetely planning to experiment!  I'm also researching a component LMC662 which I cant really find anything on.
Quint

> >When I was digging around for 303 parts I discovered that BAxxxx
>ICs seem to
> >be manufactured by Rohm.
> >They currently produce another OTA, BA6110, which bears a
>remarkable
> >similarity to the BA662.
> >
> >Check out
>http://www.rohmelectronics.com/pdfs/strd_ic/strd_ic_pdf.htm
> >
> >Colin f
>
>Hi Colin,
>
>this is very interesting, thanks for digging it up !
>Someone took the diode bias scheme from the 3280
>and the buffers from the 13700 ??
>I think I'll buy a few. Reichelt has them, too.
>(They also have c1583's, btw.)
>
>JH.

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From pfperry at melbpc.org.au  Mon Dec  7 11:00:42 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Mon, 7 Dec 1998 21:00:42 +1100 (EST)
Subject: book recomendations
Message-ID: <1.5.4.16.19970303002941.37c79182@popa.melbpc.org.au>

At 12:14 AM 7/12/98 -0600, Rocket Queen  wrote:

> 		I am already aware of the following...
>
"The Art of Electronics" Horowitz and Hill, Cambridge University Press
(available at every college bookshop, and pirated throughout asia & 
eastern europe)

"Troubleshooting Analog Circuits" Robert A. Pease
(available Powell's Technical, etc)

IC Op Amp Cookbook by Walter G. Jung (Sams)

These are my fave picks & the ones the staff "borrow"!

paul perry melbounre australia




From vco at mindspring.com  Mon Dec  7 11:04:38 1998
From: vco at mindspring.com (tomg)
Date: Mon, 07 Dec 1998 05:04:38 -0500
Subject: Mad Mouse Update #2
Message-ID: <yam7645.1916.120317456@mail.mindspring.com>



No false modiste here. WOW! the Mad Mouse is tooo much.
It's way too deceiving in that small plain black box. I'll
do a demo track today and you can make your own decision.
I'll have to let my ears rest first though...DAMM!

Playing with the MM over the weekend. I thought it sounded
ok.. nothing special.. the ota vcos were very smooth, the
waveforms being perfect and all that. They tracked almost 
perfectly and it sounded BLAH! Much too clean and smooth 
to be called the "Mad Mouse".  

So I ripped the ota vcos off the perf-board and built a pair 
of my "rogue" clones there instead. Ahhhhhhh.. much much better!
Could be the best decision I've made this year. 

When I dial in that low low offset I can't help but smile.
Those saws banging together just make me feel good all over.
DAMM that filter! It made my EYES hurt. Ouch! 
You guys are gona like it.

Here's another temp page to look at. I need to make a few 
changes and enlarge the pics but this very close to the final.
 
http://www.mindspring.com/~vco/madm/temp2.html

More tomorrow..

There may be something up in the pcb department...:)

-tg




From jhaible at primus-online.de  Mon Dec  7 11:30:30 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 7 Dec 1998 11:30:30 +0100
Subject: JH. homepage update
Message-ID: <19981207103050.2092.qmail@nuernberg2.pop.metronet.de>

Hi,

for anybody who is interested in my DIY stuff, I have recently updated
my homepage.

There's some new schemos there (a simple, but ultra low noise
optoelectronic compressor; ARP Quadra phaser), but the major part
of the update is - audio.

Several people have asked me how all this stuff I'm building actually
*sounds*, and I have finally made some samples available (in mpeg 3 
format). These are no "demo samples" of certain instruments, but
short excerpts from my music. I have included elaborate descriptions
which instruments are playing which part, however.
I hope you enjoy it ! (And if you like it, you can buy a CD, too (;->) )

Homepage at synthfool (Thanks to Kevin):
http://www.synthfool.com/diy/hj.html

Mirror Page in Sweden (Thanks to Magnus):
http://www.it.kth.se/~e93_mda/synths/friends/haible/

Regards,

JH.




From jorgen.bergfors at idg.se  Mon Dec  7 12:42:49 1998
From: jorgen.bergfors at idg.se (jorgen.bergfors at idg.se)
Date: Mon, 7 Dec 1998 12:42:49 +0100
Subject: book recomendations
Message-ID: <TFSBSVEX@idg.se>

I recieved the IC opamp cookbook from Amazon.com today! It is out of of print, but they found an used copy for me. I have only looked through it. I don't doubt that it is good, but it is rather old. It was written 1974 and that was before the jfet and cmos opamps came out. So there is no information about them. Just thought you might want to know.

/Jorgen




MIME:pfperry at melbpc.org.au on 98-12-07 12:32:40
To:  synth-diy at mailhost.bpa.nl @ SMTP cc:  (bcc: Jorgen Bergfors/IDGSE)
Subject: Re: book recomendations 

At 12:14 AM 7/12/98 -0600, Rocket Queen  wrote:

>   I am already aware of the following...
>
"The Art of Electronics" Horowitz and Hill, Cambridge University Press
(available at every college bookshop, and pirated throughout asia & eastern europe)

"Troubleshooting Analog Circuits" Robert A. Pease
(available Powell's Technical, etc)

IC Op Amp Cookbook by Walter G. Jung (Sams)

These are my fave picks & the ones the staff "borrow"!

paul perry melbounre australia










From jhaible at primus-online.de  Mon Dec  7 13:58:10 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 7 Dec 1998 13:58:10 +0100
Subject: MXR Envelope Filter
Message-ID: <19981207125910.4104.qmail@nuernberg2.pop.metronet.de>

Hi Perry, and diy list,

I just got the schemos of the MXR envelope filter - thanks !

You asked for comments - This is how I understand it:

All 4069 gates, except 3 gates in the PWM section, are used
in linear mode. Think of them as opamps with negative inputs
only, limited DC gain (but remarkable gain at higher frequencies),
and a rather high output impedance.

Three gates from A-2 form a biquad filter in the audio path.
There are two integrators, one of them with an extra resistor
(R-19) to set the Q of the filter. U-1 and U-2 form variable
resistors in combination with the 47k resistors, and pulse
width modulation. (This is not "switched capacitor" stuff.
In SC filters you emulate a resistor thru a C and switches,
and you vary the resistance by changing clock frequency.
In our circuit, the resistance is changed by altering the
pulse width, or "on/off-ratio" of the switches.)
On the right, below the audio path, there's the PWM circuit:
one gate set as integrator, two gates set as schmitt trigger,
a fourth gate used as comparator.
The control path is a fixed gain inverting amplifier (1 gate),
a variable gain inverting amplifier (next gate), a passive,
AC-coupled rectifier and peak detector, an inverting buffer
stage (next gate), and a manually adjustable low pass
filter (next gate). Then the control path meets the 
comparator for PWM.

JH.



From pfperry at melbpc.org.au  Mon Dec  7 14:08:17 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Tue, 8 Dec 1998 00:08:17 +1100 (EST)
Subject: book recomendations
Message-ID: <1.5.4.16.19970303033722.36cf9bb6@popa.melbpc.org.au>

At 12:42 PM 7/12/98 +0100, jorgen.bergfors wrote:
>I recieved the IC opamp cookbook from Amazon.com today! 
It is out of of print, but they found an used copy for me. 
I have only looked through it. I don't doubt that it is good, 

Sorry for the bum steer, Jorgen.
My copy is 3rd edition, 1986.
The material in it is pretty well covered (and exceeded) by
the Franco book (2nd ed 1998).

A good source for electronics books new & secondhand is 
Powell's technical Books in Seattle (I think seattle, near there anyway)
they have a web catalog. I bought a pile of stuff there and about
half of them were good (you can't tell much from the titles sometimes).
There were two I **HAD** to have, so i chanced a few others as well.

paul perry melb aust

BTW Jung also did one specifically on audio applications of op amps,
but no specifically synth stuff.




From jhaible at primus-online.de  Mon Dec  7 14:32:37 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 7 Dec 1998 14:32:37 +0100
Subject: book recomendations
Message-ID: <19981207133555.4648.qmail@nuernberg2.pop.metronet.de>

> IC Op Amp Cookbook by Walter G. Jung (Sams)

... and CMOS Cookbook by Don Lancaster (Amazone has it.)

JH.



From mark at spooky-solutions.co.uk  Mon Dec  7 14:53:42 1998
From: mark at spooky-solutions.co.uk (Mark Havard-Brown)
Date: Mon, 7 Dec 1998 13:53:42 -0000
Subject: 4016, switching audio and VCO signals
Message-ID: <01be21e9$005acd80$0100007f@default>

All,

Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
they are okay to switch audio, (the fact sheet on them says they will), but
I'd rather hear it coming from someone who has used them. I'm looking at
using them to construct complex oscillator shapes by switching voltages
clocked via a counter. Could they be used in a MIDI controlled audio patch
bay, or is the audio response poor if I were to switch CD quality audio
signals through them.



Mark.




From Chris.List at sc.siemens.com  Mon Dec  7 15:35:48 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Mon, 7 Dec 1998 09:35:48 -0500
Subject: More stuff on the 303...
Message-ID: <81A062BC5305D111A9D700805F065968012EE901@maildepo.sc.siemens.com>

> I just bought 50 pieces of SC1583 for less than DM 1,- a piece.
> You can never kow ... 
> 
	What is this part? Datasheets online somewhere? Sorry if this
has been covered, I haven't been paying very close attention lately.

	- Thanks,
	Chris



From b.layer at vikingelectronics.com  Mon Dec  7 16:33:39 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Mon, 07 Dec 1998 09:33:39 -0600
Subject: OT: Pentium chips
Message-ID: <3.0.6.32.19981207093339.007d8a40@192.168.210.18>

Hey All,

Anyone know about the quirks of of 'old-school' Pentium chips (ie. P90)?
Does Intel have a support site with technical info for obsolete parts?

Pri-vat replies, thanks.


Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From jorgen.bergfors at idg.se  Mon Dec  7 16:43:00 1998
From: jorgen.bergfors at idg.se (jorgen.bergfors at idg.se)
Date: Mon, 7 Dec 1998 16:43:00 +0100
Subject: 4016, switching audio and VCO signals
Message-ID: <TFSCBAJS@idg.se>

I'm using the 4066 with good results. It's equivalent to the 4016, except the on-resistance is lower. Forget the 4016 and use the 4066 instead. It normally works as a replacement too. The price is about the same.

/Jorgen





MIME:mark at spooky-solutions.co.uk on 98-12-07 16:10:44
To:  synth-diy at mailhost.bpa.nl @ SMTP cc:  (bcc: Jorgen Bergfors/IDGSE)
Subject: 4016, switching audio and VCO signals 

All,

Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
they are okay to switch audio, (the fact sheet on them says they will), but
I'd rather hear it coming from someone who has used them. I'm looking at
using them to construct complex oscillator shapes by switching voltages
clocked via a counter. Could they be used in a MIDI controlled audio patch
bay, or is the audio response poor if I were to switch CD quality audio
signals through them.



Mark.










From jhaible at primus-online.de  Mon Dec  7 18:42:21 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 7 Dec 1998 18:42:21 +0100
Subject: SC1583 (was: Re: More stuff on the 303...)
Message-ID: <19981207174445.8190.qmail@nuernberg2.pop.metronet.de>

> 	What is this part? Datasheets online somewhere? Sorry if this
> has been covered, I haven't been paying very close attention lately.

Dual npn transistor with common emitter, which aparently was the standard
choice in many Korg and Roland synthesizers. I don't have any specs or
data sheets, unfortunately. It's very easy to use, as it's a 5 pin SIL
package
(b1, c1, e1/2, c2, b2).

JH.

PS: I was wrong with "less than DM 1,- . That's without VAT. So it's
slightly more than DM 1,- at Reichelt Elektronik.



From oakley at techrepairs.freeserve.co.uk  Mon Dec  7 19:35:27 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Mon, 7 Dec 1998 18:35:27 -0000
Subject: 303 VCO and VCA question.
Message-ID: <000501be221c$56a90a20$7234883e@default>

Hi,

I noticed today that my clone has 50Hz (mains frequency) FM on its VCO.
Nice on some notes, but not wanted at all. I traced it down to the SCR.
The trigger point of the SCR is being modulated by stray hum field, so
the saw resets at different levels, producing a mild FM. Good layout can
certainly reduce this, my original stripboard design had to be changed,
and now it is considerably better, but not gone if you know what you are
listening out for. Has anyone else noticed this problem? I reckon the
base of Q27 with the collector of Q25 is high impedance enough to be of
a problem. This may make my board layout VERY VERY critical.

Can anyone confirm that R126 on the VCA input biasing is 2K2?

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From jhaible at primus-online.de  Mon Dec  7 20:18:09 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 7 Dec 1998 20:18:09 +0100
Subject: 4016, switching audio and VCO signals
Message-ID: <19981207194400.9974.qmail@nuernberg2.pop.metronet.de>

> I'm using the 4066 with good results. It's equivalent to the 4016, except
the on-resistance is > lower. Forget the 4016 and use the 4066 instead. It
normally works as a replacement too. > 

The same for me. I use them, and many synth manufacturers did use them,
too.
There are some caveat's, like charge being coupled into the audio path at
fast
switching, capacitance across the chip that would decrease attenuation in
off-state
in high impedance applications, or distortion because of the nonlinear
resistance
of the switch in on-state (but this would only be a problem in low
impedance
applications, where the on-resistance is not musch smaller than the load
resistance ... in one word, you cannot use it blindly in any application,
but it's
still a good, and unexpensive, component.
Too bad that it can only handle 15V total. That's why I use discrete JFETs
for switching in most of my +/-15V circuits.

JH.
 



From camotse at france-mail.com  Tue Dec  8 02:05:53 1998
From: camotse at france-mail.com (GreG)
Date: Tue, 8 Dec 1998 02:05:53 +0100
Subject: a beginner question - scopes
Message-ID: <001b01be2247$d128ffa0$6115eec3@bs132506>

Hi list.

I am needing (arg) to buy an oscilloscope. At the local shop they adviced me a pc based one, saying it was a cheap alternative to classic models, a bit more expensive then cheapcheappo models but far more reliable. What do u guys'n'girls think? Is this worth it? Is it precise enough for audio based circuits? Please tell me..as they ordered it for me, but i think i can still say no if i'm quick enough... i'm **hesitating**.. maybe a cheapo one could do the trick for me? (but they're not THAT cheaper compared to pro scopes they talked to me about...) So maybe u could at least tell what characteristics i DO need from a scope...
thanx

greg.
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From camotse at france-mail.com  Tue Dec  8 02:11:47 1998
From: camotse at france-mail.com (GreG)
Date: Tue, 8 Dec 1998 02:11:47 +0100
Subject: anyone from belgium in here? - i need a +/-15v ps
Message-ID: <001c01be2247$d224c4c0$6115eec3@bs132506>

Hi list again.

Lastly i called for advice for what ps i needed for the asm1. I now know that i need like 1.5a to be safe with my 2asm1's. Would it be enough for 2asms , 1 midi2cv8 and maybe some mods from Mr tomg? 
Ok my real question was: I need +15/-15v .. i went to shops here in brussels and they don't even have that in their catalogs. (but they suck:) I also asked my 'usual' retailer (which is located in namur for those that know - the belgians i was talking about.) and he's trying to locate one or two for me, but didn't find at his usual adresses. Does anyone know where i could find that here in belgium or maybe france, netherlands, germany, somewhere near...?? And.. no thanks mr Blacet, i don't really want a wallwart thingy-that-stuff-my-wall :o))), i'm looking for something i could put in the back of the rack of the asm1s...
So...got any idea chaps?

thanx again
greg.
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From THEKn0TiS at aol.com  Tue Dec  8 02:14:40 1998
From: THEKn0TiS at aol.com (THEKn0TiS at aol.com)
Date: Mon, 7 Dec 1998 20:14:40 EST
Subject: evil 606 mod questions
Message-ID: <f6162a58.366c7d80@aol.com>

imagine a +5v -5v cv controll pot for each step on the tr606 sequencer wouldnt
this effectivly make the 606 into a analogue sequencer ??? any ideas how to do
this i have schamatics for the whole beast ...



From THEKn0TiS at aol.com  Tue Dec  8 03:09:31 1998
From: THEKn0TiS at aol.com (THEKn0TiS at aol.com)
Date: Mon, 7 Dec 1998 21:09:31 EST
Subject: 606 mod question
Message-ID: <7a3e0622.366c8a5b@aol.com>

imagine a +5v -5v cv controll pot for each step on the tr606 sequencer wouldnt
this effectivly make the 606 into a analogue sequencer ??? any ideas how to do
this i have schamatics for the whole beast ...



From ijfritz at earthlink.net  Tue Dec  8 03:12:30 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Mon, 07 Dec 1998 19:12:30 -0700
Subject: 4016, switching audio and VCO signals
References: <01be21e9$005acd80$0100007f@default>
Message-ID: <366C8B0E.358BCDB7@earthlink.net>

They're not useful for wide-swing bipolar signals. I'd recommend
something like the DG211, or its descendents.

  Ian

Mark Havard-Brown wrote:
> 
> All,
> 
> Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
> they are okay to switch audio, (the fact sheet on them says they will), but
> I'd rather hear it coming from someone who has used them. I'm looking at
> using them to construct complex oscillator shapes by switching voltages
> clocked via a counter. Could they be used in a MIDI controlled audio patch
> bay, or is the audio response poor if I were to switch CD quality audio
> signals through them.
> 
> Mark.



From travis at it.net.au  Tue Dec  8 03:36:32 1998
From: travis at it.net.au (Travis Endersby)
Date: Tue, 8 Dec 1998 10:36:32 +0800 (WST)
Subject: book recomendations - for a beginner
In-Reply-To: <001401be225a$733c8660$11754e0c@hpcustomer>
Message-ID: <Pine.LNX.3.96.981208103548.1127A-100000@belgarion.it.net.au>

may i please ask if any one can recognise a SMALL book for an absolute
BEGINNER.

thanx again
trav




From theremin1 at worldnet.att.net  Tue Dec  8 04:25:47 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 7 Dec 1998 19:25:47 -0800
Subject: book recomendations
Message-ID: <001401be225a$733c8660$11754e0c@hpcustomer>

Just let me know if you need any antique Fairchild uA702 op amps to go with
your antique book!  (;

-Art

-----Original Message-----
From: jorgen.bergfors at idg.se <jorgen.bergfors at idg.se>
To: pfperry at melbpc.org.au <pfperry at melbpc.org.au>; synth-diy at mailhost.bpa.nl
<synth-diy at mailhost.bpa.nl>
Date: Monday, December 07, 1998 6:11 AM
Subject: Re: book recomendations


>I recieved the IC opamp cookbook from Amazon.com today! It is out of of
print, but they found an used copy for me. I have only looked through it. I
don't doubt that it is good, but it is rather old. It was written 1974 and
that was before the jfet and cmos opamps came out. So there is no
information about them. Just thought you might want to know.
>
>/Jorgen
>
>
>
>
>MIME:pfperry at melbpc.org.au on 98-12-07 12:32:40
>To:  synth-diy at mailhost.bpa.nl @ SMTP cc:  (bcc: Jorgen Bergfors/IDGSE)
>Subject: Re: book recomendations
>
>At 12:14 AM 7/12/98 -0600, Rocket Queen  wrote:
>
>>   I am already aware of the following...
>>
>"The Art of Electronics" Horowitz and Hill, Cambridge University Press
>(available at every college bookshop, and pirated throughout asia & eastern
europe)
>
>"Troubleshooting Analog Circuits" Robert A. Pease
>(available Powell's Technical, etc)
>
>IC Op Amp Cookbook by Walter G. Jung (Sams)
>
>These are my fave picks & the ones the staff "borrow"!
>
>paul perry melbounre australia
>
>
>
>
>
>
>




From theremin1 at worldnet.att.net  Tue Dec  8 05:02:08 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 7 Dec 1998 20:02:08 -0800
Subject: 4016, switching audio and VCO signals
Message-ID: <001b01be225f$8756c200$11754e0c@hpcustomer>

The CD4016 is a fine quad analog switch for many applications,
however, note that there is considerable on-resistance variation
that is signal-voltage dependent.  This is the characteristic that
inevitably leads to signal distortion in some audio (and other)
applications.  However, you may not notice this in your oscillator
application, since you are apparently commutating fixed voltages,
and these voltages may be "pre-distorted" to compensate for switch
resistance variations.

On the other hand, applying these devices in a music or voice audio
circuit _may_ introduce noticeable distortion depending on relative
impedances in the switch path.  Also, be aware of the charge injection
parameter for this device.  Such charge injection might cause audible
"pops" during commutation.  Even if charge injection were infinitesimal,
the rate of change, i.e., the abrupt switching action of such devices,
will most certainly cause a noticeable "click" during program transitions.
Also be aware of channel separation between switches in the same package.

The 4016 is very inexpensive, and manufactured by a number of vendors.
These are great benefits.  However, high-end audio switchers do not
generally
use them for the above-mentioned reasons.  Here's an alternative choice:
Analog Devices SSM2404.  A blurb with further links may be seen at:
http://products.analog.com/products/info.asp?product=SSM2404
This device incorporates a "ramping" technique to assure "clickless"
switching.

Aside from these application-specific audio switches, there are also a great
number of devices available with very low charge injection and essentially
"flat"
on resistance.  Both Analog Devices and Maxim are good places to start
looking.

-Art in thereminland

"If you met yourself, would you form a band and harmonize?"


-----Original Message-----
From: Mark Havard-Brown <mark at spooky-solutions.co.uk>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Monday, December 07, 1998 7:00 AM
Subject: 4016, switching audio and VCO signals


>All,
>
>Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
>they are okay to switch audio, (the fact sheet on them says they will), but
>I'd rather hear it coming from someone who has used them. I'm looking at
>using them to construct complex oscillator shapes by switching voltages
>clocked via a counter. Could they be used in a MIDI controlled audio patch
>bay, or is the audio response poor if I were to switch CD quality audio
>signals through them.
>
>
>
>Mark.
>
>




From theremin1 at worldnet.att.net  Tue Dec  8 05:11:36 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 7 Dec 1998 20:11:36 -0800
Subject: Roland BA662 data
Message-ID: <002e01be2260$da033280$11754e0c@hpcustomer>


-----Original Message-----
From: Quint <qfulsom at usa.net>
To: DIY <synth-diy at mailhost.bpa.nl>; Haible Juergen
<Juergen.Haible at nbgm.siemens.de>
Date: Monday, December 07, 1998 7:58 AM
Subject: RE: Roland BA662 data


[snip]  >I'm also researching a component LMC662 which I cant really find
anything on.

>Quint

http://www.national.com/pf/LM/LMC662.html has information on this device.
For new designs, I suggest the LMC6482IN  (that's an "I," not a "1" in the
part number.)
Also, there are many other, more recent, CMOS op amp introductions that may
be
worth investigating.

-Art in thereminland




From theremin1 at worldnet.att.net  Tue Dec  8 05:16:17 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 7 Dec 1998 20:16:17 -0800
Subject: SC1583 (was: Re: More stuff on the 303...)
Message-ID: <003901be2261$98df5da0$11754e0c@hpcustomer>

NTE, by the way, crosses this device as their type "NTE42."

-Art

-----Original Message-----
From: jhaible <jhaible at primus-online.de>
To: List, Christopher <Chris.List at sc.siemens.com>; synth diy
<synth-diy at mailhost.bpa.nl>
Date: Monday, December 07, 1998 12:38 PM
Subject: SC1583 (was: Re: More stuff on the 303...)


>> What is this part? Datasheets online somewhere? Sorry if this
>> has been covered, I haven't been paying very close attention lately.
>
>Dual npn transistor with common emitter, which aparently was the standard
>choice in many Korg and Roland synthesizers. I don't have any specs or
>data sheets, unfortunately. It's very easy to use, as it's a 5 pin SIL
>package
>(b1, c1, e1/2, c2, b2).
>
>JH.
>
>PS: I was wrong with "less than DM 1,- . That's without VAT. So it's
>slightly more than DM 1,- at Reichelt Elektronik.
>




From Aranakin at aol.com  Tue Dec  8 06:11:43 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Tue, 8 Dec 1998 00:11:43 EST
Subject: MPU-104=>MPU-105?
Message-ID: <659b6968.366cb50f@aol.com>

does anyone know if you can take a MPU-104, change something around in it, and
make a MPU-105?

that isto say, can you take a 1 in, 5 out box and make it a 5 in, 1 out box?
anthony



From Aranakin at aol.com  Tue Dec  8 06:13:45 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Tue, 8 Dec 1998 00:13:45 EST
Subject: TB-303 for sale or trade
Message-ID: <5fedc7b3.366cb589@aol.com>

I have a mint TB-303 for sale for $900 or trade for a VS-880 or VS-840
Aranakin at aol.com



From Aranakin at aol.com  Tue Dec  8 07:39:14 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Tue, 8 Dec 1998 01:39:14 EST
Subject: MPU104=>MPU105?
Message-ID: <e204236c.366cc992@aol.com>

does anyone know if you can take a MPU-104, change something around in it, and
make a MPU-105?

that isto say, can you take a 1 in, 5 out box and make it a 5 in, 1 out box?
anthony



From martin.czech at intermetall.de  Tue Dec  8 08:20:44 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Tue, 8 Dec 1998 08:20:44 +0100 (MET)
Subject: a beginner question - scopes
Message-ID: <199812080720.IAA02756@window.intermetall.de>

> Hi list.
> 
> I am needing (arg) to buy an oscilloscope. At the local shop they adviced me a pc based one, saying it was a cheap alternative to classic models, a bit more expensive then cheapcheappo models but far more reliable. What do u guys'n'girls think? Is this worth it? Is it precise enough for audio based circuits? Please tell me..as they ordered it for me, but i think i can still say no if i'm quick enough... i'm **hesitating**.. maybe a cheapo one could do the trick for me? (but they're not THAT cheaper compared to pro scopes they talked to me about...) So maybe u could at least tell what characteristics i DO need from a scope...
> thanx
> 
> greg.

Greg, this is like the washing machine story, you know... When I was young
(;->), I thought it would be a good idea to save money and so I bought
a used one, . Ok, after one year it broke down in a cloud of smoke,
the service man said "not repairable", charged me with 40DM (you know
Zappa's Flakes?)  and disappeared. I had to pay for the removal of the
old machine also, alltogether 990 DM.

And then I was enlightened. I went to the local shop and bougth the
most expensive, highest quality machine (a Miele). Cost me an awfull
lot of cash.  Dropped it in into th e cellar, and it works, and works,
and works..... Never any problems, peace of mind.  I'm shure this was a
good deal, cheapo machines would have cost me a lot of grief and repair
money, so it is a reall cost saver.

A few weeks ago, I was in the same situation, trying to find a scope. Well
I tryed the cheapo first, and then I remembered, man... don't be
stupid, a scope is a lifetime buy, so I took a reasonable scope with
150MHz bandwidth, dual timebase, processor controlled, and user menu
callibration. For 2300 DM. (1$ = 1.67 DM).  Today I get it from the
post office.

The scope is the main tool on the electronic workbench, I don't want
to work with crap tools.

The simple DSO you can get for a PC today seem to be quite crappy.
Very limited analog bandwidth, no spec for ADC resolution, no specs for
display refresh times ... etc. In general no specs at all. You didn't
mention any specs in your mail... This is supposed to be a measurement
tool, if it has no specs, now, what should this be ?  In most cases such
a PC slot card may do, there are others where it won't.

And the better ones (I've seen a 60 MHz bandwidth recently, Conrad
Electronic) go straight into the 1000 DM direction.

Even the really high price DSO here at work (that we bought a couple of
years ago) have quite slow aquisition rates, so if you have a sporadic
problem, but you can't trigger it right, you most probably won't see
it. In these cases it is time to pull out the good old Tektronics analog
scope, ahhh there is the glitch.

DSO manufacturers know this problem, they try to make their scopes faster
to give them a more analog feel in the readout.




So: be very carefull to where you spend your money! At least you should
try the PC scope card in the shop, or even better at home. Try e.g. a
burst signal that has very low mark/space ratio. Try higher frequencys,
go to the analog bandwidth limit. Never buy it blind.

You get nothing for nothing.

And remember my washing machine...   ;->

m.c.




From vco at mindspring.com  Tue Dec  8 08:47:15 1998
From: vco at mindspring.com (tomg)
Date: Tue, 08 Dec 1998 02:47:15 -0500
Subject: Mad Mouse Update #3
Message-ID: <yam7646.758.120866600@mail.mindspring.com>

Put up the demo wave file. Maybe final pcb/skiz tomorrow.

http://www.mindspring.com/~vco/madm/pics/mm_wave.wav

-tg




From vco at mindspring.com  Tue Dec  8 08:48:02 1998
From: vco at mindspring.com (tomg)
Date: Tue, 08 Dec 1998 02:48:02 -0500
Subject: Dr. Q
Message-ID: <yam7646.108.120866600@mail.mindspring.com>


Put up my reverse-eng EH Dr.Q. It you're the guy with 
the broken one, this might help.


http://www.mindspring.com/~vco/effects/page_003.html

-tg




From vco at mindspring.com  Tue Dec  8 09:16:36 1998
From: vco at mindspring.com (tomg)
Date: Tue, 08 Dec 1998 03:16:36 -0500
Subject: AD: Mad Mouse Update #3
Message-ID: <yam7646.1809.118768488@mail.mindspring.com>

>Put up the demo wave file. Maybe final pcb/skiz tomorrow.

>http://www.mindspring.com/~vco/madm/pics/mm_wave.wav

>-tg

Sorry I had to go so quick last time. The demo was recorded
directly to the Amiga HD over 5 tracks then mixed to one
,using my Sunrise audio card, then converted to 8 bit 11.6.
It's about 275K.

I connected the MM to the D5 with a paia midi2cv8.

Just a note to say thanks to John Simonton. I started the 
MM because I was inspired by his "Gnome", to build a micro 
synth. I finished it thanks to inspiration from his "Fatman".
I owe you one John, thanks.

L8R

-tg
 








From zzynt at swipnet.se  Tue Dec  8 09:40:23 1998
From: zzynt at swipnet.se (BJ)
Date: Tue, 08 Dec 1998 00:40:23 -0800
Subject: 4016, switching audio and VCO signals
References: <000f01be22e2$d313dc40$a034883e@default>
Message-ID: <366CE5F7.52D1@swipnet.se>

Tony Allgood wrote:
> 
> Hi,

HiHo! 

> I would not want to pass the final mix out through one, or a 4066
> directly. Why?
> 1. Distortion is too high

In singel switch mode usage at high voltage and at CD quality audio
allmost YES!

> 2. Limited output swing +7V5 to -7V5 is your max. This will also make

Usually YES, but there is a +18Volt version of 4066,4016.

> your control signal rather tricky. You could bias the audio up to half
> of 15V before switching.

Take a NPN and let it sving between rails.

> 3. You have to use two. One series pass, the other shunt. NOT control
> required.

YES, improves tremendously, now CD quality and better are achived.

> 4. They do thump a bit, you will hear it.

Many sources of this phenomen , one is leek currents, a cure is switch
when amplitude is low or at zero crossing, but usually not a problem.

> 5. Some better parts exist. SSM used to do a click less audio one. I do
> not know whether they still do. The DG2xx series are quite good, but
> again should be used with an op-amp. DBX vca's are good too, but pricey.

Hmm!

> 6. Op amp and two fets are better. No click. Controlled on times. And
> less bleedthrough. If used near the virtual earth they are switching
> current not voltage (except for Rds on), output swing limited by the
> op-amp.

Right.
 
> If anyone needs the circuit for this, mail me and I will do a copy in a
> few days. I don't feel up to ascii drawing at the moment. My baby
> daughter's teeth are deciding to come down today.

Nice! Dont use a 4066 for switch off baby crying!! 
 
BJ



From blacet at metro.net  Tue Dec  8 09:56:09 1998
From: blacet at metro.net (John Blacet)
Date: Tue, 08 Dec 1998 08:56:09 +0000
Subject: Cable kits
Message-ID: <366CE9A8.28A5@metro.net>

I just finished up a pretty slick color coded 1/8" patch cable kit. More
details below!

Regards.
-------------------------
John Blacet
Blacet Research Music Electronics
-------------------------
blacet at metro.net
http://metro.net/blacet/music.html



From costello at seanet.com  Tue Dec  8 10:19:34 1998
From: costello at seanet.com (Sean Costello)
Date: Tue, 08 Dec 1998 01:19:34 -0800
Subject: Mad Mouse Update #3
References: <yam7646.758.120866600@mail.mindspring.com>
Message-ID: <366CEF26.D35D9114@seanet.com>

tomg wrote:
> 
> Put up the demo wave file. Maybe final pcb/skiz tomorrow.
> 
> http://www.mindspring.com/~vco/madm/pics/mm_wave.wav

Wow!  I was listening to "Mambo Sun" on my computer's CD player while
downloading your demo, & your music started playing on it's own.  T.Rex
never sounded quite like that.  Very tasty filter!  Congrats!

Sean Costello



From vco at mindspring.com  Tue Dec  8 10:54:38 1998
From: vco at mindspring.com (tomg)
Date: Tue, 08 Dec 1998 04:54:38 -0500
Subject: Mad Mouse Update #4
Message-ID: <yam7646.1937.119646016@mail.mindspring.com>

Got the final (I hope) drawing up.

http://www.mindspring.com/~vco/madm/pics/mm_sd.gif

-tg
 








From vco at mindspring.com  Tue Dec  8 10:55:20 1998
From: vco at mindspring.com (tomg)
Date: Tue, 08 Dec 1998 04:55:20 -0500
Subject: Mad Mouse Update #3
In-Reply-To: <366CEF26.D35D9114@seanet.com>
Message-ID: <yam7646.1005.119646016@mail.mindspring.com>

On 08-Dec-98, Sean Costello wrote:
>tomg wrote:
>> 
>> Put up the demo wave file. Maybe final pcb/skiz tomorrow.
>> 
>> http://www.mindspring.com/~vco/madm/pics/mm_wave.wav

>Wow!  I was listening to "Mambo Sun" on my computer's CD player while
>downloading your demo, & your music started playing on it's own.  T.Rex
>never sounded quite like that.  Very tasty filter!  Congrats!

>Sean Costello

Thanks!

-tg





From zimage at cs.wisc.edu  Tue Dec  8 11:28:32 1998
From: zimage at cs.wisc.edu (Tim Nowaczyk)
Date: Tue, 8 Dec 1998 04:28:32 -0600 (CST)
Subject: a beginner question - scopes
In-Reply-To: <199812080720.IAA02756@window.intermetall.de>
Message-ID: <Pine.GSO.3.96L.981208042704.26874A-100000@nova29.cs.wisc.edu>

	Does anyone have any experience with the scope at bitscope.com?
I'm also a beginner, and this sound like a good deal.

Thanks,
Tim Nowaczyk




From martin.czech at intermetall.de  Tue Dec  8 15:05:11 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Tue, 8 Dec 1998 15:05:11 +0100 (MET)
Subject: aluminum plates and profiles
Message-ID: <199812081405.PAA06448@window.intermetall.de>

Hello,

I just got an answer from Schaeffer Apparatebau (these people do engraved
front panels). I asked if they could also cut aluminum plates for the
other 5 sides of a module box, and also alu profiles in order to connect
front panel and the 5 other sides.  Well, they can do this, but since
they have no saw but only a computer controlled engraving machine this
can get very expensive. OTOH aluminum cutting is an awful job, I guess
a proper saw (be it circular or not) would cost about 600 DM.

Does anybody know a shop in Germany or nearby where I can get my aluminum
cut?

m.c.





From beszedes at cc.u-szeged.hu  Tue Dec  8 15:17:38 1998
From: beszedes at cc.u-szeged.hu (Beszedes Arpad)
Date: Tue, 08 Dec 1998 15:17:38 +0100
Subject: a beginner question - scopes
References: <Pine.GSO.3.96L.981208042704.26874A-100000@nova29.cs.wisc.edu>
Message-ID: <366D3502.8D3988B5@cc.u-szeged.hu>

Hi!

I am also interested in this stuff. About the custom chips, are they
easy to find?
(I mean mainly of: LATTICE ispLSI 1016-80)

Arpad.


Tim Nowaczyk wrote:
> 
>         Does anyone have any experience with the scope at bitscope.com?
> I'm also a beginner, and this sound like a good deal.
> 
> Thanks,
> Tim Nowaczyk

-- 
***********************************************
*  Arpad Beszedes                             *
*                                             *
*  Research Group on Artificial Intelligence  *
*  Hungarian Academy of Sciences              *
*  Attila Jozsef University, Szeged, Hungary  *
*  e-mail: beszedes at cc.u-szeged.hu            *
*  tel.: (+36) 62/45-41-45                    *
***********************************************



From marc at outputs.com  Tue Dec  8 15:21:51 1998
From: marc at outputs.com (Marc Houle)
Date: Tue, 08 Dec 1998 09:21:51 -0500
Subject: minimoog part
Message-ID: <199812081339.IAA27598@godzilla.outputs.com>

I went to fix a couple broken keys on a friend's minimoog and pulled it
apart only to find that
a couple of those plastic bands that pull the springs to make a contact for
each key were gone.

1. What are these called?

2. Where can I find some?

THANKS guys,

Marc



From b.layer at vikingelectronics.com  Tue Dec  8 15:59:11 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 08 Dec 1998 08:59:11 -0600
Subject: Scope FAQs and Washing Machines
Message-ID: <3.0.6.32.19981208085911.007d99f0@192.168.210.18>

Hi Martin, All,

Ok. Who wants to write the Synth-DIYer's O-scope FAQ? The question comes up
every other week - and it's a good (hard) one to answer in a word or two.
We need two people: one from the digital world and one from the analog
world - to meld their minds and write a document that covers both bases.

That being said, I'll reiterate that I get by with my British Telequipment
Model 67, made in 1973 and bought two years back for $75.00(USD). It has 2
rocking Megahertz o' bandwidth, and never fails in audio service.

On a seperate note, sorry to hear about the experience with the washing
machine Martin. Mine was much luckier; I bought a used washer/dryer pair
for $200 when I moved into my house. That was six years ago - no trouble
yet, save one $2 smubber pad. KNOCK ON WOOD.

Then again, they were so mint that they still had all the showroom stickers
affixed, from the late 1960's! What kind of a mind does it take to do that?


=======================================================================
This message and any attachments to it are subject to copying and are 
sent solely for the personal amusement the sender.  It may include 
information which is technically wrong and exempt from disclosure. If 
you receive this communication in any way, please ignore us immediately.
========================================================================




From marc at outputs.com  Tue Dec  8 16:04:26 1998
From: marc at outputs.com (Marc Houle)
Date: Tue, 08 Dec 1998 10:04:26 -0500
Subject: minimoog part
Message-ID: <199812081422.JAA27783@godzilla.outputs.com>

I went to fix a couple broken keys on a friend's minimoog and pulled it
apart only to find that
a couple of those plastic bands that pull the springs to make a contact for
each key were gone.

1. What are these called?

2. Where can I find some?

THANKS guys,

Marc 



From chris.crosskey at metrics.co.uk  Tue Dec  8 17:26:11 1998
From: chris.crosskey at metrics.co.uk (Chris Crosskey)
Date: Tue, 8 Dec 1998 16:26:11 -0000 
Subject: UK source of 2SC1583's......
Message-ID: <988331E4E8A4D011A02500A024F00AE71EB520@host2.oxfordmetrics.co.uk>

Hi Folks, for all of you in the UK, there is a UK source of 2SC1583's, CPC
do them for 75 pence pluis VAT each for up to five and 67 pence plus VAT
from there on. They actually do a staggering array of stuff, there's a load
of Rohm BA-xxx series stuff in tehre too, what was the part number of that
potential Roland OTA replacement......I don't get the list at work so I
don't have it to hand ATM...

chrisc



From ka4hjh at gte.net  Tue Dec  8 20:09:53 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Tue, 8 Dec 1998 14:09:53 -0500
Subject: Bitscope (was a beginner question - scopes)
In-Reply-To: <366D3502.8D3988B5@cc.u-szeged.hu>
References: <Pine.GSO.3.96L.981208042704.26874A-100000@nova29.cs.wisc.edu>
Message-ID: <v04011701b2932862cd27@[208.255.152.197]>

>Hi!
>
>I am also interested in this stuff. About the custom chips, are they
>easy to find?
>(I mean mainly of: LATTICE ispLSI 1016-80)

I seem to remember the author saying in the original Circuit Cellar Ink
article that he deliberately used readily available stuff. There were two
oddballs in the design, one of which is on every '486 motherboard ever made
(or something like that). Check the website and/or try e-mailing him. I
roughly calculated that even if you bought the PC board and the hard to get
chips from him, the total cost (minus enclosure, probes, etc.) would be
well under $200--insanely cheap for a device like this!

Terry Bowman, KA4HJH
"The Mac Doctor"



From oakley at techrepairs.freeserve.co.uk  Tue Dec  8 20:27:19 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Tue, 8 Dec 1998 19:27:19 -0000
Subject: More stuff on the 303...
Message-ID: <000c01be22e2$cfbd5e40$a034883e@default>

Hi,

The 2SC1583 is a dual NPN in a funny looking 5-pin package. It is a
Japanese part and used in the TB303 in the expo in the VCO, the bottom
pair in the diode ladder, and the diff amp in the filter. Some people
reckon it is this part that makes the TB sound as it does.

Talking of which. Check out:
http://techno.303.org/secrets.html

It made me chuckle....

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html


-----Original Message-----
From: List, Christopher <Chris.List at sc.siemens.com>
To: synth diy <synth-diy at mailhost.bpa.nl>
Date: Monday, 07th December, 1998 5:04 PM
Subject: RE: More stuff on the 303...


> I just bought 50 pieces of SC1583 for less than DM 1,- a piece.
> You can never kow ...
>
What is this part? Datasheets online somewhere? Sorry if this
has been covered, I haven't been paying very close attention lately.

- Thanks,
Chris





From b.layer at vikingelectronics.com  Tue Dec  8 20:39:36 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 08 Dec 1998 13:39:36 -0600
Subject: For Sale: EH Q-Tron
Message-ID: <3.0.6.32.19981208133936.007e8ac0@192.168.210.18>

Hi All,

For Sale: Electro-Harmonix Q-Tron envelope controlled filter. As new, in
box with full documentation warranty etc. Mint mint mint as the day it was
made - not a scratch on it.

Designed by Mike Biegel of Mutron fame.

$120 b/o - or partial trade for Mutron Bi-Phase. Pri-vat replies please.


Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From pab210 at is8.nyu.edu  Tue Dec  8 20:40:03 1998
From: pab210 at is8.nyu.edu (Plinio Andres Barraza)
Date: Tue, 8 Dec 1998 14:40:03 -0500 (EST)
Subject: Boring Question
Message-ID: <Pine.OSF.3.95.981208143025.21570B-100000@is8.nyu.edu>



Can anyone please confirm these pinouts for me.  I am troubleshooting a
circuit and I still can't get it to work:

TLO72:

      -------  
 -in  -|   |- +V
 +in  -|   |- out
  -V  -------

CA3080:

      ------- +V
 -in  -|   |- 
 +in  -|   |- out
  -V  ------- gain

I pardon the ignorance but I will be very grateful if anyone can help.

Thanks in advance,

Plinio




From oakley at techrepairs.freeserve.co.uk  Tue Dec  8 20:40:29 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Tue, 8 Dec 1998 19:40:29 -0000
Subject: 4016, switching audio and VCO signals
Message-ID: <000f01be22e2$d313dc40$a034883e@default>

Hi,

I would not want to pass the final mix out through one, or a 4066
directly. Why?
1. Distortion is too high
2. Limited output swing +7V5 to -7V5 is your max. This will also make
your control signal rather tricky. You could bias the audio up to half
of 15V before switching.
3. You have to use two. One series pass, the other shunt. NOT control
required.
4. They do thump a bit, you will hear it.
5. Some better parts exist. SSM used to do a click less audio one. I do
not know whether they still do. The DG2xx series are quite good, but
again should be used with an op-amp. DBX vca's are good too, but pricey.
6. Op amp and two fets are better. No click. Controlled on times. And
less bleedthrough. If used near the virtual earth they are switching
current not voltage (except for Rds on), output swing limited by the
op-amp.

If anyone needs the circuit for this, mail me and I will do a copy in a
few days. I don't feel up to ascii drawing at the moment. My baby
daughter's teeth are deciding to come down today.

However, for switching VCO outputs & inputs, etc the 4016/66 is fine.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html



All,

Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
they are okay to switch audio, (the fact sheet on them says they will),
but
I'd rather hear it coming from someone who has used them. I'm looking at
using them to construct complex oscillator shapes by switching voltages
clocked via a counter. Could they be used in a MIDI controlled audio
patch
bay, or is the audio response poor if I were to switch CD quality audio
signals through them.



Mark.














From lbupp at eagle.ycp.edu  Tue Dec  8 20:45:05 1998
From: lbupp at eagle.ycp.edu (Lewis Bupp)
Date: Tue, 8 Dec 1998 14:45:05 -0500 (EST)
Subject: IC and Trasnsister updates
Message-ID: <Pine.SOL.3.96.981208144108.28161D-100000@goose.ycp.edu>

Hi all. Can anyone suggest a good crossref for transistors and IC's which
will show updates, new numbers and things?

thanks ahead of time.

Lew Bupp II
Audio/Video Technician
York College of Pa.
York, Pa. 17403
717-815-1395
717-852-8543




From buchanan at qualcomm.com  Tue Dec  8 20:52:36 1998
From: buchanan at qualcomm.com (Buck Buchanan)
Date: Tue, 08 Dec 1998 11:52:36 -0800
Subject: a beginner question - scopes
In-Reply-To: <001b01be2247$d128ffa0$6115eec3@bs132506>
Message-ID: <3.0.3.32.19981208115236.01408440@mage.qualcomm.com>

A non-text attachment was scrubbed...
Name: not available
Type: text/enriched
Size: 2310 bytes
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From fa_diy at fa.camelot.de  Tue Dec  8 21:31:00 1998
From: fa_diy at fa.camelot.de (Florian Anwander)
Date: 08 Dec 1998 22:31:00 +0200
Subject: desperately ssekin'
Message-ID: <76SFlOY4HFB@fa.camelot.de>

Hello folks

I am looking for service-manual / schematics of a "Concert-Mate DG1" (Pseudo  
Moog Rogue with additional polyphonic oscillator and ring mod). Exists it on  
the Web? Or could someone make a copy for me?


Gruss,
 Florian Anwander
-------------------------------------------------------------------------
Maus-Netz: Florian Anwander at M4
Internet:  fa at fa.camelot.de           http://www.camelot.de/~fa/
## CrossPoint v3.11 R ##



From pab210 at is8.nyu.edu  Tue Dec  8 22:00:18 1998
From: pab210 at is8.nyu.edu (Plinio Andres Barraza)
Date: Tue, 8 Dec 1998 16:00:18 -0500 (EST)
Subject: Mad Mouse Update #3
In-Reply-To: <yam7646.758.120866600@mail.mindspring.com>
Message-ID: <Pine.OSF.3.95.981208155326.15462A-100000@is8.nyu.edu>


* * *   **   * * *  *
* * *  *  *  * * *  *
* * *  *  *  * * *  *
* * *  *  *  * * *
 * *    **    * *   *

Awesome sounds, was this all done real time or did you lay down tracks?

I think I'll have to build this little devil.

Plinio

-----------
On Tue, 8 Dec 1998, tomg wrote:

> Put up the demo wave file. Maybe final pcb/skiz tomorrow.
> 
> http://www.mindspring.com/~vco/madm/pics/mm_wave.wav
> 
> -tg
> 
> 




From aschrock at cs.brandeis.edu  Tue Dec  8 22:07:12 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Tue, 8 Dec 1998 16:07:12 -0500 (EST)
Subject: Boring Question
In-Reply-To: <Pine.OSF.3.95.981208143025.21570B-100000@is8.nyu.edu>
Message-ID: <Pine.HPP.3.95.981208160358.10816B-100000@bay.cs.brandeis.edu>

On Tue, 8 Dec 1998, Plinio Andres Barraza wrote:
> Can anyone please confirm these pinouts for me.  I am troubleshooting a
> circuit and I still can't get it to work:
> 
> TLO72:

This is a corrected ascii-matic: 

>  out1 ------- V+
>  -in1 -|   |- out2
>  +in1 -|   |- -in2
>   -V  ------- +in2

TL072 is a _dual_ opamp, not a single. If you just need a single, use one
side of it. 

> CA3080:
> 
>       ------- +V
>  -in  -|   |- 
>  +in  -|   |- out
>   -V  ------- gain

I don't have the specs in my head for the 3080 off the top of my head, but
I don't think the 4th pin is V-. Maybe somebody can clarify. 

> I pardon the ignorance but I will be very grateful if anyone can help.

NP! 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|







From jhaible at primus-online.de  Tue Dec  8 22:39:52 1998
From: jhaible at primus-online.de (jhaible)
Date: Tue, 8 Dec 1998 22:39:52 +0100
Subject: aluminum plates and profiles
Message-ID: <19981208213928.143.qmail@nuernberg2.pop.metronet.de>

At the moment I have a similar problem. I consider putting
the HiFli into a 19" / 3 or 4 HE box, and have the front panel made at
Schaeffer.
I can think of two alternatives: Buy one of these black 19" boxes from 
Conrad Electronic. They are very nice, with two handles left and right, and
cost
under DM 100,- . Then I would replace the blank panel with the one from
Schaeffer.
I also think about using a Schaeffer Front panel and a wooden enclosure.
I will have all inputs and outputs on the front panel, anyway, so I could
build the rest from plywood. Very cheap, and you won't see it as long
as it's rack mounted.

JH.

----------
> Von: Martin Czech <martin.czech at intermetall.de>
> An: synth-diy at mailhost.bpa.nl
> Betreff: aluminum plates and profiles
> Datum: Dienstag, 8. Dezember 1998 15:05
> 
> Hello,
> 
> I just got an answer from Schaeffer Apparatebau (these people do engraved
> front panels). I asked if they could also cut aluminum plates for the
> other 5 sides of a module box, and also alu profiles in order to connect
> front panel and the 5 other sides.  Well, they can do this, but since
> they have no saw but only a computer controlled engraving machine this
> can get very expensive. OTOH aluminum cutting is an awful job, I guess
> a proper saw (be it circular or not) would cost about 600 DM.
> 
> Does anybody know a shop in Germany or nearby where I can get my aluminum
> cut?
> 
> m.c.
> 
> 
> 



From b.layer at vikingelectronics.com  Tue Dec  8 22:54:52 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 08 Dec 1998 15:54:52 -0600
Subject: a beginner question - scopes
In-Reply-To: <3.0.3.32.19981208115236.01408440@mage.qualcomm.com>
References: <001b01be2247$d128ffa0$6115eec3@bs132506>
Message-ID: <3.0.6.32.19981208155452.007e9aa0@192.168.210.18>

 Hey All,

>As a general rule for analog synth stuff I believe the following (and I
>believe others will believe this general rule): If you can only have one
>scope, you must have an analog.  

Ditto on the Analog scope bit. We've got plenty of both here, and when
someone comes my direction with a digital model, I just run the other way
as fast as I can. 


=======================================================================
This message and any attachments to it are subject to copying and are 
sent solely for the personal amusement the sender.  It may include 
information which is technically wrong and exempt from disclosure. If 
you receive this communication in any way, please ignore us immediately.
========================================================================




From dcd at gower.net  Tue Dec  8 23:46:23 1998
From: dcd at gower.net (Dr. Davis)
Date: Tue, 8 Dec 1998 16:46:23 -0600
Subject: aluminum plates and profiles
Message-ID: <003601be22fc$98eca0a0$541ee6cd@dcd>

Just out of curiosity, why do you say cutting aluminum is an awful job?
It has been my experience that, so long as you have a fine-toothed metal
cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
$10), a relatively low-power bandsaw works just fine.  And while it does
create aluminum "sawdust", it does not send it flying like a circular saw
does.  If you buy or make a ripfence, then cutting nice square panels is
quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
just my opinion.

Dave
-----Original Message-----
From: Martin Czech <martin.czech at intermetall.de>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 9:27 AM
Subject: aluminum plates and profiles


>Hello,
>
>I just got an answer from Schaeffer Apparatebau (these people do engraved
>front panels). I asked if they could also cut aluminum plates for the
>other 5 sides of a module box, and also alu profiles in order to connect
>front panel and the 5 other sides.  Well, they can do this, but since
>they have no saw but only a computer controlled engraving machine this
>can get very expensive. OTOH aluminum cutting is an awful job, I guess
>a proper saw (be it circular or not) would cost about 600 DM.
>
>Does anybody know a shop in Germany or nearby where I can get my aluminum
>cut?
>
>m.c.
>




From tpaddock at seanet.com  Wed Dec  9 00:52:10 1998
From: tpaddock at seanet.com (Toby Paddock)
Date: Tue, 8 Dec 1998 15:52:10 -0800
Subject: a beginner question - scopes
Message-ID: <01BE22C2.BF770240@a20.dialup.seanet.com>

Buck Buchanan wrote:

>As a general rule for analog synth stuff I believe the following 
>(and I believe others will believe this general rule): 
>If you can only have one scope, you must have an analog.  
I believe that I believe this.

>A cheap PC based scope is ganna be neat for a couple 
>of things (capturing one-shots, saving screen shots, etc)
>but it's ganna have all kinds of weird effects due to it's 
>budget AND digital nature.  It's ganna alias, it's ganna 
>miss glitches that your not specifically looking for, it's 
>not ganna show you good amplitude envelope information 
>(high freq. in w/low time base setting).
Digital scopes are cool and do cool stuff, especially the 
cooler ones.  BUT THEY LIE.  Don't turn your back on one.
You need to know what you are looking for and then set it
up to see it.  Don't trust them farther than you can 
comfortably spit a rat.

>I use a fully loaded TDS640 here at work ... 
I use a TDS540 at work for capturing mechanical shock 
waveforms.  Wonderful digital machine, calculates peak 
of the shock, and it runs a printer.  But in this case you 
know fairly close what the waveform will be.  Works great.

>Even a VERY CHEAP analog scope in working order 
>will be a better overall tool for analog synth work.  
Sounds like my scope.

I think it depends how much you are going to use it.  For me,
a cheap scope is fine for occasional light-duty work.
Your waveform may vary.

Hoping this finds you,
Toby Paddock
- -- -  - -- -  - -- -  - -- -  - -- -
http://www.seanet.com/~tpaddock
Pronteon Approved, 
Cult of the Mighty Radio Shack Reverb




From aschrock at cs.brandeis.edu  Wed Dec  9 00:55:59 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Tue, 8 Dec 1998 18:55:59 -0500 (EST)
Subject: aluminum plates and profiles
In-Reply-To: <003601be22fc$98eca0a0$541ee6cd@dcd>
Message-ID: <Pine.HPP.3.95.981208185216.11056B-100000@bay.cs.brandeis.edu>

Which leads nicely into my question.. where can I get large pieces of 19"
aluminum suitable for panel mounting? Would need to be fairly sturdy,
since I don't like my panels to flex at all when I insert/remove jacks. I
would prefer to be able to purchase them in 1U width increments. I'm
definitely looking to do this on the cheap, so any info is welcome. I
realize this is probably a FAQ, but I couldn't find info on it anywhere. 

Thanks, 
Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Tue, 8 Dec 1998, Dr. Davis wrote:

> Just out of curiosity, why do you say cutting aluminum is an awful job?
> It has been my experience that, so long as you have a fine-toothed metal
> cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
> $10), a relatively low-power bandsaw works just fine.  And while it does
> create aluminum "sawdust", it does not send it flying like a circular saw
> does.  If you buy or make a ripfence, then cutting nice square panels is
> quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
> just my opinion.
> 
> Dave
> -----Original Message-----
> From: Martin Czech <martin.czech at intermetall.de>
> To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
> Date: Tuesday, December 08, 1998 9:27 AM
> Subject: aluminum plates and profiles
> 
> 
> >Hello,
> >
> >I just got an answer from Schaeffer Apparatebau (these people do engraved
> >front panels). I asked if they could also cut aluminum plates for the
> >other 5 sides of a module box, and also alu profiles in order to connect
> >front panel and the 5 other sides.  Well, they can do this, but since
> >they have no saw but only a computer controlled engraving machine this
> >can get very expensive. OTOH aluminum cutting is an awful job, I guess
> >a proper saw (be it circular or not) would cost about 600 DM.
> >
> >Does anybody know a shop in Germany or nearby where I can get my aluminum
> >cut?
> >
> >m.c.
> >
> 
> 




From synth1 at airmail.net  Wed Dec  9 01:02:41 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Tue, 8 Dec 1998 18:02:41 -0600
Subject: Tempcos have arrived!
Message-ID: <000301be2307$4f803ca0$411488cf@paults>

The 1K 1% tempcos have arrived. I will start shipping these Thursday. I will
try to
ship all of the orders by Wednesday of next week (I have about 39!) I can do
about
7-8/day.

Paul Schreiber
Synthesis Technology
www.synthtech.com/news <<<Tempco Info!!






From gt7276a at prism.gatech.edu  Wed Dec  9 01:35:49 1998
From: gt7276a at prism.gatech.edu (Brian Towles)
Date: Tue, 08 Dec 1998 19:35:49 -0500
Subject: a beginner question - scopes
References: <3.0.3.32.19981208115236.01408440@mage.qualcomm.com>
Message-ID: <366DC5E5.63397E46@prism.gatech.edu>

Buck Buchanan wrote:

> Hi Greg,
>
> As a general rule for analog synth stuff I believe the following (and I believe others will believe this general rule): If you can only have one scope, you must have an analog.
>

< remaining cut >i agree ... if you have the money to invest in a good analog scope, it's well worth it.  i bought mine at a ham radio convention, a tektronix 465b ( 100Mhz dual trace ) with full manual and schematics for less than $300US.  really, this is the high end of used analog scopes.  for those interested, i bought it from bob garcia who lives in marietta, georiga.  i think he's a retired gentleman who buys and repairs scopes for a living - a good source for diyers.  his number is (770)977-5701.

brian




From papareil at netsud.fr  Wed Dec  9 01:42:08 1998
From: papareil at netsud.fr (papareil)
Date: Wed, 09 Dec 1998 01:42:08 +0100
Subject: 4016, switching audio and VCO signals
References: <01be21e9$005acd80$0100007f@default>
Message-ID: <366DC75F.70E5CC73@netsud.fr>

Hi

I' m not sure 4016/4066 will work well with MIDI , the bandwith seems too
straigth
about 30kHz , MIDI freq is 31.9kHz... if i remind well...
But if you want to digitaly switch MIDI signal you can use 4051..4053 i've
tested  and it work well
(use a +5V/GND psu for the 405x and some Schmitt trigger (ie: 74HCT14) for
regenerating
the signal ....
Look at these url , ive put here the scheme of a MIDI patch bay builded arount
405x circuits
http://members.xoom.com/papareil

papareil

Mark Havard-Brown a ?crit:

> All,
>
> Has anyone used these 4016 Quad Bi-Lateral Switches. I'd like to know if
> they are okay to switch audio, (the fact sheet on them says they will), but
> I'd rather hear it coming from someone who has used them. I'm looking at
> using them to construct complex oscillator shapes by switching voltages
> clocked via a counter. Could they be used in a MIDI controlled audio patch
> bay, or is the audio response poor if I were to switch CD quality audio
> signals through them.
>
> Mark.






From camotse at france-mail.com  Wed Dec  9 01:44:59 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Wed, 9 Dec 1998 01:44:59 +0100
Subject: a beginner question - scopes
Message-ID: <00e401be230d$44f4e640$2f14eec3@bs132506>

Hum.
They lie.. But do they lie enough to justify the price difference???? I know
nothing about scopes so i'm affraid it'd be hard to buy one 2nd hand...i
wouldn't know if it's good or not... and also here in belgium 2nd hands and
bargain shops are much rarer than in uk or us...
humm

well

thanks anyway

greg.


-----Message d'origine-----
De : Toby Paddock <tpaddock at seanet.com>
? : 'synth-diy at mailhost.bpa.nl' <synth-diy at mailhost.bpa.nl>
Cc : 'camotse at france-mail.com' <camotse at france-mail.com>;
'buchanan at qualcomm.com' <buchanan at qualcomm.com>
Date : mercredi 9 d?cembre 1998 0:50
Objet : Re: a beginner question - scopes


>Buck Buchanan wrote:
>
>>As a general rule for analog synth stuff I believe the following
>>(and I believe others will believe this general rule):
>>If you can only have one scope, you must have an analog.
>I believe that I believe this.
>
>>A cheap PC based scope is ganna be neat for a couple
>>of things (capturing one-shots, saving screen shots, etc)
>>but it's ganna have all kinds of weird effects due to it's
>>budget AND digital nature.  It's ganna alias, it's ganna
>>miss glitches that your not specifically looking for, it's
>>not ganna show you good amplitude envelope information
>>(high freq. in w/low time base setting).
>Digital scopes are cool and do cool stuff, especially the
>cooler ones.  BUT THEY LIE.  Don't turn your back on one.
>You need to know what you are looking for and then set it
>up to see it.  Don't trust them farther than you can
>comfortably spit a rat.
>
>>I use a fully loaded TDS640 here at work ...
>I use a TDS540 at work for capturing mechanical shock
>waveforms.  Wonderful digital machine, calculates peak
>of the shock, and it runs a printer.  But in this case you
>know fairly close what the waveform will be.  Works great.
>
>>Even a VERY CHEAP analog scope in working order
>>will be a better overall tool for analog synth work.
>Sounds like my scope.
>
>I think it depends how much you are going to use it.  For me,
>a cheap scope is fine for occasional light-duty work.
>Your waveform may vary.
>
>Hoping this finds you,
>Toby Paddock
>- -- -  - -- -  - -- -  - -- -  - -- -
>http://www.seanet.com/~tpaddock
>Pronteon Approved,
>Cult of the Mighty Radio Shack Reverb
>




From bjacquot at CALAMITY.WYOMING.COM  Wed Dec  9 03:25:24 1998
From: bjacquot at CALAMITY.WYOMING.COM (Byron Jacquot)
Date: Tue, 08 Dec 1998 19:25:24 -0700
Subject: aluminum plates and profiles
Message-ID: <1.5.4.32.19981209022524.008dfdfc@mailhost.wyoming.com>

>Which leads nicely into my question.. where can I get large pieces of 19"
>aluminum suitable for panel mounting? Would need to be fairly sturdy,
>since I don't like my panels to flex at all when I insert/remove jacks. I
>would prefer to be able to purchase them in 1U width increments. I'm
>definitely looking to do this on the cheap, so any info is welcome. I
>realize this is probably a FAQ, but I couldn't find info on it anywhere. 

In the states, 19" aluminum blanks are available.  I'm not certain who makes
them (possibly Bud or Hammond), but Tech America carries them.  They have a
wide variety of sizes, including 19 X 4 and 19 X 8 in both .04 and .06
thicknesses, between $6 and $15.  Its on page 295 of their current catalog,
and probably on their webpage at www.techam.com

Byron




From aschrock at cs.brandeis.edu  Wed Dec  9 04:58:23 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Tue, 8 Dec 1998 22:58:23 -0500 (EST)
Subject: aluminum plates and profiles
In-Reply-To: <1.5.4.32.19981209022524.008dfdfc@mailhost.wyoming.com>
Message-ID: <Pine.HPP.3.95.981208223243.11336A-100000@bay.cs.brandeis.edu>

I'm in the states, yes, but I couldn't find the panels you're referring to
on the page.. nor do any searches seem to find anything. Perhaps because
the web page abbreviates everything so much my searches just don't see it. 

Mouser has panels for not-so-cheap... $13.90 for a 2U panel.. but they're
1/8" thick, which is nice. I'd prefer something cheaper, but I'll take
what I can get. I've tried midwest analog products 19" panels, but they're
pretty soft, not so cheap, and bend with jack insertion. Very
dissapointing. I don't want any more flukes like this. On non-modular gear
(eg fatman) it's not that much of an issue, but when you're
inserting/removing so many 1/4" jacks it really is of primary importance. 

Schaeffer is getting more and more appetizing... but the $$ is a problem.
Mostly I worry about labeling problems... but that's been discussed here
quite a bit in the recent past. I'm debating printing up a graphic with
all the appropriate bits on it and then epoxying it to the panel... this
certainly seems the nicest "budget" option. I get depressed thinking of
doing dry-transfers again... doesn't seem to be worth the time, and it's
just generally a royal pain to sit down and do. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|






From dave.halliday at greymatter.com  Wed Dec  9 06:11:38 1998
From: dave.halliday at greymatter.com (Dave Halliday)
Date: Wed,  9 Dec 1998 05:11:38 GMT
Subject: aluminum plates and profiles
Message-ID: <9812082243161836@greymatter.com>

I noticed the .edu address - you might want to check your school's 
physics or science departments - frequently they will have an
in-house machine shop and would have a large sheet-metal shear.

Check for local commercial metal vendors - they will want to sell you 
sheets a couple feet by a couple tens of feet but since they also cut 
to size, they may well have a pile of shorts that you can paw through 
and buy for a buck or two a pound.  Take these to the physics metal 
shop and have them cut them for you.  Offer to trade something fun - a 
CD of your music or a simple synth circuit or couple pints or...



>     From: Andrew Schrock <aschrock at cs.brandeis.edu>
>     To: synth-diy at mailhost.bpa.nl
>     Date: Tue, 8 Dec 1998 18:55:59 -0500 (EST)
>     Subject: Re: aluminum plates and profiles
>      
>     Which leads nicely into my question.. where can I get large pieces of 
>     19" aluminum suitable for panel mounting? Would need to be fairly 
>     sturdy, since I don't like my panels to flex at all when I 
>     insert/remove jacks. I would prefer to be able to purchase them in 1U 
>     width increments. I'm definitely looking to do this on the cheap, so 
>     any info is welcome. I realize this is probably a FAQ, but I couldn't 
>     find info on it anywhere. 
>     Thanks, 
>     Andrew
>      


--- Via Silver Xpress V4.4 [Reg]



From bduggan at netcom.com  Wed Dec  9 06:14:12 1998
From: bduggan at netcom.com (Brett Duggan)
Date: Tue, 8 Dec 1998 21:14:12 -0800 (PST)
Subject: ASM-1 VCF "external" audio input?
Message-ID: <Pine.3.89.9812082046.A12901-0100000@netcom10>


Hi guys,

I was considering making a decidated standalone VCF device out of an ASM-1
PCB (utilizing the VCF, 1 VCA, and an ASDR for each of them) for
processing mic/guitar level to line level signals.  Problem is, I don't
know how to design the input circuit that would be necessary to knock the
signal down to the level needed by the ASM-1 VCF.  Has anyone here
designed such a circuit yet, or considered it?  Or is such a circuit
pretty generic and therefore fairly easy to find info on?  I'm hoping to
be able to intentionally overdrive the VCF if enough gain is cranked back
into it.  I assume the input impedance would need to be pretty high, up to
1 Megaohm I think. 

Can anyone help me out in some way?  Thanks very much if you can!
Brett D




From dave.halliday at greymatter.com  Wed Dec  9 06:20:28 1998
From: dave.halliday at greymatter.com (Dave Halliday)
Date: Wed,  9 Dec 1998 05:20:28 GMT
Subject: aluminum plates and profiles
Message-ID: <9812082243171837@greymatter.com>

One thought - I used to live in the Boston area about 20 years ago and
there was an absolute hotbed of electronics surplus stores.  I know that
some have closed ( John Meshna and Sons, Delta, PolyPaks - sniff! ) but
some are still very much in business.  B&F Enterprises, Eli Hefron's
which is going under the E.L.I. name.  You might try visiting them and
seeing if they have anything available.  You might also be able to find
some used panels - they will have holes in them but you could figure
out some way to plug them - an extra patch point maybe???  Hmmm???


>     I'm in the states, yes, but I couldn't find the panels you're 
>     referring to on the page.. nor do any searches seem to find anything. 
>     Perhaps because the web page abbreviates everything so much my 
>     searches just don't see it. 
>     Mouser has panels for not-so-cheap... $13.90 for a 2U panel.. but 
>     they're 1/8" thick, which is nice. I'd prefer something cheaper, but 
>     I'll take what I can get. I've tried midwest analog products 19" 
>     panels, but they're pretty soft, not so cheap, and bend with jack 
>     insertion. Very dissapointing. I don't want any more flukes like this. 
>     On non-modular gear (eg fatman) it's not that much of an issue, but 
>     when you're inserting/removing so many 1/4" jacks it really is of 
>     primary importance. 






--- Via Silver Xpress V4.4 [Reg]



From pfperry at melbpc.org.au  Wed Dec  9 06:47:53 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Wed, 9 Dec 1998 16:47:53 +1100 (EST)
Subject: aluminum plates and profiles
Message-ID: <1.5.4.16.19970304201647.382f3dae@popa.melbpc.org.au>

At 10:58 PM 8/12/98 -0500, Andrew Schrock  wrote:

>what I can get. I've tried midwest analog products 19" panels, but they're
>pretty soft, not so cheap, and bend with jack insertion. 

What you want, for rigidity, is not a flat piece but a "U" section.
The only difficult thing abt panels, is doing a standard rack mount hole..
but, you can always drill and file.
Any small sheet metal assembly shop can guillotine & bend easily and
cheaply. My one-offs are done by a place specialising in oven hoods.
You will get a cheap price at a one or 2 person shop. Not everyoune is 
interested in doing this work.
I got a rackmount irregular quadrilateral cross section steel box for $US 60.
You take it out of the rack, and it sits on the table with a sloping front
like a block of Tobler-1. Nothing like it in the catalogs!

paul perry melbourne australia




From theremin1 at worldnet.att.net  Wed Dec  9 07:27:10 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 8 Dec 1998 22:27:10 -0800
Subject: Scope FAQs and Washing Machines
Message-ID: <005301be233c$f473eb00$31794e0c@hpcustomer>

Hello scopers,

http://hem2.passagen.se/sm0vpo/scope/osc-0.htm
is a nice primer on simple analogue scopes.
The rest of this page is very cool, too.

-Art

-----Original Message-----
From: Bill Layer <b.layer at vikingelectronics.com>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 9:52 AM
Subject: Scope FAQs and Washing Machines


>Hi Martin, All,
>
>Ok. Who wants to write the Synth-DIYer's O-scope FAQ? The question comes up
>every other week - and it's a good (hard) one to answer in a word or two.
>We need two people: one from the digital world and one from the analog
>world - to meld their minds and write a document that covers both bases.
>
>That being said, I'll reiterate that I get by with my British Telequipment
>Model 67, made in 1973 and bought two years back for $75.00(USD). It has 2
>rocking Megahertz o' bandwidth, and never fails in audio service.
>
>On a seperate note, sorry to hear about the experience with the washing
>machine Martin. Mine was much luckier; I bought a used washer/dryer pair
>for $200 when I moved into my house. That was six years ago - no trouble
>yet, save one $2 smubber pad. KNOCK ON WOOD.
>
>Then again, they were so mint that they still had all the showroom stickers
>affixed, from the late 1960's! What kind of a mind does it take to do that?
>
>
>=======================================================================
>This message and any attachments to it are subject to copying and are
>sent solely for the personal amusement the sender.  It may include
>information which is technically wrong and exempt from disclosure. If
>you receive this communication in any way, please ignore us immediately.
>========================================================================
>




From aschrock at cs.brandeis.edu  Wed Dec  9 07:35:13 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Wed, 9 Dec 1998 01:35:13 -0500 (EST)
Subject: ASM-1 VCF "external" audio input?
In-Reply-To: <Pine.3.89.9812082046.A12901-0100000@netcom10>
Message-ID: <Pine.HPP.3.95.981209012215.11536B-100000@bay.cs.brandeis.edu>

Brett, 

The ASM-1 VCF sounds kinda bad overdriven... it clips easily and generally
doesn't sound very "rough". (no offense to anybody out there) Actually, I
had the same question when I first built mine. The filter is very
utilitarian, and I use it all the time in series with my sh-101, but it's
really not too good for getting that overdriven filter sound. 

Tony Allgood makes a _very_ nice VCF PCB. Mine is currently in the
assembly stages, but I can tell you that the PCB looks absolute top rate.
Plated through holes, very nice design w/silkscreen, etc. Definitely worth
the money.. it's a moog transistor ladder filter design, and can be
overdriven quite nicely. (or so I'm told) I should be ready to do a proper
review of it after new years and it's all built. 

Moog transistor ladder designs are pretty nice.. very smooth response, but
if you're trying to get that aphex twin feel, get a few CEM 3320's!
(they're still pretty cheap) 

I put an attenuator on the inputs to my ASM-1 VCF, and this brings the
signal down to a managable voltage. (of course in series with the asm-1's
audio inputs..) 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Tue, 8 Dec 1998, Brett Duggan wrote:
> I was considering making a decidated standalone VCF device out of an ASM-1
> PCB (utilizing the VCF, 1 VCA, and an ASDR for each of them) for
> processing mic/guitar level to line level signals.  Problem is, I don't
> know how to design the input circuit that would be necessary to knock the
> signal down to the level needed by the ASM-1 VCF.  Has anyone here
> designed such a circuit yet, or considered it?  Or is such a circuit
> pretty generic and therefore fairly easy to find info on?  I'm hoping to
> be able to intentionally overdrive the VCF if enough gain is cranked back
> into it.  I assume the input impedance would need to be pretty high, up to
> 1 Megaohm I think. 
> 
> Can anyone help me out in some way?  Thanks very much if you can!
> Brett D
> 
> 




From theremin1 at worldnet.att.net  Wed Dec  9 07:39:52 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 8 Dec 1998 22:39:52 -0800
Subject: Boring Question
Message-ID: <006001be233e$ba886cc0$31794e0c@hpcustomer>

PDF file data sheet for T.I. TL08x op amps is at:
http://www-s.ti.com/sc/psheets/slos080d/slos080d.pdf

PDF file data sheet for Harris CA3080 ota is at:
http://wwwnt.semi.harris.com/data/fn/fn4/fn475/fn475.pdf

Happy amplifying!

-Art

-----Original Message-----
From: Plinio Andres Barraza <pab210 at is8.nyu.edu>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 2:09 PM
Subject: Boring Question


>
>
>Can anyone please confirm these pinouts for me.  I am troubleshooting a
>circuit and I still can't get it to work:
>
>TLO72:
>
>      -------  
> -in  -|   |- +V
> +in  -|   |- out
>  -V  -------
>
>CA3080:
>
>      ------- +V
> -in  -|   |- 
> +in  -|   |- out
>  -V  ------- gain
>
>I pardon the ignorance but I will be very grateful if anyone can help.
>
>Thanks in advance,
>
>Plinio
>
>




From theremin1 at worldnet.att.net  Wed Dec  9 07:52:35 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 8 Dec 1998 22:52:35 -0800
Subject: IC and Trasnsister updates
Message-ID: <006701be2340$815d3140$31794e0c@hpcustomer>

A company called "D.A.T.A."
(http://data.ihs.com)
has one of the most comprehensive CD ROM and hard-copy databases
for semiconductors and other devices.  These guys are TOP NOTCH
in service!  BIG bucks, though!  Most of their customers are large
corporations and universities.

Their address:

D.A.T.A.
15 Inverness Way East, Englewood CO, 80112
Phone 800-447-4666, 303-799-0381
Fax 303-799-4082

At the other end of the cost spectrum:   The NTE replacement semiconductor
database is a FREE download, but it is basically only good for finding the
NTE
equals or semi-equals.  If you want, I'll dig up the URL, or simply use your
search
engine.

-Art

-----Original Message-----
From: Lewis Bupp <lbupp at eagle.ycp.edu>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 2:19 PM
Subject: IC and Trasnsister updates


>Hi all. Can anyone suggest a good crossref for transistors and IC's which
>will show updates, new numbers and things?
>
>thanks ahead of time.
>
>Lew Bupp II
>Audio/Video Technician
>York College of Pa.
>York, Pa. 17403
>717-815-1395
>717-852-8543
>
>




From vco at mindspring.com  Wed Dec  9 08:41:12 1998
From: vco at mindspring.com (tomg)
Date: Wed, 09 Dec 1998 02:41:12 -0500
Subject: The Mad Mouse is online
Message-ID: <yam7647.616.119190056@mail.mindspring.com>

Thanks to everyone who wrote to say how cool you thought
the Mad Mouse is. I like it too! 

I'm still working on those pcbs. Maybe after the 1st.
Should be in the $20 range.

http://www.mindspring.com/~vco/madm/title.html

-tg
 








From theremin1 at worldnet.att.net  Wed Dec  9 08:45:43 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 8 Dec 1998 23:45:43 -0800
Subject: a beginner question - scopes
Message-ID: <008601be2347$ed632320$31794e0c@hpcustomer>

Ditto that!!!  (The Tek salesmen loath me.)  I have a special circuit
great for showing how digital 'scopes compare to analogs at:
http://home.att.net/~theremin1/circuitlibrary/wheel.htm.

On the other hand, digital 'scopes can be invaluable for fast,
non-recurring events.  Just don't try to use them for viewing
crossover distortion!

-Art


-----Original Message-----
From: Bill Layer <b.layer at vikingelectronics.com>
To: Buck Buchanan <buchanan at qualcomm.com>; synth-diy at mailhost.bpa.nl
<synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 3:56 PM
Subject: Re: a beginner question - scopes


> Hey All,
>
>>As a general rule for analog synth stuff I believe the following (and I
>>believe others will believe this general rule): If you can only have one
>>scope, you must have an analog.
>
>Ditto on the Analog scope bit. We've got plenty of both here, and when
>someone comes my direction with a digital model, I just run the other way
>as fast as I can.
>
>
>=======================================================================
>This message and any attachments to it are subject to copying and are
>sent solely for the personal amusement the sender.  It may include
>information which is technically wrong and exempt from disclosure. If
>you receive this communication in any way, please ignore us immediately.
>========================================================================
>




From theremin1 at worldnet.att.net  Wed Dec  9 08:55:33 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 8 Dec 1998 23:55:33 -0800
Subject: aluminum plates and profiles
Message-ID: <008b01be2349$4d8502e0$31794e0c@hpcustomer>

For 0.062" or less thick aluminum of most alloys (6061, 5052, etc.), a small
shear is far
preferable to a saw.  Of course, engraved panels may be 0.093" or more,
and that will require a relatively big shear.  (I understand that some of
the finest shears
are made in Germany.)  Here in the US, a good shear with capacity for 0.62"
thick, 2'
wide material costs about $2500.  BTW, cutting aluminum in the thickness
range
of 0.125"and up is indeed a chore, even with a BIG bandsaw.

-Art


-----Original Message-----
From: Dr. Davis <dcd at gower.net>
To: Martin Czech <martin.czech at intermetall.de>; synth-diy at mailhost.bpa.nl
<synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 08, 1998 5:03 PM
Subject: Re: aluminum plates and profiles


>Just out of curiosity, why do you say cutting aluminum is an awful job?
>It has been my experience that, so long as you have a fine-toothed metal
>cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
>$10), a relatively low-power bandsaw works just fine.  And while it does
>create aluminum "sawdust", it does not send it flying like a circular saw
>does.  If you buy or make a ripfence, then cutting nice square panels is
>quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
>just my opinion.
>
>Dave
>-----Original Message-----
>From: Martin Czech <martin.czech at intermetall.de>
>To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
>Date: Tuesday, December 08, 1998 9:27 AM
>Subject: aluminum plates and profiles
>
>
>>Hello,
>>
>>I just got an answer from Schaeffer Apparatebau (these people do engraved
>>front panels). I asked if they could also cut aluminum plates for the
>>other 5 sides of a module box, and also alu profiles in order to connect
>>front panel and the 5 other sides.  Well, they can do this, but since
>>they have no saw but only a computer controlled engraving machine this
>>can get very expensive. OTOH aluminum cutting is an awful job, I guess
>>a proper saw (be it circular or not) would cost about 600 DM.
>>
>>Does anybody know a shop in Germany or nearby where I can get my aluminum
>>cut?
>>
>>m.c.
>>
>




From vco at mindspring.com  Wed Dec  9 09:00:15 1998
From: vco at mindspring.com (tomg)
Date: Wed, 09 Dec 1998 03:00:15 -0500
Subject: Mad Mouse Update #3
In-Reply-To: <Pine.OSF.3.95.981208155326.15462A-100000@is8.nyu.edu>
Message-ID: <yam7647.764.118764248@mail.mindspring.com>

On 08-Dec-98, Plinio Andres Barraza wrote:

>* * *   **   * * *  *
>* * *  *  *  * * *  *
>* * *  *  *  * * *  *
>* * *  *  *  * * *
> * *    **    * *   *

>Awesome sounds, was this all done real time or did you lay down tracks?

>I think I'll have to build this little devil.

>Plinio

>-----------
>On Tue, 8 Dec 1998, tomg wrote:

>> Put up the demo wave file. Maybe final pcb/skiz tomorrow.
>> 
>> http://www.mindspring.com/~vco/madm/pics/mm_wave.wav
>> 
>> -tg
>> 
>> 

Thanks! It's 5 hd tracks. Warm up your iron, it's all 
online mow ...:)

-tg






From beszedes at cc.u-szeged.hu  Wed Dec  9 09:09:12 1998
From: beszedes at cc.u-szeged.hu (Beszedes Arpad)
Date: Wed, 09 Dec 1998 09:09:12 +0100
Subject: PAiA midi2cv8
Message-ID: <366E3028.8B5AC471@cc.u-szeged.hu>

Hi all!

I don't know about the legal policies of the above device, but I'll ask
this anyway:
I downloaded the schematics for the converter and there are some missing
references, so my question is:

if somebody built this stuff, could he/she tell what the following parts
are:
IC11 and IC12 (guess some FET opamps),
IC6 (74HC04 or what?),
Q1 (2N4124 ?),
Q4-Q7 and Q8-Q15
and also the power supply voltage is not displayed.

By the way, I think that the circuit is really well designed (the system
is especially versatile with this new firmware for the MCU).

Hope I'm not violating some legal rights of PAiA with these questions...
(if I am, please accept my apologies!)

Anyway, thanks for the help,
  Arpad.


-- 
***********************************************
*  Arpad Beszedes                             *
*                                             *
*  Research Group on Artificial Intelligence  *
*  Hungarian Academy of Sciences              *
*  Attila Jozsef University, Szeged, Hungary  *
*  e-mail: beszedes at cc.u-szeged.hu            *
*  tel.: (+36) 62/45-41-45                    *
***********************************************



From vco at mindspring.com  Wed Dec  9 09:17:08 1998
From: vco at mindspring.com (tomg)
Date: Wed, 09 Dec 1998 03:17:08 -0500
Subject: Mad Mouse Update #4 (was private)
In-Reply-To: <2E12619580C0D1118C6400805F9F4C95DB2675@nj7460exch001u.ho.lucent.com>
Message-ID: <yam7647.433.119395112@mail.mindspring.com>


This was private, but I thought others might be interested.

On 08-Dec-98, Curtin, Steven D (Steven) wrote:
>Congrants on the Mad Mouse- I built a Gnome myself about twenty years ago.
>I added a bunch of patch points to it as as well, it was my first synth.

>Why do you use the 13600?   I thought it was an obsolete version and that
>the 13700 is the preferred TCA to use.   I bought a bunch of 13700's for use
>as VCAs sometime.

The MM is also a good place to start there are a lot of
mods that can be done. I might even add a mod page.

I used 13600s because I got 'em cheep ($.80) from Mouser. I
subed 13700s and TLO84s tonight. There is no audable differance
and it worked fine. Feel free to sub one for the other.

-tg




From theremin1 at worldnet.att.net  Wed Dec  9 13:18:22 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 9 Dec 1998 04:18:22 -0800
Subject: bounces
Message-ID: <000901be236e$049b1680$6fb14e0c@hpcustomer>

Hi everybody,

Can anyone decipher this alphabet soup and determine if there is
information that can point to where all my bounced messages are occurring?

Does anyone know who "steve at winserver.com" or his ISP is?  He is always
referenced in these bounces.

My sincere apologies for this off-topic mundanity and my relative ignorance
in things email.

[example of header from typical bounce follows]

This message was addressed to a user that does not exist at this address.
Please verify the name and domain in the original message that follows.
The message was addressed to: steve at winserver.com

              ----- Original message follows -----
Received: from mailhost.bpa.nl ([193.172.36.4])
by winserver.com (wcSMTP [445])
with SMTP id 1302409956; Wed, 09 Dec 1998 05:49:30 GMT
Received: (from majordom at localhost)
by mailhost.bpa.nl (8.8.8/8.8.8) id FAA03647
for synth-diy-outgoing; Wed, 9 Dec 1998 05:46:35 +0100 (MET)
Received: from mtiwmhc02.worldnet.att.net (mtiwmhc02.worldnet.att.net
[204.127.131.37])
by mailhost.bpa.nl (8.8.8/8.8.8) with ESMTP id FAA03643
for <synth-diy at mailhost.bpa.nl>; Wed, 9 Dec 1998 05:46:32 +0100 (MET)
Received: from hpcustomer ([12.78.121.49]) by mtiwmhc02.worldnet.att.net
          (InterMail v03.02.05 118 121 101) with SMTP
          id <19981209044631.CEPS26485 at hpcustomer>
          for <synth-diy at mailhost.bpa.nl>; Wed, 9 Dec 1998 04:46:31 +0000
Message-ID: <008601be2347$ed632320$31794e0c at hpcustomer>
Reply-To: "Arthur Harrison" <theremin1 at worldnet.att.net>
From: "Arthur Harrison" <theremin1 at worldnet.att.net>
To: "DIY" <synth-diy at mailhost.bpa.nl>
Subject: Re: a beginner question - scopes
Date: Tue, 8 Dec 1998 23:45:43 -0800
MIME-Version: 1.0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 4.72.2106.4
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4
Sender: owner-synth-diy at mailhost.bpa.nl
Precedence: bulk

[end example]

Art Harrison
theremin1 at worldnet.att.net




From martin.czech at intermetall.de  Wed Dec  9 13:19:03 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 9 Dec 1998 13:19:03 +0100 (MET)
Subject: aluminum plates and profiles
Message-ID: <199812091219.NAA13632@window.intermetall.de>


> Just out of curiosity, why do you say cutting aluminum is an awful job?
> It has been my experience that, so long as you have a fine-toothed metal
> cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
> $10), a relatively low-power bandsaw works just fine.  And while it does
> create aluminum "sawdust", it does not send it flying like a circular saw
> does.  If you buy or make a ripfence, then cutting nice square panels is
> quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
> just my opinion.
> 
 Well, I didn't try a bandsaw (this is also circular in a way, right?),
but a hand pendulum saw (no circular blade). The blade is 2mm thick,
but it still goes to the left or right, and there is a lot of 
vibration. So the cut is very ugly, 0.5-0.7mm tolerance.

m.c.




From martin.czech at intermetall.de  Wed Dec  9 13:31:58 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 9 Dec 1998 13:31:58 +0100 (MET)
Subject: a beginner question - scopes
Message-ID: <199812091231.NAA13662@window.intermetall.de>


> and there we are at the end they say
> (i think i didn't even read that. god bless me)
> - oscilloscope:
> .timebase 100ns to 100ms / division
> .starting source (this is basic french translation, hope u understand what
> it means..i don't anyway...) CH1, CH2, or zero point
> .starting flank/side: up or down
> .Starting level: adjustale by 1/2 division step
> .Interpolation: linear or rounded
> .Marks for U and f
> .Input sensibility: 10mV to 5V/division   (oh my god isn't that too small if
> i need to see CV signals or even outputs from vcos (asm1 talks about 10V
> from vco out)
> .Prestart function (what the hell is that??)
> .True RMS reading (noly CA composant (??)
> .datas format : ASCII

SOME DSO DATA  TABLE SNIPPED

These figures are the usuall ones, allmost every DSO has these features.
But what's really interesting is:

analog bandwidth: some manufactures cheat, high sample rate but low bandwidth
(the preamp gets expensive with higher bandwidth).

display refresh time: if the display needs a second to refresh, you'll most probably
miss seldom events. But these events are the main reason for using a scope.

trigger: how clever is the trigger logic? How many modes does it have?
If I buy a DSO I want the full benefits of the digital world, ie. a lot
of clever trigger modes. Not only rising/falling edge. Conditional trigger,
counter trigger, long trigger holdoff times etc. Otherwise the DSO will
allways trigger in the "wrong" moment, ie. display uninteresting parts
of the waveform.

But I have to admit: PC-DSOs get more and more attractive these days.
But perhaps your soundcard together with cooledit will do most of the audio
DSO stuff? Could be.

You should test scopes not only with pulse and sine signals, that's only for 
bandwidth and pulse waveform distortion. Also try complex
signals, like two sines, CD-player output, signals with noise etc.
Let's see how the trigger will cope with that.
You can create such signals also with your soundcard.


m.c.




From theremin1 at worldnet.att.net  Wed Dec  9 13:41:45 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 9 Dec 1998 04:41:45 -0800
Subject: aluminum plates and profiles
Message-ID: <002301be2371$48697520$6fb14e0c@hpcustomer>

My experience with the Bud 19" panel blanks is that they
are made of unbelievably soft, gummy alloy not at all great
for milling or drilling.
It seems they use the stuff convenient for them to stamp the
four or more mounting notches at the edges.

Then, they charge way too much for them.

Well, I suppose Bud isn't distributed in Australia, anyway.
When I need precut rack panels, I order them cut to size from Baltimore
(USA).
That way, I know precisely what alloy I am getting.  The mounting notches
are easy to mill as needed.

-Art


-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 09, 1998 12:38 AM
Subject: Re: aluminum plates and profiles


>At 10:58 PM 8/12/98 -0500, Andrew Schrock  wrote:
>
>>what I can get. I've tried midwest analog products 19" panels, but they're
>>pretty soft, not so cheap, and bend with jack insertion.
>
>What you want, for rigidity, is not a flat piece but a "U" section.
>The only difficult thing abt panels, is doing a standard rack mount hole..
>but, you can always drill and file.
>Any small sheet metal assembly shop can guillotine & bend easily and
>cheaply. My one-offs are done by a place specialising in oven hoods.
>You will get a cheap price at a one or 2 person shop. Not everyoune is
>interested in doing this work.
>I got a rackmount irregular quadrilateral cross section steel box for $US
60.
>You take it out of the rack, and it sits on the table with a sloping front
>like a block of Tobler-1. Nothing like it in the catalogs!
>
>paul perry melbourne australia
>




From theremin1 at worldnet.att.net  Wed Dec  9 13:44:31 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 9 Dec 1998 04:44:31 -0800
Subject: theremin problems!
Message-ID: <002a01be2371$ab82b860$6fb14e0c@hpcustomer>

Cool, Paul.

(If anyone is interested in my theremin ramblings,
just let me know, and I"ll CC my rants to the list.)

-Art


-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
To: Arthur Harrison <theremin1 at worldnet.att.net>
Date: Tuesday, December 08, 1998 9:55 PM
Subject: Re: theremin problems!


>Thanks Art! I feel much less lonely now!
>
>If nothing gets done on this soon, I might go to a digital approach,
>actually counting the pulses and working from that.. the figs seem to work,
>just! (500KHz and a PIC)
>
>paul perry melb aust
>
>
>




From martin.czech at intermetall.de  Wed Dec  9 13:51:49 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Wed, 9 Dec 1998 13:51:49 +0100 (MET)
Subject: got a scope
Message-ID: <199812091251.NAA13714@window.intermetall.de>

Just want to say, that I got my Hameg scope yesterday from the
Post Office.  Model 1504. Very clean, no visible noise at 1mV /
cm. Microprocessor controlled, autoset, save/recall, readout, delayed time
base, calibration without opening the scope right from the menu, very
bright tube, test generator 1kHz/1MHz for probe calibration, everything
you want from an analog scope.  I tortured it with signal generators, CD
player and soundcard.  Nice xy display on stereo signals gives correlation
meter. {My CDs are absolutetly not mono compatible (not intended to be)}.

Caveats (*so far*):
The user interface is a bit weird, some buttons have tripple functions,
so you have to look into the manual for some special funtions.  But some
Tek DSO with "analog feel" are much worse... Also the scope has no 50
Ohm input option, you have to buy special 50 Ohm adapters, but I'm not
shure if I need any. And , errr they could have adapted the readout
to the 10:1 probes via menu, ok, I'll always work with these probes, so
100mV means actually 1V, I think I can remember this all the time.
Tek and HP scopes try to determine wether you use a 10:1 probe or not,
after some time this mechanism beginns to fail due to contact problems,
so the readout starts to randomly toggle 1mV... 10mV ... 1mV.  So ,
not changing at all is still the better way...

Some years ago Hameg (it is a German manufacturer) was known for trash
scopes, now they are much better. Forget about the past.

2300 DM for 150 MHz -3 dB bandwidth, I think a good price.

If you don't want to spend so much money: modells 1004 (2100 DM) and
404 (1300 DM) have the same technology, but less bandwidth.  I *think*
they work as good as my top notch model.

It seems that ELV has pushed all other vendors out of the market, via
aggreement with Hameg. Other vendors get no scopes, or with ridicolous
latency.

>From my point of view, one day after recieving mine, I can recommend
these scopes.


The problem here in Germany is, that there seems to be no market for used
scopes etc. There are companys that sell refurbished used gear, but still
very expensive.  So it appeared to me a better deal to get a new one...

See washing machines ;->.

m.c.






From Juergen.Haible at nbgm.siemens.de  Wed Dec  9 14:51:01 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 9 Dec 1998 14:51:01 +0100 
Subject: AW: a beginner question - scopes
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D58201032746@nbgm336a.nbgm.siemens.de>

	>But I have to admit: PC-DSOs get more and more attractive these
days.
	>But perhaps your soundcard together with cooledit will do most of
the audio
	>DSO stuff? Could be.

Just a little side note:
Have you seen HP's latest top model digital scopes ? 
These actually *are* PC's, complete with Win 95 - and the 
salesperson even said that you can run WinWord and 
Netscape on them.
Funny, isn't it ?

JH.





From wils0450 at itlabs.umn.edu  Wed Dec  9 15:04:30 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Wed, 9 Dec 1998 08:04:30 -0600 (CST)
Subject: aluminum plates and profiles
In-Reply-To: <Pine.HPP.3.95.981208223243.11336A-100000@bay.cs.brandeis.edu>
Message-ID: <Pine.GSO.4.05.9812090759500.27459-100000@whale.itlabs.umn.edu>

Just thought I would take the time to remind you that I will be doing
silkscreening and possibly panel machineing as early as March. Hopefully I
can make this the cheapest alternative around.  :)

            <<< << The obvious solution is to kill you all >> >>>




From pab210 at is8.nyu.edu  Wed Dec  9 15:12:56 1998
From: pab210 at is8.nyu.edu (Plinio Andres Barraza)
Date: Wed, 9 Dec 1998 09:12:56 -0500 (EST)
Subject: aluminum plates and profiles
In-Reply-To: <008b01be2349$4d8502e0$31794e0c@hpcustomer>
Message-ID: <Pine.OSF.3.95.981209090004.16702D-100000@is8.nyu.edu>




The best thing to cut sheet metal (only in straight lines though) is to
use a bench press.  Most people wouldn't want to buy one because it is an
industrial thing (although I have seen samll portable ones), but if you
find someone who would be willing to let you use theirs you could make
fifty pannels in an hour (not including hole punching/drilling).  

A bench press is alot like a guillotine but much heavier, it can cut 1/8"
aluminum like butter (you use your body weight). I know a guy here in 
New York that has several in his shop- he does copper roofing, but many
shops have them (I really don't think they are that uncomon) check out an
industrial area or talk to artist friends (artist doing etching need them
all the time.

Plinio



On Tue, 8 Dec 1998, Arthur Harrison wrote:

> For 0.062" or less thick aluminum of most alloys (6061, 5052, etc.), a small
> shear is far
> preferable to a saw.  Of course, engraved panels may be 0.093" or more,
> and that will require a relatively big shear.  (I understand that some of
> the finest shears
> are made in Germany.)  Here in the US, a good shear with capacity for 0.62"
> thick, 2'
> wide material costs about $2500.  BTW, cutting aluminum in the thickness
> range
> of 0.125"and up is indeed a chore, even with a BIG bandsaw.
> 
> -Art
> 
> 
> -----Original Message-----
> From: Dr. Davis <dcd at gower.net>
> To: Martin Czech <martin.czech at intermetall.de>; synth-diy at mailhost.bpa.nl
> <synth-diy at mailhost.bpa.nl>
> Date: Tuesday, December 08, 1998 5:03 PM
> Subject: Re: aluminum plates and profiles
> 
> 
> >Just out of curiosity, why do you say cutting aluminum is an awful job?
> >It has been my experience that, so long as you have a fine-toothed metal
> >cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
> >$10), a relatively low-power bandsaw works just fine.  And while it does
> >create aluminum "sawdust", it does not send it flying like a circular saw
> >does.  If you buy or make a ripfence, then cutting nice square panels is
> >quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
> >just my opinion.
> >
> >Dave
> >-----Original Message-----
> >From: Martin Czech <martin.czech at intermetall.de>
> >To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
> >Date: Tuesday, December 08, 1998 9:27 AM
> >Subject: aluminum plates and profiles
> >
> >
> >>Hello,
> >>
> >>I just got an answer from Schaeffer Apparatebau (these people do engraved
> >>front panels). I asked if they could also cut aluminum plates for the
> >>other 5 sides of a module box, and also alu profiles in order to connect
> >>front panel and the 5 other sides.  Well, they can do this, but since
> >>they have no saw but only a computer controlled engraving machine this
> >>can get very expensive. OTOH aluminum cutting is an awful job, I guess
> >>a proper saw (be it circular or not) would cost about 600 DM.
> >>
> >>Does anybody know a shop in Germany or nearby where I can get my aluminum
> >>cut?
> >>
> >>m.c.
> >>
> >
> 
> 




From s9610068 at chelt.ac.uk  Wed Dec  9 15:19:53 1998
From: s9610068 at chelt.ac.uk (James Dunn)
Date: Wed, 09 Dec 1998 14:19:53 +0000
Subject: cs-50
Message-ID: <366E8709.7D0B@chelt.ac.uk>

I recently purchased a Yamaha CS-50 for ?40 (uk sterling). A bargain?
The only problem with it is that a high pitched noise starts after about
15 minutes of switching on. It is independent of the volume controls,
and sounds the same as when pressing the highest key with the sine wave
an octave up. I assume somehow this setting is shorting to the output.
Does anyone have any ideas before I take a look inside? It makes some
great sounds but it's getting really annoying.

Thanks,

James.




From wils0450 at itlabs.umn.edu  Wed Dec  9 16:08:09 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Wed, 9 Dec 1998 09:08:09 -0600 (CST)
Subject: aluminum plates and profiles
In-Reply-To: <Pine.OSF.3.95.981209090004.16702D-100000@is8.nyu.edu>
Message-ID: <Pine.GSO.4.05.9812090905400.16672-100000@barney.itlabs.umn.edu>

On Wed, 9 Dec 1998, Plinio Andres Barraza wrote:
> 
> The best thing to cut sheet metal (only in straight lines though) is to
> use a bench press.  Most people wouldn't want to buy one because it is an
> industrial thing (although I have seen samll portable ones)
*snip* God no... Do not I REPEAT do not get one of those flimsey portable
"bench presses." I have nothing but bad luck with them. *spits to the
left in disgust* 

            <<< << The obvious solution is to kill you all >> >>>




From aschrock at cs.brandeis.edu  Wed Dec  9 16:20:39 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Wed, 9 Dec 1998 10:20:39 -0500 (EST)
Subject: aluminum plates and profiles
In-Reply-To: <9812082243171837@greymatter.com>
Message-ID: <Pine.SGI.3.95.981209101707.29812A-100000@opal.cs.brandeis.edu>

Is this the same ELI which sells sun 3/50's for $200 at flea markets? I
have some friends which have had bad experiences with him... apparently
he's jacked up his prices somewhat in recent years. I walked past his
place every day this summer, they seem to be catering to buisnesses mainly
now. For what it's worth.. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Wed, 9 Dec 1998, Dave Halliday wrote:
> One thought - I used to live in the Boston area about 20 years ago and
> there was an absolute hotbed of electronics surplus stores.  I know that
> some have closed ( John Meshna and Sons, Delta, PolyPaks - sniff! ) but
> some are still very much in business.  B&F Enterprises, Eli Hefron's
> which is going under the E.L.I. name.  You might try visiting them and
> seeing if they have anything available.  You might also be able to find
> some used panels - they will have holes in them but you could figure
> out some way to plug them - an extra patch point maybe???  Hmmm???




From dfevans at barrow.uwaterloo.ca  Wed Dec  9 16:22:13 1998
From: dfevans at barrow.uwaterloo.ca (David Evans)
Date: Wed, 9 Dec 1998 10:22:13 -0500 (EST)
Subject: [AH] cs-50
In-Reply-To: <366E8709.7D0B@chelt.ac.uk> from "James Dunn" at Dec 9, 98 02:19:53 pm
Message-ID: <199812091522.KAA29571@barrow.uwaterloo.ca>

James Dunn wrote:
> 
> I recently purchased a Yamaha CS-50 for #40 (uk sterling). A bargain?

  Yep--great synth!

> The only problem with it is that a high pitched noise starts after about
> 15 minutes of switching on.

  I can't help much there but Jurgen Haible will chime in sure enough, I'm
sure.

-- 
David Evans          (NeXTMail/MIME OK)             dfevans at bbcr.uwaterloo.ca
Computer/Synth Junkie                      http://bbcr.uwaterloo.ca/~dfevans/
University of Waterloo         "Default is the value selected by the composer
Ontario, Canada           overridden by your command." - Roland TR-707 Manual



From ryckebu at subasehp.san.mrms.navy.mil  Wed Dec  9 16:31:28 1998
From: ryckebu at subasehp.san.mrms.navy.mil (ryckebu at subasehp.san.mrms.navy.mil)
Date: Wed, 9 Dec 1998 15:31:28 +0000
Subject: audio to trigger
In-Reply-To: <199812091921.FAA21770@uq.net.au>
Message-ID: <199812092149.NAA14692@subasehp.san.mrms.navy.mil>

You need an envelope follower. They are real easy to biuild with a 
diode cap and resistor, possibly an opamp stage for 
buffering or to set output levels.

Jules

> Date:          Thu, 10 Dec 1998 
05:16:59 +1100
> To:            "synth-diy at mailhost.bpa.nl" <synth-diy at mailhost.bpa.nl>
> From:          Stewart Pye <stew at uq.net.au>
> Subject:       audio to trigger

> Hi All,
> 
> I'm looking for a way to convert the audio outs of my TR 707 to short
> trigger pulses for triggering analog drum sounds. I thought about a
> differentiator but I'd get several pulses with that, or a 555 one shot but
> I guess I'd get the same problem. Any help would be greatly appreciated.
> 
> Thanks,
> 
> Stewart Pye
> 
> 
> 



From ryckebu at subasehp.san.mrms.navy.mil  Wed Dec  9 16:32:54 1998
From: ryckebu at subasehp.san.mrms.navy.mil (ryckebu at subasehp.san.mrms.navy.mil)
Date: Wed, 9 Dec 1998 15:32:54 +0000
Subject: which Paia unit is better?...
In-Reply-To: <a5ec87ae.366ec7fa@aol.com>
Message-ID: <199812092150.NAA14919@subasehp.san.mrms.navy.mil>

I would go with the Tube mic pre-amp and a small modification to 
bring an instrument level in to it. I'll post the mod if you are 
interested.

Jules

> From:          Aranakin at aol.com
> Date:          Wed, 9 Dec 1998 13:56:58 EST
> To:            synth-diy at mailhost.bpa.nl
> Subject:       which Paia unit is better?...

> i want to build a mic and guitar preamp for my HD recorder.
> 
> I'd like to buy it out of PAIA and build it (unless you guys recommend a
> better way)
> Which is better? 
> 
> their stereo compressor (9601)? 
> their direct interface (9110)?
> their vaccum tube amp (9305)?
> their tube mic preamp (9407)?
> (i already have the stack in the box, how does that factor in in this
> comparrison?)
> 
> or from Craig Anderton's book, the Preamp(CA-1)? and Compressor and Limiter
> (CA-8)?
> 
> keeping in mind that i want to record both bands and my own electronic music.
> which means i will recording anything from overdriven half stacks to low
> impedence keyboards.
> 
> p.s. I am getting a Roland Vs-840 , just for reference
> 
> thanks, but somewhat lost and confused,
> anthony
> 
> 



From buchanan at qualcomm.com  Wed Dec  9 16:59:17 1998
From: buchanan at qualcomm.com (Buck Buchanan)
Date: Wed, 09 Dec 1998 07:59:17 -0800
Subject: a beginner question - scopes
In-Reply-To: <00e401be230d$44f4e640$2f14eec3@bs132506>
Message-ID: <3.0.3.32.19981209075917.01439170@mage.qualcomm.com>

At 01:44 AM 12/9/98 +0100, ^cAmOtSe^ wrote:
>Hum.
>They lie.. But do they lie enough to justify the price difference???? I know
>nothing about scopes so i'm affraid it'd be hard to buy one 2nd hand...i
>wouldn't know if it's good or not... and also here in belgium 2nd hands and
>bargain shops are much rarer than in uk or us...


Hi all, (this will be my last scope post to the list since this is really
off topic - off list is another story)

DSOs don't really lie per-se - it just seems like they do because they can
trick you into looking at the wrong thing.  It's just such a different
beast than an analog scope that problems can arise.  Here at work have new
engineers right out of school that have never used an analog scope and
complain about them the way most people complain about digitals.  So I
guess lot of it depends on what you learn on.  But with an analog you can
turn knobs till you find your signal until at some point you figure out
how/why the thing is working.  But with digital you better know your scope
theory at least a little....

Price difference making analogs seem more expensive that digitals?  You
must be comparing apples to oranges.  I looked at the bit scope and it's
about $400US.  There are tons of brand new 20MHz dual trace analog scopes
(though not Tek...) sold via mail order for the same price that are sure to
stomp on the bit scope in terms of everyday audio useability.  And you
don't have to drag a computer around either (you can add that to your scope
cost too!).  No, they won't capture a one shot, save a waveform, do your
math or your dishes.  But, they will (within the limits of
bandwidth/risetime/etc.) show you reality every time!  Most digital scopes
cost $1,500US for the cheap ones and go WAY up from there.  And for $1,500
there's still stuff you will miss that will show up on your $500
reconditioned Tek 465!

I'm not saying you can't work with a digital box.  NO WAY!  They're great
things and I'm saving for a TDS210 w/FFT option myself.  But where should
the digital box sit on the bench?  Right on top of the analog box!

Pick up a copy of the American zine Electronics Now or Nuts & Volts - tons
of adds for places that will ship you a new or calibrated/reconditioned
used scope overseas.

Ok, I'll finish blabbing for now.  Last thing I'll say is Belgium!  I love
Belgium!  I used to live in Waterloo... but I still don't know where to buy
a scope there....

Buck

 




A lot of cool shit way more advanced than synthesizers was designed before
DSOs came around.


Buck Buchanan  AA-436   x84377
RF Eng. Tech  Advanced Technology

---------------------
Interviewer:  Have you ever had an original idea?
Mark Ryden: When I painted Abraham Lincoln lyning on the ground giving
birth from his cheek to the baby Venus delivered by Colonel Sanders - I
thought that was pretty original."
-Mark Ryden from interview in Juxtapoze"-



From mmcintos at ball.com  Wed Dec  9 17:07:53 1998
From: mmcintos at ball.com (McIntosh, Malcolm)
Date: Wed, 9 Dec 1998 09:07:53 -0700 
Subject: a beginner question - scopes
Message-ID: <09DB74475204D1119C8200805F19D00302E20BC3@aeromsg1.ball.com>

Just what I needed - an instrument that makes highly accurate measurements
based on M$ Windows 95/98!  What's next, jet-liners?

> -----Original Message-----
> From:	Haible Juergen [SMTP:Juergen.Haible at nbgm.siemens.de]
> Sent:	Wednesday, December 09, 1998 6:51 AM
> To:	martin czech
> Cc:	DIY synth-diy at mailhost.bpa.nl
> Subject:	AW: a beginner question - scopes
> 
> 	>But I have to admit: PC-DSOs get more and more attractive these
> days.
> 	>But perhaps your soundcard together with cooledit will do most of
> the audio
> 	>DSO stuff? Could be.
> 
> Just a little side note:
> Have you seen HP's latest top model digital scopes ? 
> These actually *are* PC's, complete with Win 95 - and the 
> salesperson even said that you can run WinWord and 
> Netscape on them.
> Funny, isn't it ?
> 
> JH.
> 



From Juergen.Haible at nbgm.siemens.de  Wed Dec  9 17:27:25 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 9 Dec 1998 17:27:25 +0100 
Subject: AW: cs-50
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D58201032A6F@nbgm336a.nbgm.siemens.de>

	>I recently purchased a Yamaha CS-50 for ?40 (uk sterling). A
bargain?

Absolutely. I'd pay that price for a completely non-working
(but physically intact) one without hesitation. (I'd even pay that
for the mere keyboard action, if it's mint condition ...)

	>The only problem with it is that a high pitched noise starts after
about
	>15 minutes of switching on. It is independent of the volume
controls,
	>and sounds the same as when pressing the highest key with the sine
wave
	>an octave up. I assume somehow this setting is shorting to the
output.
	>Does anyone have any ideas before I take a look inside? It makes
some
	>great sounds but it's getting really annoying.

Hmm, I'm quite bad on repair stuff (modifying is much more my
deal), but anyway, a few guesses:

You don't have the Ring Modulator on all the time ?
("Off" means that the Modulation Slider is UP, not down !!)
The 15 minute delay is strange, though ...
Your Ring modulator sliders might have an intermittent contact ...
Does the pitch change, if you alter the ring modulator frequency ?

If it's not the Ring mod, it might be one of the voices. Does the pitch
change if you play a four-fingered chord in the lower range ?
If so, the VCA might leak. If not, you would have a leaking VCA
*and* a stuck pitch CV or bad VCO at the same time. Not
likely, but possible ...

That's all that comes to mind at the moment. Next step should
be a careful inspection of the interior, loose wires, conductive
objects stuck between the boards, that stuff.

If you have to trace the error thru the circuit, Yamaha still sell service
manuals.

Good luck !

JH.




From a-davidh at microsoft.com  Wed Dec  9 18:28:47 1998
From: a-davidh at microsoft.com (David Halliday (Volt Computer))
Date: Wed, 9 Dec 1998 09:28:47 -0800 
Subject: aluminum plates and profiles
Message-ID: <C35556591D34D111BB5600805F1961B90BBEAE68@RED-MSG-47>

Could be. He was always a bit of a "dealer" in the sense that he charged as
much as he could but you could always find good deals if he didn't know what
something was.

I just checked http://www.eli.com and there is an entry for company history.
It is the same place but I guess that they are out of the surplus market as
well...


-----Original Message-----
From: Andrew Schrock [mailto:aschrock at cs.brandeis.edu]
Sent: Wednesday, December 09, 1998 7:21 AM
To: Dave Halliday
Cc: synth-diy at mailhost.bpa.nl
Subject: Re: aluminum plates and profiles


Is this the same ELI which sells sun 3/50's for $200 at flea markets? I
have some friends which have had bad experiences with him... apparently
he's jacked up his prices somewhat in recent years. I walked past his
place every day this summer, they seem to be catering to buisnesses mainly
now. For what it's worth.. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Wed, 9 Dec 1998, Dave Halliday wrote:
> One thought - I used to live in the Boston area about 20 years ago and
> there was an absolute hotbed of electronics surplus stores.  I know that
> some have closed ( John Meshna and Sons, Delta, PolyPaks - sniff! ) but
> some are still very much in business.  B&F Enterprises, Eli Hefron's
> which is going under the E.L.I. name.  You might try visiting them and
> seeing if they have anything available.  You might also be able to find
> some used panels - they will have holes in them but you could figure
> out some way to plug them - an extra patch point maybe???  Hmmm???



From costello at seanet.com  Wed Dec  9 19:08:36 1998
From: costello at seanet.com (Sean Costello)
Date: Wed, 09 Dec 1998 10:08:36 -0800
Subject: ASM-1 VCF "external" audio input?
References: <Pine.HPP.3.95.981209012215.11536B-100000@bay.cs.brandeis.edu>
Message-ID: <366EBCA3.8F4E0B2E@seanet.com>

Andrew Schrock wrote:

> Moog transistor ladder designs are pretty nice.. very smooth response, but
> if you're trying to get that aphex twin feel, get a few CEM 3320's!
> (they're still pretty cheap)

For Aphex Twin sounds, the best bet would be to construct a clone of the
Korg MS-20 filters. You could get a Sallen-Key topology out of a 3320,
but you wouldn't have independent cutoff for the highpass and lowpass
filters, and you certainly wouldn't have the raunchiness of the original
MS-20 filters.  The MS-20 filters can be constructed using the 13600
dual OTA, which is available for 80 cents or so from Mouser.  A nice
schematic can be found at
http://www.mindspring.com/~vco/maxx2/page_015.html, or check Music
Machines at Hyperreal for the original schematic.

Sean Costello



From a-davidh at microsoft.com  Wed Dec  9 19:11:27 1998
From: a-davidh at microsoft.com (David Halliday (Volt Computer))
Date: Wed, 9 Dec 1998 10:11:27 -0800 
Subject: a beginner question - scopes
Message-ID: <C35556591D34D111BB5600805F1961B90BBEAE70@RED-MSG-47>

Look on the bright side, it could have been based on the early
"math-challenged" Pentium chip...

-----Original Message-----
From: McIntosh, Malcolm [mailto:mmcintos at ball.com]
Sent: Wednesday, December 09, 1998 8:08 AM
To: 'synth-diy at mailhost.bpa.nl'
Subject: RE: a beginner question - scopes


Just what I needed - an instrument that makes highly accurate measurements
based on M$ Windows 95/98!  What's next, jet-liners?

> -----Original Message-----
> From:	Haible Juergen [SMTP:Juergen.Haible at nbgm.siemens.de]
> Sent:	Wednesday, December 09, 1998 6:51 AM
> To:	martin czech
> Cc:	DIY synth-diy at mailhost.bpa.nl
> Subject:	AW: a beginner question - scopes
> 
> 	>But I have to admit: PC-DSOs get more and more attractive these
> days.
> 	>But perhaps your soundcard together with cooledit will do most of
> the audio
> 	>DSO stuff? Could be.
> 
> Just a little side note:
> Have you seen HP's latest top model digital scopes ? 
> These actually *are* PC's, complete with Win 95 - and the 
> salesperson even said that you can run WinWord and 
> Netscape on them.
> Funny, isn't it ?
> 
> JH.
> 



From stew at uq.net.au  Wed Dec  9 19:16:59 1998
From: stew at uq.net.au (Stewart Pye)
Date: Thu, 10 Dec 1998 05:16:59 +1100
Subject: audio to trigger
Message-ID: <199812091921.FAA21770@uq.net.au>

Hi All,

I'm looking for a way to convert the audio outs of my TR 707 to short
trigger pulses for triggering analog drum sounds. I thought about a
differentiator but I'd get several pulses with that, or a 555 one shot but
I guess I'd get the same problem. Any help would be greatly appreciated.

Thanks,

Stewart Pye




From Aranakin at aol.com  Wed Dec  9 19:56:58 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Wed, 9 Dec 1998 13:56:58 EST
Subject: which Paia unit is better?...
Message-ID: <a5ec87ae.366ec7fa@aol.com>

i want to build a mic and guitar preamp for my HD recorder.

I'd like to buy it out of PAIA and build it (unless you guys recommend a
better way)
Which is better? 

their stereo compressor (9601)? 
their direct interface (9110)?
their vaccum tube amp (9305)?
their tube mic preamp (9407)?
(i already have the stack in the box, how does that factor in in this
comparrison?)

or from Craig Anderton's book, the Preamp(CA-1)? and Compressor and Limiter
(CA-8)?

keeping in mind that i want to record both bands and my own electronic music.
which means i will recording anything from overdriven half stacks to low
impedence keyboards.

p.s. I am getting a Roland Vs-840 , just for reference

thanks, but somewhat lost and confused,
anthony



From sdcurtin at lucent.com  Wed Dec  9 20:03:55 1998
From: sdcurtin at lucent.com (Curtin, Steven D (Steven))
Date: Wed, 9 Dec 1998 14:03:55 -0500 
Subject: aluminum plates and profiles
Message-ID: <2E12619580C0D1118C6400805F9F4C95DB267E@nj7460exch001u.ho.lucent.com>

While we're on the subject does anyone know of a good surplus electronics
store in the New York/New Jersey area?

-----------------------------------------------------------------
Steven Curtin  
Lucent Technologies Microelectronics
ph: (732)957-2996   fax: (732)957-6878
http://www.emf.org/subscribers/curtin/
sdcurtin at lucent.com
-----------------------------------------------------------------


> On Wed, 9 Dec 1998, Dave Halliday wrote:
> > One thought - I used to live in the Boston area about 20 years ago and
> > there was an absolute hotbed of electronics surplus stores.  I know that
> > some have closed ( John Meshna and Sons, Delta, PolyPaks - sniff! ) but
> > some are still very much in business.  B&F Enterprises, Eli Hefron's
> > which is going under the E.L.I. name.  You might try visiting them and
> > seeing if they have anything available.  You might also be able to find
> > some used panels - they will have holes in them but you could figure
> > out some way to plug them - an extra patch point maybe???  Hmmm???
> 



From wils0450 at itlabs.umn.edu  Wed Dec  9 20:41:03 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Wed, 9 Dec 1998 13:41:03 -0600 (CST)
Subject: smoke damage
Message-ID: <Pine.GSO.4.05.9812091339420.8521-100000@urchin.itlabs.umn.edu>

I have an opportunity to get a couple of MMT-8's as a package, but one of
them has "some smoke damage" (I know, it couldn't be much vauger). Is this
the kind of thing I want to stay away from, or is it an *easy* fix?

            <<< << The obvious solution is to kill you all >> >>>




From mikeri at comm.mot.com  Wed Dec  9 20:55:50 1998
From: mikeri at comm.mot.com (Mike Ricos)
Date: Wed, 09 Dec 1998 13:55:50 -0600
Subject: which Paia unit is better?...
References: <a5ec87ae.366ec7fa@aol.com>
Message-ID: <366ED5C6.4BEEB279@comm.mot.com>

I built the tube mic preamp and am very happy with it. It won't give you
monster crunch distortion but it provides great, subtle distortion. 

The kit provides phantom power toggle, a balance control between tube
amp and solid state, a polarity switch (dramatically effects single
ended signal) and balanced i/o.

I highly recommend making your own power supply for the unit and adding
a front panel pot for the "symmetry" control that effects the bias of
the tube input. This provides significant control of the distortion
quality. 

Its a great device for < $100.

Regards,

Mike

Aranakin at aol.com wrote:
> Which is better?
> 
> their stereo compressor (9601)?
> their direct interface (9110)?
> their vaccum tube amp (9305)?
> their tube mic preamp (9407)?



From costello at seanet.com  Wed Dec  9 21:34:21 1998
From: costello at seanet.com (Sean Costello)
Date: Wed, 09 Dec 1998 12:34:21 -0800
Subject: audio to trigger
References: <199812091921.FAA21770@uq.net.au>
Message-ID: <366EDECD.C90615BA@seanet.com>

Stewart Pye wrote:
> 
> Hi All,
> 
> I'm looking for a way to convert the audio outs of my TR 707 to short
> trigger pulses for triggering analog drum sounds. I thought about a
> differentiator but I'd get several pulses with that, or a 555 one shot but
> I guess I'd get the same problem. Any help would be greatly appreciated.

Before you do that, have you tried just triggering the drum sounds with
the audio outs of the 707?  Back in the analog days of yore (i.e. about
6 months ago, before I sold off most of my analog collection) I used to
sync up a 707 to my 606 and 202, and used the independent outs of the
707 to trigger the drum sounds on a Tama TS-305 drum brain.  It worked
like a charm.  The "Attack" control on the 305 allowed me to mix how
much of the original drum sound could be heard in the output (I think it
was a simple lowpass filter, designed to work with voltage triggers to
add more or less "click").  I used a Drumfire with the 707, and also got
good results.  Maybe some analog drums need a conditioned pulse, but I
have the feeling a lot of them will work with any good percussive
sound.  Twin-T filters and the like should be able to trigger from the
707, with the 707 sounds providing some nice attack coloration.

Sean Costello




From bduggan at netcom.com  Wed Dec  9 21:49:49 1998
From: bduggan at netcom.com (Brett Duggan)
Date: Wed, 9 Dec 1998 12:49:49 -0800 (PST)
Subject: aluminum plates and profiles
In-Reply-To: <1.5.4.16.19970304201647.382f3dae@popa.melbpc.org.au>
Message-ID: <Pine.3.89.9812091239.A29898-0100000@netcom10>


Standard rack-mount holes can be made perfectly with a milling machine.  
It wouldn't hurt to ask around to see if any of your heavily tool-laden 
buddies have one.  Or, as has been stated earlier, perhaps a local high 
school or college campus has one in their shop that they wouldn't mind 
letting you use either for free or a small fee.

Brett D

> The only difficult thing abt panels, is doing a standard rack mount hole..
> but, you can always drill and file.




From costello at seanet.com  Wed Dec  9 22:11:51 1998
From: costello at seanet.com (Sean Costello)
Date: Wed, 09 Dec 1998 13:11:51 -0800
Subject: smoke damage
References: <Pine.GSO.4.05.9812091339420.8521-100000@urchin.itlabs.umn.edu>
Message-ID: <366EE797.87FD06F4@seanet.com>

Clarissa Fragile wrote:
> 
> I have an opportunity to get a couple of MMT-8's as a package, but one of
> them has "some smoke damage" (I know, it couldn't be much vauger). Is this
> the kind of thing I want to stay away from, or is it an *easy* fix?

Probably means "smoke has made switches that turn sequences on and off
completely erratic, if not unusable."  These switches are fixable, or I
think you can get replacements from Alesis.  I fixed similar swithces
(on a Sequential Circuits SixTrak) with some sandpaper and alcohol (to
sand away and clean off the non-conductive parts of the little plastic
buttons that make up the switch), & then added some finely powdered
pencil shavings (for added conductivity).  

Sean Costello



From Hess.Hodge at Colorado.EDU  Wed Dec  9 22:43:21 1998
From: Hess.Hodge at Colorado.EDU (Hess Hodge)
Date: Wed, 9 Dec 1998 14:43:21 -0700 (MST)
Subject: SCI Pro-One problem
Message-ID: <Pine.GSO.3.96.981209144111.23619C-100000@rintintin.Colorado.EDU>

Sorry for the cross-post.  I posted this to Analogue Heaven and did not
receive any responses.  I am hoping that someone here can help me in
diagnosing this problem... thanks,
Hess

-/\= Hess M. Hodge
~/\  hess.hodge at colorado.edu
(/\) http://rtt.colorado.edu/~hodge


---------- Forwarded message ----------
Date: Tue, 8 Dec 1998 23:17:56 -0700 (MST)
From: Hess Hodge <hodge at rintintin.Colorado.EDU>
To: analogue <analogue at hyperreal.org>
Subject: SCI Pro-One problem

Hello,
I just received a pro-one (my very first analogue synth!) and I am
having some problems.  I found some references to the same symptoms
in the archives, but no insight into the problem itself.  Here is what is
happening (you must excuse my limited synth vocabulary):  After only
playing a few notes the synth will stop working.  The keyboard stops
responding and the unit either makes no sound, or the gate LED lights up
and the unit glides up to the highest note and stays there.  No further
tweaking of any keys switches or pots can get the unit back or produce
any different output. Only a power cycle will reset the unit and make
everything work again (temporarily).  This problem will occur on its own
(ie, I'm not doing anything but pressing keys) or when I try to use the
sequencer or the arpeggiator.  When using the sequencer or the 
arpeggiator, the synth will usually play a bunch of random notes before it
dies.  I opened it up, checked all the connections and made a visual check
of the PCB, but I couldn't find anything unusual (except for the shrooms
;)  Has anybody seen these symptoms before?  Know what the problem is?
How to fix?  By the way, it is ser # 100-5557 with a J-wire keyboard.  Any
help is very much appreciated!
hess

-/\= Hess M. Hodge
~/\  hess.hodge at colorado.edu
(/\) http://rtt.colorado.edu/~hodge






From camotse at france-mail.com  Wed Dec  9 23:03:51 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Wed, 9 Dec 1998 23:03:51 +0100
Subject: aluminum plates and profiles
Message-ID: <00f601be23c3$0c5451c0$9015eec3@bs132506>

>I got a rackmount irregular quadrilateral cross section steel box for $US
60.
>You take it out of the rack, and it sits on the table with a sloping front
>like a block of Tobler-1. Nothing like it in the catalogs!

WOW!! You mean Toblerone, the chocolate???My god i didn't know u'd have
those in australia!! Hmmmmm ok i need to go to the shop NOW.. L8R!


>
>paul perry melbourne australia
>

greg belgium


ps: ok sorry that was a bit out of topic i won't do it anymore




From wils0450 at itlabs.umn.edu  Wed Dec  9 23:03:59 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Wed, 9 Dec 1998 16:03:59 -0600 (CST)
Subject: scopes (more)
Message-ID: <Pine.GSO.4.05.9812091601540.8521-100000@urchin.itlabs.umn.edu>

Allright, I read a document or two and both have suggestions for
additions to a scope. What kind of Analog scope recieves add-ons the
best/is easiest to work with?

            <<< << The obvious solution is to kill you all >> >>>




From b.layer at vikingelectronics.com  Wed Dec  9 23:33:36 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Wed, 09 Dec 1998 16:33:36 -0600
Subject: which Paia unit is better?...
In-Reply-To: <366ED5C6.4BEEB279@comm.mot.com>
References: <a5ec87ae.366ec7fa@aol.com>
Message-ID: <3.0.6.32.19981209163336.007e9670@192.168.210.18>

Hi Mike/All,

 
>I highly recommend making your own power supply for the unit and adding
>a front panel pot for the "symmetry" control that effects the bias of
>the tube input. This provides significant control of the distortion
>quality. 
   
Unless I'm mistaken, the symmetry control on the PAiA Tube Mic Pre controls
gain for the tube section, so that when the blend knob is wound from 'full
SS' to 'full VT' the signal level remains the same. This would be required,
as no two 12AX7 have identical gain characteristics, a fact which is
magnified by the 'starved' operation of the circuit.

By breaking this out to the front panel, don't you create a situation where
the blend control acts like a vol control as well?

Just thinkin...


=======================================================================
This message and any attachments to it are subject to copying and are 
sent solely for the personal amusement the sender.  It may include 
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========================================================================




From Aranakin at aol.com  Wed Dec  9 23:50:27 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Wed, 9 Dec 1998 17:50:27 EST
Subject: What's with the motion filter?
Message-ID: <d531e60a.366efeb3@aol.com>

can anyonetell me EXACTLY what this motion filter from PAIA does?  OR how it
works?  anthony



From cyborg0 at GlobalEyes.net  Wed Dec  9 23:54:25 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Wed, 09 Dec 1998 16:54:25 -0600
Subject: smoke damage
References: <Pine.GSO.4.05.9812091339420.8521-100000@urchin.itlabs.umn.edu>
Message-ID: <366EFFA1.712F3664@globaleyes.net>

Clarissa Fragile wrote:
> 
> I have an opportunity to get a couple of MMT-8's as a package, but one of
> them has "some smoke damage" (I know, it couldn't be much vauger). Is this
> the kind of thing I want to stay away from, or is it an *easy* fix?
> 
>             <<< << The obvious solution is to kill you all >> >>>

I would say if they work, they work, and thats the bottom line.. You MAY
have to take them apart and do a little contact cleaning of the gummi
buttons and the board, but they have NO moving parts.. I have rebuilt 2
of these im my lifetime, and the are super-simple. basically a few chips
and a stringer of buttons..
rob



From camotse at france-mail.com  Thu Dec 10 00:11:35 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Thu, 10 Dec 1998 00:11:35 +0100
Subject: got a scope
Message-ID: <01c001be23cd$eec665c0$9015eec3@bs132506>


>The problem here in Germany is, that there seems to be no market for used
>scopes etc. There are companys that sell refurbished used gear, but still
>very expensive.  So it appeared to me a better deal to get a new one...
>
Same in Belgium i guess, for those who adviced me to look for used gear...

greg aka camotse (sometimes:)




From camotse at france-mail.com  Thu Dec 10 00:14:35 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Thu, 10 Dec 1998 00:14:35 +0100
Subject: aluminum plates and profiles
Message-ID: <01c101be23cd$ef7f0760$9015eec3@bs132506>

>> The best thing to cut sheet metal (only in straight lines though) is to
>> use a bench press.  Most people wouldn't want to buy one because it is an
>> industrial thing (although I have seen samll portable ones)
>*snip* God no... Do not I REPEAT do not get one of those flimsey portable
>"bench presses." I have nothing but bad luck with them. *spits to the
>left in disgust*
>
gosh i was on ur left, clarissa!! haaa please clean me up now! :-/
haha
oops
sorry i think i said i wouldn't try stupid oot jokes again
oops

greg.

(clarissa don't u irc? u write like irc ppl ;-) /me would like to know
*grin*




From lptorre at HiWAAY.net  Thu Dec 10 00:19:02 1998
From: lptorre at HiWAAY.net (Larry P. Torre)
Date: Wed, 9 Dec 1998 17:19:02 -0600
Subject: [AH] AW: cs-50
Message-ID: <00a401be23ca$7855afc0$a89493d0@lptorre.halcyon.com>

I've got a CS-50 that also makes a high whine, although possibly at lower
volume than described here. It isn't through the audio output though, and
I've always assumed it was from the power supply. The beastie works fine,
and the faint high-pitched whine has not been a problem as I often use
headphones in the studio. The whine does not start immediately upon power-up
but within a minute or so. Also, I get a faint smell within a few minutes
which smells like "warm circuitry" (the CS-50 is packed with analogue
circuitry compared to today's computer-based modules/keyboards).
 Got mine for $120 five years ago in a Seattle mom & pop organ store!

Anyone know if Kenton or somebody currently makes a midi retro-fit for this
synth?

-----Original Message-----
From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
To: s9610068 at chelt.ac.uk <s9610068 at chelt.ac.uk>
Cc: DIY <synth-diy at mailhost.bpa.nl>; analogue <analogue at hyperreal.org>
Date: December 09, 1998 10:27 AM
Subject: [AH] AW: cs-50


> >I recently purchased a Yamaha CS-50 for ?40 (uk sterling). A
>bargain?
>
>Absolutely. I'd pay that price for a completely non-working
>(but physically intact) one without hesitation. (I'd even pay that
>for the mere keyboard action, if it's mint condition ...)
>
> >The only problem with it is that a high pitched noise starts after
>about
> >15 minutes of switching on. It is independent of the volume
>controls,
> >and sounds the same as when pressing the highest key with the sine
>wave
> >an octave up. I assume somehow this setting is shorting to the
>output.
> >Does anyone have any ideas before I take a look inside? It makes
>some
> >great sounds but it's getting really annoying.
>
>Hmm, I'm quite bad on repair stuff (modifying is much more my
>deal), but anyway, a few guesses:
>
>You don't have the Ring Modulator on all the time ?
>("Off" means that the Modulation Slider is UP, not down !!)
>The 15 minute delay is strange, though ...
>Your Ring modulator sliders might have an intermittent contact ...
>Does the pitch change, if you alter the ring modulator frequency ?
>
>If it's not the Ring mod, it might be one of the voices. Does the pitch
>change if you play a four-fingered chord in the lower range ?
>If so, the VCA might leak. If not, you would have a leaking VCA
>*and* a stuck pitch CV or bad VCO at the same time. Not
>likely, but possible ...
>
>That's all that comes to mind at the moment. Next step should
>be a careful inspection of the interior, loose wires, conductive
>objects stuck between the boards, that stuff.
>
>If you have to trace the error thru the circuit, Yamaha still sell service
>manuals.
>
>Good luck !
>
>JH.
>
>




From simon at dynamite.com.au  Thu Dec 10 00:46:04 1998
From: simon at dynamite.com.au (Simon)
Date: Thu, 10 Dec 1998 09:46:04 +1000
Subject: audio to trigger (+ to MIDI?)
In-Reply-To: <366EDECD.C90615BA@seanet.com>
References: <199812091921.FAA21770@uq.net.au>
Message-ID: <l03130302b294bada6ff6@[203.23.182.33]>

I would be interested in a similar sort of DIY project to allow the
triggering of MIDI devices using acoustic drum triggers or recorded audio,
to allow playing of MIDI sounds with a real drum kit, or to replace
prerecorded drums with other drum samples.

A drum module like the Alesis DM4 or Roland D5 would do this, but I don't
need the inbuilt sounds, is there a cheaper DIY audio-trigger-MIDI project?

Thanks
Simon
Canberra
AUSTRALIA


>> I'm looking for a way to convert the audio outs of my TR 707 to short
>> trigger pulses for triggering analog drum sounds. I thought about a
>> differentiator but I'd get several pulses with that, or a 555 one shot but
>> I guess I'd get the same problem. Any help would be greatly appreciated.
>
>Before you do that, have you tried just triggering the drum sounds with
>the audio outs of the 707?  Back in the analog days of yore (i.e. about
>6 months ago, before I sold off most of my analog collection) I used to
>sync up a 707 to my 606 and 202, and used the independent outs of the
>707 to trigger the drum sounds on a Tama TS-305 drum brain.  It worked
>like a charm.  The "Attack" control on the 305 allowed me to mix how
>much of the original drum sound could be heard in the output (I think it
>was a simple lowpass filter, designed to work with voltage triggers to
>add more or less "click").  I used a Drumfire with the 707, and also got
>good results.  Maybe some analog drums need a conditioned pulse, but I
>have the feeling a lot of them will work with any good percussive
>sound.  Twin-T filters and the like should be able to trigger from the
>707, with the 707 sounds providing some nice attack coloration.
>
>Sean Costello






From aschrock at cs.brandeis.edu  Thu Dec 10 00:55:00 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Wed, 9 Dec 1998 18:55:00 -0500 (EST)
Subject: smoke damage
In-Reply-To: <366EFFA1.712F3664@globaleyes.net>
Message-ID: <Pine.SGI.3.95.981209185414.22654B-100000@peridot.cs.brandeis.edu>

I have to say that the best idea is to replace the buttons with tact
switches. Easy, and cheap. (~20$) I wrote up something on it a while ago,
I'm pretty sure it's in the alesis section of hyperreal. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Wed, 9 Dec 1998, Rob wrote:

> Clarissa Fragile wrote:
> > 
> > I have an opportunity to get a couple of MMT-8's as a package, but one of
> > them has "some smoke damage" (I know, it couldn't be much vauger). Is this
> > the kind of thing I want to stay away from, or is it an *easy* fix?
> > 
> >             <<< << The obvious solution is to kill you all >> >>>
> 
> I would say if they work, they work, and thats the bottom line.. You MAY
> have to take them apart and do a little contact cleaning of the gummi
> buttons and the board, but they have NO moving parts.. I have rebuilt 2
> of these im my lifetime, and the are super-simple. basically a few chips
> and a stringer of buttons..
> rob
> 




From aschrock at cs.brandeis.edu  Thu Dec 10 00:56:56 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Wed, 9 Dec 1998 18:56:56 -0500 (EST)
Subject: audio to trigger
In-Reply-To: <199812092149.NAA14692@subasehp.san.mrms.navy.mil>
Message-ID: <Pine.SGI.3.95.981209184909.22654A-100000@peridot.cs.brandeis.edu>

Well, voltage tends to confuse circuits which are expecting a trigger.
(retriggering and all other sorts of garbage) If anything, put the output
of the envelope follower through a schmitt trigger to get a uniform pulse.
Otherwise you're just taking a guess with what the hysteris level is. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|

On Wed, 9 Dec 1998 ryckebu at subasehp.san.mrms.navy.mil wrote:

> You need an envelope follower. They are real easy to biuild with a 
> diode cap and resistor, possibly an opamp stage for 
> buffering or to set output levels.
> > I'm looking for a way to convert the audio outs of my TR 707 to short
> > trigger pulses for triggering analog drum sounds. I thought about a
> > differentiator but I'd get several pulses with that, or a 555 one shot but
> > I guess I'd get the same problem. Any help would be greatly appreciated.





From DCMagnuson at aol.com  Thu Dec 10 01:02:37 1998
From: DCMagnuson at aol.com (DCMagnuson at aol.com)
Date: Wed, 9 Dec 1998 19:02:37 EST
Subject: aluminum plates and profiles
Message-ID: <ac2ebbe2.366f0f9d@aol.com>

In a message dated 12/9/98 9:42:25 AM Eastern Standard Time,
martin.czech at intermetall.de writes:

> 
>  > Just out of curiosity, why do you say cutting aluminum is an awful job?
>  > It has been my experience that, so long as you have a fine-toothed metal
>  > cutting blade 3/8 inches wide (I had one made for a 14 inch bandsaw for
>  > $10), a relatively low-power bandsaw works just fine.  And while it does
>  > create aluminum "sawdust", it does not send it flying like a circular saw
>  > does.  If you buy or make a ripfence, then cutting nice square panels is
>  > quite easy.  The edges need only a minimal amount of smoothing.  Anyway,
>  > just my opinion.
>  > 
>   Well, I didn't try a bandsaw (this is also circular in a way, right?),
>  but a hand pendulum saw (no circular blade). The blade is 2mm thick,
>  but it still goes to the left or right, and there is a lot of 
>  vibration. So the cut is very ugly, 0.5-0.7mm tolerance.
>  

I do metal work for a living, and I have a few comments for do-it-yourselfers.
First, someone mentioned a bench press for cutting... this is a very good
solution, as is a jump shear.  Both are a little too much for the average
hobbiest, though.  For using household saws, you can by fiber reinforced cut
off wheels that fit standard circular saws that cuts aluminum quite well.  It
would be ideal to use this type of blade in either a table saw or radial arm
saw to assure a straight cut.  

If you must use a circular saw (of any type...table, radial, handheld) and
can't find the fiber blades, I've also used plywood cutting blades (very small
teeth) with good success.  In order to cut down on burrs and kick back, put
the blade in BACKWARDS.  I learned this trick freom guys who install aluminum
siding, and it seems to make the cuts a little more controllable

Dave Magnuson
Independent Music Site
http://members.aol.com/dcmagnuson



From Aranakin at aol.com  Thu Dec 10 01:04:04 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Wed, 9 Dec 1998 19:04:04 EST
Subject: (un)balanced compressor?
Message-ID: <955f4ae0.366f0ff4@aol.com>

you're supposed to put the compressor last in your chain of effectsright?
so if the compressor is not balanced (project #8, craig anderton),
isn't it defeating the purpose to put it after your mic tube preamp, which is
balanced?

i guess my question is, is the compressor balanced?
anthony



From gt7276a at prism.gatech.edu  Thu Dec 10 01:17:08 1998
From: gt7276a at prism.gatech.edu (Brian Towles)
Date: Wed, 09 Dec 1998 19:17:08 -0500
Subject: Filter Topologies ( was ASM-1 VCF "external" audio input? )
References: <Pine.HPP.3.95.981209012215.11536B-100000@bay.cs.brandeis.edu> <366EBCA3.8F4E0B2E@seanet.com>
Message-ID: <366F1303.7349A773@prism.gatech.edu>

Sean Costello wrote:

> For Aphex Twin sounds, the best bet would be to construct a clone of the
> Korg MS-20 filters. You could get a Sallen-Key topology out of a 3320,
> but you wouldn't have independent cutoff for the highpass and lowpass
> filters, and you certainly wouldn't have the raunchiness of the original
> MS-20 filters.  The MS-20 filters can be constructed using the 13600
> dual OTA, which is available for 80 cents or so from Mouser.  A nice
> schematic can be found at
> http://www.mindspring.com/~vco/maxx2/page_015.html, or check Music
> Machines at Hyperreal for the original schematic.

i read this and began to wonder if anyone has ever done a "controlled" testof
different filter topologies?  for example, one could use a particular ota and
listen to state-variable, sallen-key, etc.  under normal conditions they should

have similar operation, but what about overdriven?  does anyone have
experiences with this?

brian







From costello at seanet.com  Thu Dec 10 01:19:00 1998
From: costello at seanet.com (Sean Costello)
Date: Wed, 09 Dec 1998 16:19:00 -0800
Subject: aluminum plates and profiles
References: <00f601be23c3$0c5451c0$9015eec3@bs132506>
Message-ID: <366F1374.6B43EAC1@seanet.com>

^cAmOtSe^ wrote:

> WOW!! You mean Toblerone, the chocolate???My god i didn't know u'd have
> those in australia!! Hmmmmm ok i need to go to the shop NOW.. L8R!

United States, too.  You can get Lindt here, too.  Gummi bears are also
freely available, which seems to astonish many German visitors to this
country.

Sean Costello (completely off-topic in Seattle)

"Mann bin ich sauer!"



From pfperry at melbpc.org.au  Thu Dec 10 02:00:50 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Thu, 10 Dec 1998 12:00:50 +1100 (EST)
Subject: audio to trigger
Message-ID: <1.5.4.16.19970305152942.388f465e@popa.melbpc.org.au>

At 05:16 AM 10/12/98 +1100, Stewart Pye  wrote:

>I'm looking for a way to convert the audio outs of my TR 707 to short
>trigger pulses for triggering analog drum sounds. I thought about a
>differentiator but I'd get several pulses with that, or a 555 one shot but
>I guess I'd get the same problem.

You could use a simple diode&cap&resistor rectifier/integrator, then run this to
a comparator with hysteresis. Parts count shd be pretty low, esp if you are
making
a bunch for a machine with sep outs.

Also, if you go 555, you can have a 'refractory' period (it triggers, but then 
cant trigger again for a fixed period). Using a comparator to trigger a
fixed period 
555 you cd probably run off the raw audio & have very few parts.

paul perry melbounre australia




From djfonzi at pacbell.net  Thu Dec 10 04:04:43 1998
From: djfonzi at pacbell.net (Mikel Zwissler)
Date: Wed, 09 Dec 1998 19:04:43 -0800
Subject: audio to trigger
References: <199812091921.FAA21770@uq.net.au> <366EDECD.C90615BA@seanet.com>
Message-ID: <366F3A4B.1F0B51DB@pacbell.net>

>  I've also triggered a SDS8 with the audio outs of a 707.  Works preety well.
> Interesting stuff with the attack when you use a longer sample (tom, etc.)

                Just for kicks, I plugged my guitar into the SDS8 trigger in one
night.   WIERD!!!    Wish I hadn't given it to my drummer the next day.  Could
be fun to mess around with.  Maybe hook up a mic and be the human beat box!

                                                                    Mikel Z





From ijfritz at earthlink.net  Thu Dec 10 05:18:58 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Wed, 09 Dec 1998 21:18:58 -0700
Subject: First Squawks
Message-ID: <366F4BB2.543A392C@earthlink.net>

Today I got the first sounds out of the analog physical modeling synth
I've been developing. At first it made nothing but an incredible amount
of strange noise -- different forms of chaotic behavior, I guess. After
putting a LP filter in the loop it still made a lot of noise, but I was
able to find a range of parameters that gave periodic waveforms.
Especially gratifying, I got it to lock at half the pilot wave
frequency, which is the correct behavior for the clarinet model that it
is running. It's going to take a lot of work to make this a useful
instrument -- its not obvious how to set the gains of the various
sections, for example -- but so far it's great fun.

  Ian



From thelab at sprint.ca  Thu Dec 10 05:37:48 1998
From: thelab at sprint.ca (Philip)
Date: Thu, 10 Dec 1998 01:37:48 -0300
Subject: [AH] AW: cs-50
References: <00a401be23ca$7855afc0$a89493d0@lptorre.halcyon.com>
Message-ID: <366F501C.5278@sprint.ca>

I had a CS-50, 60 and 80. They all worked fine but I only kept them for
short periods. They sounded dull and boring to me...however if you like
nice peaceful ENO melodies and sounds, these are the synths.

The only one with a problem was the CS-60. It came DOA. I quickly
discovered that the bridge rectifier was blown. Maybe your ps is
suffering age and the smoothing caps are letting ac ripple through?

Philip

Philip Pilgrim                  The Lab Audio Works
5 Evan's Drive                  - Analog/Digital Recording/Processing
Hammonds Plains                 - Computer/Synth Interfacing
Nova Scotia, Canada             - Hardware/Software Development
B4B 1M8

Phone     +1.902.835.7844
Email      mailto:thelab at sprint.ca

Web Page: http://www.robotnik.com/the_lab



From fa_diy at fa.camelot.de  Thu Dec 10 07:27:00 1998
From: fa_diy at fa.camelot.de (Florian Anwander)
Date: 10 Dec 1998 08:27:00 +0200
Subject: desperately ssekin'
In-Reply-To: <76SFlOY4HFB@fa.camelot.de>
Message-ID: <76$OHqbpHFB@fa.camelot.de>

Hello Duane,

>  I think you mean "MG-1". It was designsed by Bob Moog and Paul
>Schrieber,
>  if I'm not mistaken.
You are right. Often known as "Moog Realistic".

Gruss,
 Florian Anwander
-------------------------------------------------------------------------
Maus-Netz: Florian Anwander at M4
Internet:  fa at fa.camelot.de           http://www.camelot.de/~fa/
## CrossPoint v3.11 R ##



From stew at uq.net.au  Thu Dec 10 09:16:56 1998
From: stew at uq.net.au (Stewart Pye)
Date: Thu, 10 Dec 1998 19:16:56 +1100
Subject: audio to trigger
In-Reply-To: <1.5.4.16.19970305152942.388f465e@popa.melbpc.org.au>
Message-ID: <199812100921.TAA21924@uq.net.au>

At 12:00 10/12/98 +1100, Paul Perry wrote:

>You could use a simple diode&cap&resistor rectifier/integrator, then run
this to
>a comparator with hysteresis. Parts count shd be pretty low, esp if you are
>making
>a bunch for a machine with sep outs.

Thanks for all the responses. I don't want to appear biased towards fellow
Australians but this could be the answer I was looking for. I don't think
the envelope follower on its own would work well enough. I know that for
some devices the audio will trigger it okay.           ( including the HC2
hand clapper)  But some, eg: my tama DS 200 seems to need a sharp, short
pulse to get a decent sound.
This is why I like Pauls idea, but I have a great way to enhance it. Use
the output of the histeresis comparator to switch a 4066 that is passing
the rectifier/integrator signal to allow velocity sensitive (or accent
sensitive) pulses. 
Thanks for all the replys. I now have some experimenting to do but am sure
something really great will eventuate, thanks to you guys. 

Regards,

Stewart Pye
>
>Also, if you go 555, you can have a 'refractory' period (it triggers, but
then 
>cant trigger again for a fixed period). Using a comparator to trigger a
>fixed period 
>555 you cd probably run off the raw audio & have very few parts.

I'm sure the 555 will come in handy somewhere with this project





From stew at uq.net.au  Thu Dec 10 09:55:12 1998
From: stew at uq.net.au (Stewart Pye)
Date: Thu, 10 Dec 1998 19:55:12 +1100
Subject: audio to trigger
In-Reply-To: <1.5.4.16.19970305152942.388f465e@popa.melbpc.org.au>
Message-ID: <199812100959.TAA02287@uq.net.au>

A Quick Update,

I just remembered something that does trigger well from the 707 audio outs.
My MKS 100 sampler. I used to trigger an SH5 bass drum sample. Anyway, I
have the service manual for the MKS and sure enough, after the limiter (
the trig in uses the normal audio in jack) it branches off to 2 filters
(for 2 different samp freq's) and a half wave rectifier / C-R filter /
basic comparator. Why didn't I think of this earlier. I'll give it a go
tomorrow. I just bought the parts to wire wrap a midi to trigger converter
today too.

Thanks and Regards,

Stewart Pye




From Juergen.Haible at nbgm.siemens.de  Thu Dec 10 10:43:31 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 10 Dec 1998 10:43:31 +0100
Subject: AW: [AH] AW: cs-50
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D58201032E42@nbgm336a.nbgm.siemens.de>

	>I had a CS-50, 60 and 80. They all worked fine but I only kept them
for
	>short periods. They sounded dull and boring to me...

Ouch, that hurts.

(No offense intended, Philip.)

JH.



From vco at mindspring.com  Thu Dec 10 10:54:45 1998
From: vco at mindspring.com (tomg)
Date: Thu, 10 Dec 1998 04:54:45 -0500
Subject: Mad Mouse Fix #1
Message-ID: <yam7648.2291.119670536@mail.mindspring.com>



I updated the following files. I had a few things to
fix and there were a few graphic problems.


http://www.mindspring.com/~vco/madm/pics/mm_pc1.gif
http://www.mindspring.com/~vco/madm/pics/mm_pc2.gif
http://www.mindspring.com/~vco/madm/pics/mm_sd.gif

-tg




From Juergen.Haible at nbgm.siemens.de  Thu Dec 10 11:04:33 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 10 Dec 1998 11:04:33 +0100
Subject: AW: audio to trigger
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D58201032EB1@nbgm336a.nbgm.siemens.de>

	>Also, if you go 555, you can have a 'refractory' period (it
triggers, but then 
	>cant trigger again for a fixed period). Using a comparator to
trigger a
	>fixed period 
	>555 you cd probably run off the raw audio & have very few parts.
	>
	>paul perry melbounre australia

This is essentially what I meant with the "monoflop" method.
All the audio tracks on my homepage are sync'ed like
that. Only that I have used a SSM2056-based envelope
generator for the monoflop (just because it was there in
the modular - it will surely work with a simple 555 as well !)
You must adjust the "on"-time manually to fit yout beat
rate (approximately), but then it works excellent, even when 
triggered from sounds that vary in amplitude.
(which is a problem when you work with envelope detector)

JH.




From Juergen.Haible at nbgm.siemens.de  Thu Dec 10 11:14:54 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 10 Dec 1998 11:14:54 +0100
Subject: AW: First Squawks
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D58201032EDC@nbgm336a.nbgm.siemens.de>

Hi Ian,

good to hear that you're sucesfully working on this.
Does it already make "tuned" noises, V/Oct or whatever ?

Keep up the good work,

JH.

	>----------
	>Von: 	Ian Fritz[SMTP:ijfritz at earthlink.net]
	>Antwort an: 	ijfritz at earthlink.net
	>Gesendet: 	Donnerstag, 10. Dezember 1998 05:18
	>An: 	DIY list
	>Betreff: 	First Squawks
	>
	>Today I got the first sounds out of the analog physical modeling
synth
	>I've been developing. At first it made nothing but an incredible
amount
	>of strange noise -- different forms of chaotic behavior, I guess.
After
	>putting a LP filter in the loop it still made a lot of noise, but I
was
	>able to find a range of parameters that gave periodic waveforms.
	>Especially gratifying, I got it to lock at half the pilot wave
	>frequency, which is the correct behavior for the clarinet model
that it
	>is running. It's going to take a lot of work to make this a useful
	>instrument -- its not obvious how to set the gains of the various
	>sections, for example -- but so far it's great fun.
	>
	>  Ian




From pfperry at melbpc.org.au  Thu Dec 10 11:29:46 1998
From: pfperry at melbpc.org.au (Paul Perry)
Date: Thu, 10 Dec 1998 21:29:46 +1100 (EST)
Subject: [AH] Paia Synthespin?
Message-ID: <1.5.4.16.19970306005839.39476fa0@popa.melbpc.org.au>

At 12:02 AM 10/12/98 -0500, Tim Johnston  wrote:
>Anybody know what a PAIA Synthespin is? 

There is a ckt for this (and other PA1A stuff) in
"electronic music curciut guidebook' Brice Ward Tab 1975
it isn't a REALLY rare book

Uses a LM3900 Norton quad.
Has a lfo driving a transistor to vary a bandpass filter,
the (out of phase) output from which is summrd with the input
to give a phaser effect.

SPEED this is the LFO speed control

ACCENT this is 'depth' or 'intensity' of efect

SPAN as far as I can see varies the freq range of activity

CENTRE I think is the centre of freq control, with SPAN at max 
you use this to 'phase' manually

There are SPEED and CENTRE CV inputs in the rear, with 0-9v range.

paul perry melbourne australia 
Frostwave Quad rackmount midi-cv convertor back in stock for Xmas ;-)




From theremin1 at worldnet.att.net  Thu Dec 10 13:57:52 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 10 Dec 1998 04:57:52 -0800
Subject: Sequential six-trak (was: smoke damage)
Message-ID: <000a01be243c$b3691a80$3eb14e0c@hpcustomer>

I've hardly seen a mention of the Sequential "six-trak" 'till now on this
list!
I have one, and like it.  A good example of uP supervised analog circuitry,
IMHO!  Has anyone tried to clone this synth?  When I first purchased this
unit
(used) it needed one of the CEM voicing ICs replaced. Is this IC a relative
rarity,
and do you suppose I should stock a few spares just in case one goes bad
again?

-Art


-----Original Message-----
From: Sean Costello <costello at seanet.com>
To: Clarissa Fragile <wils0450 at itlabs.umn.edu>
Cc: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 09, 1998 3:34 PM
Subject: Re: smoke damage


>Clarissa Fragile wrote:
>>
>> I have an opportunity to get a couple of MMT-8's as a package, but one of
>> them has "some smoke damage" (I know, it couldn't be much vauger). Is
this
>> the kind of thing I want to stay away from, or is it an *easy* fix?
>
>Probably means "smoke has made switches that turn sequences on and off
>completely erratic, if not unusable."  These switches are fixable, or I
>think you can get replacements from Alesis.  I fixed similar swithces
>(on a Sequential Circuits SixTrak) with some sandpaper and alcohol (to
>sand away and clean off the non-conductive parts of the little plastic
>buttons that make up the switch), & then added some finely powdered
>pencil shavings (for added conductivity).
>
>Sean Costello
>




From theremin1 at worldnet.att.net  Thu Dec 10 14:03:54 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 10 Dec 1998 05:03:54 -0800
Subject: What's with the motion filter?
Message-ID: <001101be243d$8b170820$3eb14e0c@hpcustomer>

rom PAiA's catalog pages:

Motion Filter:

An envelope follower/filter combination translates the normal
dynamic properties of your axe into modulated timbral [sic] changes
as well, you could think of it as an automatic wah-wah pedal.
Independent Initial Frequency and Sensitivity knobs give you the
control you need to realize a wide range of effects and allow the
Motion Filter to be used with either electric bass or guitar.
You won't believe that so much funk and soul can be squeezed
into such a tiny box.

[end quote]

See http://www.paia.com/guitarfx.htm.

-Art


-----Original Message-----
From: Aranakin at aol.com <Aranakin at aol.com>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 09, 1998 3:55 PM
Subject: What's with the motion filter?


>can anyonetell me EXACTLY what this motion filter from PAIA does?  OR how
it
>works?  anthony
>




From theremin1 at worldnet.att.net  Thu Dec 10 14:08:19 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 10 Dec 1998 05:08:19 -0800
Subject: SCI Pro-One problem
Message-ID: <002801be243e$2947dba0$3eb14e0c@hpcustomer>

Perhaps a power supply is going awry after warm-up?

Monitor the supplies with a 'scope, if you have one, 
or at least a voltmeter.  I've got one of these synths, too, 
BTW!

-Art


-----Original Message-----
From: Hess Hodge <Hess.Hodge at Colorado.EDU>
To: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 09, 1998 4:34 PM
Subject: SCI Pro-One problem


>Sorry for the cross-post.  I posted this to Analogue Heaven and did not
>receive any responses.  I am hoping that someone here can help me in
>diagnosing this problem... thanks,
>Hess
>
>-/\= Hess M. Hodge
>~/\  hess.hodge at colorado.edu
>(/\) http://rtt.colorado.edu/~hodge
>
>
>---------- Forwarded message ----------
>Date: Tue, 8 Dec 1998 23:17:56 -0700 (MST)
>From: Hess Hodge <hodge at rintintin.Colorado.EDU>
>To: analogue <analogue at hyperreal.org>
>Subject: SCI Pro-One problem
>
>Hello,
>I just received a pro-one (my very first analogue synth!) and I am
>having some problems.  I found some references to the same symptoms
>in the archives, but no insight into the problem itself.  Here is what is
>happening (you must excuse my limited synth vocabulary):  After only
>playing a few notes the synth will stop working.  The keyboard stops
>responding and the unit either makes no sound, or the gate LED lights up
>and the unit glides up to the highest note and stays there.  No further
>tweaking of any keys switches or pots can get the unit back or produce
>any different output. Only a power cycle will reset the unit and make
>everything work again (temporarily).  This problem will occur on its own
>(ie, I'm not doing anything but pressing keys) or when I try to use the
>sequencer or the arpeggiator.  When using the sequencer or the 
>arpeggiator, the synth will usually play a bunch of random notes before it
>dies.  I opened it up, checked all the connections and made a visual check
>of the PCB, but I couldn't find anything unusual (except for the shrooms
>;)  Has anybody seen these symptoms before?  Know what the problem is?
>How to fix?  By the way, it is ser # 100-5557 with a J-wire keyboard.  Any
>help is very much appreciated!
>hess
>
>-/\= Hess M. Hodge
>~/\  hess.hodge at colorado.edu
>(/\) http://rtt.colorado.edu/~hodge
>
>
>




From theremin1 at worldnet.att.net  Thu Dec 10 14:48:11 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 10 Dec 1998 05:48:11 -0800
Subject: theremins
Message-ID: <004c01be2443$badce4c0$3eb14e0c@hpcustomer>

Travis wrote re: theremins:

>i'll hear your ramnblings quite gladly...i'll b up for making one of these
>beasts soon

I write:

Paul Perry and I were chatting about various theremin topologies,
of which there are many, and many more to come, for certain.

For many synth DIYers, the objective is to use Leon Theremin's concept
as a gestural controller for VCOs, VCFs, triggers, etc.  Of course,
the instrument can also be relegated to its original form as a stand-alone,
voiced entity.  This topology is often referred to as a "heterodyne"
theremin,
where two RF oscillators, one fixed and the other varying per hand-
capacitance, produce an audible beat frequency.  For those interested in
such a basic implementation, I humbly refer you to my recent article at:
http://home.att.net/~theremin1/SWTP.htm.

This is quite a nice little theremin which used the 1967 Louis Garner, Jr.
design
as a starting point.  Since many of the folks on this list have hardware
resources,
perhaps some of you will try it.

The nice thing about this design is that it only uses less than 10mA from a
standard 9v  battery, and will thus run for hours, and is highly portable.
I am planning  another theremin for web publication soon, and it will be
more
signal-processing oriented, e.g., will employ a "double-synthetic" topology
whereby the voice is a VCO, not the actual heterodyned signal.  This one
will
be readily adaptable for CV applications, and have some goodies like a
linearization circuit to even-out the pitch spatial relations.

In the meantime, I hope some of you will review the above mentioned, and
give
me some feedback!  If this theremin prompts enough response, I may make
some blank PCBs for distribution.

Art in thereminland


-----Original Message-----
From: Travis Endersby <travis at it.net.au>
To: Arthur Harrison <theremin1 at worldnet.att.net>
Date: Wednesday, December 09, 1998 5:26 PM
Subject: Re: theremin problems!


>i'll hear your ramnblings quite gladly...i'll b up for making one of these
>beasts soon
>
>ta
>trav
>
>On Wed, 9 Dec 1998, Arthur Harrison wrote:
>
>> Cool, Paul.
>>
>> (If anyone is interested in my theremin ramblings,
>> just let me know, and I"ll CC my rants to the list.)
>>
>> -Art
>>
>>
>> -----Original Message-----
>> From: Paul Perry <pfperry at melbpc.org.au>
>> To: Arthur Harrison <theremin1 at worldnet.att.net>
>> Date: Tuesday, December 08, 1998 9:55 PM
>> Subject: Re: theremin problems!
>>
>>
>> >Thanks Art! I feel much less lonely now!
>> >
>> >If nothing gets done on this soon, I might go to a digital approach,
>> >actually counting the pulses and working from that.. the figs seem to
work,
>> >just! (500KHz and a PIC)
>> >
>> >paul perry melb aust
>> >
>> >
>> >
>>
>
>




From thelab at sprint.ca  Thu Dec 10 15:12:17 1998
From: thelab at sprint.ca (Philip)
Date: Thu, 10 Dec 1998 11:12:17 -0300
Subject: AW: [AH] AW: cs-50
References: <1BF5E20E0C4DD111BBAB00805FE2D58201032E42@nbgm336a.nbgm.siemens.de>
Message-ID: <366FD6C1.3FEA@sprint.ca>

Haible Juergen wrote:

>         >I had a CS-50, 60 and 80. They all worked fine but I only kept them
> for
>         >short periods. They sounded dull and boring to me...
> 
> Ouch, that hurts.
> (No offense intended, Philip.)
> JH.


:)  Well it's my opinion :) Maybe I should have said "They sounded
smooth and limited in character"  Like I said they are very ENOish. The
Ring mod does help some what in creating more agressive sounds but the
synth still has this mellow organic sound that is difficult to shake. I
guess I should first qualify my comment by saying that I like the bright
punchy ARP sound.

However many of the melodic sounds on Kraftwerk's "Man Machine" can be
easily emulated with a CS-50/60/80 so it will give you a better idea of
it's abilities. As well the synths are built to very high standards
(very nice switches and sliders..but some sliders have 0 on the top and
max on the bottom!)

btw No offenses were intended...just my opinions flying out "childlike"
again....hell I wish we could all meet sometime to see where our idea's
and opinions come from :) I certainly am not "politicly correct" nor
"diplomatic" I usually see in black and white and simply blurt out my
opinions with no emotion, consideration or empathy...geeze I'm a
computer :)

kindest regards
Philip

-- 
Philip Pilgrim                  The Lab Audio Works
5 Evan's Drive                  - Analog/Digital Recording/Processing
Hammonds Plains                 - Computer/Synth Interfacing
Nova Scotia, Canada             - Hardware/Software Development
B4B 1M8

Phone     +1.902.835.7844
Email      mailto:thelab at sprint.ca

Web Page: http://www.robotnik.com/the_lab



From debus at cityweb.de  Thu Dec 10 15:22:57 1998
From: debus at cityweb.de (Ingo Debus)
Date: Thu, 10 Dec 1998 15:22:57 +0100
Subject: got a scope
References: <199812091251.NAA13714@window.intermetall.de>
Message-ID: <366FD940.663C@cityweb.de>

Martin Czech wrote:
> Some years ago Hameg (it is a German manufacturer) was known for trash
> scopes

I heard this often too, but I think that was not more than a rumour. I
bought my used Hameg HM412 in 1981 and still use it. One zener diode in
the power supply had to be replaced once but that was the only repair
ever since. Where I worked there were several Hameg scopes too, and they
were ok.

Ingo




From dfevans at barrow.uwaterloo.ca  Thu Dec 10 17:59:43 1998
From: dfevans at barrow.uwaterloo.ca (David Evans)
Date: Thu, 10 Dec 1998 11:59:43 -0500 (EST)
Subject: [AH] AW: cs-50
In-Reply-To: <00a401be23ca$7855afc0$a89493d0@lptorre.halcyon.com> from "Larry P. Torre" at Dec 9, 98 05:19:02 pm
Message-ID: <199812101659.LAA06648@barrow.uwaterloo.ca>

Larry P. Torre wrote:
> 
> Also, I get a faint smell within a few minutes
> which smells like "warm circuitry" (the CS-50 is packed with analogue
> circuitry compared to today's computer-based modules/keyboards).

  Yes, I get this toasty smell too.  Mmmmmmm!

-- 
David Evans          (NeXTMail/MIME OK)             dfevans at bbcr.uwaterloo.ca
Computer/Synth Junkie                      http://bbcr.uwaterloo.ca/~dfevans/
University of Waterloo         "Default is the value selected by the composer
Ontario, Canada           overridden by your command." - Roland TR-707 Manual



From Elias.Holman at oberlin.edu  Thu Dec 10 18:13:59 1998
From: Elias.Holman at oberlin.edu (Elias Holman)
Date: Thu, 10 Dec 1998 12:13:59 -0500 (EST)
Subject: Motion Filter
Message-ID: <Pine.OSF.3.96.981210121006.31473B-100000@mercury.cc.oberlin.edu>

A very simple implementation of a motion filter is a envelope follower,
essentially, a diode, a resistor and a capacitor, which controls the
cutoff fq of a VCF.  Essentially, the current amplitude of your sound
changes the current timbre, giving your sound a "timbre envelope", it's
a pretty neat effect.  If you want to hear an example of one, check
out "Make My Funk(the P. Funk)" by Parliament on the Mothership Connection
album, or basically get a Bootsy Collins album, at least one of the songs
will make use of the Motion Filter.  It's pretty funky.

						Elias





From bmcdonald at chyron.com  Thu Dec 10 19:24:21 1998
From: bmcdonald at chyron.com (Brian McDonald)
Date: Thu, 10 Dec 1998 10:24:21 -0800
Subject: Odyssey VCO calibrate problem
Message-ID: <367011D5.D3D1450D@chyron.com>

Sorry to keep continuing to pester the list with my Odyssey problems,
but some future person may benefit from this...

I downloaded the online Odyssey service manual, which is here BTW,

http://aupe.phys.andrews.edu/diy_archive/manuals/arp/index.html

But I still have a problem calibrating VCO 2.  VCO 1 calibrates fine,
but VCO 2 will not scale down to 20Hz (this is step 5, section 3.3,
bottom of page 14 in the service manual for those of you following along
at home).  

The lowest it will go is about 50Hz at the lowest coarse tune setting
with the trimmer all the way down.  And it goes way, way too high in
frequency at the high end of the coarse tune.  So it is shifted (and
scaled?) in frequency somehow.  And this throws off the V/Oct trimming
in the next section, because the two oscillators will never match.

Any ideas?  Probably a bad component somewhere?  Thanks for any help!

brian

-- brian mcdonald ---- -- --- -- - --- -- --- --- - software engineer --
-- bmcdonald at chyron.com -- --- Liberty! -- --- - -- chyron west coast --
-- (408) 873-3818 -- --- ---- -- - --- -- - ---- -- cupertino, ca     --



From bduggan at netcom.com  Thu Dec 10 22:27:14 1998
From: bduggan at netcom.com (Brett Duggan)
Date: Thu, 10 Dec 1998 13:27:14 -0800 (PST)
Subject: Sequential six-trak (was: smoke damage)
In-Reply-To: <000a01be243c$b3691a80$3eb14e0c@hpcustomer>
Message-ID: <Pine.3.89.9812101324.A29715-0100000@netcom10>


Art,

The Six-Trak uses the CEM3394 "analog synth on a chip" IC, which
fortunately are still readily available from Paul Schreiber at $16 each
(he claims to have over 1000 of them in stock). 

Brett D

> I've hardly seen a mention of the Sequential "six-trak" 'till now on this
> list!
> I have one, and like it.  A good example of uP supervised analog circuitry,
> IMHO!  Has anyone tried to clone this synth?  When I first purchased this
> unit
> (used) it needed one of the CEM voicing ICs replaced. Is this IC a relative
> rarity,
> and do you suppose I should stock a few spares just in case one goes bad
> again?




From bduggan at netcom.com  Thu Dec 10 22:51:25 1998
From: bduggan at netcom.com (Brett Duggan)
Date: Thu, 10 Dec 1998 13:51:25 -0800 (PST)
Subject: Sawing your own IC sockets?
Message-ID: <Pine.3.89.9812101352.A29715-0100000@netcom10>


Hi folks,

I was about to purchase a quantity of the Augat 500 Series machined
contact IC sockets pre-cut for certain pin amounts/lengths.  However, in a
local electronics store I noticed that I could purchase a long 2-3 foot
strip of 0.3" width IC socket of the same exact type, and it would end up
being far more economical to buy this long strip and then saw the socket
lengths I need myself.  This particular line of socket is supposed to meet
military specs for high shock and vibration, so can anyone here tell me if
it would be safe to cut these sockets with a small bandsaw without doing
any damage to them?  The tray of the bandsaw vibrates like hell, so maybe 
I could just hold it up to the blade (albeit very carefully)?  Or maybe I 
could just use a hacksaw?

Thanks very much for any advice,
Brett D




From mike at p-w-m.demon.co.uk  Thu Dec 10 23:13:12 1998
From: mike at p-w-m.demon.co.uk (Michael Rogers)
Date: Thu, 10 Dec 1998 22:13:12 +0000
Subject: PWM distortion pedal
Message-ID: <qJiQwDA4dEc2Ewk7@p-w-m.demon.co.uk>

The first draft of the schematic for my PWM distortion pedal is now on
the web at http://www.cs.ucl.ac.uk/students/M.Rogers/. Any comments,
criticisms or advice very welcome! This is my first project, so I assume
there will be some corrections to make. I haven't bought the parts yet
just in case...

Michael Rogers




From ijfritz at earthlink.net  Fri Dec 11 00:23:24 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Thu, 10 Dec 1998 16:23:24 -0700
Subject: AW: First Squawks
References: <1BF5E20E0C4DD111BBAB00805FE2D58201032EDC@nbgm336a.nbgm.siemens.de>
Message-ID: <367057EC.89C24518@earthlink.net>

Juergen --

Good question. The noise seems pretty much broadband, i.e. decoupled
from the pilot wave. Sometimes -- before I had any filtering in the loop
-- it was mixed in with some multiphonic sounds. When the system syncs
up with the pilot it's often at a 2:3 frequency ratio. At 1:1 it tends
to slip -- like a soft sync that doesn't quite lock. I need to get some
problems with levels sorted out before I do much more experimenting with
the sounds. The main issue right now is the multiplier, for which I used
an AD633. I kinda forgot about its output being normed to xy/10! The
system should be much better when I get the levels right.

  Ian

Haible Juergen wrote:
> 
> Hi Ian,
> 
> good to hear that you're sucesfully working on this.
> Does it already make "tuned" noises, V/Oct or whatever ?
>



From rob at secret-secret.com  Fri Dec 11 00:59:09 1998
From: rob at secret-secret.com (Rob)
Date: Thu, 10 Dec 1998 15:59:09 -0800
Subject: Filter Layout question
Message-ID: <v04003a03b2960e2fbb02@[208.254.230.124]>

It looks like I'm going to finally get back to building the Gene Stopp
machines and I had a layout question.

At the school I goto (I'm studying Japanese, not music!, but I volunteered
as a tutor) they have a couple of Serge panels (super basic ones), but the
filter section caught my eye.  It has an out put for each type of filter
that it does.  One input and one set of controls but you can tap into the
lowpass, or band, or high or a 4th one that I can't think of at the moment
but it doesn't matter.

I've not looked at Gene's boards in a while so I don't remember if he set
the filter up to do different mods, so for this project the question might
be mute, but I'll ask it anyway.

Do you find it useful to be able to patch into a different mod, or more
then one at a time, or is it nicer to just use a switch to select the mode?
The xpander uses the switch method even though it could have used the multi
method, but they prolly made their decision for different reason., but then
again it have modes that mix the different versions, which could be done
with a switch too.

hmmm....

-Rob-

Secret Secret
http://secret-secret.com





From rob at secret-secret.com  Fri Dec 11 01:58:34 1998
From: rob at secret-secret.com (Rob)
Date: Thu, 10 Dec 1998 16:58:34 -0800
Subject: Filter Layout question
Message-ID: <v04003a07b2961e9d9900@[208.254.230.124]>

It looks like I'm going to finally get back to building the Gene Stopp
machines and I had a layout question.

At the school I goto (I'm studying Japanese, not music!, but I volunteered
as a tutor) they have a couple of Serge panels (super basic ones), but the
filter section caught my eye.  It has an out put for each type of filter
that it does.  One input and one set of controls but you can tap into the
lowpass, or band, or high or a 4th one that I can't think of at the moment
but it doesn't matter.

I've not looked at Gene's boards in a while so I don't remember if he set
the filter up to do different mods, so for this project the question might
be mute, but I'll ask it anyway.

Do you find it useful to be able to patch into a different mod, or more
then one at a time, or is it nicer to just use a switch to select the mode?
The xpander uses the switch method even though it could have used the multi
method, but they prolly made their decision for different reason., but then
again it have modes that mix the different versions, which could be done
with a switch too.

hmmm....

-Rob-

Secret Secret
http://secret-secret.com





From jlarryh at iquest.net  Fri Dec 11 02:12:14 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Thu, 10 Dec 1998 19:12:14 -0600
Subject: [AH] Paia Synthespin?
Message-ID: <199812110006.BAA29264@mailhost.bpa.nl>

Hmmm...  I wonder if this is the same circuit as the PAiA Leslie simulator
oublished in Popular Electronics in the early 70s?  I have a copy of that
here "somewhere."

Larry Hendry
----------
> From: Paul Perry <pfperry at melbpc.org.au>
> To: synth-diy at mailhost.bpa.nl
> Subject: Re: [AH] Paia Synthespin?
> Date: Thursday, December 10, 1998 4:29 AM
> 
> At 12:02 AM 10/12/98 -0500, Tim Johnston  wrote:
> >Anybody know what a PAIA Synthespin is? 
> 
> There is a ckt for this (and other PA1A stuff) in
> "electronic music curciut guidebook' Brice Ward Tab 1975
> it isn't a REALLY rare book
> 
> Uses a LM3900 Norton quad.
> Has a lfo driving a transistor to vary a bandpass filter,
> the (out of phase) output from which is summrd with the input
> to give a phaser effect.
> 
> SPEED this is the LFO speed control
> 
> ACCENT this is 'depth' or 'intensity' of efect
> 
> SPAN as far as I can see varies the freq range of activity
> 
> CENTRE I think is the centre of freq control, with SPAN at max 
> you use this to 'phase' manually
> 
> There are SPEED and CENTRE CV inputs in the rear, with 0-9v range.
> 
> paul perry melbourne australia 
> Frostwave Quad rackmount midi-cv convertor back in stock for Xmas ;-)
> 



From aschrock at cs.brandeis.edu  Fri Dec 11 03:35:45 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Thu, 10 Dec 1998 21:35:45 -0500 (EST)
Subject: Filter Layout question
In-Reply-To: <v04003a03b2960e2fbb02@[208.254.230.124]>
Message-ID: <Pine.HPP.3.95.981210202413.14205B-100000@bay.cs.brandeis.edu>

On Thu, 10 Dec 1998, Rob wrote:
> At the school I goto (I'm studying Japanese, not music!, but I volunteered
> as a tutor) they have a couple of Serge panels (super basic ones), but the
> filter section caught my eye.  It has an out put for each type of filter
> that it does.  One input and one set of controls but you can tap into the
> lowpass, or band, or high or a 4th one that I can't think of at the moment
> but it doesn't matter.

Either Allpass or Notch would be my guess. I don't know Serge gear tho. 

> I've not looked at Gene's boards in a while so I don't remember if he set
> the filter up to do different mods, so for this project the question might
> be mute, but I'll ask it anyway.
sp.. ^^^^ moot? 

> Do you find it useful to be able to patch into a different mod, or more
> then one at a time, or is it nicer to just use a switch to select the mode?
> The xpander uses the switch method even though it could have used the multi
> method, but they prolly made their decision for different reason., but then
> again it have modes that mix the different versions, which could be done
> with a switch too.

IMO, seperate jacks for different passes all the way. It's nice to have
the option to mix the outputs. I believe the concensus is that it's bad to
make modular gear with lotsa switches to go between modulations.. sorta
defeats the purpose, plus once you've filled up a box with switches,
you'll have trouble expanding.. plus it doesn't look as cool. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|






From harv23 at leland.Stanford.EDU  Fri Dec 11 05:54:45 1998
From: harv23 at leland.Stanford.EDU (Harvey Devoe Thornburg)
Date: Thu, 10 Dec 1998 20:54:45 -0800 (PST)
Subject: Filter Layout question
In-Reply-To: <Pine.HPP.3.95.981210202413.14205B-100000@bay.cs.brandeis.edu> from "Andrew Schrock" at Dec 10, 98 09:35:45 pm
Message-ID: <199812110454.UAA21692@elaine0.Stanford.EDU>

> 
> On Thu, 10 Dec 1998, Rob wrote:
> > At the school I goto (I'm studying Japanese, not music!, but I volunteered
> > as a tutor) they have a couple of Serge panels (super basic ones), but the
> > filter section caught my eye.  It has an out put for each type of filter
> > that it does.  One input and one set of controls but you can tap into the
> > lowpass, or band, or high or a 4th one that I can't think of at the moment
> > but it doesn't matter.
> 
> Either Allpass or Notch would be my guess. I don't know Serge gear tho. 
>

Notch.  It's actually a mix of the lowpass and highpass outputs (phase
cancellation at the cutoff frequency).  As you increase the resonance
the notch gets narrower, but no side peaking, so it becomes less audible.

--Harvey



From chordman at flash.net  Fri Dec 11 06:44:34 1998
From: chordman at flash.net (Scott Gravenhorst)
Date: Fri, 11 Dec 98 06:44:34
Subject: Filter Layout question
Message-ID: <199812111446.IAA04925@endeavor.flash.net>

"List, Christopher" <Chris.List at sc.siemens.com> wrote:

>Yes there's more flexibility, but it's sort of that old 80/20 (or in
>this case for me more like a 95/5) rule. I hardly ever use multiple outs
>from the filters that have them. OTOH, I constantly sweep from low-pass
>to high-pass with the mix knob, and also flip the switch back and forth
>between lowpass and bandpass ...

This is probably an unprofound remark/question, but midway thru the pan
you get sort of a notch filter?  Or does the response go pretty well flat?

-- Scott Gravenhorst
-- FatMan Site: http://www.teklab.com/~chordman
-- RedWebMail by R?? ? ???r ? W?r?
-- Linux Rex, Linux Vobiscum





From theremin1 at worldnet.att.net  Fri Dec 11 08:08:57 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 10 Dec 1998 23:08:57 -0800
Subject: audio to trigger
Message-ID: <001601be24d5$43548880$44784e0c@hpcustomer>

I've also heard this called a "non-retriggerable multivibrator." 
The 4538 has two in one package.

-Art

-----Original Message-----
From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
To: DIY <synth-diy at mailhost.bpa.nl>; Paul Perry <pfperry at melbpc.org.au>
Date: Thursday, December 10, 1998 3:42 AM
Subject: AW: audio to trigger


> >Also, if you go 555, you can have a 'refractory' period (it
>triggers, but then 
> >cant trigger again for a fixed period). Using a comparator to
>trigger a
> >fixed period 
> >555 you cd probably run off the raw audio & have very few parts.
> >
> >paul perry melbounre australia
>
>This is essentially what I meant with the "monoflop" method.
>All the audio tracks on my homepage are sync'ed like
>that. Only that I have used a SSM2056-based envelope
>generator for the monoflop (just because it was there in
>the modular - it will surely work with a simple 555 as well !)
>You must adjust the "on"-time manually to fit yout beat
>rate (approximately), but then it works excellent, even when 
>triggered from sounds that vary in amplitude.
>(which is a problem when you work with envelope detector)
>
>JH.
>




From q_bot at yahoo.com  Fri Dec 11 08:22:17 1998
From: q_bot at yahoo.com (Andrew Puls Q-Bot Eye)
Date: Fri, 11 Dec 1998 18:22:17 +1100 (EST)
Subject: Adding external trigger/gate/cv jacks
Message-ID: <19981211072217.9172.rocketmail@send104.yahoomail.com>


Hello,

I have a Jen sx-2000 (I doubt if you are familiar with it, simple one
oscilator mono synth) and I want to add external cv/gate & or trigger
jacks to it. I am the orriginal owner and I have the full schematics,
but when I open the thing up, it is not apparent to me where these
parts of the circuit board are! Can anyone pont me in the right
direction toward finding these things (where on the circuit board are
the connections for cv/gate?)? Also, I would like to add an external
audio in to the filter. Will this involve added circuitry, or can I
simply find the filter's input point and wire up a jack to it? It
doesn't have a level mixer for the oscilator, so I would probably have
to add some sort of switch to turn off the vco when I wanted to filter
external sounds without the vco, right? Actually with all these
thoughts of modding it, I am thinking I would like to make it
completely patchable, but I guess I should take it one step at a time!

Thanks in advance
-Andy-

==
Q-Bot, a02p20: q_bot at yahoo.com  Visit the home of the  most high-tech musical experiment around the globe: the Automations Orchestra at: http://www.angelfire.com/wi/CYO
["""]      ["""] ["""] """"""
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[  \]      [   \ [   ]   []
[___\      [___] [___]   []


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Get your free @yahoo.com address at http://mail.yahoo.com




From jorgen.bergfors at idg.se  Fri Dec 11 09:59:19 1998
From: jorgen.bergfors at idg.se (jorgen.bergfors at idg.se)
Date: Fri, 11 Dec 1998 9:59:19 +0100
Subject: Filter Layout question
Message-ID: <TFSACLQM@idg.se>

>IMO, seperate jacks for different passes all the way. It's nice to have
>the option to mix the outputs. I believe the concensus is that it's bad to
>make modular gear with lotsa switches to go between modulations.. sorta
>defeats the purpose, plus once you've filled up a box with switches,
>you'll have trouble expanding.. plus it doesn't look as cool. 

Patching up everything from separate jacks is the most flexible solution, but it is very time-consuming to use. On my modular, I provide switches and normalisations for the most useful connections, but also separate jacks if I want to try something really weird. For me it is important that the synth is reasonably quick to use, otherwise it will probably not be used much.

/Jorgen




From Colin.Fraser at scottishpower.plc.uk  Fri Dec 11 10:09:30 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Fri, 11 Dec 1998 09:09:30 -0000
Subject: Filter Layout question
Message-ID: <BA865FF10473D211BC6F00805F0D830702D243@catsprntp01.scottishpower.plc.uk>

> -----Original Message-----
> From: Andrew Schrock [mailto:aschrock at cs.brandeis.edu]
> Sent: 11 December 1998 02:36
> To: Rob
> Cc: synth-diy at mailhost.bpa.nl
> Subject: Re: Filter Layout question
> 
> IMO, seperate jacks for different passes all the way. It's 
> nice to have
> the option to mix the outputs. I believe the concensus is 
> that it's bad to
> make modular gear with lotsa switches to go between 
> modulations.. sorta
> defeats the purpose, plus once you've filled up a box with switches,
> you'll have trouble expanding.. plus it doesn't look as cool. 
> 

I agree with that - what's a patch lead if it's not just a highly flexible
'switch', with outputs as 'contacts'.
The only switches in my modular are to save having to pull patch leads out
to turn off oscillator sync.
I prefer to use a cross-fade knob rather than a switch.
I have 2 SEM type filters - they have a knob to fade between the hi and lo
pass outputs, and another knob to fade between the hi/lo output and the
bandpass. They have a final output for the crossfades, plus separate hi and
lo direct outputs.
The next stage will be to add a Haible Interpolating Scanner when I have
time (christmas holiday coming up...)

Sweeping between different filter mode outputs is a feature well worth
having.

Colin f




From aschrock at cs.brandeis.edu  Fri Dec 11 12:03:32 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Fri, 11 Dec 1998 06:03:32 -0500 (EST)
Subject: Filter Layout question
In-Reply-To: <BA865FF10473D211BC6F00805F0D830702D243@catsprntp01.scottishpower.plc.uk>
Message-ID: <Pine.HPP.3.95.981211055040.14901A-100000@bay.cs.brandeis.edu>

On Fri, 11 Dec 1998, Fraser, Colin J wrote:
> Sweeping between different filter mode outputs is a feature well worth
> having. 

If you wanted to go 100% modular connections, you could easily run the
seperate outs into a VCA and modulate it with an envelope or LFO. Sweeping
filter modes with a time-variable c/v is nice as well, very nice for
rich-sounding strings. 

Again on the switching question.. I think it's a good idea to have
normalized connections. (ADSR to VCF, ADSR to VCA, etc) It does save time
in making patches, altho it does make the inside a little messier. But
who sees that? ;) Just remember to keep leads short, neat, etc. Personally
I wouldn't want to allocate room on a synth I build for pots for all the
various modulation sources a la arp 2600... panel space and pots are the
most expen$ive part of a synth.. 

Andrew

BTW I got my hands on 2 CEM3330's.. gonna get cracking on a quad VCA! in a
rack with my paia CEM VCO and VCF... slobber. 

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|








From ms6gpm at bath.ac.uk  Fri Dec 11 12:55:08 1998
From: ms6gpm at bath.ac.uk (Gez)
Date: Fri, 11 Dec 1998 11:55:08 +0000 (BST)
Subject: Mad Mouse
In-Reply-To: <yam7646.1809.118768488@mail.mindspring.com>
Message-ID: <Pine.GSO.4.04.9812111142230.20802-100000@midge.bath.ac.uk>


Hello.  Mad Mouse looks and sounds good.  Would anyone (ie.tomg) be able
to supply info on modularising it slightly? - what I'd really like to know
is if there are points on the schematic where an external signal could be
put through the filter, or the envelope or both and would the input signal
have to be modified, if so how?

 Another question I have is about MIDI continuous controllers.  How
difficult is it to make a CV-MIDI to provide as many controllers as
possible and is there anywhere where I could find schematics/PCBs for
this.  I've noticed PAIA do a midi interface like this, would it be
feasable to make this without buying the kit or doing any programming? 

Cheers   - Geraint




From Colin.Fraser at scottishpower.plc.uk  Fri Dec 11 13:26:48 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Fri, 11 Dec 1998 12:26:48 -0000
Subject: Filter Layout question
Message-ID: <BA865FF10473D211BC6F00805F0D830702D247@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Andrew Schrock [mailto:aschrock at cs.brandeis.edu]
> Sent: 11 December 1998 11:04
> To: synth-diy at mailhost.bpa.nl
> Subject: RE: Filter Layout question
> 
> Again on the switching question.. I think it's a good idea to have
> normalized connections. (ADSR to VCF, ADSR to VCA, etc) It 
> does save time
> in making patches, altho it does make the inside a little messier. But
> who sees that? ;) Just remember to keep leads short, neat, 
> etc. 

I convinced myself normalised connections were a *bad* thing, after I
decided to use banana leads ;-)

One thing I would suggest is not to make the mistake of having all your
patch leads the same colour - you rapidly lose the ability to see where
everything is going if it's just a big mass of the same cable.
On the down side, this costs more...

Colin f



From pharding at mail.ndirect.co.uk  Fri Dec 11 14:36:47 1998
From: pharding at mail.ndirect.co.uk (pharding at mail.ndirect.co.uk)
Date: Fri, 11 Dec 1998 13:36:47 +0000
Subject: Jupiter 8 filter
Message-ID: <199812111341.NAA26489@sioux.netdirect.net.uk>

Hello all,
              I recently borrowed a Jupiter8 and hated having to 
give it back....I especially loved the way the synth sounded;- not 
just the billions of oscillators but the general tone of the synth.By 
this i mean that the J8 sounds [to me] not too fat nor too thin yet 
very Hi-Fi. I was particularly impressed by the VCF which sounded 
very clean yet doesn't thin out at high res like many filters do.
    Does anyone on this list know if the filter is a transistor 
ladder or ic based as i'm considering building one for my modular if 
this is possible.
   Also i dont have the schematics for the J8,is there anywhere on 
the net i can see them? I tried Music Machines where there are 
interconnection diagrams for the Jupiter8 but no actual schematics of 
the circuits.
   Any help in this matter will be appreciated.

thanks, Paul Harding.          



From s9610068 at chelt.ac.uk  Fri Dec 11 14:43:20 1998
From: s9610068 at chelt.ac.uk (James Dunn)
Date: Fri, 11 Dec 1998 13:43:20 +0000
Subject: audio to trigger (+ to MIDI?)
References: <199812091921.FAA21770@uq.net.au> <l03130302b294bada6ff6@[203.23.182.33]>
Message-ID: <36712178.260A@chelt.ac.uk>

Simon wrote:
> 
> I would be interested in a similar sort of DIY project to allow the
> triggering of MIDI devices using acoustic drum triggers or recorded audio,

This does sound interesting. I am interested in interfacing real live
drums with a modular synthesizer, triggering sounds and perhaps
processing the drum sounds with a drum kit. 
Does anyone know if this has been done or have any ideas for the
triggering circuitry?

Thanks,

James.



From Chris.List at sc.siemens.com  Fri Dec 11 15:09:14 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Fri, 11 Dec 1998 09:09:14 -0500
Subject: Filter Layout question
Message-ID: <81A062BC5305D111A9D700805F065968012EE91A@maildepo.sc.siemens.com>

Sorry Andrew, but I must respectfully disagree with you on this one.
Having a made a couple of these filters with each topology (2 from
scratch with 4 jacks and two as part of the ASM-1 board) I have to say
that having 4 output jacks takes up only slightly less panel space as
the switch + pot + single output jack, and gave me very little in
functionality. (If you're using 1/4" jacks, a mini-switch takes up LESS
space than a jack!) 

Yes there's more flexibility, but it's sort of that old 80/20 (or in
this case for me more like a 95/5) rule. I hardly ever use multiple outs
from the filters that have them. OTOH, I constantly sweep from low-pass
to high-pass with the mix knob, and also flip the switch back and forth
between lowpass and bandpass while the synth is playing for a dj-cut
kind of filter sound. With a "pure modular" setup, this is would only be
possible with 3 or 4 extra patch cords and another module. I dunno, It's
just my opinion. I started out building things that were very flexible
from a patching point of view, and more and more I'm wishing that I had
switches and pots for the most common functions instead. Unfortunately,
switch holes are smaller than jack holes, so switching to switches gets
messy. Obviously, if all your gear is hard-wired together in a generic
way, it's not going to be that "special" for you - but if you hardwire a
few choice things that are a little unique to begin with (like sweepable
LP to HP) I think the convenience is worth it.

(Note for clarity to any who don't realize: With a knob to sweep from
lowpass to highpass, a 50% setting is the same as a notch output - so
all the same settings are available.)

I guess it's easy for me to say because I have one of each, and if
you're building two of these filters, I think that's the way to go - one
for flexibility, one for practicality. Otherwise, If I had just one, I'd
probably go with; pot + switch + 3 output jacks (lowpass, highpass, and
variable) - a little more panel space, but hell, if you've only got one
state-var. filter in your setup, panel space is probably not that much
of an issue for you...

Oh yeah, one more thing, I think switches look way cooler than jacks :)

Just MHO,
- CList


ps.
For notes on converting the ASM-1 PCB so that it can do the switch + pot
method described, check here;
http://www.mindspring.com/~clist/resource/asm1tips.html  


> -----Original Message-----
> From:	Andrew Schrock [SMTP:aschrock at cs.brandeis.edu]
> Sent:	Thursday, December 10, 1998 9:36 PM
> To:	Rob
> Cc:	synth-diy at mailhost.bpa.nl
> Subject:	Re: Filter Layout question
> 
> IMO, seperate jacks for different passes all the way. It's nice to
> have
> the option to mix the outputs. I believe the concensus is that it's
> bad to
> make modular gear with lotsa switches to go between modulations..
> sorta
> defeats the purpose, plus once you've filled up a box with switches,
> you'll have trouble expanding.. plus it doesn't look as cool. 
> 
> Andrew
> 
> | Andrew Schrock
> |
> | Network Programmer, Synthesizer and electronic music enthusiast
> |
> | aschrock at cs.brandeis.edu
> |
> 
> 



From chris at scp.de  Fri Dec 11 15:14:39 1998
From: chris at scp.de (Christian Hofmann)
Date: Fri, 11 Dec 1998 15:14:39 +0100
Subject: Obx chip
In-Reply-To: <  >
References: <  >
Message-ID: <199812111414.PAA01468@dilbert.scp.de>

On Thu, 10 Dec 1998 21:43:34 +0100
Kevin Hill <kevin at starplace.com> wrote:

> My friends ob-x is dead, there was comming
> smoke from a LM1458N chip on the
> controllerboard.
> 
> The synth power light is all that lights up
> and the casette light works when using
> the switch on the back of the synth.
> 
> Anyone have an idea? also how hard is
> there finding replacement parts for the OB-X?.

Hi,
the 1458 is just a dual op amp, should be easy to find or to replace
with somthing similar.

But this seems to be a problem with the power supply unit, hopefully it
didn't fry more than a cheap op amp. To prevent further damage, it may be
wise to check the PSU disconnected from the other circuits (don't know if
there's a removable PSU connector in the OB-X). 

cu
Christian




From Aranakin at aol.com  Fri Dec 11 16:06:56 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Fri, 11 Dec 1998 10:06:56 EST
Subject: Mad Mouse
Message-ID: <cd374524.36713510@aol.com>


I don't kniow ifthis is answering your question or not, but asfar as the
layoutgoes fortom's synthesizer (mad mouse) controller goes, check out... 
<A HREF="http://www.tomg.vivid.net/control/content.html">How to build a
synthesizer keyboard</A>
anthony

ps.
I'm not sure why these two pages aren't connected.
 awesome stuff though



From blayer at uswest.net  Fri Dec 11 17:10:35 1998
From: blayer at uswest.net (Bill Layer)
Date: Fri, 11 Dec 1998 10:10:35 -0600
Subject: Personal to Terry Bowman - aka MacDoctor
Message-ID: <3.0.6.32.19981211101035.007d0ec0@pop.mpls.uswest.net>

Hi,

I'd have sent this privately to you, but I don't have an old message to
reply to... and I don't remember your email.

I need to pick your brain if possible regarding a MacPortable that I/my
girlfriend just got. It more or less wakes up >dead<...

Thanks,

excuse the bandwidth...

Bill




From keen at austin.ibm.com  Fri Dec 11 17:36:26 1998
From: keen at austin.ibm.com (R.G. Keen)
Date: Fri, 11 Dec 98 10:36:26 -0600
Subject: [AH] Paia Synthespin? 
In-Reply-To: (Your message of Thu, 10 Dec 98 19:12:14 -0600.)
             <199812110006.BAA29264@mailhost.bpa.nl>
Message-ID: <199812111636.KAA25610@keen.austin.ibm.com>


>Hmmm...  I wonder if this is the same circuit as the PAiA Leslie 
>simulator published in Popular Electronics in the early 70s?  I 
>have a copy of that here "somewhere."

I don't think so, although the technology is similar. The "Leslie
Simulator" was a discrete transistor twin t bandpass filter driven
by a discrete transistor LFO, the Synthespin was an IC version using
the LM3900. Same concept.



From johns at oei.com  Fri Dec 11 18:07:02 1998
From: johns at oei.com (John Speth)
Date: Fri, 11 Dec 1998 09:07:02 -0800
Subject: audio to trigger (+ to MIDI?)
In-Reply-To: <36712178.260A@chelt.ac.uk>
Message-ID: <000501be2528$abefeda0$2c15d7d0@johns.oei.com>

> > I would be interested in a similar sort of DIY project to allow the
> > triggering of MIDI devices using acoustic drum triggers or
> recorded audio,
>
> This does sound interesting. I am interested in interfacing real live
> drums with a modular synthesizer, triggering sounds and perhaps
> processing the drum sounds with a drum kit.
> Does anyone know if this has been done or have any ideas for the
> triggering circuitry?

Yes!  I've done this with my buddy's drum set.  I used piezo crystals
driving some special simple circuitry that I designed to provide triggers
for my Prophet.  The Prophet was programmed to make drum sounds.  You can
build or get a trigger-to-midi controller too.

For the transducers: I got a few piezo buzzers and took out the
quarter-sized peizo element inside.  I soldered a wire on each side, I
potted each in a silicon "button" for which I made a clay mold to do the
potting.  Let it cure and trimmed it with a knife.  The button had a pigtail
that I added a 1/4 inch plug.

For the circuitry: If I remember right, the crystal gave off a ringing short
duration burst of about 50V max.  This made the circuitry simple because all
I had to do was limit the voltage with diodes and trigger a CMOS gate setup
as a one-shot.  It was extremely simple and I made a 3 channel gadget that
ran on a single 9V battery.

If anyone wants more info, please email me.

John Speth
Object Engineering, Inc
mailto:johns at oei.com





From josue.arias at infomail.lacaixa.es  Fri Dec 11 19:15:18 1998
From: josue.arias at infomail.lacaixa.es (Josue Arias)
Date: Fri, 11 Dec 1998 19:15:18 +0100
Subject: System100 (not 100M) schemos
Message-ID: <36716133.2D00DDA8@infomail.lacaixa.es>

Hi People,

I need your help to locate the system100 schematics, for all modules if
it's possible.
I own 2x 101, 2x102, 103, 104 and speakers, and I ned to fix some
problems, and also I'd like to add more patchpoints.
I'll pay copies + shipping, or trade, or...
Thanks,

Josue Arias.




From Romeo_Fahl at stream.com  Fri Dec 11 19:42:38 1998
From: Romeo_Fahl at stream.com (Romeo_Fahl at stream.com)
Date: Fri, 11 Dec 1998 13:42:38 -0500
Subject: Forward: sensors...
Message-ID: <852566D7.007730AD.00@galaxy.support.stream.com>




Thought this might be of interest to DIYers.




John,

Here is a compilation of sensor sources, culled from a recent discussion on
the Max list.  I can't vouch for any of these companies, as this is 2nd
hand information, but here you go:

Check these places out for sensors

Images Company
POB 140742
Staten Island NY 10314
ph 718-698-8305 sales and information
fax 718- 982-6145
They have a catalog which lists bend/flex sensors like the ones
in the Mattel Power Glove, Peizo-Electric Film Sensors and lots of other
potentially useful stuff.

InterLink Electronics
ph. 800-340-1331 toll free in North America
fax 805-484-8989
Interlink makes the FSR (force sensing resistor) sensors. You can get an
FSR
design kit with several of their sensors and documentation which has
schematics and info on their stuff.

Engineers Mini-Notebook
Sensors Projects
by Forest M. Mimms III
cat. no. 62-5026
This book from Radio Shack describes lots of ways to make your own
sensors. Lots of great ideas.

Honeywells Micro Switch division
ph. 1-800-537-6945 to get a cataloge with descriptions, parts, and
application notes.
They make all kinds of solid state sensors: pressure, vaccum gauge,
temperature, airflow,etc.

All these sensors will interface with the iCube or a Basic Stamp 1 or 2.

Other Sensor Information on the WWW:

The "flex" sensor from Jameco might do the trick:
http://www.jameco.com/cfm/viewdesc.cfm?part_num=150551

A source for Bend Sensors:
http://www.imagesco.com

A source for FSR (force sensing resistors)
http://www.ace.co.uk/simltd/fsrhome.htm

Art & Robotics Group site: http://www.interaccess.org/arg


Peter Nyboer
pnyboer at sirius.com

http://www.sirius.com/~pnyboer/
--home of Slambassador multimedia gallery--
http://www.sirius.com/~pnyboer/product
--product prototype!--





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From honcho at paia.com  Fri Dec 11 20:09:53 1998
From: honcho at paia.com (honcho at paia.com)
Date: Fri, 11 Dec 1998 13:09:53 -0600 (CST)
Subject: [AH] Paia Synthespin?
In-Reply-To: <199812110006.BAA29264@mailhost.bpa.nl>
Message-ID: <199812111909.NAA17010@qns1.qns.net>

Larry Hendry wrote:

>Hmmm...  I wonder if this is the same circuit as the PAiA Leslie 
simulator oublished in Popular Electronics in the early 70s?  I have a 
copy of that here "somewhere."
>>>

It is the same. Soon after the "leslie effect simulator" appeared in 
PE we got a letter from CBS's attorneys (Flynn and Phlam, if you can 
believe it) stating that CBS had rights to the trademark "Leslie" and 
that we were infringing this trademark because the was no such thing 
as a "Leslie effect". As a result, the name was changed to 
"Synthespin", which really was a cooler name anyway.

I think there was mention of the "motion filter" here over the last 
few days (we've been having server _nighmares_) and this is a similar 
situation. This device was originally called the Mojo Filter but we 
received notice for a bunch of attorneys on behalf of a guy who had 
trademark status on "mojo" for musical gear. So Mojo became Motion 
(not as cool a name).

-John

---------------------------------------------------------
John Simonton                  PAiA Electronics, Inc
3200 Teakwood Ln.              honcho at paia.com
Edmond OK 73013                http://www.paia.com
405-340-6300                   fax 405-340-6378



From johns at oei.com  Fri Dec 11 22:12:15 1998
From: johns at oei.com (John Speth)
Date: Fri, 11 Dec 1998 13:12:15 -0800
Subject: Any Americans using Schaeffer Apparatebau?
Message-ID: <000101be254a$ed66d6a0$2c15d7d0@johns.oei.com>

Hi all ...

I've been looking at different methods for front panel production and I'm
considering using Schaeffer Apparatebau's services.  Are there any Americans
who have used their services?  I'd like to here some first hand experiences
particularly about the following:

-Is it cost effective and affordable?
-Was getting it shipped overseas risk free or costly?
-Was there any communications problems?  (I'm an English only type)
-Any bad experiences or "not quite what I expected" results?

Maybe some Europeans can answer too?

John Speth
Object Engineering, Inc
mailto:johns at oei.com





From honcho at paia.com  Fri Dec 11 22:32:54 1998
From: honcho at paia.com (honcho at paia.com)
Date: Fri, 11 Dec 1998 15:32:54 -0600 (CST)
Subject: [AH] Paia Synthespin? 
In-Reply-To: <199812111636.KAA25610@keen.austin.ibm.com>
Message-ID: <199812112132.PAA18668@qns1.qns.net>

>>Hmmm...  I wonder if this is the same circuit as the PAiA Leslie 
>simulator published in Popular Electronics in the early 70s?  I 
>have a copy of that here "somewhere."

I don't think so, although the technology is similar. The "Leslie
Simulator" was a discrete transistor twin t bandpass filter driven
by a discrete transistor LFO, the Synthespin was an IC version using
the LM3900. Same concept.
>>>

Oh, yeah, I forgot. The design did change so that most of the things 
sold as "Synthespin" were different in details of the design than the 
"Leslie Effect Simulator", but the basic concept was the same for 
both.

-John

---------------------------------------------------------
John Simonton                  PAiA Electronics, Inc
3200 Teakwood Ln.              honcho at paia.com
Edmond OK 73013                http://www.paia.com
405-340-6300                   fax 405-340-6378



From jeffry at aracnet.net  Fri Dec 11 23:30:29 1998
From: jeffry at aracnet.net (Jeffry James)
Date: Fri, 11 Dec 1998 22:30:29 GMT
Subject: BARE KEYBOARDS for sale
Message-ID: <199812112230.WAA18869@trapdoor.aracnet.net>

To All who may be interested,

I have some bare piano and synth-type keyboards with and without switches.
I have used them for some of my own projects and would like to make them
available to any other similarily-minded nut case.  Here is a teaser:
 - Weighted Cantilever Action Fatar 88 Note Keyboards with silver spring
velocity swithches.  This is a high quality keyboard of which I have only a
few I will spare.
 - 57 Note Solid Wood Keyboard Manuals.  Real wood probably makes these
antiques!
 - 5 Octave Plastic Keyboards

(Electronic midi circuitry is also availlable.)
Sketches of my keyboards may be viewed at www.aracnet.net/~jeffry/
Look under 'MIDI Keyboards'.




From vco at mindspring.com  Sat Dec 12 04:55:52 1998
From: vco at mindspring.com (tomg)
Date: Fri, 11 Dec 1998 22:55:52 -0500
Subject: Mad Mouse
In-Reply-To: <cd374524.36713510@aol.com>
Message-ID: <yam7649.2609.119037256@mail.mindspring.com>

On 11-Dec-98, Aranakin at aol.com wrote:

>I don't kniow ifthis is answering your question or not, but asfar as the
>layoutgoes fortom's synthesizer (mad mouse) controller goes, check out... 
><A HREF="http://www.tomg.vivid.net/control/content.html">How to build a
>synthesizer keyboard</A>
>anthony

>ps.
>I'm not sure why these two pages aren't connected.
> awesome stuff though

It's a long sorted story. BTW the vivid.net address is not
active at all. I expect vivid net to remove it as soon as
they find out it's there. They will need to find their ass
first though.

A better address is...

http://www.synthesist.xsystem.net/efm/control/content.html

At least I can send Adrian updates here.

Adrian is working on getting me active here (I think?) so 
I can update the older files without him having to do the 
middle man thing.

-tg






From vco at mindspring.com  Sat Dec 12 04:56:17 1998
From: vco at mindspring.com (tomg)
Date: Fri, 11 Dec 1998 22:56:17 -0500
Subject: Mad Mouse
In-Reply-To: <Pine.GSO.4.04.9812111142230.20802-100000@midge.bath.ac.uk>
Message-ID: <yam7649.870.119037256@mail.mindspring.com>

On 11-Dec-98, Gez wrote:

>Hello.  Mad Mouse looks and sounds good.  Would anyone (ie.tomg) be able
>to supply info on modularising it slightly? - what I'd really like to know
>is if there are points on the schematic where an external signal could be
>put through the filter, or the envelope or both and would the input signal
>have to be modified, if so how?

> Another question I have is about MIDI continuous controllers.  How
>difficult is it to make a CV-MIDI to provide as many controllers as
>possible and is there anywhere where I could find schematics/PCBs for
>this.  I've noticed PAIA do a midi interface like this, would it be
>feasable to make this without buying the kit or doing any programming? 

>Cheers   - Geraint


Why Yes! As soon as I can (I'm busy with the pcb) I
will put up a page of mods and patch points for the MM.
Stay tuned here for developing news.

-tg







From chordman at flash.net  Sat Dec 12 07:22:35 1998
From: chordman at flash.net (Scott Gravenhorst)
Date: Sat, 12 Dec 98 07:22:35
Subject: VC Gyrator
Message-ID: <199812121522.JAA06601@endeavor.flash.net>

Anybody try replacing the opamp in a gyrator with an OTA?  Would that
allow voltage control of the frequency or would controlling a gyrator
be more complex than this simple substitution?

-- Scott Gravenhorst
-- RedWebMail by RedStarWare
-- FatMan Site: www.teklab.com/~chordman
-- Linux Rex, Linux Vobiscum
	





From Aranakin at aol.com  Sat Dec 12 09:40:14 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Sat, 12 Dec 1998 03:40:14 EST
Subject: best way to do labeling on chassis?
Message-ID: <55cf6071.36722bee@aol.com>

what's the best way to dothe labeling on a chassis?
that contact stuff or whatever it is?
is there some rub on paper that's good?
can i print it right out of my laser printer?
thanks in advanced
anthony



From gjalass at snafu.de  Sat Dec 12 12:22:15 1998
From: gjalass at snafu.de (Gert Jalass)
Date: Sat, 12 Dec 1998 11:22:15 GMT
Subject: Looking for : Schematics Polyfusion Keyboard 2051
Message-ID: <3672515a.1110896214@berlin.snafu.de>

Hi there,

I'm looking for schematics of the Polyfusion Keyboard 2051.

Any hint ( personal EMail, please ) will be appreciated.

Stay tuned.

Gert



From oakley at techrepairs.freeserve.co.uk  Sat Dec 12 20:02:43 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sat, 12 Dec 1998 19:02:43 -0000
Subject: Adding external trigger/gate/cv jacks
Message-ID: <006c01be2602$1cc7d180$7a26883e@default>

Andrew wrote:
I have a Jen sx-2000 (I doubt if you are familiar with it, simple one
oscilator mono synth) and I want to add external cv/gate & or trigger
jacks to it.

Tony says,

Sorry. I believe that the Jen has no gate, or CV available for the VCOs.
Its a switch matrix digital oscillator. There may be a way to put CV on
the filter though.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html







From rob at secret-secret.com  Sat Dec 12 20:16:26 1998
From: rob at secret-secret.com (Rob)
Date: Sat, 12 Dec 1998 11:16:26 -0800
Subject: best way to do labeling on chassis?
In-Reply-To: <55cf6071.36722bee@aol.com>
Message-ID: <v04003a06b2986fdd7831@[208.255.86.172]>

>what's the best way to dothe labeling on a chassis?
>that contact stuff or whatever it is?
>is there some rub on paper that's good?
>can i print it right out of my laser printer?

One thing I've been thinking of is printing it out on some sort of computer
thing, either laser, or color inkjet and then laminating it and either
gluing or just using the face plate components to hold it on to the chases.

I've not tried it yet, but it seems like the most affordable way for a diy
panel and still get it to look decent.  The laminate could be done at a
copy shop (like kinkos or some such).

If I end up doing my own face place for the ASM-1 (Chris seems to have a
very nice one that I just might go ahead and use) this is the way I'll
prolly proceed.

-Rob-

Secret Secret
http://secret-secret.com





From grichter at execpc.com  Sat Dec 12 20:31:10 1998
From: grichter at execpc.com (Grant Richter)
Date: Sat, 12 Dec 1998 13:31:10 -0600
Subject: theremins
Message-ID: <199812121933.NAA06157@pop02.execpc.com>

One trick I used successfully comes from a hobby magazine circuit (don't
remember which one).
Take a CD4046 PLL chip and tie the VCO control line to +V. Program the RC
values to give a fixed
oscillator in the range of 100kHz to 400KHz. Attaching an antenna to one
leg of the timing capacitor
will give a usable range of six inches or so from the antenna. Another 4046
can be used to turn the
varying oscillator frequency into a control voltage.

The problem is the coupling to the antenna. The theremin design uses large
inductors to decouple
the antenna from the oscillator and give a much smoother and longer control
range. As I recall
the output variation from the 4046 circuit running at 350kHz was about
25Khz from full contact
to about six inches away. The Big Briar Etherwave runs about 162?Khz and
changes about 2Khz
for twenty four inches of motion near the antenna.


Two 4046's can be used to make a direct conversion unit using the 
EXOR gate in one as the RF mixer. Nasty sounding square wave though,
and the same problem of excess range over too short of a distance.
It doesn't get much cheaper or simpler than a 4046 as a good place to
start experimenting with a home built proximity controller. The same
principle of
decoupling the antenna with large L values (60 millihenry?) would apply.
Even a 2Khz variation in RF oscillator output could be scaled with the 4046
circuit to give 0-10V over a usable range.

Electronotes issue #111 page 12 has an article by John Valente with two
designs
for Body Proximity controllers.

----------
> From: Arthur Harrison <theremin1 at worldnet.att.net>
> To: DIY <synth-diy at mailhost.bpa.nl>
> Subject: theremins
> Date: Thursday, December 10, 1998 7:48 AM
> 
> Travis wrote re: theremins:
> 
> >i'll hear your ramnblings quite gladly...i'll b up for making one of
these
> >beasts soon
> 
> I write:
> 
> Paul Perry and I were chatting about various theremin topologies,
> of which there are many, and many more to come, for certain.
> 
> For many synth DIYers, the objective is to use Leon Theremin's concept
> as a gestural controller for VCOs, VCFs, triggers, etc.  Of course,
> the instrument can also be relegated to its original form as a
stand-alone,
> voiced entity.  This topology is often referred to as a "heterodyne"
> theremin,
> where two RF oscillators, one fixed and the other varying per hand-
> capacitance, produce an audible beat frequency.  For those interested in
> such a basic implementation, I humbly refer you to my recent article at:
> http://home.att.net/~theremin1/SWTP.htm.
> 
> This is quite a nice little theremin which used the 1967 Louis Garner,
Jr.
> design
> as a starting point.  Since many of the folks on this list have hardware
> resources,
> perhaps some of you will try it.
> 
> The nice thing about this design is that it only uses less than 10mA from
a
> standard 9v  battery, and will thus run for hours, and is highly
portable.
> I am planning  another theremin for web publication soon, and it will be
> more
> signal-processing oriented, e.g., will employ a "double-synthetic"
topology
> whereby the voice is a VCO, not the actual heterodyned signal.  This one
> will
> be readily adaptable for CV applications, and have some goodies like a
> linearization circuit to even-out the pitch spatial relations.
> 
> In the meantime, I hope some of you will review the above mentioned, and
> give
> me some feedback!  If this theremin prompts enough response, I may make
> some blank PCBs for distribution.
> 
> Art in thereminland
> 
> 
> -----Original Message-----
> From: Travis Endersby <travis at it.net.au>
> To: Arthur Harrison <theremin1 at worldnet.att.net>
> Date: Wednesday, December 09, 1998 5:26 PM
> Subject: Re: theremin problems!
> 
> 
> >i'll hear your ramnblings quite gladly...i'll b up for making one of
these
> >beasts soon
> >
> >ta
> >trav
> >
> >On Wed, 9 Dec 1998, Arthur Harrison wrote:
> >
> >> Cool, Paul.
> >>
> >> (If anyone is interested in my theremin ramblings,
> >> just let me know, and I"ll CC my rants to the list.)
> >>
> >> -Art
> >>
> >>
> >> -----Original Message-----
> >> From: Paul Perry <pfperry at melbpc.org.au>
> >> To: Arthur Harrison <theremin1 at worldnet.att.net>
> >> Date: Tuesday, December 08, 1998 9:55 PM
> >> Subject: Re: theremin problems!
> >>
> >>
> >> >Thanks Art! I feel much less lonely now!
> >> >
> >> >If nothing gets done on this soon, I might go to a digital approach,
> >> >actually counting the pulses and working from that.. the figs seem to
> work,
> >> >just! (500KHz and a PIC)
> >> >
> >> >paul perry melb aust
> >> >
> >> >
> >> >
> >>
> >
> >



From oakley at techrepairs.freeserve.co.uk  Sat Dec 12 20:33:35 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sat, 12 Dec 1998 19:33:35 -0000
Subject: PWM pedal.
Message-ID: <00c801be2606$755952c0$7a26883e@default>

Michael wrote:
>The first draft of the schematic for my PWM distortion pedal is now on
the web at http://www.cs.ucl.ac.uk/students/M.Rogers/. Any comments,
criticisms or advice very welcome!



Can I make a few comments?

Your two ?? resistors can be 22k, but you need a 100uF cap in parallel
with the bottom one. This will ensure any ac is effectively grounded.

You really do need a buffer for your output. Why not use a standard
active baxandall tone network, instead of the passive one. This will
give you a better sound and make your output less dependant on input
impedance. Use a TL074 as your op-amp, and you won't notice the extra
space required. See the data sheet on the TL074 on the Farnell web site
for the circuit.

God knows what it will sound like. Rail to rail clipping, as introduced
by the schmitt will sound pretty fuzz-like. I prefer a softer knee to my
distortion. Put two green LEDs, each in parallel, in parallel with the
10K resistor in the mixer op-amp's feedback. One led points one way, the
other points the other way. This will give you a nicer sound. Works
great with my TB-3030. Mind you this will also distort your straight
through signal as well.

Ditch the 18K res on the non-inv input on the first op-amp. Not needed
with a FET op-amp. Use a 10uF cap on each of the opamps outputs to give
some dc blocking. Otherwise, your pots will crackle.

Have great fun and welcome to the world of wacky effects.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html








From oakley at techrepairs.freeserve.co.uk  Sat Dec 12 21:00:11 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sat, 12 Dec 1998 20:00:11 -0000
Subject: 909 circuit diagrams
Message-ID: <00d001be260a$0b969920$7a26883e@default>

Hi all,

For 909 circuits look no further than...
http://hardware.freepage.de/raf909/


Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From jeffry at aracnet.net  Sat Dec 12 21:47:35 1998
From: jeffry at aracnet.net (Jeffry James)
Date: Sat, 12 Dec 1998 20:47:35 GMT
Subject: AW: First Squawks
Message-ID: <199812122047.UAA07399@trapdoor.aracnet.net>

Hi, I am intrigued!
What kind of platform are you building your analog physical modeling synth
upon?  (Is is discrete components or software?)
Jeff.




From theremin1 at worldnet.att.net  Sun Dec 13 00:49:03 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 12 Dec 1998 15:49:03 -0800
Subject: theremins
Message-ID: <000d01be262a$0051df00$f6784e0c@hpcustomer>

Grant Richter wrote, re: theremins:

>One trick I used successfully comes from a hobby magazine circuit (don't
>remember which one).
>Take a CD4046 PLL chip and tie the VCO control line to +V. Program the RC
>values to give a fixed
>oscillator in the range of 100kHz to 400KHz. Attaching an antenna to one
>leg of the timing capacitor
>will give a usable range of six inches or so from the antenna. Another 4046
>can be used to turn the
>varying oscillator frequency into a control voltage.

Hi Grant,

Yes, I've seen some 4046-based theremins as well.  My experience with these
circuits
was also about a half-foot range, which isn't too good for a stand-alone,
voiced theremin
unless constrained to only an octave or two.

>The problem is the coupling to the antenna. The theremin design uses large
>inductors to decouple
>the antenna from the oscillator and give a much smoother and longer control
>range.

There is an article by Robert Moog in which he gives a one or two line
explanation
of the function of the series inductance.  (The original patent kinda talks
around the
specific theory of operation of this inductance.)  In practice, I've usually
avoided the
series inductance to conserve temperature drift and cost. Depending on the
circuit
topology, sufficient sensitivity is readily available without this inductor.
To his credit,
Theremin did quite well without the luxury of the signal processing
techniques
readily at our disposal, and the series inductance was one such method of
adding
gain without the cost and bulk of additional active circuitry.

>As I recall
>the output variation from the 4046 circuit running at 350kHz was about
>25Khz from full contact
>to about six inches away. The Big Briar Etherwave runs about 162?Khz and
>changes about 2Khz for twenty four inches of motion near the antenna.

Yes, this seems correct.  Moog specifically chose frequencies in a
seldom-used
part of the LF band, not coincidentally around some popular IF frequencies,
so it would seem.


>Two 4046's can be used to make a direct conversion unit using the
>EXOR gate in one as the RF mixer. Nasty sounding square wave though,
>and the same problem of excess range over too short of a distance.

I endorse the EXOR detection scheme; I believe it preserves a maximum
amount of signal information.  A two-pole Sallen-Key filter will remove the
upper products, and you can actually obtain a useful timbre in the audible
beat with such a filter.  The appropriate ratio of hand-to-static
capacitance
in the oscillator should be a way to tailor the sensitivity.

>It doesn't get much cheaper or simpler than a 4046 as a good place to
>start experimenting with a home built proximity controller. The same
>principle of
>decoupling the antenna with large L values (60 millihenry?) would apply.

Yes, that series inductance does need to be rather large to rhyme with the
small static antenna capacitance and hand offset capacitance (only a few pF
at best!).  The cost of such inductors is quite high.  Moog strings a bunch
of them in series in his Etherwave, and that adds a lot to the unit's cost.

>Even a 2Khz variation in RF oscillator output could be scaled with the 4046
>circuit to give 0-10V over a usable range.

Temperature drift, however, as well as phase noise, will prevent the 4046
approach of providing the same quality as an inductance-based oscillator
such as in the Etherwave.  The key to a good detection oscillator is a Q-
factor as high as possible without sacrificing the required
hand-capacitance-induced deviation.  Of course, if the objective is simply
to provide a few spacial triggers, these RC oscillator schemes may be just
fine.

Much of my work, actually, is in the techniques of frequency-to-voltage
conversion
needed for a heterodyne-to-voltage-to-VCO approach.  The popular method of
a simple RC averager following a monostable works, but is lossy and
non-linear.
Tachometer approaches are much better.

>Electronotes issue #111 page 12 has an article by John Valente with two
>designs
>for Body Proximity controllers.

I have to look into that.  I wrote a "circuits ideas" entry with a fellow at
Maxim
Integrated Products earlier this year that was put in an industry mag.  It
used
a phase-detection scheme, as opposed to a heterodyne scheme.  (I am under
the impression that Electronotes is a print subscription only, so I'll have
to do
some looking.  I have a contact who might loan me 111.)

Thanks for getting in touch.  I will be putting some more circuits on my
page in
early '99, if all goes well!

-Art






From jeffry at aracnet.net  Sun Dec 13 01:02:35 1998
From: jeffry at aracnet.net (Jeffry James)
Date: Sun, 13 Dec 1998 00:02:35 GMT
Subject: BARE KEYBOARDS
Message-ID: <199812130002.AAA18188@trapdoor.aracnet.net>

All,

>Where are you located and how much would these Controllers run me?

>I'm wondering how much you would charge for some of those keyboards.

I am located in Toronto, Canada.
I have "ideal" prices posted on my page and they range from < $100 to $400 U.S.

>I am looking for one of these *organ* (not synth) style keyboards from Fatar.
>As far as I've seen on your page, you don't have one of these. But aparently
>you have good contact to Fatar (?) - how did you get the ones you have ?
>I asked them at Frankfurt Musikmesse, but they would not sell to private
persons...

...Jeff adds: ..and if they did, single unit orders are costly.

Over the years I have bought and collected these keyboards from development
companies I have worked for.  The wooden keyboards, for example, are made of
wood especially good for keyboards, imported from England and cut for
electronic organ manuals.

One contact I had was with a U.S. importer "Lo Duca Bros., Inc." who were
wholesale distributors for Italian produced keyboards.  My notes tell me
that I last talked with them May 6, 1991.  Their address then was:
400 N. Broadway, Milwaukee, WI 53202, phone 414-347-1400
Who knows if they are still around?  It was from them, an electronic organ
manufacturer I was working for, ordered a surplus of plastic, 5 octave
*organ*? style keyboards.  I have one of these on hand and a lead on 100's
more from the organ company--but one would have to make up their own
switches.  I have no picture or drawing.  (I am not aware of any difference
between a 5 octave plastic synth keyboard and a 5 octave platic organ keyboard.)

Jeff.




From zzynt at swipnet.se  Sun Dec 13 05:06:02 1998
From: zzynt at swipnet.se (BJ)
Date: Sat, 12 Dec 1998 20:06:02 -0800
Subject: Filter Layout question
References: <1.5.4.32.19970307072301.006a3318@popa.melbpc.org.au>
Message-ID: <36733D2A.4689@swipnet.se>

Paul Perry wrote:
> 
> At 12:26 PM 11/12/98 -0000, Fraser, Colin J wrote:
> 
> >One thing I would suggest is not to make the mistake of having all your
> >patch leads the same colour -
> 
> If you are really anal (not always a bad thing) you can NUMBER your patch
> leads like
> resistors, with colour tape bands on each end, and clear heatshrink over them)
> 
> paul perry Frostwave P/l melbounre australia
> (41 deg c again today.. phew what a scorcher)

Or by numbers instead of colour's!

BJ
[-13 degrees to day, and 2 meters of snow at the eastcoast, The town
"Gevle" 
is closed for anyone for one week!! as seen on the news! ]



From technical at image.dk  Sun Dec 13 16:00:14 1998
From: technical at image.dk (Cai Bojsen-M=?ISO-8859-1?B?+A==?=ller)
Date: Sun, 13 Dec 1998 16:00:14 +0100
Subject: <no subject>
Message-ID: <199812131500.QAA05729@mailhost.bpa.nl>

Hi,

I?m looking for schematics of the Moog Parametric EQ and the Moog drum
controller. Better would be if anyone wants to sell. Any hint will be
appreciated. Please send personal e-mail.

Best wishes,

Cai Bojsen-M?ller



From technical at image.dk  Sun Dec 13 16:10:24 1998
From: technical at image.dk (Cai Bojsen-M=?ISO-8859-1?B?+A==?=ller)
Date: Sun, 13 Dec 1998 16:10:24 +0100
Subject: Moog Parametric EQ/Moog Drum Controller
Message-ID: <199812131510.QAA05857@mailhost.bpa.nl>


----------
From: "Cai Bojsen-M?ller" <technical at image.dk>
To: synth-diy at mailhost.bpa.nl
Subject:Moog Parametric EQ/Moog Drum Controller
Date: s?n 13. dec 1998 16:00


Hi,

I?m looking for schematics of the Moog Parametric EQ and the Moog drum
controller. Better would be if anyone wants to sell. Any hint will be
appreciated. Please send personal e-mail.

Best wishes,

Cai Bojsen-M?ller



From mark at surfacemount.ml.org  Sun Dec 13 17:49:07 1998
From: mark at surfacemount.ml.org (Mark Bolding)
Date: Sun, 13 Dec 1998 10:49:07 -0600
Subject: best way to do labeling on chassis?
Message-ID: <199812131649.KAA14096@surfacemount.ml.org>

Check out the latest issue of Nuts and VOldtolts they have an good
artical elle on making rack mount chassis .  Basically he suggests
drawing out the lables els on on your computer then printing out 
and taking them to a copy shop and having them transfer the
artwork to clear sticky backed material. You can yuse the resut
as a decal. If you clear coat the panel (a good idea) then use
lots of very thin coats of paint spray paint , so that the ink on the decals
wont run. 
I have tried this method and it works quite well.
Nuts an d vottls lts is on the web at www.nustvolts.comtsvolts.com 
the latest issue as of this email is December 98

cheers 
Mark



From theremin1 at worldnet.att.net  Sun Dec 13 18:09:11 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 13 Dec 1998 09:09:11 -0800
Subject: theremins
Message-ID: <000e01be26bb$4e8c25e0$25774e0c@hpcustomer>

Hi Paul, Grant, and everyone,

Monolythic RC oscillators tend to be too noisy for heterodyne
theremins.  The Exar emitter-coupled multivibrators, however,
are a bit better than a 4046 scheme, especially in terms of tempco
(about +/-20ppm/deg.C at optimum).  Still, inductance-based
oscillators such as a dual-differential pair type
(http://home.att.net/~theremin1/circuitlibrary/differentialpairosc.html)
or even a thermally stabilized Colpitts will provide much better service
than any of these approaches.  BTW, once the temperature drift in the
variable oscillator is sufficiently tamed, then crystal-controlled LOs are
perfectly reasonable, and very inexpensive in the form of those
ubiquitous "TTL" oscillator modules.

One thing I've been intending to do is trying the above-referenced circuit
with a transistor array to see if the added Vbe tracking further enhances
temperature stability.  It is also possible to add thermostatic regulation,
if there are enough transistors left over in the array.  (This doesn't
address
inductance tempcos, of course, but I've found the Miller 4652 phenolic-core
jobs to be pretty good for the purpose.)

-Art


-----Original Message-----
From: Paul Perry <pfperry at melbpc.org.au>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 12, 1998 6:31 PM
Subject: Re: theremins


>At 01:31 PM 12/12/98 -0600, Grant Richter wrote:
>
>>Take a CD4046 PLL chip and tie the VCO control line to +V. Program the RC
>>values to give a fixed
>>oscillator in the range of 100kHz to 400KHz. Attaching an antenna to one
>>leg of the timing capacitor
>>will give a usable range of six inches or so from the antenna. Another
4046
>>can be used to turn the
>>varying oscillator frequency into a control voltage.
>
>this hasn't been stable enough for me.
>OK as a 'special fx' woo-woo sort of thing, but not musically useful.
>Without a good (or any) specrtum analyser I don't know where the prob is,
>the v+ is stabilised (but, it would have to be stabilised to a few
>millivolts at least).
>
>I remember seeing ambient RF changing the characteristics of fets (try
using
>a mobile phone
>and putting the antenna near a desk phone while it is ringing.. the
>electronics in the desk
>phone go haywire & the local ring sound generator sounds wacky! a good
laugh
>on a slow day)
>
>I have tried replacing the antenna with a fixed cap & it is still unstable,
>so the
>interference (if that is the prob) is not coming from the antenna.
>
>paul perry melb aust
>




From aschrock at cs.brandeis.edu  Sun Dec 13 20:01:30 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Sun, 13 Dec 1998 14:01:30 -0500 (EST)
Subject: best way to do labeling on chassis?
In-Reply-To: <199812131649.KAA14096@surfacemount.ml.org>
Message-ID: <Pine.HPP.3.95.981213133157.18431B-100000@bay.cs.brandeis.edu>

You know, several companies make labeling devices... I know they can print
different size fonts, white and black, on clear tape. They're supposed to
be used for file folders and the like, but I'm sure they'd be fine for
panels if you use epoxy, or ya could do a final coat of clear acrylic. 
Personally I don't need fancy graphics on mine, just need to be sure what
cables go where. I also don't like spending forever on a front panel like
I did with dry transfer letters :) 

I seem to remember they're still pretty pricey, ($200? maybe) but I'm sure
you could buy one on credit at a place like Staples, punch up all your
labeling, and then return it. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|





From cyborg0 at GlobalEyes.net  Sun Dec 13 22:25:38 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sun, 13 Dec 1998 15:25:38 -0600
Subject: best way to do labeling on chassis?
References: <Pine.HPP.3.95.981213133157.18431B-100000@bay.cs.brandeis.edu>
Message-ID: <367430D2.6B52578A@globaleyes.net>

Spend 250 bux for a Alps md1000 wax transfer printer, use it to print
an  iron on transfer, iron it onto the panel, maybe give it a little bit
of clearcoat, and WHAM! you will have the most kik ass panel labeling
and graphics available.. 
My panel graphic rock severe.. Looks better than a screenprint shop cuz
I can do fades and whatever.. full panel graphics if I want..cover with
a light coat of acrylic or whatever.. beautiful and fast.

Rob



From fastcar at potentialunlocked.com  Mon Dec 14 00:04:13 1998
From: fastcar at potentialunlocked.com (fastcar at potentialunlocked.com)
Date: Sun, 13 Dec 98 18:04:13 -0500
Subject: Dream Car
Message-ID: <bulk.1149.19981213230321@allegra.sosglb.com>



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From jlarryh at iquest.net  Mon Dec 14 04:27:49 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Sun, 13 Dec 1998 21:27:49 -0600
Subject: cheap labeling printers available WAS: labeling on chassis 
Message-ID: <199812140222.DAA13266@mailhost.bpa.nl>

> From: Andrew Schrock <aschrock at cs.brandeis.edu>
> You know, several companies make labeling devices... I know they can
print
> different size fonts, white and black, on clear tape. 

These things make GREAT looking labels on clear tape.  I bought one I use
at work and at home.  The tape comes in all kinds of colors for background
with both black and white print.  The one I have uses 3 different widths
and automatically sizes the font depending on one through four lines of
text.

> I seem to remember they're still pretty pricey, ($200? maybe) 

Normally, these things run about $100 and up.  However, right now a local
office supply place has Casio reconditioned models with a full warranty for
$35.  I bought several.  One for me and for work associates and family. 
They look and operate just like new.  And, it comes with a roll of tape
($20 value) so you are getting the machine for $15.  The tape is expensive
at $20 a roll, BUT, that's 26 feet which will mkae a lot of cool labels. 
Of course you can have a variety of colors and change tapes in mid roll.

If any one is SERIOUSLY interested on one of these, I will make a run to
the office supply place and see if they have any left.  It is actually
about 1 hour away, but I am going that way Tuesday for work anyhow..

Larry Hendry





From cyborg0 at GlobalEyes.net  Mon Dec 14 05:41:55 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sun, 13 Dec 1998 22:41:55 -0600
Subject: labeling on chassis
References: <199812140222.DAA13266@mailhost.bpa.nl>
Message-ID: <36749713.9CB5CB9E@globaleyes.net>

Ok, heres the deal with the Alps md-1000 printer: If you are careful,
you can get some pretty good results. The lettering is fairly scratch
resistant as is, and you can actually "feel" the wax lettering on the
panel. It prolly wouldnt stand up to a LOT of abuse, and I knew that..
Thats why I clearcoated my panel with a very light coat of acrylic.

So for ease and cost, its a great way to go. Its also really good if you
want four-color graphics on your panels. But, the caveat is that you
will prlly need to protect it somehow. But you would need to do this
with the stickers too, and I suppose you have to do this with the
rub-ons also. 
Overall, for ease of use, speed, and general coolness, the MD-1000 iron
on is the way to go! :)

Rob



From theremin1 at worldnet.att.net  Mon Dec 14 06:16:33 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 13 Dec 1998 21:16:33 -0800
Subject: bounch
Message-ID: <001601be2720$eb2108c0$db7c4e0c@hpcustomer>

BJ and everyone,

I am resigned to accept DIY bounces as an inevitable attribute of the list.
That's okay, because the quality of the folks here and the great information
they offer more than compensate for this minor inconvenience.

Just FYI, I've recently been getting bounces from:
"Mailer-Daemon at telos.com (Mailer-Daemon)"
I will save the bounces for a while, just in case any of the network
experts care to see the headers.

-Art

-----Original Message-----
From: BJ <zzynt at swipnet.se>
To: Arthur Harrison <theremin1 at worldnet.att.net>
Date: Sunday, December 13, 1998 2:36 PM
Subject: bounch


>Arthur Harrison wrote:
>>
>> Hi everybody,
>Hi Arthur!
>
>You are not alone,i have checked with some other people from the
>DIY-list
>whom i now privately, and we all get all kinds of strange bounces!!!
>And none of us is not wery happy whit this situation.
>
>In my case for example i have had bounces since 2 months back and the
>bounce source changes from time to time?
>The only thing i can do at the moment is to "delete" the bounces!!
>
>Is far as i know there is a need for "Rick Jansen" to do a clean up
>of the list.
>
>BJ





From pjson at pacbell.net  Mon Dec 14 06:23:08 1998
From: pjson at pacbell.net (Kirke Sonnichsen)
Date: Sun, 13 Dec 1998 21:23:08 -0800
Subject: Moog Parametric EQ/Moog Drum Controller
Message-ID: <v02130500b29a50af1aa9@[206.170.33.208]>

I have a Moog 12 Stage Phase Shifter from that same era
and the schematics and service docs were located in a
plastic "pouch" INSIDE the unit!

-Kirke
(shifting phases constantly


>----------
>From: "Cai Bojsen-M?ller" <technical at image.dk>
>To: synth-diy at mailhost.bpa.nl
>Subject:Moog Parametric EQ/Moog Drum Controller
>Date: s?n 13. dec 1998 16:00
>
>
>Hi,
>
>I?m looking for schematics of the Moog Parametric EQ and the Moog drum
>controller. Better would be if anyone wants to sell. Any hint will be
>appreciated. Please send personal e-mail.
>
>Best wishes,
>
>Cai Bojsen-M?ller





From zzynt at swipnet.se  Mon Dec 14 08:37:43 1998
From: zzynt at swipnet.se (BJ)
Date: Sun, 13 Dec 1998 23:37:43 -0800
Subject: Bananas to the beat!
References: <852566D7.007730AD.00@galaxy.support.stream.com>
Message-ID: <3674C047.24DE@swipnet.se>

Is the mp3 format the most common wave format on the net or
is the wav format bigger?

Can anyone direct me to a freeware, shareware or whatever f-s ware
mp3 writer and reader who is easy to deal with for a person who hates
M-soft??

BJ



From qfulsom at usa.net  Mon Dec 14 09:22:27 1998
From: qfulsom at usa.net (Quint)
Date: Mon, 14 Dec 1998 02:22:27 -0600
Subject: labeling on chassis
Message-ID: <001601be273a$e392fcc0$459a5380@s8p8t9>

If you will use an acrylic clear spray evenly, then after drying it you can
use clear "shelving paper" and it wont hurt the original as youve coated it.
I dont spray coat unless it is a restored area but I do protect all my
boards with the shelving paper.  It comes in pretty nice size rolls for
about $8 at hardware stores, its like the kind you put in your cupboards but
clear.  It will not harm it in any way, i've had some covered about 10-12
years now and keeps them mint.
Quint


-----Original Message-----
From: Rob <cyborg0 at GlobalEyes.net>
To: J. Larry Hendry <jlarryh at iquest.net>
Cc: <synth-diy at mailhost.bpa.nl>
Date: Sunday, December 13, 1998 11:56 PM
Subject: Re: labeling on chassis


>Ok, heres the deal with the Alps md-1000 printer: If you are careful,
>you can get some pretty good results. The lettering is fairly scratch
>resistant as is, and you can actually "feel" the wax lettering on the
>panel. It prolly wouldnt stand up to a LOT of abuse, and I knew that..
>Thats why I clearcoated my panel with a very light coat of acrylic.
>
>So for ease and cost, its a great way to go. Its also really good if you
>want four-color graphics on your panels. But, the caveat is that you
>will prlly need to protect it somehow. But you would need to do this
>with the stickers too, and I suppose you have to do this with the
>rub-ons also.
>Overall, for ease of use, speed, and general coolness, the MD-1000 iron
>on is the way to go! :)
>
>Rob




From Colin.Fraser at scottishpower.plc.uk  Mon Dec 14 10:40:51 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Mon, 14 Dec 1998 09:40:51 -0000
Subject: Adding external trigger/gate/cv jacks
Message-ID: <BA865FF10473D211BC6F00805F0D830702D24B@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Tony Allgood [mailto:oakley at techrepairs.freeserve.co.uk]
> Sent: 12 December 1998 19:03
> To: Andrew Puls Q-Bot Eye; synth diy
> Subject: Re: Adding external trigger/gate/cv jacks
> 
> 
> Sorry. I believe that the Jen has no gate, or CV available 
> for the VCOs.
> Its a switch matrix digital oscillator. There may be a way to 
> put CV on
> the filter though.

This is the much more common sx1000. I have heard of cv input mods for this
synth, so I'm not sure whether the processor that scans the keys is also the
oscillator, or if it is just doing frequency division for the different
octaves as well as key scan.
Anyone know for sure ?

The model Andrew has, the sx2000, is an older model designed to sit on top
of an organ, with limited controls along the front, and some preset buttons.
It makes monster warped noises from hell, greta for basses, and is easily
modded for 1v/oct cv and gate.

Colin f



From thudson at cygnus.com  Mon Dec 14 12:33:37 1998
From: thudson at cygnus.com (Thomas Hudson)
Date: Mon, 14 Dec 1998 06:33:37 -0500
Subject: $5 digital delay chips
Message-ID: <3674F791.5E1A4FD0@cygnus.com>


The was a discussion some time ago about the Holtek HT8955A
"Voice Echo" chip
(http://www.holtek.com/docum/Consumer/8955a.htm)

I was never able to find a price or a source for the chips, so I
eventually forgot about them. I was flipping through a Tech-
America catalog this weekend and found them. They sell
for $5. The catalog number is  900-7548.
(http://www.techam.com)

.8 seconds delay at 25khz sampling rate (can go as high as
50khz)
10bit AD/DA converters.

Delay time is controlled by a resistor, maybe an LDR or
OTA could be used to have a voltage controlled delay?

Add the 4164 DRAM at $1.83, and a handful of resistors
and caps, and have a VCDD for under $20...

I bought two of them, I'll post to the list when I try
them out.

Thomas




From Colin.Fraser at scottishpower.plc.uk  Mon Dec 14 12:56:37 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Mon, 14 Dec 1998 11:56:37 -0000
Subject: 909 circuit diagrams
Message-ID: <BA865FF10473D211BC6F00805F0D830702D255@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Tony Allgood [mailto:oakley at techrepairs.freeserve.co.uk]
> Sent: 12 December 1998 20:00
> To: synth diy
> Subject: 909 circuit diagrams
> 
> 
> Hi all,
> 
> For 909 circuits look no further than...
> http://hardware.freepage.de/raf909/
> 

Quote of the day from the site above: "Anyone can sample a sound, but
there's nothing like having a knob in your hand to play with."

Colin f



From martin.czech at intermetall.de  Mon Dec 14 13:28:03 1998
From: martin.czech at intermetall.de (Martin Czech)
Date: Mon, 14 Dec 1998 13:28:03 +0100 (MET)
Subject: ELV F-Counter kit
Message-ID: <199812141228.NAA23249@window.intermetall.de>

Hello, some time ago I mentioned the ELV frequency counter kit.
Saturday I soldered it, took 2.5 hours. Unfortunately the description was
unaccurate, not to say wrong (so it took some detective work and half
an hour to figure out that the jumpers work in a different way, that
the clamp diodes of the segment driver ic is NOT connected to Vdd etc)

But the decription is the only wrong thing, the hardware works perfectly.
So this is nothing for the beginner, he won't figure out what's wrong.

The cool thing is that the microcontroller detects if the input
frequency is very low (<100kHz or so) and uses a period measurement,
then it calculates the reciprocal value, ie. you can measure directly
very low frequencys with rapid display update times, something that other
counters can't do, or only high line models of about 1000DM (1.65 DM =
1$). This kit cost me 89 DM.

I think it is idealy suited for music applications and I may use it as
a module for my modular for module calibration and tuning.
It needs a 5V power supply (regulator) and a perfect ttl-level pulse input.


ELV has agents in other countrys, like USA etc.

www.elv.de

m.c.




From Chris.List at sc.siemens.com  Mon Dec 14 15:33:50 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Mon, 14 Dec 1998 09:33:50 -0500
Subject: best way to do labeling on chassis?
Message-ID: <81A062BC5305D111A9D700805F065968012EE922@maildepo.sc.siemens.com>

Yes, I've done this. Gene Stopp actually described his procedure for it
about 8 or 9 months ago so I was inspired, gave it a try, and it worked
great. It's definitely the simplest and easiest method I've found. You
do the layout and print it with any old laser printer. Put a border on
the image that is about 1/4" (60mm) smaller than the size of the panel.
Cut the paper out along the boarder. Bring it to you local film
developing place or copy center (Kinko's, etc) - they should do
laminating there. It takes about a minute and costs about $3, and they
can usually do pieces up to 11x17, but maybe not - so you might need two
pieces for a full panel.

I highly recommend gluing it down. I used a combination of Elmer's
Glu-all (gooey, in a tube stuff) and 3M Spray77. There's other 3M spray
#?? type glues that are harder to find (but you can order them through
Newark) that look like they'd work better - Spray 80 and Spray90 I think
- but I haven't tried them. Anyway, you should glue it so the corners
stay down. 
The finish looks nice and clean and smooth and is actually much stronger
than I thought it would be, I've been very happy with the results -
mainly 'cause it's **so** quick, simple, and easy to do with
(relatively) "common household items". The only problem I had was
drilling through the lamination, as it tends to get a little gross
around the holes. The laminate frays, and the metal underneath pushes up
making a little bump under it, undoing the glue a little - even with a
high-speed drill press. No big deal though, because the knobs and jacks
cover this up 99% of the time. Gene mentioned that he punched all the
holes out of his laminate (with a punch) before gluing it down - but I
see that as a lot of extra work for little gain...

- CList



> -----Original Message-----
> From:	Rob [SMTP:rob at secret-secret.com]
> Sent:	Saturday, December 12, 1998 2:16 PM
> To:	synth-diy at mailhost.bpa.nl
> Subject:	Re: best way to do labeling on chassis?
> 
> >what's the best way to dothe labeling on a chassis?
> >that contact stuff or whatever it is?
> >is there some rub on paper that's good?
> >can i print it right out of my laser printer?
> 
> One thing I've been thinking of is printing it out on some sort of
> computer
> thing, either laser, or color inkjet and then laminating it and either
> gluing or just using the face plate components to hold it on to the
> chases.
> 



From wils0450 at itlabs.umn.edu  Mon Dec 14 15:57:54 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Mon, 14 Dec 1998 08:57:54 -0600 (CST)
Subject: Bananas to the beat!
In-Reply-To: <3674C047.24DE@swipnet.se>
Message-ID: <Pine.GSO.4.05.9812140856570.8253-100000@barney.itlabs.umn.edu>

Try  <www.mp3.com>. 

            <<< << The obvious solution is to kill you all >> >>>




From deknow at tiac.net  Mon Dec 14 16:39:47 1998
From: deknow at tiac.net (Dean Stiglitz)
Date: Mon, 14 Dec 1998 11:39:47 -0400
Subject: best way to do labeling on chassis?
References: <81A062BC5305D111A9D700805F065968012EE922@maildepo.sc.siemens.com>
Message-ID: <36753134.750245B3@tiac.net>

also, you can drill your pannels first (deburr them carefuly), and then
lay them on your scanner...import into your fav. graphic design (or even
photoshop) and the lables are based on where the holes are, rather than
where you planned to put them.

deknow




From gmuir at sympatico.ca  Mon Dec 14 16:40:51 1998
From: gmuir at sympatico.ca (Gavin Muir)
Date: Mon, 14 Dec 1998 10:40:51 -0500
Subject: Test, Introduction and Questions (All in One!)
Message-ID: <199812141543.KAA02794@smtp11.bellglobal.com>

Greetings all,

	I've been lurking around the list for a few months now, but this is my
first post so I thought I should give a brief intro on myself. I'm a
university student in Canada, and I'm just getting into the DIY thing. My
Electronics background is sketchy, but I'm doing a few projects with a
friend who works for an amp manufacturer in town and is guiding me along.
Problem here is, he knows amps inside out, but little about synths! I've
been studying schematics for various projects for about a year now, and can
recognize some patterns when I see them, but a great deal remains pretty
sketchy and the theory is totally beyond me at this point. In light of
this, please forgive any stupid questions I may ask!! (I'll keep them to a
minimum anyway, as I hope to force myself through as much as I can) 

	Anyways, to the question portion of our show! I have an SSM2040 and 2020,
and would like to build the now infamous 2040/2020 VCF. I have checked out
the datasheets for both, but they don't seem as clearly laid out as the
Curtis sheets, thus I have a few questions in this regard.

	1. How would the control pots be wired up for both the 2040 and 2020? I
would hate to wire things up with the wrong voltage or something and fry
one of these babies!

	2. In the VCF schematic, an oddball op amp is used. Am I right in assuming
that a reasonable replacement would not effect the sound? What would be a
reasonable replacement here?

	3. The VCF only uses 1/2 of the 2020, so it would be nice to use the other
half for a VCA. The datasheet for the 2020 seems REALLY bizarre to me on
this, as it relies on a lot of theory. Is there anyone out there with a
simple VCA schematic using 1/2 of a 2020? I just can't seem to recognize
what is going on in the control section!

	Anyways, thanks for putting up with my backwardness. If anyone can help me
out, I would be GREATLY appreciative!!

Thanks in advance,
Gavin Muir

P.S. This is a great list, so much thanks to everyone for keeping me
entertained and distracted for the last few months!




From alexandr at irit.fr  Mon Dec 14 16:41:37 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Mon, 14 Dec 1998 16:41:37 +0100 (MET)
Subject: ba662 
Message-ID: <199812141541.QAA22079@zeus.irit.fr>



	Hi all,

	I'm writing you cause i just finished my 303 clone this weekend and I have a problem
	with the VCA. I replaced the BA662 with a CA3080 and a npn follower (i have no chances 
	to find an original ba662). I changed some resistor (r124,r125) values so the input 
	voltage swing does not exced 10mv peak to peak, but i have some very anoying unilateral 
	cliping. I added a bias trimmer to ota, but no way, i can reduce the cliping, but i get
	a sort of dc offset whcih changes with the CV (some CV feedthru ?).
	I'm not very familiar with OTA design, and would be quite happy if someone can help me.

	

			Karl.



From Chris.List at sc.siemens.com  Mon Dec 14 17:59:24 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Mon, 14 Dec 1998 11:59:24 -0500
Subject: $5 digital delay chips
Message-ID: <81A062BC5305D111A9D700805F065968012EE923@maildepo.sc.siemens.com>

Hey this looks pretty cool, and cheap too! Another feature that might be
cool is the variable sampling rate - to get a lofi sound.

Definitely let us know how it goes. I'd especially be interested in the
minimum value for the delay resistor and the minimum delay time (I
didn't see that given in the datasheet, but I only did a quick scan).
It's too bad they aren't more specific about the kind of roll that
resistor is playing in controlling the internal delay osc. 

- CList


> -----Original Message-----
> From:	Thomas Hudson [SMTP:thudson at cygnus.com]
> Sent:	Monday, December 14, 1998 6:34 AM
> To:	Synth-DIY
> Subject:	$5 digital delay chips
> 
> 
> The was a discussion some time ago about the Holtek HT8955A
> "Voice Echo" chip
> (http://www.holtek.com/docum/Consumer/8955a.htm)
> 
> I was never able to find a price or a source for the chips, so I
> eventually forgot about them. I was flipping through a Tech-
> America catalog this weekend and found them. They sell
> for $5. The catalog number is  900-7548.
> (http://www.techam.com)
> 
> .8 seconds delay at 25khz sampling rate (can go as high as
> 50khz)
> 10bit AD/DA converters.
> 
> Delay time is controlled by a resistor, maybe an LDR or
> OTA could be used to have a voltage controlled delay?
> 
> Add the 4164 DRAM at $1.83, and a handful of resistors
> and caps, and have a VCDD for under $20...
> 
> I bought two of them, I'll post to the list when I try
> them out.
> 
> Thomas



From jeffry at aracnet.net  Mon Dec 14 18:27:53 1998
From: jeffry at aracnet.net (Jeffry James)
Date: Mon, 14 Dec 1998 17:27:53 GMT
Subject: AW: First Squawks
Message-ID: <199812141727.RAA04518@trapdoor.aracnet.net>

Hi, I am still intrigued!!

Is your synth based upon already published works: research and/or
implementation?  (ie. Has anyone else made an electronic analog
implementation of a pure math model of a musical instrument??)  Most
institutes spend their time playing with numbers on a digital computers, not
analog ones.  For the musician, an analog synth may have obvious control
advantages over its digital counter-part...
Or, it seems that you still have the same problem that Yamaha always has.
You have a model of the instrument but no model for a human interface!! --
You have no mathematical or algorithmic means to generate numbers for all of
the possible input arguments and co-efficients, etc.
Please forgive me if I am stealing time probably better spent on your novel
project!

Regards, Jeff.


I made a model of the 'Titanic' once, but it sank.




From WeAreAs1 at aol.com  Mon Dec 14 20:36:22 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Mon, 14 Dec 1998 14:36:22 EST
Subject: $5 digital delay chips
Message-ID: <3b0704a8.367568b6@aol.com>


In a message dated 12/14/98 9:08:53 AM, thudson at cygnus.com wrote:

<<> Delay time is controlled by a resistor, maybe an LDR or
> OTA could be used to have a voltage controlled delay?
> 
> Add the 4164 DRAM at $1.83, and a handful of resistors
> and caps, and have a VCDD for under $20...>>

I wonder if there might be a way to connect more RAM to this chip (to double,
triple, or quadruple the maximum delay time).  Would it be possible to devise
some kind of RAS/CAS addressing circuit that would allow additional RAM chips?

For instance, if one wanted to double the max delay time, would it be possible
to simply run the RAS and CAS signals through a couple of flip-flops (set up
as divide-by-2's), and send the Q and notQ outputs of the F/F's to the
respective RAS and CAS inputs of the two RAM chips? (you would clock the F/F's
with the original RAS and CAS signals)

Or maybe - send the RAS/CAS signals through a 1-in/2-out multiplexer
(74LS157?), and switch the multiplexer *every other time* that the RAM
addresses get up to their highest count (when A0 through A? are all in high
state).  This would effectively route the RAS/CAS signal back and forth
between the two chips.  Adding additional RAM would be done by expanding the
number of multiplexer outputs.

As might be painfully obvious, I haven't really thought this out very
carefully.  Although I have done a lot of work with static RAM, I don't know
much about how dynamic RAM works.  I am especially unclear on the "refresh"
concept.  Also, I'm not sure if both RAS and CAS signals need be switched for
the above scenario to work, or if just one of them need be multiplexed.  Can
anyone offer any ideas, or a basic explanation of dynamic RAM operation?

Michael Bacich



From blayer at uswest.net  Mon Dec 14 22:23:28 1998
From: blayer at uswest.net (Bill Layer)
Date: Mon, 14 Dec 1998 15:23:28 -0600
Subject: Proxy server test.
Message-ID: <3.0.6.32.19981214152328.007a0220@192.168.0.1>

BLAYER at POP.MPLS.USWEST.NET VIA PROXY 192.168.0.1

Thanks. Sorry.


  / /  (_)__  __ ____  __     
 / /__/ / _ \/ // /\ \/ /  
/____/_/_//_/\_,_/ /_/\_\  The choice of a GNU generation.  



From magnus at analogue.org  Mon Dec 14 22:27:27 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Mon, 14 Dec 1998 22:27:27 +0100
Subject: FETs on the ASM-1 VCO.
Message-ID: <199812142127.WAA16811@mail2.it.kth.se>

Hi there!

Since the questions keeps poping up of which FETs that might be
usefull for the ASM-1 VCO reset curcuit (Q3 in my schematic).

Let's collect information on what would work and what that would not
work. There ought to be some experience on this out there, and maybe
some people have made experiments.

While at it, let's pop an idea of mine and see how it survives the criticism.
I have been considering using a MOSFET, that would be interesting
since there is MOSFETs offering Rds(on) resistances way below 1 ohm,
which could reduce the reset fall-time and thereby can the reset-time
be reduced. The reduction of the reset-time can then reduce the R17
resistance for the France compensation and thus the waveform
distorsion experienced at higher frequencies. BTW, the compensation
dimensioning work like this:

	t      = R   * C					(1)
	 reset    17    3

Given C3 and treset we get

	      t
	       reset
	R   = ------						(2)
	 17     C
	         3

The floor raise that R17 causes is linear with the control current and
thus the frequency. Thus, it is obvious that R17 should be minimized
while still having the effect of compensating the reset time and thus
the reset time itself should be minimized, thus giving the reason for
my discussion of the Rds(on) in Q3. Cutting the reset time is ofcourse
also involving the cursuitry around U4, thus R18 and C3.

Cheers,
Magnus



From zimage at cs.wisc.edu  Tue Dec 15 01:11:36 1998
From: zimage at cs.wisc.edu (Tim Nowaczyk)
Date: Mon, 14 Dec 1998 18:11:36 -0600 (CST)
Subject: Transister ID Help :(
Message-ID: <Pine.GSO.3.96L.981214180504.26648A-100000@nova27.cs.wisc.edu>

I hope this is on topic.  If not, could you please refer me to the correct
place to ask so i don't do it again :)

There are two transisters with..
H945
   P
9G 2

written on the flat side.  Any info is apprecated.

I'm trying to recreate an old Gemini turntable mixer I have plus add some
other features.  It uses JRC(nowNJR)2043, 4556, and 4558.  Should I keep
these or are there others I could use for a better sound.  This is my
first audio project.  I'll post schamatics when I'm done :)

Thanks a lot

Tim Nowaczyk




From g.ramsay at easynet.co.uk  Tue Dec 15 01:20:33 1998
From: g.ramsay at easynet.co.uk (Gordon Ramsay)
Date: Tue, 15 Dec 1998 00:20:33 -0000
Subject: AW: First Squawks
Message-ID: <001101be27c0$bb27bba0$f340d4d4@oemcomputer>

I am curenntly builing this for my final year project, the design and buid
of the algorithms and human (tactile) interface for a modelled analog
synthesiser, if that is what you mean.

Max Ramsay
m.ramsay at easynet.co.uk


-----Original Message-----
From: Jeffry James <jeffry at aracnet.net>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: 14 December 1998 18:51
Subject: Re: AW: First Squawks


>Hi, I am still intrigued!!
>
>Is your synth based upon already published works: research and/or
>implementation?  (ie. Has anyone else made an electronic analog
>implementation of a pure math model of a musical instrument??)  Most
>institutes spend their time playing with numbers on a digital computers,
not
>analog ones.  For the musician, an analog synth may have obvious control
>advantages over its digital counter-part...
>Or, it seems that you still have the same problem that Yamaha always has.
>You have a model of the instrument but no model for a human interface!! --
>You have no mathematical or algorithmic means to generate numbers for all
of
>the possible input arguments and co-efficients, etc.
>Please forgive me if I am stealing time probably better spent on your novel
>project!
>
>Regards, Jeff.
>
>
>I made a model of the 'Titanic' once, but it sank.
>
>




From ijfritz at earthlink.net  Tue Dec 15 03:21:51 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Mon, 14 Dec 1998 19:21:51 -0700
Subject: FETs on the ASM-1 VCO.
References: <199812142127.WAA16811@mail2.it.kth.se>
Message-ID: <3675C7BF.3228982E@earthlink.net>

Magnus --

We discussed this a few months ago. What you write is fine as far as it
goes, but, as Terry Michaels pointed out, MOSFETS have a disadvantage in
capacitance, and also in leakage. In addition, if you are using an opamp
integrator, the rate at which the output can slew also matters.  It
would be interesting to see some actual data, though -- details on
spikes in the waveforms and on tuning accuracy and range. 

BTW, my updated version of Terry's VCO switches pretty fast and only
needs a touch of HF compensation. Maybe it could be improved, but it's
hard to see why you would need anything better -- unless you
specifically need ultrasonic frequencies. 

I've tried unsuccesfully several times to download your ASM-1
schematics, so I still don't know exactly what Gene's version of this
circuit looks like.

  Ian
  http://home.earthlink.net/~ijfritz


Magnus Danielson wrote:
> 
> Hi there!
> 
> Since the questions keeps poping up of which FETs that might be
> usefull for the ASM-1 VCO reset curcuit (Q3 in my schematic).
> 
> Let's collect information on what would work and what that would not
> work. There ought to be some experience on this out there, and maybe
> some people have made experiments.
> 
> While at it, let's pop an idea of mine and see how it survives the criticism.
> I have been considering using a MOSFET, that would be interesting
> since there is MOSFETs offering Rds(on) resistances way below 1 ohm,
> which could reduce the reset fall-time and thereby can the reset-time
> be reduced. The reduction of the reset-time can then reduce the R17
> resistance for the France compensation and thus the waveform
> distorsion experienced at higher frequencies. BTW, the compensation
> dimensioning work like this:
> 
>         t      = R   * C                                        (1)
>          reset    17    3
> 
> Given C3 and treset we get
> 
>               t
>                reset
>         R   = ------                                            (2)
>          17     C
>                  3
> 
> The floor raise that R17 causes is linear with the control current and
> thus the frequency. Thus, it is obvious that R17 should be minimized
> while still having the effect of compensating the reset time and thus
> the reset time itself should be minimized, thus giving the reason for
> my discussion of the Rds(on) in Q3. Cutting the reset time is ofcourse
> also involving the cursuitry around U4, thus R18 and C3.
> 
> Cheers,
> Magnus





From ijfritz at earthlink.net  Tue Dec 15 03:44:12 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Mon, 14 Dec 1998 19:44:12 -0700
Subject: AW: First Squawks
References: <199812141727.RAA04518@trapdoor.aracnet.net>
Message-ID: <3675CCFC.CB03C685@earthlink.net>

Jeffry --

The classic reference for simple 1D physical modeling is the following
review article:

ME McIntyre, RT Schumacher and J Woodhouse, "On the oscillations of
musical instruments", J. Acoustic Soc. Am., vol. 74, p. 1325 (1983)

Simplified digital implementations were developed at Stanford by JO
Smith. See for example:

JO Smith, "Musical applications of digital waveguides", Stanford
Department of Music Report No. STAN-M-39. 

There is also a tutorial on the Stanford CCRMA web site.

You can also learn a lot from the many Yamaha patents and the VL1
programmers' guide.

I've heard rumors of somebody else doing an analog implementation but I
don't know the details.

Your comments about modeling the control interface and exploring all the
combinations of model parameters are 100% correct. These factors don't
worry me because I'm interested in exploring new sounds rather than in
realistic immitation. Also I use a wind controller, so the interfacing
should be more natural than with a keyboard.

At least your model of the Titanic worked.

  Ian


Jeffry James wrote:
> 
> Hi, I am still intrigued!!
> 
> Is your synth based upon already published works: research and/or
> implementation?  (ie. Has anyone else made an electronic analog
> implementation of a pure math model of a musical instrument??)  Most
> institutes spend their time playing with numbers on a digital computers, not
> analog ones.  For the musician, an analog synth may have obvious control
> advantages over its digital counter-part...
> Or, it seems that you still have the same problem that Yamaha always has.
> You have a model of the instrument but no model for a human interface!! --
> You have no mathematical or algorithmic means to generate numbers for all of
> the possible input arguments and co-efficients, etc.
> Please forgive me if I am stealing time probably better spent on your novel
> project!
> 
> Regards, Jeff.
> 
> I made a model of the 'Titanic' once, but it sank.





From jlarryh at iquest.net  Tue Dec 15 04:38:05 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Mon, 14 Dec 1998 21:38:05 -0600
Subject: best way to do labeling on chassis?
Message-ID: <199812150232.DAA09091@mailhost.bpa.nl>

 Anyway, you should glue it so the corners stay down. 

One cool looking way I have used with this process recently to assure the
corners stay down (in addition to glue) is to actually screw them down.  I
picked up some # 8/32 black allen-head bolts about 1/2 inch long at Lowes. 
I drilled throught the panel near the corners and added these 4 bolts. 
They actually add to reather than detract from the look of the panel.
Larry



From zzynt at swipnet.se  Tue Dec 15 07:58:28 1998
From: zzynt at swipnet.se (BJ)
Date: Mon, 14 Dec 1998 22:58:28 -0800
Subject: Bananas to the beat!
References: <852566D7.007730AD.00@galaxy.support.stream.com> <3674C047.24DE@swipnet.se> <3674E859.2372@eunet.yu>
Message-ID: <36760894.19E2@swipnet.se>

<<>> wrote:
> 
> BJ wrote:
> >
> > Is the mp3 format the most common wave format on the net or
> > is the wav format bigger?
> >
> > Can anyone direct me to a freeware, shareware or whatever f-s ware
> > mp3 writer and reader who is easy to deal with for a person who hates
> > M-soft??
> >
> > BJ
> 
> Claro que si :)
> 
> http://users.skynet.be/somnus/mp3encoders.html
> http://users.skynet.be/somnus/mp3players.html
> 
> marjan

Hehe!:)
There was only one of you on synth d-i-y  list who understod
my hint in the subjekt line in my email about mp3.
And who responded in the same way!

The "rubber" band of the day is "YELLO" say hello!

BJ 
[who some times , some days go tonto!]



From m.rogers at cs.ucl.ac.uk  Tue Dec 15 10:06:03 1998
From: m.rogers at cs.ucl.ac.uk (Michael Rogers)
Date: Tue, 15 Dec 1998 01:06:03 -0800
Subject: $5 digital delay chips
References: <3b0704a8.367568b6@aol.com>
Message-ID: <3676267B.75C9@cs.ucl.ac.uk>

WeAreAs1 at aol.com wrote:
> I wonder if there might be a way to connect more RAM to this chip (to double,
> triple, or quadruple the maximum delay time).  Would it be possible to devise
> some kind of RAS/CAS addressing circuit that would allow additional RAM chips?

If the delay chips are so cheap, couldn't you just chain several of them
together with the analogue out of each chip going to the analogue in of
the next (with one DRAM for each chip)? Sorry if I'm being stupid and
this isn't possible.


Michael Rogers




From WeAreAs1 at aol.com  Tue Dec 15 11:06:58 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Tue, 15 Dec 1998 05:06:58 EST
Subject: $5 digital delay chips
Message-ID: <46e7526a.367634c2@aol.com>


Michael Rogers wrote:

<<If the delay chips are so cheap, couldn't you just chain several of them
together with the analogue out of each chip going to the analogue in of
the next (with one DRAM for each chip)?>>

Yes, you could.  But the accumulated noise, distortion, and hi-end rolloff
would result in fidelity not much better than an analog bucket-brigade delay.
On the other hand, if you could increase the amount of RAM that one chip could
address, there would be zero reduction in fidelity.  In fact, there would even
be a potential increase in fidelity, because you could achieve proportionally
longer delay times at higher sampling rates.

Michael Bacich



From alexandr at irit.fr  Tue Dec 15 11:20:18 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Tue, 15 Dec 1998 11:20:18 +0100 (MET)
Subject: new comer
Message-ID: <199812151020.LAA22802@zeus.irit.fr>



	hi,

	First i have to introduce myself (i did't do it :) ). I'm a PhD student in
	computer architecture, nothing to do with analog electronic, which i'm learning
	on the fly. I was mainly interrested in microprocessors, microcontrollers and
	all kind of numeric problems. But being passionated in music synthesis i wanted
	to build my own analog stuff, i started last year but nothing serious.

	Today i have a 303 clone ready analog et digital board, two eurocard, the analog
	being double sided. I also started a modular, i only have a few modules, some
	i designed, others from the tomg site. If interrested i have pcb ready for some
	tomg modules (it includes arp 2600 filter, ems diode ladder filter, 13600 vco with
	wave shaper). My own modules are an enveloppe generator using a 4051 instead of
	all those 4066 switch, a clone of the moog filter and it's vca, and a big noise
	generator (ala doepfer) including white, pink, roland x0x noises etc...

	All my pcb are fraction of euroboard, ie : they are one half or one third of it.
	the pot are soldered on it, and the pcb is attached to the faceplate by nothing
	else but the pot. It's crude but cheap. My problem is that the noise module have
	no pot :)

	Well I wish i can setup a web site to share my work.

	
					Karl



From alexandr at irit.fr  Tue Dec 15 11:40:46 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Tue, 15 Dec 1998 11:40:46 +0100 (MET)
Subject: ba662
Message-ID: <199812151040.LAA22805@zeus.irit.fr>


	Well, i finally fixed my problem with some un-scietific manipulations.
	 
> What value output resistor are you using for the 3080? Remember it
> outputs current and not voltage. 10k to the 5V3 rail should be OK. Then
> put this into your follower. A fet is probably better here, source
> follower.

	You'll laught, but my knowledge in OTA and transistors being poor 
	i did the followig :
	
	i reduced r124 and r125 to something small enough to get a very few
	milivolt at the 3080 input. The other input of the vca is connected
	via 1M resistor the the cursor of a trimer, the two others terminals
	are connected to ground and 12v.
	The ota output is connected to the base of the npn via a 10k resistor. 
	The npn colector is connected to the 12v. The emited is charged with 
	10k to ground.

	It more or less works, sometime it clips (but softly), with a low 
	cutoff frequency i can hear some high frequencies at very low level
	(i don't know where they come from). The overall is very noisy.
	
	My question, which one of these two alternative is the best : 

	1 - Reduce the input swing of the ota and boost the control current ?
	2 - Raise the input and scale down the control current ?

	
	I'll try other ota, but as i'm not skill, i burn them :) I never burnt
	an opamp, but i burned ton of OTAs. They are very expensive (in my situation)
	a 3080 cost me  1.5$, a 13600 or BA6110 cost me 2.5$
	
> How are you triggering accent and slide on your clone? I am hoping to
> use velocity CV to control these on mine.

	The sequencer part is a 8051 with2 back ram and rom, basic midi circuit, nothing
	to be proud of.
	The code is inspired by the description of the sequencer I found on a 303 site.
	This description included an ascii chronogram of the slide an gate signals. 
	As i don't have an original 303 i can't compare, but it seems to be ok. I get 
	the feeling, but not the quite the sound. I compared it the rebirth, but it 
	seems that the rebirth sequencer is not the same as the original. I download
	the user manual to have a clue about the note duration.






						Karl.

PS: OTA clipping is certainly not wanted, but sounds great (fat soft crying sounds)

 






From WeAreAs1 at aol.com  Tue Dec 15 11:48:48 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Tue, 15 Dec 1998 05:48:48 EST
Subject: Hard Sync for Minimoog?
Message-ID: <ef40b9f2.36763e90@aol.com>

Hello DIY'ers -

Has anyone ever come up with a good hard sync modification for old-style
Minimoog oscillators?  (3046-based, not ua726)  I have a great hard sync mod
for the new-style VCO's, but it's not applicable to the old ones.  Any ideas?

Michael Bacich



From rsowa at WizjaTV.pl  Tue Dec 15 11:54:44 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Tue, 15 Dec 1998 11:54:44 +0100
Subject: fine book
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D6801@demon>

Hi all,

I just got some fine gooks I ordered 3 months ago from amazon.
One of them is "Vintage Synthesizers" by Mark Vail.
Maaan! It's so great. Everything is there. Almost all
pictures I've seen on the web are in that book
(or maybe they were scanned from it).
All famous synths are described.

Just need to share my jou with you.

Roman




From rsowa at WizjaTV.pl  Tue Dec 15 12:49:00 1998
From: rsowa at WizjaTV.pl (Roman Sowa)
Date: Tue, 15 Dec 1998 12:49:00 +0100
Subject: ssm2164 VCO is back!
Message-ID: <2BF6F749A4A3D11185AD00A0C94CF67A4D6802@demon>

Hi all,

If you rememmber my posts about VCO with SSM2164...
Well, it's done!
Actually it's *quad* VCO with V/oct and linear FM inputs each,
not hard, but "strong" sync in, running from 0.3 Hz to almost 40kHz
and even beyond 100kHz if you don't care for clean saw.
outputs: saw, triangle and sine (well, not exactly a sine, but I had
one spare opamp in TL074 so I made 2-zener sine shaper).
SSM2164 is not temperature stabilized or compensated in any way.
When I first pluged it in, I was shocked... Must say that integrator
caps were selected to match each other and resistors were 1%,
but I didn't expect the SSM to be so acurate.
All four VCOs were running in no more than one semitone intervals
without trimming. Then I trimmed those babies, and listen to this
beautifull sound for half an hour like dork.
Additionally each VCO can be modulated via 3 VCAs. One for FM
and two for V/oct. It gives 12 VCAs onboard :-O
why so many? my modular will be all-VC, meaning no hardwired pots,
everything set up from ugly display with 10 buttons, or 15 assignable pots.
For this I need sea of VCAs.
So far I didn't have time to tweek it like mad (don't have this 15 pot
module), so can not tell you how it matches CV through entire range.
BTW, if anyone is interested, the pcb was made in "pcb-factory"
(ordered 2 pieces) for about 8$ each, double sided, hole platted,
10X12cm.

I'm looking now for a free website. I found one which gives me
up to 2 megs space, so maybe I'll put there some pictures, schemos,
but for .wavs it wont be enough.
If you can recommend a better service, please mail me privately.
I don't know if it would matter that I live in Poland.

Roman




From Colin.Fraser at scottishpower.plc.uk  Tue Dec 15 16:56:41 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Tue, 15 Dec 1998 15:56:41 -0000
Subject: Tempcos
Message-ID: <BA865FF10473D211BC6F00805F0D830702D25F@catsprntp01.cat.scottishpower.plc.uk>

I took delivery of my tempco resistors this morning from Synthesis
Technology (thanks Paul !).
?
I plan either to build the SEM vco design, or possibly the ASM-1 design.
Has anyone compared these side by side and if so, was there any noticable
difference between them ?
?
Any other suggestions for a vco design welcome. I want something with plenty
of presence - these will be replacing the 3340s in my modular, as I've got a
bit tired of their extreme accuracy...
?
?
Colin f
?



From b.layer at vikingelectronics.com  Tue Dec 15 18:04:44 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 15 Dec 1998 11:04:44 -0600
Subject: Excellent *free* proxy server
Message-ID: <3.0.6.32.19981215110444.007c8af0@192.168.210.18>

Hi All,

Found something really cool but OT; so I'll make it quick.

Feeling like a home LAN or just getting some added security on the net via
Proxy server? Download WinProxy 1.4 from LANProjekt in Czech Republic. The
'free' license covers two concurrent users, 3 mailboxes, and is elsewise
fully functional except for a limited cache size. The software supports
every thing you could imagine.

This program is awesome, *very* reliable, and actually does what they say
it does. The free license is more than generous, and the basic 5-user
version is only $99.95 USD.

Best shareware I've ever found. Do NOT confuse it with WinProxy 2.1d from
another firm; that is an inferior product.



Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From dbalvage at ptdcs2.ra.intel.com  Tue Dec 15 18:43:48 1998
From: dbalvage at ptdcs2.ra.intel.com (Duane R Balvage)
Date: Tue, 15 Dec 1998 09:43:48 -0800
Subject: Prophet-2000 info
Message-ID: <36769F33.41C6@ptdcs2.intel.com>

Hello all -

Hope this is not too far OT - I am looking for the addendum to the 

Prophet-2000's operations manual that includes operation of the 1 Meg

expansion module, local off, and the 8-output card. I believe it is the

software version 4.3 or 4.3B. I have the "normal" manual that came w/ 

the synth, and only need the additional update.

	-Again, I hope this is not too far OT.


			Thanks In Advance!!!

					- Duane
-- 
   "That boy's got a mouth like a cannon ... Always shootin' it off..."
                                
                             - Foghorn Leghorn
                      ________________________________
                     / o o oo              o ooo o   /\
       -------------/ ////  Duane R. Balvage   //// / /---------
                   /    _________________________  / /
                  / // / // /// // /// // /// / / / /
                 /___ //////////////////////////_/ /
                 \____\________________________\_\/

                     Intel Corporation, RA1-303
                   Portland Technology Development
       =========================================================

              Phone: (503) 613-8055    FAX: (503) 613-8261
                   E-Mail: dbalvage at ptdcs2.intel.com



From uzs159 at uni-bonn.de  Tue Dec 15 22:58:25 1998
From: uzs159 at uni-bonn.de (Rene Schmitz)
Date: Tue, 15 Dec 1998 22:58:25 +0100
Subject: FETs on the ASM-1 VCO.
In-Reply-To: <3675C7BF.3228982E@earthlink.net>
References: <199812142127.WAA16811@mail2.it.kth.se>
Message-ID: <3.0.5.32.19981215225825.0079b380@ibm.rhrz.uni-bonn.de>

At 19:21 14.12.98 -0700, you wrote:
>Magnus --
>
>We discussed this a few months ago. What you write is fine as far as it
>goes, but, as Terry Michaels pointed out, MOSFETS have a disadvantage in
>capacitance, and also in leakage. In addition, if you are using an opamp
>integrator, the rate at which the output can slew also matters.  It
>would be interesting to see some actual data, though -- details on
>spikes in the waveforms and on tuning accuracy and range.

I use MOSFETs as discharge switches, and have compared them to jFETs.
(though I'm still not sure if it acts more like a diode in my circuit, that
would lead to another interesting topic, why not use diodes as discharge
switches? A diode made from a jFET has pA leakage! This would work only for
the VCOs that have the cap to the supply.)
The MOSFETs have higher leakage, and there *are* effects from the capacitance.
I get a tiny wiggle at the reset, the waveform that I see at the output is
further 
distorted by the opamp buffer. When I use a FET here the wiggle disappears.
I use small signal FET (BS108) these don't have the low Rds(on) of the
power FETs 
(BUZ et al.)
These small signal devices have channel resistances equal in magnitude to
that of jFETs, 
so I would prefer the jFET (though I use MOSFETs... kind of schizophrenic :) 


>BTW, my updated version of Terry's VCO switches pretty fast and only
>needs a touch of HF compensation. Maybe it could be improved, but it's
>hard to see why you would need anything better -- unless you
>specifically need ultrasonic frequencies.

The fact here is that the reset pulse that is generated when the comparator
switches has the same length regardless of frequency. It has to be made
long enough to allow the cap to discharge fully. 
There were a lot of discussions about the ASMs VCO not oscillating, since
the cap (C3 18p or C4 in Ians schem) that determines the reset spike was
rather on the small side. 
I personally prefer a true schmitt-trigger where there are two tresholds, a
high one when the reset cycle begins, and when the cap is discharged to the
lower threshold the pulse ends, that way you have the fastest possible
reset spike, and if your trigger circuit is fast enough and of sufficiently
low inpedance you won't have trouble with the MOSFETs higher gate source
capacitance. Leakage is of course bigger than that of the jFET, but if you
don't need the *centi* Hz ranges this is no problem. The performance in the
ultrasonic range (20k+) is better with MOSFETS, but my ears are not that
good to hear any THD at 100Khz ;-)

Ok, besides this is sort of an apples and oranges thing, since my VCO is
completely different.
But I think the differences between MOS and j-FETs apply to all VCOs.

Bye
 Ren?

             ,   : (uzs159 at uni-bonn.de)
|") [" |\ | ["   : (http://www.uni-bonn.de/~uzs159)
|"\ [_ | \| [_   : (http://members.xoom.com/Rene_Schmitz)
                       




From magnus at analogue.org  Wed Dec 16 00:47:41 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Wed, 16 Dec 1998 00:47:41 +0100
Subject: FETs on the ASM-1 VCO.
In-Reply-To: Your message of "Mon, 14 Dec 1998 19:21:51 -0700"
References: <3675C7BF.3228982E@earthlink.net>
Message-ID: <199812152347.AAA14793@mail2.it.kth.se>

>>>>> "IF" == Ian Fritz <ijfritz at earthlink.net> writes:

 IF> Magnus --
 IF> We discussed this a few months ago. What you write is fine as far as it
 IF> goes, but, as Terry Michaels pointed out, MOSFETS have a disadvantage in
 IF> capacitance, and also in leakage. In addition, if you are using an opamp
 IF> integrator, the rate at which the output can slew also matters.  It
 IF> would be interesting to see some actual data, though -- details on
 IF> spikes in the waveforms and on tuning accuracy and range. 

I am aware of the slewrate issue, but recall that I want to go from
1.5 us downto some figure below 1 us, the lower the better. Recall
that we are talking about a 5 V swing, while the LM311 makes a 15 V
swing in much less time (was it 25ns? it was fast anyway).

Actually, the falltime in itself is something like 300-600 ns on the
ASM-1, but a lot time is lost for some reason that I haven't dwelved
into yeat (my lazy bum).

 IF> BTW, my updated version of Terry's VCO switches pretty fast and only
 IF> needs a touch of HF compensation. Maybe it could be improved, but it's
 IF> hard to see why you would need anything better -- unless you
 IF> specifically need ultrasonic frequencies. 

Well, if you want to go deep ultrasound at maybe 200-500 MHz ;)

 IF> I've tried unsuccesfully several times to download your ASM-1
 IF> schematics, so I still don't know exactly what Gene's version of this
 IF> circuit looks like.

Strange, I just downloaded it all very nicely... using
Netscape/Mozilla "Save Link As" menuchoice of the left mouse button
work great. Lynx is failsave otherwise.

Gene's VCO is fairly straigth forward with nothing strange really.

Cheers,
Magnus



From theremin1 at worldnet.att.net  Wed Dec 16 01:52:37 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 15 Dec 1998 16:52:37 -0800
Subject: FETs on the ASM-1 VCO.
Message-ID: <000601be288e$61c7be60$4e7d4e0c@hpcustomer>

Has anyone considered using an integrated analog switch
for the integrator reset?  (Or would that disqualify the oscillator
from being a true "clone?")  These parts are available in a
variety of form factors, and some newer devices have Rds(ON)
specifications of 5 ohms, and very little charge injection.
Maxim and Analog Devices come to mind as possible sources.
(No pun intended!)

-Art

-----Original Message-----
From: Magnus Danielson <magnus at analogue.org>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Cc: Magnus Danielson <magnus at analogue.org>
Date: Monday, December 14, 1998 3:37 PM
Subject: FETs on the ASM-1 VCO.


>Hi there!
>
>Since the questions keeps poping up of which FETs that might be
>usefull for the ASM-1 VCO reset curcuit (Q3 in my schematic).
>
>Let's collect information on what would work and what that would not
>work. There ought to be some experience on this out there, and maybe
>some people have made experiments.
>
>While at it, let's pop an idea of mine and see how it survives the
criticism.
>I have been considering using a MOSFET, that would be interesting
>since there is MOSFETs offering Rds(on) resistances way below 1 ohm,
>which could reduce the reset fall-time and thereby can the reset-time
>be reduced. The reduction of the reset-time can then reduce the R17
>resistance for the France compensation and thus the waveform
>distorsion experienced at higher frequencies. BTW, the compensation
>dimensioning work like this:
>
> t      = R   * C (1)
> reset    17    3
>
>Given C3 and treset we get
>
>       t
>        reset
> R   = ------ (2)
> 17     C
>          3
>
>The floor raise that R17 causes is linear with the control current and
>thus the frequency. Thus, it is obvious that R17 should be minimized
>while still having the effect of compensating the reset time and thus
>the reset time itself should be minimized, thus giving the reason for
>my discussion of the Rds(on) in Q3. Cutting the reset time is ofcourse
>also involving the cursuitry around U4, thus R18 and C3.
>
>Cheers,
>Magnus




From jhaible at primus-online.de  Wed Dec 16 02:42:31 1998
From: jhaible at primus-online.de (jhaible)
Date: Wed, 16 Dec 1998 02:42:31 +0100
Subject: Omni 2 schemos ?
Message-ID: <19981216014556.13271.qmail@nuernberg2.pop.metronet.de>

Hi,

I played an Omni 2 today, and I like the sound. No way to buy a 3rd string
ensemble,
though. But I'd love to know what is different from other ones. Are there
readable
schemos of the Omni 2 on the web somewhere ?

JH.



From clark at andrews.edu  Wed Dec 16 04:20:15 1998
From: clark at andrews.edu (Tony Clark)
Date: Tue, 15 Dec 1998 22:20:15 -0500 (EST)
Subject: FETs on the ASM-1 VCO.
In-Reply-To: <199812152347.AAA14793@mail2.it.kth.se>
Message-ID: <Pine.SOL.3.91.981215220453.22866B-100000@edmund.cs.andrews.edu>

> I am aware of the slewrate issue, but recall that I want to go from
> 1.5 us downto some figure below 1 us, the lower the better. Recall
> that we are talking about a 5 V swing, while the LM311 makes a 15 V
> swing in much less time (was it 25ns? it was fast anyway).

   I might make a suggestion.  Reduce your swing to 1 volt.  You ought to 
get better reset timing that way.

   Tony

------------------------------------,----------------------------------
I can't drive (my Moog) 55!         |     The E-Music DIY Archive
------------------------------------|  
Tony Clark -- clark at andrews.edu     | aupe.phys.andrews.edu/diy_archive
http://aupe.phys.andrews.edu/~clark |     Contributions welcomed!
------------------------------------'----------------------------------




From pharding at mail.ndirect.co.uk  Wed Dec 16 11:22:31 1998
From: pharding at mail.ndirect.co.uk (pharding at mail.ndirect.co.uk)
Date: Wed, 16 Dec 1998 10:22:31 +0000
Subject: More stuff on the 303...
In-Reply-To: <001f01be2159$a4909fa0$c227883e@default>
Message-ID: <199812161026.KAA30302@sioux.netdirect.net.uk>

Hi Tony,
             Just thought i would share some thoughts on the 303 
with you.I've never built any 303 bits myself although i've put 
together a modular synth.....[there's a picture of it on Paul 
Maddox's Modulus web site..]

I've got 2 303's in the studio right now[jammy git or what!]mine's a 
bog standard 303 with sockets added by Kenton for gate,cv,slide ,etc 
and the other one belongs to a friend and has an older kenton midi
retrofit.This is where the 303 sits on top of a steel case which 
presumably contains all their electronics +PSU,i've never has cause 
to open it.....

I dont want to put you off in your 303 studies and i'll try not to 
write a thesis now but i've come to the conclusion that it's the 
sequencer part of the 303 that gives it the biggest part of it's 
characteristic sound that we all love.IN fact i'd go as far as saying 
that both 303's sound worse over midi compared to when they are 
programmed with their own sequencer.With my 303 connected via gate /cv 
it takes longer to program a decent pattern than using the 
internal/infernal? sequencer.All 303 clones suffer from this as you 
have to program the slides and accents via midi controllers.The 
kenton retrofit 303 has a switch on the front panel to allow midi 
velocity to control filter cutoff,yet whilst this is amusing for a 
bit the resulting patterns are never quite as satisfying as those 
programmed on the 303's own sequencer.   As an experiment i've 
connected my modular up to the 303's own gate/cv outs and now my 
modular can sound quite like a 303 as all the slides and rests are 
transmitted too ......irrespective of what modular components i use[ie 
i can change over the filter module to a different sounding LP filter 
or even change VCO from an ASM-1 vco to a LM13700 vco ]the resulting 
sound still has that certain,303ness to it.

Both my 303's internal sequencers also have this other quirk which 
may be to do with the way they follow the incoming Sync 24 
pulses,i'm not sure but what happens is that no 2 bars are absolutely 
the same timing wise.I proved this when trying to sample a 303 
pattern and i could visually see the difference in the waveform on my 
akai..The timing is only a tiny bit out[real small amounts]but i fell 
that this certainly adds to the all important groove of the pattern 
where as over midi you get a more static pattern.[you could say that 
this staticness applies to all digital synths though].
 The accents are well important too,[so it's vital to 
incorporate an accent feature on your design.]especially when feeding 
the 303 in to that all important distortion unit,if that's you're 
thing.The accents get flattened out slightly when distorted and this 
compression makes the sound even more immense.  

> 
> The filter resonance is not only dependent on the res pot, but also on
> the actual value of the 5V3 power supply. If it is only a little higher,
> the gain of the diff amp becomes large enough to cause the filter to
> self oscillate with the res pot fully clockwise. The 5V3 is set up to
> feed the dac, and hence to give 1v/oct, so I suppose most 303s will have
> fairly similar power supplies.
  IIRC the resonance or cutoff? pot is dual ganged.what is the 2nd 
element in the pot doing? 
> The mixer is greatly affected by output load. When loaded with a 22k
> input impedance from my bench amp, it clips on negative swings, and the
> positive is affected in an unusual way. This generates some nice
> distortion. This may well be a cause of that TB sound. However, the
> amount of distortion is dependent on the level of signal from the volume
> pot. I am experimenting with additional overdrive circuitry to enhance
> the sound. But I can't decide whether to put it before the VCA or after
> it.

What would be really cool is for you have 2 VCA's one as normal then 
feed into a distortion circuit then another VCA post distortion set 
up as an expander gate.Maybe have 2 separate outs,1 clean sounding 
and one distorted?

One problem with Basstations and other 303 clones is that they have 
too many knobs.In theory the more adjustments the better but in 
practice i find that all that happens is that the 303 sound that you 
want goes "off the boil" too quickly whereas on the 303 all the 
parameter ranges are usable.

 The more I look at the waveforms, the less I am convinced that the
> BA662 actually affects the sound... but more tests have yet to be done.

I doubt if the VCA is that important to the overall sound which is 
also a combination of all the above things,i guess that as with all 
analogue synths it's the imperfections that make them sound so great!

I hope this may be of some use in your research

Good luck
Paul Harding.

 



From jocke at netcontrol.fi  Wed Dec 16 11:49:05 1998
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Wed, 16 Dec 1998 12:49:05 +0200 (EET)
Subject: FETs on the ASM-1 VCO.
In-Reply-To: <000601be288e$61c7be60$4e7d4e0c@hpcustomer>
Message-ID: <Pine.LNX.3.96.981216121758.15163A-100000@alf.netcontrol.fi>

Arthur Harrison wrote:

> Has anyone considered using an integrated analog switch
> for the integrator reset?  (Or would that disqualify the oscillator
> from being a true "clone?")  These parts are available in a
> variety of form factors, and some newer devices have Rds(ON)
> specifications of 5 ohms, and very little charge injection.

I'm not sure how IC switches will react to the high discharge
current spike with such a low on-resistance. Also, I fear crosstalk
between switches may be a problem.

As for using MOSFETs, I've found that they work well in circuits
where the integrating cap is (dis)charged against a constant voltage
rail, and less well in designs with the cap in the feedback path
of an op-amp (I guess this was already mentioned).

One VCO design I've used a lot uses a BS250 P-channel MOSFET to
discharge the integrating cap to a local +5V rail. I guess almost
any P-channel MOSFET would so the job as long as its ABS(Vgs) is
around 3 or 4 volts, maximum.

I've deliberately slowed down the reset time to around 1 microsecond,
because I feel it doesn't need to be faster as long as you're working
in the audio range. Less chance of inter-VCO lock-up, etc...

I've posted a schematic at

http://www.netcontrol.fi/~jocke/circuits/osc1.gif


cheers,

-joachim





From Colin.Fraser at scottishpower.plc.uk  Wed Dec 16 12:22:00 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Wed, 16 Dec 1998 11:22:00 -0000
Subject: FETs on the ASM-1 VCO.
Message-ID: <BA865FF10473D211BC6F00805F0D830702D265@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Arthur Harrison [mailto:theremin1 at worldnet.att.net]
> Sent: 16 December 1998 00:53
> To: DIY
> Subject: Re: FETs on the ASM-1 VCO.
> 
> 
> Has anyone considered using an integrated analog switch
> for the integrator reset?  (Or would that disqualify the oscillator
> from being a true "clone?")  These parts are available in a
> variety of form factors, and some newer devices have Rds(ON)
> specifications of 5 ohms, and very little charge injection.
> Maxim and Analog Devices come to mind as possible sources.
> (No pun intended!

I think I'll give this a try over my christmas holiday (if I can keep away
from Tomb Raider 3 long enough...)
I want to add a bit of extra logic to allow reset of the oscillator to a
halfway point. This is to allow for normal oscillator sync plus an extra
sync mode that resets a tri-wave output to the start or midpoint of its
cycle depending on its current position.
Maybe another sync mode with voltage control of reset point will be useful.
This should be pretty easy with analogue switches, as long as I can find one
with very low on resistance.

Colin f



From Colin.Fraser at scottishpower.plc.uk  Wed Dec 16 13:15:08 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Wed, 16 Dec 1998 12:15:08 -0000
Subject: More stuff on the 303...
Message-ID: <BA865FF10473D211BC6F00805F0D830702D267@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: pharding at mail.ndirect.co.uk [mailto:pharding at mail.ndirect.co.uk]
> Sent: 16 December 1998 10:23
> To: oakley at techrepairs.freeserve.co.uk
> Cc: synth-diy at mailhost.bpa.nl
> Subject: Re: More stuff on the 303...
> 
> I dont want to put you off in your 303 studies and i'll try not to 
> write a thesis now but i've come to the conclusion that it's the 
> sequencer part of the 303 that gives it the biggest part of it's 
> characteristic sound that we all love.

It's the combination of the synth and the sequencer. You just won't get the
full range of 303 sounds/patterns from anything else - including another
synth with the 303 sequencer or a 303 synth clone driven via midi.
My own 303 clone is only indistinguishable from the original when it is
driven by the original sequencer.

> IN fact i'd go as far as saying 
> that both 303's sound worse over midi compared to when they are 
> programmed with their own sequencer.

I found this too...

> irrespective of what modular components 
> i use[ie 
> i can change over the filter module to a different sounding LP filter 
> or even change VCO from an ASM-1 vco to a LM13700 vco ]the resulting 
> sound still has that certain,303ness to it.

You really need to add an accent output to the 303 to get the best results.
This can easily be taken from the non-inverted output of the accent
flip-flop.
303ness is still no substitute for 303ity.

> Both my 303's internal sequencers also have this other quirk which 
> may be to do with the way they follow the incoming Sync 24 
> pulses,i'm not sure but what happens is that no 2 bars are absolutely 
> the same timing wise.I proved this when trying to sample a 303 
> pattern and i could visually see the difference in the waveform on my 
> akai..The timing is only a tiny bit out[real small amounts]but i fell 
> that this certainly adds to the all important groove of the pattern 
> where as over midi you get a more static pattern.

I noticed this when I tried to exactly recreate a 303 pattern using Seq303
via midi - it just didn't move the same way.

The 303 cpu has the din sync inputs connected to its IO lines. The IRQ line
of the cpu is connected to an oscillator generates a pulse every 2ms.
I believe that the IRQ handler performs the scanning of the keyboard and
switch matrix, and the led driving.
The handling of sync inputs is not in the interrupt handler, but is carried
out in the normal program loop.
This will lead to timing variations depending on where a clock pulse arrives
relative to the interrupt generating oscillator - if the interrupt routine
has just started when a clock pulse arrives, it will continue to completion
before the pulse is processed.
I haven't put a frequency counter on the cpu clock osc, but I suspect its
clock speed is in the order of 500kHz.
You could test this theory by stopping the IRQ oscillator during playback,
and observing whether the leds go out and the timing is improved.

Colin f







From Juergen.Haible at nbgm.siemens.de  Wed Dec 16 13:21:58 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 16 Dec 1998 13:21:58 +0100
Subject: spikes (was:AW: FETs on the ASM-1 VCO.)
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BD208@nbgm336a.nbgm.siemens.de>

With all this talk about MOSFETs, JFETs and even diodes:

Is there anything wrong doing it with BJTs ?
I've used bipolar transistors for discharging in my VCOs all 
the time. I haven't done much research myself, just copied what
I saw in many commercial circuits. It works ok, though the spike
in the (converted) triangle could be smaller ...
Is this a general problem with BJTs, I mean do I get much shorter
reset times with FETs ?

IMO, the only reason for ultra short reset time is triangle
conversion. And the problem is worst in LFO applications.
Sure, I know, first rule in Building VCOs: Start with triangle,
not with saw. But then I absolutely love the variable shape
of Osc 3 of the VCS3 for modulation - it's a very unique
effect - and you can only get that when your oscillator core 
is producing a saw wave. So here is an application where
short discharge times are important. (I don't speak of
nanoseconds here, but not of 1nF capacitors either. It's
a 1u electrolytic, if memory serves.) I could improove things
a little when I used a darlington.

JH.




From cyborg0 at GlobalEyes.net  Wed Dec 16 14:37:39 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Wed, 16 Dec 1998 07:37:39 -0600
Subject: 303 sequencer/res dual pot
References: <199812161026.KAA30302@sioux.netdirect.net.uk>
Message-ID: <3677B7A3.42737EE5@globaleyes.net>

pharding at mail.ndirect.co.uk wrote:

>   IIRC the resonance or cutoff? pot is dual ganged.what is the 2nd
> element in the pot doing?
>

Sequencer, sequencer.. You obviously have not heard the Syntecno
TeeBee.. It can crank out the most convincing tb303 patterns using
seq303.. Having heard and fixed a few tb303s in my day, and I am
convinced that with either a Syntecno OR a FutureRetro, there is no need
for a tb303.. The FutureRetro, of course, if you want a *devilfish* sort
of modded tb303 sound with a sequencer built in. Supposedly, the tbs303
cranks fairly well also.

tb303 clones like the syntecno TeeBee have been made without the second
(rightmost) element and it works just fine for the most part. The
rightmost part on the schematics looks like it just regulates the amount
of accent cv being fed into the resonance lines. Fairly simple. Mind
you, you have to figure out a different way to regulate the accent cv in
the proper increments according to where the res pot is. One could
probably scale a simple op amp or transistor circuit to take care of
this by looking at the feedback voltage or current (whichever is more
appropriate) somewhere in the filter circuit and using that to drive the
amount of voltage allowed to come in via the accent. I guess an OTA
would work too..Many different ways.. I know Jared at FutureRetro would
prlly like to do away with the dual-ganged pot since it is a special
order item. It *looks* like Robert Honsbeek @ Syntecno did away with it,
and did a fairly good job of it.

NO one likes the dual-ganged pot... Everybody pick on the dual-ganged
pot!!!! :)

Rob



From theremin1 at worldnet.att.net  Wed Dec 16 14:41:15 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 16 Dec 1998 05:41:15 -0800
Subject: FETs on the ASM-1 VCO.
Message-ID: <000801be28f9$c1e79520$13b14e0c@hpcustomer>


-----Original Message-----
From: BJ <zzynt at swipnet.se>
To: Arthur Harrison <theremin1 at worldnet.att.net>
Date: Tuesday, December 15, 1998 3:54 PM
Subject: Re: FETs on the ASM-1 VCO.


Arthur Harrison wrote:

>> Yup, as we converse, I've downloaded the .pdf files for Analog Devices'
>> ADG451,  2, and 3 quad switches.  These are for a F-V design for a
>> theremin (what else?!).

BJ wrote:

>I wold belive that using them would be some sort of overkill,
>suicide twice :)!

AH:

Agreed, some of these schemes don't yield that much of an improvement
for the effort. But, sometimes the satisfaction of getting an extra 1 or 2
percent
linearity, or reducing ripple, is worth the try.   Those new AD switches,
BTW,
are really fine, at the initial observation.

BJ:

>Othervice Lattice has a huge application server for strange V-F designs!

AH:

I'd like to see that, if you or anyone else knows the web location.






From 104065.2340 at compuserve.com  Wed Dec 16 14:44:25 1998
From: 104065.2340 at compuserve.com (terry michaels)
Date: Wed, 16 Dec 1998 08:44:25 -0500
Subject: spikes (was:AW: FETs on the ASM-1 VCO.)
Message-ID: <199812160844_MC2-63D4-FDDF@compuserve.com>

Message text written by Haible Juergen
>With all this talk about MOSFETs, JFETs and even diodes:

Is there anything wrong doing it with BJTs ?
I've used bipolar transistors for discharging in my VCOs all 
the time. I haven't done much research myself, just copied what
I saw in many commercial circuits. It works ok, though the spike
in the (converted) triangle could be smaller ...
Is this a general problem with BJTs, I mean do I get much shorter
reset times with FETs ?

IMO, the only reason for ultra short reset time is triangle
conversion. And the problem is worst in LFO applications.
Sure, I know, first rule in Building VCOs: Start with triangle,
not with saw. But then I absolutely love the variable shape
of Osc 3 of the VCS3 for modulation - it's a very unique
effect - and you can only get that when your oscillator core 
is producing a saw wave. So here is an application where
short discharge times are important. (I don't speak of
nanoseconds here, but not of 1nF capacitors either. It's
a 1u electrolytic, if memory serves.) I could improove things
a little when I used a darlington.

JH.

<

Hi Juergen

I admit I've never tried a bipolar transistor for VCO reset, but I think
its a less than optimum choice.  The reset point cannot go to zero volts,
because of the saturation voltage of the BJT.  The offset voltage so
created might be temperature dependent.  The saturation voltage will vary
with collector current, which changes as you change frequency.  Charge
storage might cause problems in trying to turning the BJT off quickly. The
beta of the transistor, and so the discharge current, approaches zero as
the collector to emitter voltage approches zero.

I think a darlington would be a bad choice, as you then have a saturation
voltage of at least one diode drop, and it definately varies with
temperature.  Getting a darlington to turn off quickly at the end of the
reset can be tricky, they are much slower than a single BJT.

TM



From Colin.Fraser at scottishpower.plc.uk  Wed Dec 16 15:08:51 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Wed, 16 Dec 1998 14:08:51 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D26A@catsprntp01.cat.scottishpower.plc.uk>

Thinking about using analogue switches to reset the cap in a saw wave core,
it occurs to me that it should be possible to use analogue switches so that
the capacitor does not need to be discharged to be 'reset'.
?
If you have a dual two-way analogue switch, with very low on resistance, you
could connect the capacitor so that you can reverse its polarity in the
circuit - ie a comparator detects the peak level and toggles the switches so
that the connections from the cap to the ref voltage and the current source
are swapped. At the next peak, they are swapped back. This should give near
instant reset times.
I would expect this has been done before if it's workable.
Is this likely to have any advantage over discharging the cap ?
Disadvantages ?
?
?
Colin f
?
?
?
?



From clark at andrews.edu  Wed Dec 16 15:48:42 1998
From: clark at andrews.edu (Tony Clark)
Date: Wed, 16 Dec 1998 09:48:42 -0500 (EST)
Subject: Osc reset time
In-Reply-To: <BA865FF10473D211BC6F00805F0D830702D26A@catsprntp01.cat.scottishpower.plc.uk>
Message-ID: <Pine.SOL.3.91.981216094144.16033A-100000@edmund.cs.andrews.edu>

> Thinking about using analogue switches to reset the cap in a saw wave core,
> it occurs to me that it should be possible to use analogue switches so that
> the capacitor does not need to be discharged to be 'reset'.
> ?
> If you have a dual two-way analogue switch, with very low on resistance, you
> could connect the capacitor so that you can reverse its polarity in the
> circuit - ie a comparator detects the peak level and toggles the switches so
> that the connections from the cap to the ref voltage and the current source
> are swapped. At the next peak, they are swapped back. This should give near
> instant reset times.

   This is pretty much the principle of voltage inverter chips.  I 
imagine that what you'd have would be a symmetrical sawtooth on the 
output.  Whether or not that would be any "faster", I haven't a clue.

> I would expect this has been done before if it's workable.
> Is this likely to have any advantage over discharging the cap ?

   Well just symmetrical waveform output, if that's what happens.  That 
would be a plus, actually, as at high frequencies I notice uneven 
waveform distortion.  So perhaps having a symmetrical integrator would 
maintain better waveform integrity at higher frequencies?
   Disadvantage?  More suppy noise, I'd hazard a guess.  My experiences 
with voltage inverters are that they are fairly noisy.

   Tony

------------------------------------,----------------------------------
I can't drive (my Moog) 55!         |     The E-Music DIY Archive
------------------------------------|  
Tony Clark -- clark at andrews.edu     | aupe.phys.andrews.edu/diy_archive
http://aupe.phys.andrews.edu/~clark |     Contributions welcomed!
------------------------------------'----------------------------------




From Colin.Fraser at scottishpower.plc.uk  Wed Dec 16 15:51:32 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Wed, 16 Dec 1998 14:51:32 -0000
Subject: spikes (was:AW: FETs on the ASM-1 VCO.)
Message-ID: <BA865FF10473D211BC6F00805F0D830702D26C@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Haible Juergen [mailto:Juergen.Haible at nbgm.siemens.de]
> Sent: 16 December 1998 12:22
> To: DIY
> Subject: spikes (was:AW: FETs on the ASM-1 VCO.)
> 
> IMO, the only reason for ultra short reset time is triangle
> conversion. And the problem is worst in LFO applications.
> Sure, I know, first rule in Building VCOs: Start with triangle,
> not with saw. But then I absolutely love the variable shape
> of Osc 3 of the VCS3 for modulation - it's a very unique
> effect - and you can only get that when your oscillator core 
> is producing a saw wave. 

I'm not familiar with this - what does the variable shape function of the
vcs3 do, and how ?

Colin f





From per.mattsson at mkv.mh.se  Wed Dec 16 16:10:20 1998
From: per.mattsson at mkv.mh.se (Per Mattsson)
Date: Wed, 16 Dec 1998 16:10:20 +0100
Subject: Re(2): More stuff on the 303...
Message-ID: <fc.000f49240037bb5c3b9aca00b84b7367.37bb63@mkv.mh.se>

pharding at mail.ndirect.co.uk skriver:
>The timing is only a tiny bit out[real small amounts]but i fell 
>that this certainly adds to the all important groove of the pattern 
>where as over midi you get a more static pattern.
Sounds similar to the "swinginess" of an AKAI MPC-60. 
That one is not very exakt in it's timing either.

---Per




From ijfritz at earthlink.net  Wed Dec 16 16:13:22 1998
From: ijfritz at earthlink.net (Ian Fritz)
Date: Wed, 16 Dec 1998 08:13:22 -0700
Subject: FETs on the ASM-1 VCO.
References: <199812142127.WAA16811@mail2.it.kth.se> <3.0.5.32.19981215225825.0079b380@ibm.rhrz.uni-bonn.de>
Message-ID: <3677CE12.9CA533C3@earthlink.net>

Rene Schmitz wrote:
> I use MOSFETs as discharge switches, and have compared them to jFETs.
> (though I'm still not sure if it acts more like a diode in my circuit, that
> would lead to another interesting topic, why not use diodes as discharge
> switches? A diode made from a jFET has pA leakage! This would work only for
> the VCOs that have the cap to the supply.)
> The MOSFETs have higher leakage, and there *are* effects from the capacitance.
> I get a tiny wiggle at the reset, the waveform that I see at the output is
> further
> distorted by the opamp buffer. When I use a FET here the wiggle disappears.
> I use small signal FET (BS108) these don't have the low Rds(on) of the
> power FETs
> (BUZ et al.)
> These small signal devices have channel resistances equal in magnitude to
> that of jFETs,
> so I would prefer the jFET (though I use MOSFETs... kind of schizophrenic :)

Thanks for the description of your experiments. One other point to watch
out for -- small signal JFETs have limited current carrying capability.
This can also limit the discharge time ( cap. charge = av. current X
disch. time). MOSFETS, of course, are much better in this aspect of the
problem.

> I personally prefer a true schmitt-trigger where there are two tresholds, a
> high one when the reset cycle begins, and when the cap is discharged to the
> lower threshold the pulse ends, that way you have the fastest possible
> reset spike, and if your trigger circuit is fast enough and of sufficiently
> low inpedance you won't have trouble with the MOSFETs higher gate source
> capacitance. Leakage is of course bigger than that of the jFET, but if you
> don't need the *centi* Hz ranges this is no problem. The performance in the
> ultrasonic range (20k+) is better with MOSFETS, but my ears are not that
> good to hear any THD at 100Khz ;-)

Interesting points. The old Electronotes triangle VCOs used a discrete
Schmitt trigger approach.  I got one of those to track reasonable well
at ultrasonic frequencies (it drives a 10-step waveform generator, which
is an example where good ultrasonic response is needed).

 Ian




From Juergen.Haible at nbgm.siemens.de  Wed Dec 16 16:31:48 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 16 Dec 1998 16:31:48 +0100
Subject: AW: spikes (was:AW: FETs on the ASM-1 VCO.)
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BD623@nbgm336a.nbgm.siemens.de>

	>I'm not familiar with this - what does the variable shape function
of the
	>vcs3 do, and how ?

It's very simple: It's an ordinary one-transistor saw to triangle
converter, and there is a variable DC offset voltage that
will vary the point where the slope "folds over".
If you don't have perfect symmetry, there will always be 
a "jump" in the waveform. 
In theory one might think this is pretty useless, but it will
produce certain "trademark VCS3" modulations that
are very pleasant. You can hear it on the noise sound
at the beginning of this sample from my web site, for
example:

http://www.synthfool.com/diy/hj_adl4_turi.mp3

There is some filtered white noise, and the filter is
modulated with such an assymmetric triangle.
Once you know where this effect comes from, you might
recognize it on other recordings that use a VCS3, too.

JH.

PS.: Magnus, that might be an interesting addition for
you know what, too !




From Juergen.Haible at nbgm.siemens.de  Wed Dec 16 16:40:44 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Wed, 16 Dec 1998 16:40:44 +0100
Subject: AW: Osc reset time
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BD651@nbgm336a.nbgm.siemens.de>

	>If you have a dual two-way analogue switch, with very low on
resistance, you
	>could connect the capacitor so that you can reverse its polarity in
the
	>circuit - ie a comparator detects the peak level and toggles the
switches so
	>that the connections from the cap to the ref voltage and the
current source
	>are swapped. At the next peak, they are swapped back. This should
give near
	>instant reset times.
	>I would expect this has been done before if it's workable.
	>Is this likely to have any advantage over discharging the cap ?
	>Disadvantages ?

That's brilliant !

And now, connect two high impedance buffers and a differential
amplifier directly to the capacitor, and you have a triangle wave
without extra conversion as well.

I haven't checked for disadvantages yet, but it looks very promising !

JH.




From Colin.Fraser at scottishpower.plc.uk  Wed Dec 16 17:53:05 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Wed, 16 Dec 1998 16:53:05 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D26D@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Haible Juergen [mailto:Juergen.Haible at nbgm.siemens.de]
> Sent: 16 December 1998 15:41
> To: DIY; Fraser, Colin J
> Subject: AW: Osc reset time
> 
> 	>If you have a dual two-way analogue switch, with very low on
> resistance, you
> 	>could connect the capacitor so that you can reverse 
> its polarity in
> the
> 	>circuit - ie a comparator detects the peak level and 
> toggles the
> switches so
> 	>that the connections from the cap to the ref voltage and the
> current source
> 	>are swapped.
> 
> And now, connect two high impedance buffers and a differential
> amplifier directly to the capacitor, and you have a triangle wave
> without extra conversion as well.

The triangle wave would be an octave lower than the saw - but that might be
a plus.
You could have a triangle 'sub' osc output, and a tri convertor (with
variable DC offset ;-) for the normal tri output, or just rectify the sub
octave tri-wave.
The control signal for the cap swapping switch would also be a sub octave
square wave for free.

I'll have a look for a suitable analogue switch over the weekend and
prototype this idea.

> I haven't checked for disadvantages yet, but it looks very promising !

Hopefully you wont find any show-stoppers :-)
One question is how to implement the extra cap for precise linear detune.


Colin f





From oakley at techrepairs.freeserve.co.uk  Wed Dec 16 18:29:02 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Wed, 16 Dec 1998 17:29:02 -0000
Subject: D-50 weirdness
Message-ID: <001701be291e$2cfd2d60$5320883e@default>

Hi,

Not quite a diy question this, but I have just discovered a bit of weird
behaviour from my beloved D-50. I wonder whether other people have
noticed the same thing with theirs. In standalone operation, i.e. no
midi connections, everything is fine. When the d-50 is connected to
Cubase everything is fine, except when the output channel of the
sequencer is set the same as the d-50. That is, the d-50 keyboard and
key pad are controlling the d-50's internal sounds via the computer.
When I select patch I-64 and then any other, or indeed I-64 again, the
patch changes to I-36. There is nothing wrong with any other part of my
very long midi chain. In fact the problem even occurs when the d-50's
midi out is fed back into the midi in of the d-50. It appears that the
d-50 is sending out the correct patch change and then almost immediately
sending out the erroneous I-36. I have tried recording the patch change
information, but all I get is the erroneous one. But, remember, the
patch change is actually correct unless the d-50 receives its own
information back, then it sends out the duff one. If you program patch
changes in Cubase, everything is fine. It only happens with I-64, and
the change is always to I-36.

Weird.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From oakley at techrepairs.freeserve.co.uk  Wed Dec 16 18:42:34 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Wed, 16 Dec 1998 17:42:34 -0000
Subject: 1.44M on atari
Message-ID: <001901be291e$2f829fc0$5320883e@default>

Hi,

This one is a diy question but only loosely related to synths...

I fitted a pc 1.44M floppy drive on my Atari ages ago to replace the old
one that died. It works fine, so long as you don't try and format a HD
disk without covering over the hole with a bit of tape. But how easy is
it to get the computer to read and write in the higher format. I have
seen adverts for such a mod, but can I do it at home. I am currently
running TOS 1.4 on a MegaST4. I have been quoted 70 pounds by Keychange
Music to do this, and with an upgrade to TOS 2.06 as well, which
actually seems very good, but if I can save a few bob....

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From hallgeir at ovation.musicpower.net  Wed Dec 16 19:02:37 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Wed, 16 Dec 1998 19:02:37 +0100
Subject: Sequential's C64 thingy
Message-ID: <199812161810.TAA28000@louise.netpower.no>

Hello all DIYers,

I recently got a copy of Vintage Synthesizers by Mark Vail
(great book, BTW), and I found mentioned an interesting 
device by Sequential Circuits.
 It is not described in detail, nor have I found a name, but it
is (or was) an add-on keyboard (with software) for the Commodore
C-64. It seemed rather interesting to me.

So: Does anyone have any info on this thing? Or know where 
to get info on it? Anything at all would be greatly appreciated.

Thanks,
Hallgeir

BTW: I never knew Stopp had worked on Emerson's Mt.MOOG.



From magnus at analogue.org  Wed Dec 16 20:33:53 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Wed, 16 Dec 1998 20:33:53 +0100
Subject: AW: spikes (was:AW: FETs on the ASM-1 VCO.)
In-Reply-To: Your message of "Wed, 16 Dec 1998 16:31:48 +0100"
References: <1BF5E20E0C4DD111BBAB00805FE2D582010BD623@nbgm336a.nbgm.siemens.de>
Message-ID: <199812161933.UAA05705@mail2.it.kth.se>

>>>>> "HJ" == Haible Juergen <Juergen.Haible at nbgm.siemens.de> writes:

 >> I'm not familiar with this - what does the variable shape function
 HJ> of the
 >> vcs3 do, and how ?

 HJ> It's very simple: It's an ordinary one-transistor saw to triangle
 HJ> converter, and there is a variable DC offset voltage that
 HJ> will vary the point where the slope "folds over".
 HJ> If you don't have perfect symmetry, there will always be 
 HJ> a "jump" in the waveform. 
 HJ> In theory one might think this is pretty useless, but it will
 HJ> produce certain "trademark VCS3" modulations that
 HJ> are very pleasant. You can hear it on the noise sound
 HJ> at the beginning of this sample from my web site, for
 HJ> example:

 HJ> http://www.synthfool.com/diy/hj_adl4_turi.mp3

 HJ> There is some filtered white noise, and the filter is
 HJ> modulated with such an assymmetric triangle.
 HJ> Once you know where this effect comes from, you might
 HJ> recognize it on other recordings that use a VCS3, too.

 HJ> JH.

 HJ> PS.: Magnus, that might be an interesting addition for
 HJ> you know what, too !

Hmm.. this is certainly something that I need to test myself... but it
surely sounds promessing.

Thanks for the hint!

Cheers,
Magnus



From oakley at techrepairs.freeserve.co.uk  Wed Dec 16 23:28:36 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Wed, 16 Dec 1998 22:28:36 -0000
Subject: Your dream studio????
Message-ID: <000201be29f1$485d8c20$6e26883e@default>

Nice studio....

http://www.klaus-schulze.com/photos/studiot.htm

Tony Allgood





From synth1 at airmail.net  Thu Dec 17 03:23:14 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Wed, 16 Dec 1998 20:23:14 -0600
Subject: For Sale: Roland System 100M -181 Keyboard
Message-ID: <000b01be2964$338b7b00$341488cf@paults>

Monophonic, simple 4 octave keyboard for Roland 100M.

Or, if you can drive power into it over the 6 pin DIN cable, can
be used for most any 1v/oct homebrew synth.

Cosmetically, a 9/10.

$95 plus shipping.

Paul Schreiber
Synthesis Technology





From vco at mindspring.com  Thu Dec 17 03:40:30 1998
From: vco at mindspring.com (tomg)
Date: Wed, 16 Dec 1998 21:40:30 -0500
Subject: DMX Mod 2
Message-ID: <yam7654.1514.121473272@mail.mindspring.com>

I found a way to get all 24 drum triggers out of my DMX....
This is a much better solution than my last effort.

http://www.mindspring.com/~vco/misc/dmx2.html

-tg




From vco at mindspring.com  Thu Dec 17 03:41:11 1998
From: vco at mindspring.com (tomg)
Date: Wed, 16 Dec 1998 21:41:11 -0500
Subject: Mad Mouse PCBs
Message-ID: <yam7654.574.121473272@mail.mindspring.com>

YES! There will be Mad Mouse PC boards! I'll notify the
list as soon as they are ready. Thanks to everybody who
asked. I may have to run more boards..:-)

BTW I'm using EZTrax. It seems to work really well for
an old DOS proggy.

-tg




From vco at mindspring.com  Thu Dec 17 04:04:28 1998
From: vco at mindspring.com (tomg)
Date: Wed, 16 Dec 1998 22:04:28 -0500
Subject: AD: Mad Mouse PCBs
Message-ID: <yam7654.1414.119036240@mail.mindspring.com>

>YES! There will be Mad Mouse PC boards! I'll notify the
>list as soon as they are ready. Thanks to everybody who
>asked. I may have to run more boards..:-)

>BTW I'm using EZTrax. It seems to work really well for
>an old DOS proggy.

-tg

One more thing.. A pair or those 1K tempco's Paul has 
would be perfect for a MM. hint hint...

-tg





From Colin.Fraser at scottishpower.plc.uk  Thu Dec 17 10:26:51 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Thu, 17 Dec 1998 09:26:51 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D270@catsprntp01.cat.scottishpower.plc.uk>

I knocked up a quick prototype oscillator last night on stripboard using the
cap 'flipping' idea.

I used a 4066 switch, half a 4013 flip-flop and half a LM319 comparator.
I used a 5 volt reference for the 'top' of the cap, and set the comparator
to trigger the flip-flop to swap the ends of the cap between the current
source and the 5v ref when the voltage at the current source end of the cap
reached 2.5v.

End result was as expected - a falling sawtooth between 7.5 and 2.5 volts. I
didn't add a diff amp around the cap for tri output, but I put my scope
probes across the cap and there it was...

Adding up worst case response times for the comparator, flip-flop and
switch, I estimate the 'reset' time in this configuration to be about 300ns.
Oscillator sync isn't so straightforward as a normal ramp osc. I could use a
sync pulse to clock the other half of the 4013 to open a fet which would
drain the cap quickly at the current source end, and use the comparator
output to reset the flip-flop and turn off this fet when the limit is
reached - need to test this but in theory it should be fine.
Also, I can add another 'sync' input that triggers the cap swap flip-flop
directly. This will invert the position of the sawtooth wave around it's
midpoint, and also reverse the direction of the tri wave (I think...).
Need to test what this sounds like to see if it's worthwhile.
I still haven't figured out how I can add precise linear detune...

I'll add a proper expo converter with 1v/oct cv input at the weekend and see
how it performs.


Colin f




From afas at git.com.au  Thu Dec 17 10:50:25 1998
From: afas at git.com.au (geoffery francis james)
Date: Thu, 17 Dec 1998 17:50:25 +0800
Subject: SCI sixtrack-----------HELP
Message-ID: <199812171004.SAA23276@defiant.git.com.au>

could someone please help with the following:
1     best procedure to fix faulty silicon rubber switches (i have seached
the archives for same and found a lot of comments , but for some reason the
"solution " was deleted. so all in all that avenue was about as useful as
an ashtray on a motorbike!!!!!!)
2     scaling / tuning procedure 
3     website address for service manual?
thanks in advance
geoff james 



From Juergen.Haible at nbgm.siemens.de  Thu Dec 17 10:51:30 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 17 Dec 1998 10:51:30 +0100
Subject: AW: Your dream studio????
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BDC05@nbgm336a.nbgm.siemens.de>


	>Nice studio....
	>
> http://www.klaus-schulze.com/photos/studiot.htm
> 
> 
It sure does look impressive, but his music was much 
better when he only had a fraction of these instruments.

JH.





From hekovala at lyseolukio2.kajaani.fi  Thu Dec 17 11:00:49 1998
From: hekovala at lyseolukio2.kajaani.fi (Henri Kovalainen)
Date: Thu, 17 Dec 1998 12:00:49 +0200 (EET)
Subject: Mad Mouse PCBs
In-Reply-To: <yam7654.574.121473272@mail.mindspring.com>
Message-ID: <Pine.LNX.3.96.981217115919.23254A-100000@lyseolukio2.kajaani.fi>

On Wed, 16 Dec 1998, tomg wrote:
> BTW I'm using EZTrax. It seems to work really well for
> an old DOS proggy.

 "for an old DOS proggy", as far as I know these tend to work better than
 the modern windoze ones =)

 ------------------.                  
 theadvancementand |  henri kovalainen    hoikankatu 19
 diffusionofknowle |  phone: +08-626555   87100 kajaani
 dgeistheonlyguard |  irc: AcidRain       finland
 ianoftrueliberty. |  http://lyseolukio2.kajaani.fi/~dh
                   '-




From Juergen.Haible at nbgm.siemens.de  Thu Dec 17 12:29:26 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 17 Dec 1998 12:29:26 +0100
Subject: AW: Osc reset time
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BDD8C@nbgm336a.nbgm.siemens.de>

	>I knocked up a quick prototype oscillator last night on stripboard
using the
	>cap 'flipping' idea.
	>
	>I used a 4066 switch, half a 4013 flip-flop and half a LM319
comparator.
	>I used a 5 volt reference for the 'top' of the cap, and set the
comparator
	>to trigger the flip-flop to swap the ends of the cap between the
current
	>source and the 5v ref when the voltage at the current source end of
the cap
	>reached 2.5v.
	>
	>End result was as expected - a falling sawtooth between 7.5 and 2.5
volts. I
	>didn't add a diff amp around the cap for tri output, but I put my
scope
	>probes across the cap and there it was...

Good to hear that it works !

I was so fascinated by the idea that I intended to breadboard
it myself. But first I couldn't get away from my Wurlie (it's
finally working again!), and then "the monkey sat watching the
war on TV" (to paraphrase Roger Waters).

	> Also, I can add another 'sync' input that triggers the cap swap
flip-flop
	> directly. This will invert the position of the sawtooth wave
around it's
	> midpoint, and also reverse the direction of the tri wave (I
think...).

In a normal triangle VCO this would mean thru zero FM, when
you combine it with sign / magnitude extraction of the CV.

	> I still haven't figured out how I can add precise linear detune...

You still can build a V in / V out expo converter and a linear
current source. This was tricky when 741 was the standard
opamp, but nowadays we have LF411's for low offset voltage
drift ...

	>I'll add a proper expo converter with 1v/oct cv input at the
weekend and see
	>how it performs.

I'm curious if the finite resistance of the switches has an effect
on the waveform. 

JH.




From Colin.Fraser at scottishpower.plc.uk  Thu Dec 17 12:59:54 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Thu, 17 Dec 1998 11:59:54 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D278@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Haible Juergen [mailto:Juergen.Haible at nbgm.siemens.de]
> Sent: 17 December 1998 11:29
> To: DIY; Fraser, Colin J
> Subject: AW: Osc reset time
> 
> You still can build a V in / V out expo converter and a linear
> current source. This was tricky when 741 was the standard
> opamp, but nowadays we have LF411's for low offset voltage
> drift ...

Do you know of anywhere I might find a schematic of such an expo convertor ?
Do I just use a normal expo convertor with the output current passing thru a
resistor and extract the voltage across the resistor ?
What constitutes a stable linear current source ? Will a transistor in the
feedback path of an op-amp do ?

> 	>I'll add a proper expo converter with 1v/oct cv input at the
> weekend and see
> 	>how it performs.
> 
> I'm curious if the finite resistance of the switches has an effect
> on the waveform. 

Me too. The on resistance for the 4066 is 80 ohms max. Given that in a
normal osc the cap would be connected to the +v supply, how much extra
resistance does the switch present in addition to the output of the supply
regulator ?
And what sort of impedance does a typical current source have ? 
Come to think of it, what sort of series resistance does a capacitor have ?
(Wish I'd taken a degree in electronics instead of computing !)

I expect I will need to experiment more over the weekend to determine if
this design will be stable enough.

Colin f



From Juergen.Haible at nbgm.siemens.de  Thu Dec 17 13:36:28 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 17 Dec 1998 13:36:28 +0100
Subject: AW: Osc reset time
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BDEA8@nbgm336a.nbgm.siemens.de>

	> Do you know of anywhere I might find a schematic of such an expo
convertor ?

Korg Polysix, for example. (It's multiplexed for all 6 voices,
but the basic principle is there.)

	>Do I just use a normal expo convertor with the output current
passing thru a
	>resistor and extract the voltage across the resistor ?

Yes. But I'd keep the Vce of the expo converter constant,
and feed it into a virtual GND node. Opamp with resistor in
feedback path, collector of expo transistor directly connected
to opamp "-" input. 

	>What constitutes a stable linear current source ? Will a transistor
in the
	>feedback path of an op-amp do ?

That's how it's usually done, and how I would start, too.
voltage input is "+" input of opamp, opamp output drives
transistor base, transistor emitter tied to opamp "-" input,
resistor from the same connection to GND to set the
I / V conversion ratio. You can switch in separeate
resistors here to vary footage. 100k, 200k, 400k.

The Korg MS-20 shows a slightly different approach for
the current source (schemos are on the web, too): They
built a standard expo converter (for the linear current source,
that is ! Remember they already have an expo Keyboard 
voltage ...), but only used the "linear FM" input of this expo
converter for the keyboard. Footage range was set by
a set of 100k / 200k / 400k / 800k resistors, too.
(all built from a string of 8 equal 100k resistors, of course)
They only use the expo input for uncritical stuff (in terms of
linearity and tempco), like modulation and tuning.

(side note: The theorethical sonical benefits of linear VCOs
are completely spoiled in the MS-20 by the huge interlock of
the Oscillators. On the Polysix, you can hear it in unison mode,
but alas here it's 6 VCOs and not just 2 at one time. If you
have the chance to play a Trident - that was the instrument
that triggered it all for me.)

Now the general drawback of these linear VCOs was that
you *had* to make the footage switching, because if you
wanted to cover the full range with one expo CV you came
in conflict with offset voltages, and more important, offset
voltage drift.

My assumtion (still untested) is that we would have much less 
trouble today with low offset opamps. I think that it would still
be difficult to cover ultra low LFO range and audio range with
one CV, but audio range down to fast LFO range might work.
(It does in my Frequency Shifter VCO, but then I have only
built one single unit.)

	>> I'm curious if the finite resistance of the switches has an
effect
	>> on the waveform. 
	>
	>Me too. The on resistance for the 4066 is 80 ohms max. Given that
in a
	>normal osc the cap would be connected to the +v supply, how much
extra
	>resistance does the switch present in addition to the output of the
supply
	>regulator ?

I'd expect some glitch on the saw waveform, but the (usually
more critical) triangle wave should be quite smooth by definition.

	> And what sort of impedance does a typical current source have ? 

Depends on how you build it. from 100s of kOhms to 100s of
MegOhms if you build a cascode. But that wouldn't interfere
with the switches' on-resistance, anyway, would it ?

	>Come to think of it, what sort of series resistance does a
capacitor have ?

MilliOhms. Magnitudes lower than the CMOS switches.

JH.



From Colin.Fraser at scottishpower.plc.uk  Thu Dec 17 14:19:58 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Thu, 17 Dec 1998 13:19:58 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D279@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Haible Juergen [mailto:Juergen.Haible at nbgm.siemens.de]
> Sent: 17 December 1998 12:36
> To: JH; DIY; Fraser, Colin J
> Subject: AW: Osc reset time
>  
> 	> Do you know of anywhere I might find a schematic of such an expo
> convertor ?
>
> Korg Polysix, for example. (It's multiplexed for all 6 voices,
> but the basic principle is there.)

Should have rememebered that - I have the service manual somewhere.

> Now the general drawback of these linear VCOs was that
> you *had* to make the footage switching, because if you
> wanted to cover the full range with one expo CV you came
> in conflict with offset voltages, and more important, offset
> voltage drift.
> My assumtion (still untested) is that we would have much less 
> trouble today with low offset opamps. I think that it would still
> be difficult to cover ultra low LFO range and audio range with
> one CV, but audio range down to fast LFO range might work.
> (It does in my Frequency Shifter VCO, but then I have only
> built one single unit.)

Let's hope so - I will test this over the weekend, assuming Maplin have a
411 in stock !

> 	> And what sort of impedance does a typical current 
> source have ? 
> 
> Depends on how you build it. from 100s of kOhms to 100s of
> MegOhms if you build a cascode. But that wouldn't interfere
> with the switches' on-resistance, anyway, would it ?

I don't know - the on resistance is specified for a given load resistance.
I'm not sure what sort of interaction there might be.
I guess experimentation will tell.

One more question for now - what would be the benefits of thru-zero FM ?


Colin f



From Juergen.Haible at nbgm.siemens.de  Thu Dec 17 14:50:00 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Thu, 17 Dec 1998 14:50:00 +0100
Subject: AW: FETs on the ASM-1 VCO.
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010BE01D@nbgm336a.nbgm.siemens.de>

	> I was a little concerned,
	> though, about possible instabilites in U1A resulting from C1's
direct
	> connection
	> to its output. 

No, it's perfect the way Joachim has done it. There is a
certain *range* of capacitance values that will make an
opamp instable. You can either stay below that range
(very small cap), or go above that range (very large
cap). Think of it as a 2-pole filter, one pole being the
internal compensation cap, and the second one being
formed by the output resistance and the capacitive load.
It's only when the two poles are relativly close together
that you get high Q factors, and thus overshot or
oscillation.
Normally you don't have much choice, of course: You will
use low capacitive load when the opamp output voltage
has to change fast, and high capacitance when you want
to bypass a constant voltage.
It's the same principle with voltage regulators: They even
*need* a certain capacitive load to be stable !

	> Can C1 be moved across R6, instead, or does the transient
	> response of Q1's source node degrade too much? 

This would give you a good reference voltage at the opamp
input. But at the output, it would only be good at low frequencies.
For higher frequencies, the internal gain of the opamp goes
down, and thus the output resistance of the closed loop goes up.
With the cap at the output, you have the precision buffer of the
opamp at low frequencies, plus the low impedance of the 10u 
at high frequencies.

JH.







From tech4 at freshmilk.com  Thu Dec 17 14:53:23 1998
From: tech4 at freshmilk.com (Louis Otero)
Date: Thu, 17 Dec 1998 08:53:23 -0500
Subject: EZ tRacks
Message-ID: <36790CD2.4841085@freshmilk.com>

Wha make this EZ tracks and where can i get it?

tech4
--
-----------------------------
Just me and my Nova 101
-----------------------------
tech4 at freshmilk.com





From theremin1 at worldnet.att.net  Thu Dec 17 15:20:00 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 17 Dec 1998 06:20:00 -0800
Subject: FETs on the ASM-1 VCO.
Message-ID: <000601be29c8$55f57420$52754e0c@hpcustomer>


-----Original Message-----
From: Fraser, Colin J <Colin.Fraser at scottishpower.plc.uk>
To: 'Arthur Harrison' <theremin1 at worldnet.att.net>; DIY
<synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 16, 1998 3:23 AM
Subject: RE: FETs on the ASM-1 VCO.


AH:

>> Has anyone considered using an integrated analog switch
>> for the integrator reset?  (Or would that disqualify the oscillator
>> from being a true "clone?")  These parts are available in a
>> variety of form factors, and some newer devices have Rds(ON)
>> specifications of 5 ohms, and very little charge injection.
>> Maxim and Analog Devices come to mind as possible sources.
>> (No pun intended!)

CF:

>I think I'll give this a try over my christmas holiday (if I can keep away
>from Tomb Raider 3 long enough...)
>I want to add a bit of extra logic to allow reset of the oscillator to a
>halfway point. This is to allow for normal oscillator sync plus an extra
>sync mode that resets a tri-wave output to the start or midpoint of its
>cycle depending on its current position.
>Maybe another sync mode with voltage control of reset point will be useful.
>This should be pretty easy with analogue switches, as long as I can find
one
>with very low on resistance.

>Colin f

AH:

In some theremin designs, I use an analog switch to reset the VCO to the
0v level.  This minimizes the "pop" when the oscillator is reinitiated.
By adding a little logic between the oscillator's output and the switch
control,
I can also synch the oscillator's turn-off to the first zero-crossing.
This minimizes the turn-off "pop" as well.
Your idea for selective synch seems especially nice for synth LFO apps.

-Art




From theremin1 at worldnet.att.net  Thu Dec 17 15:59:13 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 17 Dec 1998 06:59:13 -0800
Subject: FETs on the ASM-1 VCO.
Message-ID: <000f01be29cd$d03325c0$52754e0c@hpcustomer>

AH:

>> Has anyone considered using an integrated analog switch
>> for the integrator reset?  (Or would that disqualify the oscillator
>> from being a true "clone?")  These parts are available in a
>> variety of form factors, and some newer devices have Rds(ON)
>> specifications of 5 ohms, and very little charge injection.


JV:

>I'm not sure how IC switches will react to the high discharge
>current spike with such a low on-resistance. Also, I fear crosstalk
>between switches may be a problem.

AH:

There is some concern if the value of the integrating capacitor is
relatively large.
A precise determination can be made by calculating the joules of
energy dissipated by the switch.  For a vast majority of synth applications,
there should be no danger to the switch whatsoever.  These switches,
after all, are integrated versions of the discrete JFETs or MOSFETs
routinely
used in all kinds of discharge applications.

If crosstalk is a concern, individual switches are available in eight-pin
packages.
The MAX319 is one such switch.

JV:

>As for using MOSFETs, I've found that they work well in circuits
>where the integrating cap is (dis)charged against a constant voltage
>rail, and less well in designs with the cap in the feedback path
>of an op-amp (I guess this was already mentioned).

AH:

In such cases, you may have to contend with marginal Vgs conditions in
which the switch can not be fully enhanced.  The nice thing about many
integrated switches is that they contain the level shifters and other
goodies
to ensure proper enhancement of the output switch, regardless of Vds.
Also, the control can be treated as any logic input.

JV:

>One VCO design I've used a lot uses a BS250 P-channel MOSFET to
>discharge the integrating cap to a local +5V rail. I guess almost
>any P-channel MOSFET would so the job as long as its ABS(Vgs) is
>around 3 or 4 volts, maximum.

>I've deliberately slowed down the reset time to around 1 microsecond,
>because I feel it doesn't need to be faster as long as you're working
>in the audio range. Less chance of inter-VCO lock-up, etc...

AH:

Agreed, limiting is a good idea in any case, just as bandwidth limiting is
a good idea in signal paths.

JV:

>I've posted a schematic at
>http://www.netcontrol.fi/~jocke/circuits/osc1.gif

AH:

I can see the reset limiter as R1, and that seems fine.  I was a little
concerned,
though, about possible instabilites in U1A resulting from C1's direct
connection
to its output.  Can C1 be moved across R6, instead, or does the transient
response of Q1's source node degrade too much?  Have you measured the
linearity of this oscillator and R1's relationship to linearity?

regards, Art





From theremin1 at worldnet.att.net  Thu Dec 17 16:02:22 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 17 Dec 1998 07:02:22 -0800
Subject: spikes (was:AW: FETs on the ASM-1 VCO.)
Message-ID: <001401be29ce$40c1d840$52754e0c@hpcustomer>

If bipolars do the trick, then why not?  I suppose the key parameter is 
saturation resistance.

-Art

-----Original Message-----
From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
To: DIY <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 16, 1998 5:38 AM
Subject: spikes (was:AW: FETs on the ASM-1 VCO.)


>With all this talk about MOSFETs, JFETs and even diodes:
>
>Is there anything wrong doing it with BJTs ?
>I've used bipolar transistors for discharging in my VCOs all 
>the time. I haven't done much research myself, just copied what
>I saw in many commercial circuits. It works ok, though the spike
>in the (converted) triangle could be smaller ...
>Is this a general problem with BJTs, I mean do I get much shorter
>reset times with FETs ?
>
>IMO, the only reason for ultra short reset time is triangle
>conversion. And the problem is worst in LFO applications.
>Sure, I know, first rule in Building VCOs: Start with triangle,
>not with saw. But then I absolutely love the variable shape
>of Osc 3 of the VCS3 for modulation - it's a very unique
>effect - and you can only get that when your oscillator core 
>is producing a saw wave. So here is an application where
>short discharge times are important. (I don't speak of
>nanoseconds here, but not of 1nF capacitors either. It's
>a 1u electrolytic, if memory serves.) I could improove things
>a little when I used a darlington.
>
>JH.
>




From theremin1 at worldnet.att.net  Thu Dec 17 16:10:44 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 17 Dec 1998 07:10:44 -0800
Subject: Osc reset time
Message-ID: <002301be29cf$6c0b46c0$52754e0c@hpcustomer>

This idea is very interesting.  Essentially, zero-current switching of the
integrating capacitor?  Can you put up a sketch?

-Art

-----Original Message-----
From: Fraser, Colin J <Colin.Fraser at scottishpower.plc.uk>
To: 'synth-diy at mailhost.bpa.nl' <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 16, 1998 8:48 AM
Subject: Osc reset time


Thinking about using analogue switches to reset the cap in a saw wave core,
it occurs to me that it should be possible to use analogue switches so that
the capacitor does not need to be discharged to be 'reset'.

If you have a dual two-way analogue switch, with very low on resistance, you
could connect the capacitor so that you can reverse its polarity in the
circuit - ie a comparator detects the peak level and toggles the switches so
that the connections from the cap to the ref voltage and the current source
are swapped. At the next peak, they are swapped back. This should give near
instant reset times.
I would expect this has been done before if it's workable.
Is this likely to have any advantage over discharging the cap ?
Disadvantages ?


Colin f








From per.mattsson at mkv.mh.se  Thu Dec 17 17:01:30 1998
From: per.mattsson at mkv.mh.se (Per Mattsson)
Date: Thu, 17 Dec 1998 17:01:30 +0100
Subject: PSU design?
Message-ID: <fc.000f49240037c67d000f49240037c67d.37c69d@mkv.mh.se>

I'm about to build  a new +/-15 v PSU. Currently I'm choosing between two
designs, either one based on 7815/7915 or the Digisound 80 design using
two uA723C's.

It's meant power a modular unit with your average mix of oscillators,
filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
to drive those digital ICs but I already have a small computer PSU for
this. 

Any thoughts on what to design to use?

---Per Mattsson




From jocke at netcontrol.fi  Thu Dec 17 18:09:37 1998
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Thu, 17 Dec 1998 19:09:37 +0200 (EET)
Subject: FETs on the ASM-1 VCO.
In-Reply-To: <000f01be29cd$d03325c0$52754e0c@hpcustomer>
Message-ID: <Pine.LNX.3.96.981217182655.16608F-100000@alf.netcontrol.fi>

> For a vast majority of synth applications,
> there should be no danger to the switch whatsoever.  These switches,
> after all, are integrated versions of the discrete JFETs or MOSFETs
> routinely used in all kinds of discharge applications.

You're right, a lot of the currently available analog switches
can handle peak currents of several hundred milliamps.

> If crosstalk is a concern, individual switches are available in eight-pin
> packages. The MAX319 is one such switch.

I'm having difficulties catching up with all these new Maxim
releases. :-)

> In such cases, you may have to contend with marginal Vgs conditions in
> which the switch can not be fully enhanced.  The nice thing about many
> integrated switches is that they contain the level shifters and other
> goodies to ensure proper enhancement of the output switch, regardless of
> Vds.

A valid point.

> I was a little concerned, though, about possible instabilites in U1A
> resulting from C1's direct connection to its output.

Juergen already answered this more thoroughly than I ever could. :-)

> Have you measured the linearity of this oscillator and R1's relationship
> to linearity?

No, I haven't made any precise measurements yet -- I've so far only
used the oscillator in applications with microcontroller compensated
scaling, but from debugging the scaling code I seem to recall that
the required compensation was rather small. R2 should compensate for
some of the HF-tracking error due to the 1 ms retrace time.

cheers,

-joachim





From don at till.com  Thu Dec 17 18:09:52 1998
From: don at till.com (Don Tillman)
Date: Thu, 17 Dec 1998 09:09:52 -0800 (PST)
Subject: Osc reset time
In-Reply-To: 	<BA865FF10473D211BC6F00805F0D830702D26A@catsprntp01.cat.scottishpower.plc.uk>
	(Colin.Fraser@scottishpower.plc.uk)
Message-ID: <199812171709.JAA01312@shell9.ba.best.com>

Some thoughts on Colin's VCO idea:

Isn't this the way that Exar function generator chip works?  No
matter, I think this approach is new for electronic music work.

It's interesting...  It really is a triangle wave generator, at least
as far as the capacitor is concerned, but it beats out building a
clasic triangle wave generator and waveshaping that to get a sawtooth
because there there no offsets to trim out and therefore no
subharmonic annoyances.

The advantages are nice: you don't require a high current pulse to
discharge the cap and the timing inaccuarcies due to discharge time
are far less.

Note: If you use a 3PDT switch, the switch's on resistance isn't an
issue.  Use separate switches for directing the current source to the
cap and for sampling the cap voltage -- each of those connects to a
very high impedance device so the on resistance doesn't matter.

As Colin pointed out, a simultaneous triangle output would be an
octave below.  It would also have glitches at the peaks.  Better to
run a second current source, cap, and buffer for the triangle --
effectively a second VCO, heavily syncd.

  -- Don



From Colin.Fraser at scottishpower.plc.uk  Thu Dec 17 18:18:05 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Thu, 17 Dec 1998 17:18:05 -0000
Subject: Osc reset time
Message-ID: <BA865FF10473D211BC6F00805F0D830702D27D@catsprntp01.cat.scottishpower.plc.uk>

> -----Original Message-----
> From: Don Tillman [mailto:don at till.com]
> Sent: 17 December 1998 17:10
> To: Colin.Fraser at scottishpower.plc.uk
> Cc: synth-diy at mailhost.bpa.nl
> Subject: Re: Osc reset time
> 
> Isn't this the way that Exar function generator chip works?  No
> matter, I think this approach is new for electronic music work.

I always expect any workable idea to have been found before - the chances of
finding anything new are tiny :-))

> As Colin pointed out, a simultaneous triangle output would be an
> octave below.  It would also have glitches at the peaks.  Better to
> run a second current source, cap, and buffer for the triangle --
> effectively a second VCO, heavily syncd.

The glitches that are present must only last as long as the switch over time
(300ns) - I would expect these to be well above audio range, so they could
disappear with a bit of high frequency roll-off in the buffer amp.

Need to buy a better scope - mine is a cute but semi-useless student design
(liberated from a closing school) that struggles at 100kHz.

Colin f




From MHELIN at tne01.ntc.nokia.com  Thu Dec 17 18:52:20 1998
From: MHELIN at tne01.ntc.nokia.com (Mikko Helin)
Date: Thu, 17 Dec 1998 19:52:20 +0200
Subject: Switching Capacitor VCO (Re: Osc reset time)
Message-ID: <981217195220.4f400a55@tnclus.ntc.nokia.com>

Interesting, could this be used on ASM-1/EN/TM type VCO in this way
(curren sink not shown, sorry for the quality):
 
 http://www.uta.fi/~helin/scvco.gif

I think this could give output voltage from -5V to +5V, the exponential
converter should work like on original VCO design (I think).

BTW. Are the CA3240 (dual) opamps similar to 3140, or can they
source more current?

-Mikko

>This idea is very interesting.  Essentially, zero-current switching of the
>integrating capacitor?  Can you put up a sketch?
>
>-Art
>
>-----Original Message-----
>From: Fraser, Colin J <Colin.Fraser at scottishpower.plc.uk>
>To: 'synth-diy at mailhost.bpa.nl' <synth-diy at mailhost.bpa.nl>
>Date: Wednesday, December 16, 1998 8:48 AM
>Subject: Osc reset time
>
>
>Thinking about using analogue switches to reset the cap in a saw wave core,
>it occurs to me that it should be possible to use analogue switches so that
>the capacitor does not need to be discharged to be 'reset'.
>
>If you have a dual two-way analogue switch, with very low on resistance, you
>could connect the capacitor so that you can reverse its polarity in the
>circuit - ie a comparator detects the peak level and toggles the switches so
>that the connections from the cap to the ref voltage and the current source
>are swapped. At the next peak, they are swapped back. This should give near
>instant reset times.
>I would expect this has been done before if it's workable.
>Is this likely to have any advantage over discharging the cap ?
>Disadvantages ?
>
>
>Colin f
>
>
>
>
>



From don at till.com  Thu Dec 17 19:09:17 1998
From: don at till.com (Don Tillman)
Date: Thu, 17 Dec 1998 10:09:17 -0800 (PST)
Subject: Osc reset time
In-Reply-To: <199812171709.JAA01312@shell9.ba.best.com> (message from Don
	Tillman on Thu, 17 Dec 1998 09:09:52 -0800 (PST))
Message-ID: <199812171809.KAA22685@shell9.ba.best.com>

   Date: Thu, 17 Dec 1998 09:09:52 -0800 (PST)
   From: Don Tillman <don at till.com>

   Some thoughts on Colin's VCO idea:

[...]
   Note: If you use a 3PDT switch, the switch's on resistance isn't an
   issue.  

I spoke too quickly -- the switch's on resistance does make a
difference (because the ground connection to the cap carries current).

But the effect will only be a small amount of control voltage added
into the waveform, so it's not a major problem.  

  --  Don 



From Chris.List at sc.siemens.com  Thu Dec 17 19:52:05 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Thu, 17 Dec 1998 13:52:05 -0500
Subject: Switching Capacitor VCO (Re: Osc reset time)
Message-ID: <81A062BC5305D111A9D700805F065968012EE937@maildepo.sc.siemens.com>

I think this may have been covered already, but why is the 4066 being
used instead of the 4053? Wouldn't the 4053 be a little simpler and
leave you with a free switch for something else? Same on-resistance...

- Chris



From jhaible at primus-online.de  Thu Dec 17 19:56:56 1998
From: jhaible at primus-online.de (jhaible)
Date: Thu, 17 Dec 1998 19:56:56 +0100
Subject: PSU design?
Message-ID: <19981217191138.14593.qmail@nuernberg2.pop.metronet.de>

723 !

JH. 

> I'm about to build  a new +/-15 v PSU. Currently I'm choosing between two
> designs, either one based on 7815/7915 or the Digisound 80 design using
> two uA723C's.
> 
> It's meant power a modular unit with your average mix of oscillators,
> filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
> to drive those digital ICs but I already have a small computer PSU for
> this. 
> 
> Any thoughts on what to design to use?
> 
> ---Per Mattsson
> 
> 



From MHELIN at tne01.ntc.nokia.com  Thu Dec 17 20:22:30 1998
From: MHELIN at tne01.ntc.nokia.com (Mikko Helin)
Date: Thu, 17 Dec 1998 21:22:30 +0200
Subject: Switching Capacitor VCO
Message-ID: <981217212230.4b8d4a7f@tnclus.ntc.nokia.com>

>
>I think this may have been covered already, but why is the 4066 being
>used instead of the 4053? Wouldn't the 4053 be a little simpler and
>leave you with a free switch for something else? Same on-resistance...
>
>- Chris

Actually the switch on my schem at http://www.uta.fi/~helin/scvco.gif
is a 4053. There's also no square out which is the Q out on 4013.
What good be done with the free switch on 4053? With two 4053's
you could build three VCO's. If we use SMD's that thing takes
not much space, too. VCO's for polyphonic synths?

-Mikko




From dbalvage at ptdcs2.ra.intel.com  Thu Dec 17 20:29:50 1998
From: dbalvage at ptdcs2.ra.intel.com (Duane R Balvage)
Date: Thu, 17 Dec 1998 11:29:50 -0800
Subject: PSU design?
References: <001f01be2ab8$67085160$1b31883e@default>
Message-ID: <36795BAE.6201@ptdcs2.intel.com>

Hi all -

How about using LM 337 / LM 317 adjustable regulators? They're pretty
quiet, and easy to use.

Just a thought.

			- Duane

========================================================================
> 
> The 723 is a great chip. Go for it. Quiter and more stable. It will need
> an external transistor. How about a 18V split rail with the 723s and
> then a 7815 and a 7915 on each module? See the archive for more details,
> as this has been covered before.
> 
> Regards,
> 
> Tony Allgood, Cumbria, UK
========================================================================
> 
> I'm about to build  a new +/-15 v PSU. Currently I'm choosing between
> two
> designs, either one based on 7815/7915 or the Digisound 80 design using
> two uA723C's.
> 
> It's meant power a modular unit with your average mix of oscillators,
> filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
> to drive those digital ICs but I already have a small computer PSU for
> this.
> 
> Any thoughts on what to design to use?
> 
> ---Per Mattsson

-- 
   "That boy's got a mouth like a cannon ... Always shootin' it off..."
                                
                             - Foghorn Leghorn
                      ________________________________
                     / o o oo              o ooo o   /\
       -------------/ ////  Duane R. Balvage   //// / /---------
                   /    _________________________  / /
                  / // / // /// // /// // /// / / / /
                 /___ //////////////////////////_/ /
                 \____\________________________\_\/

                     Intel Corporation, RA1-303
                   Portland Technology Development
       =========================================================

              Phone: (503) 613-8055    FAX: (503) 613-8261
                   E-Mail: dbalvage at ptdcs2.intel.com



From Chris.List at sc.siemens.com  Thu Dec 17 20:40:24 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Thu, 17 Dec 1998 14:40:24 -0500
Subject: Switching Capacitor VCO
Message-ID: <81A062BC5305D111A9D700805F065968012EE938@maildepo.sc.siemens.com>

Hey Mikko you can't fool me! I've got a printout of that gif with "4066"
scrawled on it where the pretty "4053" is now!
You could also build the other switch into a gate-controlled portamento
on the CV, or make one of Ric Miller's top half/bottom half waveform
switching waveshapers to combine two of your existing waveforms...

- CList

> -----Original Message-----
> From:	Mikko Helin [SMTP:MHELIN at tne01.ntc.nokia.com]
> Sent:	Thursday, December 17, 1998 2:23 PM
> To:	synth-diy at mailhost.bpa.nl
> Cc:	MHELIN at tne01.ntc.nokia.com
> Subject:	RE: Switching Capacitor VCO
> 
> >
> >I think this may have been covered already, but why is the 4066 being
> >used instead of the 4053? Wouldn't the 4053 be a little simpler and
> >leave you with a free switch for something else? Same
> on-resistance...
> >
> >- Chris
> 
> Actually the switch on my schem at http://www.uta.fi/~helin/scvco.gif
> is a 4053. There's also no square out which is the Q out on 4013.
> What good be done with the free switch on 4053? With two 4053's
> you could build three VCO's. If we use SMD's that thing takes
> not much space, too. VCO's for polyphonic synths?
> 
> -Mikko



From oakley at techrepairs.freeserve.co.uk  Thu Dec 17 21:12:11 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Thu, 17 Dec 1998 20:12:11 -0000
Subject: Sorry this is a long one.
Message-ID: <006e01be29f9$b9473640$6e26883e@default>

Hi,

Right, the prime mover for my 303 clone exercise is to see what the hell
is the fuss about and to make a nice analogue bass synth for my MC-303.
There will no midi controllers required, because they can't be recorded
on the MC-303. Its just gate, velocity and note CV, that will come out
of the convertor. Therefore velocity alone will control the slide and
accent. Couple this with legato playing and you should be away. Cubase
users, etc will be able to use velocity bars to fix everything. However,
for those of you with fancy MIDI-cv convertors, the option will be there
for standard logical control of the slide and accent, as well as CV on
the filter cut-off.

Yes, the imperfections of the 303 sequencer will make the sound of a
303, but let us not forget that a great cello multi-sample only sounds
(roughly) like a cello if it is played/programmed like you are a
cellist. No block chords, OK. So program Cubase or whatever, like you
would a step time thing and you're maybe half there. Go to grid edit and
shove notes in at random, and I bet it will probably sound even more
like a TB. As for timing errors giving it a groove. Groove can be
programmed, and though not trivial, it is not impossible and jolly good
fun. That groove knob on the MC303 is amazing, and the MC-303's timing
is pretty unusual as well.

As for knobs, my board will be laid out to house only the standard pots
found on the silver beast. BUT, it has been designed to have more knobs
if the user wants. There are other bits included on the board that will
make for a rather nice synth. It should fit in a half rack, 1U high for
standard clone, 2U for superbassline. You could use the other half of
the rack for jack sockets, or do another one. Or what about a 16 stage
analogue sequencer. Yes that does sound good. The design is almost done,
and I shall put the circuit up on the archive very shortly if Tony Clark
will let me.

Having said all that, there is someone on this list who wants to do a
clone of the sequencer. Watch this space.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html










From cyborg0 at GlobalEyes.net  Thu Dec 17 21:36:25 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Thu, 17 Dec 1998 14:36:25 -0600
Subject: Sorry this is a long one.
References: <000a01be2ab7$db458260$1b31883e@default>
Message-ID: <36796B49.B4BD5E97@globaleyes.net>

Tony Allgood wrote:
> 


> >but I would recommend you copy the latch and r-2r network dac and slide
> circuit from the original for driving the cv input.
> I used the autoglide circuit on my cv convertor with my clone and
> something
> was missing. I suspect there is some 'dirt' at the start of notes on the
> 303
> which doesn't happen with the cv convertor, that adds a bit of bite.
> 
> I think the slide is always on for the first few microseconds for each
> new note. This gives it the bite, you are talking about. It may even
> spike the CV as the 4066 changes state twice.

Yep, I have been beat down about this before, but there is a very quick
slide (pretty much inaudible, but there nonetheless) and the degree of
its affecting the CV depends on the last CV amount and what the cap
charged to..mind you, the pulse gets longer as the tempo gets slower
too, since every note is divided into 6ths(24ppq)..  you get a 1/6th
pulse for no glide (this updates the latch), and you get 6/6ths for a
glide. This I believe I gleaned from Robin Whittle. I would say you
could just automatically introduce this into the slide circuit by
triggering a little pulse circuit from the gate to introduce a spike to
the slide circuit. a cap, transistor, couple o resistors should do it. I
had to make one of these to go to the trig circuit in my Arp so I could
seperately trigger the ADSR independent of the GATE AR..works good.

 am therefore now
> thinking about adding the narrow trigger pulse from the EG to modulate
> the pitch CV, to introduce this. This worked well on my old Rogue when I
> used it with my analogue sequencer... now, in bits, I needed the parts.

That might work too, I would be worried it might be too long for fast
tempo stuff. 
> 
Rob



From cyborg0 at GlobalEyes.net  Thu Dec 17 21:51:28 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Thu, 17 Dec 1998 14:51:28 -0600
Subject: lm317
References: <001f01be2ab8$67085160$1b31883e@default> <36795BAE.6201@ptdcs2.intel.com>
Message-ID: <36796ED0.4477149A@globaleyes.net>

Duane R Balvage wrote:
> 
> Hi all -
> 
> How about using LM 337 / LM 317 adjustable regulators? They're pretty
> quiet, and easy to use.
> 
> Just a thought.
> 
>                         - Duane
> 
Hey, anybody know how to boost the stability and current handling of an
already existing lm317 circuit? Can you just piggyback another lm317?
Increase the capacitor in the circuit?
Rob



From cyborg0 at GlobalEyes.net  Fri Dec 18 00:45:08 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Thu, 17 Dec 1998 17:45:08 -0600
Subject: lm317
References: <1.5.4.32.19970313024600.006bf104@popa.melbpc.org.au>
Message-ID: <36799784.F776FCEB@globaleyes.net>

Paul Perry wrote:
> 
> At 02:51 PM 17/12/98 -0600, Rob <cyborg0 wrote:
> 
> >Hey, anybody know how to boost the stability and current handling of an
> >already existing lm317 circuit? Can you just piggyback another lm317?
> 
> You certainly cant run regs in paralel.
> You can add/improve heatsinking or use a to3 version.
> But, the best thing is to have a sep reg for part of the system, which
> improves isolation.
> 
Well I have found you can run regs in parallel, to my surprise!!.. I
thought by what I knew about how they work, that this *might* be a
possibility, although I thought it might cause other problems..
Sure enough, after paging through a few textbooks and circuit source
books, in one of the books I have, encyclopaedia of electronic circuits,
vol3, page 489, they have a way to piggyback lm317s! mind you, you have
to add a lm317, two 1n4002s, and a 10uf/35v cap, but thats not really
much and you wouldnt even have to cut any traces! This boosts the lm317
circuit to 3A.. This is very good info. 
Does it work? I dont know yet..more on this later, since I need to map
out the specifics of my PCB lm317 based supply. Actually, all this mod
requires is jumpering various elements of the existing lm317 with
1n4002s and a cap. The extra lm317 lays directly on top of the existing
one! Really cool.. :))

> >Increase the capacitor in the circuit?
> If it's big enough, more won't help.

>From what I see, you are right about that.. I *guess* you could decrease
the initial droop a little bit by increasing the cap on the input of the
lm317, but thats about it..
Rob



From theremin1 at worldnet.att.net  Fri Dec 18 01:31:12 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 17 Dec 1998 16:31:12 -0800
Subject: FETs on the ASM-1 VCO
Message-ID: <001401be2a1d$b7d8a7c0$dd754e0c@hpcustomer>

AH:

> > I was a little concerned,
> > though, about possible instabilites in U1A resulting from C1's
>direct
> > connection
> > to its output.

JH:

>No, it's perfect the way Joachim has done it. There is a
>certain *range* of capacitance values that will make an
>opamp instable. You can either stay below that range
>(very small cap), or go above that range (very large
>cap). Think of it as a 2-pole filter, one pole being the
>internal compensation cap, and the second one being
>formed by the output resistance and the capacitive load.
>It's only when the two poles are relativly close together
>that you get high Q factors, and thus overshot or
>oscillation.
>Normally you don't have much choice, of course: You will
>use low capacitive load when the opamp output voltage
>has to change fast, and high capacitance when you want
>to bypass a constant voltage.
>It's the same principle with voltage regulators: They even
>*need* a certain capacitive load to be stable !

AH:

Yes, I've seen certain vivid examples of the stability regions for
capacitive  loading; the TL431 shunt regulator particularly comes
to mind.

As far as linear series regulators, my experience has been that the
78xx parts are more stable with minimal or no capacitance, although
a capacitor at their outputs will, of course, improve transient rejection.
The 79xx regulators, however, certainly do require a minimum
capacitance for stability, as do many low-dropout types.

Although I agree with your explanation regarding the filter poles,
oscillations
can also occur whenever a bipolar transistor's emitter is capacitively
loaded.
This type of oscillation may occur regardless of loop phase-gain criteria.

AH:

> > Can C1 be moved across R6, instead, or does the transient
> > response of Q1's source node degrade too much?


JH:

>This would give you a good reference voltage at the opamp
>input. But at the output, it would only be good at low frequencies.
>For higher frequencies, the internal gain of the opamp goes
>down, and thus the output resistance of the closed loop goes up.
>With the cap at the output, you have the precision buffer of the
>opamp at low frequencies, plus the low impedance of the 10u
>at high frequencies.


AH:

Agreed.





From schmitz at patho.bonn.com  Fri Dec 18 08:48:18 1998
From: schmitz at patho.bonn.com (=?iso-8859-1?Q?Dr=2E_J=F6rg_Schmitz?=)
Date: Fri, 18 Dec 1998 08:48:18 +0100
Subject: AW: Your dream studio????
Message-ID: <814F53AC8CEDD111A274004F4902BAE6B7F4@bnpc1.patho.bonn.com>




	>>Nice studio....
	>>
>> http://www.klaus-schulze.com/photos/studiot.htm
>> 
>> 
>It sure does look impressive, but his music was much 
>better when he only had a fraction of these instruments.

>JH.

Especially before he had this Quasimidi stuff....


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From Colin.Fraser at scottishpower.plc.uk  Fri Dec 18 11:07:37 1998
From: Colin.Fraser at scottishpower.plc.uk (Fraser, Colin J)
Date: Fri, 18 Dec 1998 10:07:37 -0000
Subject: Switching Capacitor VCO (Re: Osc reset time)
Message-ID: <BA865FF10473D211BC6F00805F0D830702D280@catsprntp01.cat.scottishpower.plc.uk>

I used a 4066 because they are drastically cheaper from Maplin if you buy 25
of them, so I had a load of them sitting about, and not a 4053 in sight.

Colin f


> -----Original Message-----
> From: List, Christopher [mailto:Chris.List at sc.siemens.com]
> Sent: 17 December 1998 18:52
> To: synth-diy at mailhost.bpa.nl
> Subject: RE: Switching Capacitor VCO (Re: Osc reset time)
> 
> 
> I think this may have been covered already, but why is the 4066 being
> used instead of the 4053? Wouldn't the 4053 be a little simpler and
> leave you with a free switch for something else? Same on-resistance...
> 
> - Chris
> 



From Juergen.Haible at nbgm.siemens.de  Fri Dec 18 11:18:04 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Fri, 18 Dec 1998 11:18:04 +0100
Subject: AW: Your dream studio????
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010E7308@nbgm336a.nbgm.siemens.de>

	>Especially before he had this Quasimidi stuff....

I think it really started with his Midi stuff.
The real surprise (for me) is that it's not just a analogue
versus digital issue, because I really like his GDS
albums (Dig It,  Trancefer and Audentity). But when he
started Midi sequencing and Midi expanders, things went
downhill. Babel, for example, still has a lot of analogue
sounds, but it sounds quite lifeless to me. With his
later emphasis on strange samples he lost me completely.
(Dresden was the first one that really caused aversion.)
There were some signs of hope, recently. "The art
of sequencing" from his latest album has the long lost
flow and build-up again, though the sounds can't hide
their cold "virtual" origin.
These are only strong personal opinions, of course.
But I think it clearly shows what influence the sounds and
the user interface of instruments can have on the 
creative output of an artist. (Though Schulze and and
his manager will heavily deny this.)
There is an interview with KS where he compares working
with Mellotron choirs and working with samples. Mellotron
was a big pain, of course, and samples are so easy. I have
no doubt about the truth in that, and it's coincident with
the statements of other musicians. But it doesn't say
a thing about the musical output. Listening to the choirs
on "X" and on "Miditerranean (sp?) Pads" speaks louder
than words.

I hope this wasn't too much off topic - but we all are builders
of musical instruments here, aren't we ?

JH. 






From theremin1 at worldnet.att.net  Fri Dec 18 11:37:16 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 18 Dec 1998 02:37:16 -0800
Subject: PSU design?
Message-ID: <002a01be2a72$6286eac0$55754e0c@hpcustomer>

FWIW, see http://home.att.net/~theremin1/circuitlibrary/bipolarsupply.htm

-Art


-----Original Message-----
From: Per Mattsson <per.mattsson at mkv.mh.se>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Thursday, December 17, 1998 10:17 AM
Subject: PSU design?


>I'm about to build  a new +/-15 v PSU. Currently I'm choosing between two
>designs, either one based on 7815/7915 or the Digisound 80 design using
>two uA723C's.
>
>It's meant power a modular unit with your average mix of oscillators,
>filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
>to drive those digital ICs but I already have a small computer PSU for
>this. 
>
>Any thoughts on what to design to use?
>
>---Per Mattsson
>
>




From theremin1 at worldnet.att.net  Fri Dec 18 11:47:40 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 18 Dec 1998 02:47:40 -0800
Subject: Osc reset time
Message-ID: <002f01be2a73$d61bbbe0$55754e0c@hpcustomer>

DT:

>> Isn't this the way that Exar function generator chip works?  No
>> matter, I think this approach is new for electronic music work.

AH:

The 2206 and 2209, to my knowledge, are emitter-coupled multivibrators.
Good points:  Excellent temp. stability, good PSRR.
The 2206 makes a fairly nice sine, and even has a VCA of sorts, good for
about 55dB of dynamic range.

Bad points:  Non linear (too non-linear for most music apps) and a peculiar
hsyteresis at low control currents.


DT:

>> As Colin pointed out, a simultaneous triangle output would be an
>> octave below.  It would also have glitches at the peaks.  Better to
>> run a second current source, cap, and buffer for the triangle --
>> effectively a second VCO, heavily syncd.

AH:

Well, if you full-wave rectify a triangle, you will get a triangle an octave
higher.






From alexandr at irit.fr  Fri Dec 18 11:57:43 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Fri, 18 Dec 1998 11:57:43 +0100 (MET)
Subject: PSU design?
Message-ID: <199812181057.LAA25397@ares.irit.fr>


> 723 !
> 
> JH. 


	2 weeks ago, I made tests before building my +/-15v supply for my modular.
	I used a 723 with a balast transistor. The circuit was wired on those
	white lab board (the ones 2 array of 5 vertical holes). It worked very fine
	a very few mV ripple at 15v loaded with a big 12R resistor. It worked fine
	so i made a nice pcb to group the positive and negative supply. I used large
	trace for ground, unreg and reg voltage. 
	What a disapointment ! on the pcb version i get an horrible ripple, several 
	hundred mV ! there is ripple everywhere... I really don't hunderdtand why !
	Same componement were used for the preliminary test and the final soldered
	version.
	
	I use this nice regulated ( :( ) supply for my drilling machine :)

	

				Karl
	
	PS: I re-designed the digital board of my 303 clone, for rack mounting. I now 
	includes a command panel. At the end of the week end i hope it will finished. 
	Planed functionnality : internal sequencer, midi control, sysex dump of the
	patterns.
	
	

	
	
	



From theremin1 at worldnet.att.net  Fri Dec 18 11:59:15 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 18 Dec 1998 02:59:15 -0800
Subject: PSU design?
Message-ID: <004201be2a75$74688660$55754e0c@hpcustomer>

My 2 cents:  I echo the preference for those 723s.
Amazing that this oldie has withstood the test of time.
One little disadvantage it is the large drop-out voltage.
However, I believe the 723's ripple rejection is actually
better than many of those newer "LDOs."
(Go figure; all that loop gain, and only 50dB of ripple rejection!)

I like to make my own tracking VRs out of OP297s, REF10s, and
discrete power transistors.  However, adding foldback is a hassel,
and the 723s do that for you.

-Art

-----Original Message-----
From: jhaible <jhaible at primus-online.de>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>; Per Mattsson
<per.mattsson at mkv.mh.se>
Date: Thursday, December 17, 1998 1:23 PM
Subject: Re: PSU design?


>723 !
>
>JH.
>
>> I'm about to build  a new +/-15 v PSU. Currently I'm choosing between two
>> designs, either one based on 7815/7915 or the Digisound 80 design using
>> two uA723C's.
>>
>> It's meant power a modular unit with your average mix of oscillators,
>> filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
>> to drive those digital ICs but I already have a small computer PSU for
>> this.
>>
>> Any thoughts on what to design to use?
>>
>> ---Per Mattsson
>>
>>
>




From Juergen.Haible at nbgm.siemens.de  Fri Dec 18 12:12:19 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Fri, 18 Dec 1998 12:12:19 +0100
Subject: AW: Osc reset time
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010E73DB@nbgm336a.nbgm.siemens.de>

	>As Colin pointed out, a simultaneous triangle output would be an
	>octave below.  It would also have glitches at the peaks. 

Why would the triangle have glitches ?
I'd expect the *saw* wave to have a glitch, as the current source
will make the voltage shhot up when both sides of the cap are
momentarily disconnected. But the triangle should not have
glitches. The capacitor is just disconnected and reconnected
to a current source, and its capacitance would try to keep the
voltage constant during switching. You only have to keep
parasitic capacitance in the switches low, IMO.

JH.



From theremin1 at worldnet.att.net  Fri Dec 18 12:20:21 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 18 Dec 1998 03:20:21 -0800
Subject: lm317
Message-ID: <005601be2a78$6726f100$55754e0c@hpcustomer>

http://www.national.com/ds/LM/LM117.pdf
is National's data sheet for this family.
Page 8 shows the 317 with three LM195s
for a current-boost application.

A brief glance at their site showed a new
LDO version of the 317 called "LM1117."
Might be worth an investigation

-Art


-----Original Message-----
From: Rob <cyborg0 at GlobalEyes.net>
To: Duane R Balvage <dbalvage at ptdcs2.ra.intel.com>
Cc: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Thursday, December 17, 1998 2:37 PM
Subject: lm317


>Duane R Balvage wrote:
>> 
>> Hi all -
>> 
>> How about using LM 337 / LM 317 adjustable regulators? They're pretty
>> quiet, and easy to use.
>> 
>> Just a thought.
>> 
>>                         - Duane
>> 
>Hey, anybody know how to boost the stability and current handling of an
>already existing lm317 circuit? Can you just piggyback another lm317?
>Increase the capacitor in the circuit?
>Rob
>




From Juergen.Haible at nbgm.siemens.de  Fri Dec 18 13:24:24 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Fri, 18 Dec 1998 13:24:24 +0100
Subject: AW: PSU design?
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582010E7526@nbgm336a.nbgm.siemens.de>

	>. I used large
	>	trace for ground, unreg and reg voltage. 

	Make sure that the currents that charge the capacitor
	don't cause voltage drops inside your regulation loop.
	That is, connect GND from transformer/rectifier to
	capacitor, and from *there* to your regulator GND
	connection, and then from *there* to the GND output.

	If your output GND connection is between cap and
	rectifier/transformer, you'll get bad hum in the output.
	One typical error is to make very broad GND connections
	and connect everything just anywhere. The currents must
	be *forced* into a certain path, or they will find the path with
	least resistance, not least ripple.

	Don't know if that's the reason of your problem, but
	it was an error that I've made myself.

	JH.



From oakley at techrepairs.freeserve.co.uk  Fri Dec 18 15:09:49 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Fri, 18 Dec 1998 14:09:49 -0000
Subject: Sorry this is a long one.
Message-ID: <000a01be2ab7$db458260$1b31883e@default>

Hi Colin and all,

>You only need to use legato playing to control slide - the 303 always
plays
legato when it slides.

I was going to do this but how do you detect between legato playing and
using the pitch bend. I know the TB hasn't got pitch bend, but I use it
a lot. It is easy(ish) to fire a signal that detects CV change but no
gate, but it will not be able to tell whether that CV change is due to
keyboard CV or pitch bend. Most midi converters do not output a separate
CV for controllers. At least the cheap ones don't. So I planned on
having slide with or without legato, not quite TB, but easy to program
in grid edit, or on the MC.

>It doesn't sound like you are an insane 303 extremist,

I don't get extreme about anything anymore. :-)

>but I would recommend you copy the latch and r-2r network dac and slide
circuit from the original for driving the cv input.
I used the autoglide circuit on my cv convertor with my clone and
something
was missing. I suspect there is some 'dirt' at the start of notes on the
303
which doesn't happen with the cv convertor, that adds a bit of bite.

I think the slide is always on for the first few microseconds for each
new note. This gives it the bite, you are talking about. It may even
spike the CV as the 4066 changes state twice. I am therefore now
thinking about adding the narrow trigger pulse from the EG to modulate
the pitch CV, to introduce this. This worked well on my old Rogue when I
used it with my analogue sequencer... now, in bits, I needed the parts.

>A Cubase groove template with very small random shuffle may be just the
job
for simulating the 303 seq wonky timing.

Its gotta be worth a go.

Thanks for all the comments, keep 'em coming in,

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html






From alexandr at irit.fr  Fri Dec 18 17:15:57 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Fri, 18 Dec 1998 17:15:57 +0100 (MET)
Subject: AW: PSU design?
Message-ID: <199812181615.RAA25871@zeus.irit.fr>

 
> 	Make sure that the currents that charge the capacitor
> 	don't cause voltage drops inside your regulation loop.
> 	That is, connect GND from transformer/rectifier to
> 	capacitor, and from *there* to your regulator GND
> 	connection, and then from *there* to the GND output.


> 	JH.

	Ok, i should have made a mistake. On my PCB there is a huge
	ground track in the middle. The two 723 are on each side of
	this big track, and their ground (also the voltage dividers
	ground) are connected on this big track, between the cap 
	ground and the output ground...
	

			Karl.



 



From alexandr at irit.fr  Fri Dec 18 17:26:00 1998
From: alexandr at irit.fr (Karl ALEXANDRE)
Date: Fri, 18 Dec 1998 17:26:00 +0100 (MET)
Subject: 303 sequencer
Message-ID: <199812181626.RAA25881@zeus.irit.fr>


	hi all,

	For the 303 sequencer i use the following : 

	- A note takes 6 clock pulses.
	- The gate is high between the rising edge of clock pulse 0 
	  and the falling edge of clock 3 (so 3.5 clock cycles).
	- The CV and accent are loaded in the latch and the D flip
	  flop by a rising edge of slide. Slide stay high for one
	  clock pulse whether there is a slide or not.
	- The slide stay high on note n+1 if note n is set to slide.
	
	Is it right ? What about the note duration and its timing 
	influence ?


				Karl.



From cyborg0 at GlobalEyes.net  Fri Dec 18 18:39:29 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Fri, 18 Dec 1998 11:39:29 -0600
Subject: slightly randomizing uPD timing
Message-ID: <367A9351.7E72C5B8@globaleyes.net>

Ok, just a though.. 
what about taking the clock of a uPD and ANDing it with another
oscillator (audio sqr wave, 555, variable)  THEN taking the output of
the ANDed clock and sending it to the clock of the uPD? 
Could one achieve some sort of "variable randomization" that just
*might* give a digital sequencer the sort of lively shuffle of the early
gear?
Making it switchable would be good too..

Thinking hard
rob



From oakley at techrepairs.freeserve.co.uk  Fri Dec 18 19:58:25 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Fri, 18 Dec 1998 18:58:25 -0000
Subject: PSU design?
Message-ID: <001f01be2ab8$67085160$1b31883e@default>

The 723 is a great chip. Go for it. Quiter and more stable. It will need
an external transistor. How about a 18V split rail with the 723s and
then a 7815 and a 7915 on each module? See the archive for more details,
as this has been covered before.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at techrepairs.freeserve.co.uk

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html


-----Original Message-----
From: Per Mattsson <per.mattsson at mkv.mh.se>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Thursday, 17th December, 1998 6:14 PM
Subject: PSU design?


I'm about to build  a new +/-15 v PSU. Currently I'm choosing between
two
designs, either one based on 7815/7915 or the Digisound 80 design using
two uA723C's.

It's meant power a modular unit with your average mix of oscillators,
filters, mixers,  weirdo circuits etc. I probably need a second +5 v PSU
to drive those digital ICs but I already have a small computer PSU for
this.

Any thoughts on what to design to use?

---Per Mattsson







From peterc at pop.onwe.co.za  Fri Dec 18 21:17:17 1998
From: peterc at pop.onwe.co.za (peter_cornell)
Date: Fri, 18 Dec 1998 20:17:17 +0000
Subject: LM 317 alternative
Message-ID: <199812181812.UAA22582@mail-intertech.onwe.co.za>

Hi list

 LM 350 is the same pinout/design as LM 317 but handles 5A. It 
will fit directly into the circuit with no modification. There is 
also a negative version (could be LM 338???)

Peter Johannesburg



From oakley at techrepairs.freeserve.co.uk  Sat Dec 19 18:09:13 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sat, 19 Dec 1998 17:09:13 -0000
Subject: PSU design?
Message-ID: <000601be2b82$4ab56fa0$2a38883e@default>

Karl wrote: It worked fine
so i made a nice pcb to group the positive and negative supply. I used
large
trace for ground, unreg and reg voltage.
What a disapointment ! on the pcb version i get an horrible ripple,
several
hundred mV ! there is ripple everywhere...

Tony writes:

Don't use large ground conductors in any psu. Use carefully thought out
traces to give a star point grounding system. The amount of Guitar amps
that use wodges of copper for the ground supply, and they hum like
terrible. They think a guitarist won't complain (probably right), but
its crap design. Good analogue design doesn't stop after the circuit
digram has been drawn.

However, we all learn by our mistakes. You should have seen my first psu
for my poly. Oh, I laugh now... but it hummed. Talking of which, A
Danish engineer once told me the reason why transformers hum is because
they don't know the words to the tune. Ha, ha, ha, quick fetch the
doctor, my sides are splitting.

Bye for now,

Tony Allgood, Cumbria, UK






From theremin1 at worldnet.att.net  Sat Dec 19 19:57:09 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 19 Dec 1998 10:57:09 -0800
Subject: Capacitive loading of op-amps
Message-ID: <006101be2b81$62972240$82764e0c@hpcustomer>

JH wrote in reference to JV's oscillator at
http://www.netcontrol.fi/~jocke/circuits/osc1.gif
 
[excerpt]:

>There is a
>certain *range* of capacitance values that will make an
>opamp instable. You can either stay below that range
>(very small cap), or go above that range (very large
>cap). Think of it as a 2-pole filter, one pole being the
>internal compensation cap, and the second one being
>formed by the output resistance and the capacitive load.
>It's only when the two poles are relativly close together
>that you get high Q factors, and thus overshot or
>oscillation.

AH writes:

While inventorying some Analog Devices ICs today, I came 
across AD688 precision references.  The data sheet addresses
capacitive loading of the part's on-board op-amps. The technique
described is readily applicable to output-bypassed applications
such as that in Joachim's schematic.

FWIW, see page 8 of 8 in the .pdf file at:
http://www.analog.com/pdf/ad688.pdf

-Art





From qfulsom at usa.net  Sat Dec 19 21:41:38 1998
From: qfulsom at usa.net (Quint)
Date: Sat, 19 Dec 1998 14:41:38 -0600
Subject: PG200/jx3P  Cable pinout needed
Message-ID: <000a01be2b8f$fe81f500$62fe5380@s8p8t9>

Hi, I was wondering if anyone new the pinouts for the jx3p > pg200 cable?
Thanks in advace,
Quint




From pae at ar.com.au  Sat Dec 19 23:46:19 1998
From: pae at ar.com.au (Paul Eccles)
Date: Sun, 20 Dec 1998 09:46:19 +1100
Subject: PSU design?
Message-ID: <01be2ba1$64b40140$0a9412cb@pae.ar.com.au>

Tony wrote:
>Don't use large ground conductors in any psu. Use carefully thought out
>traces to give a star point grounding system. The amount of Guitar amps
>that use wodges of copper for the ground supply, and they hum like
>terrible.

and Haible wrote:
>One typical error is to make very broad GND connections
>and connect everything just anywhere. The currents must
>be *forced* into a certain path, or they will find the path with
>least resistance, not least ripple.

What is the theory behind this? I've always been quite enamoured with huge
GND tracks; in power supplies and in just about every other circuit. It was
my thinking that the broader the track, the lower the impedance and
therefore the lower the hum. What am I not considering here?

Paul.




From dragonser at clara.net  Sun Dec 20 00:01:19 1998
From: dragonser at clara.net (Peter Blackett)
Date: Sat, 19 Dec 1998 23:01:19 +0000
Subject: jx 3p / pg200 cable connections 
Message-ID: <367C303F.78AF778A@clara.net>

Plugs used are 6 pin din plugs .
pinouts for jx 3p/ pg 200 
pin 1  - 15 volts
pin 2 + 15 volts
pin 3 + 7 volts 
pin 4 ground
pin 5 signal data 
pin 6 busy 

If you are making up a cable then it needs to be pin to pin ,
pin 1 to pin 1 etc .....
later versions of the Jx 3 p have a Midi through socket, also the later
versions have an improved midi spec [updated eprom ].

regards Peter 
South London England




From jhaible at primus-online.de  Sun Dec 20 01:52:01 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 20 Dec 1998 01:52:01 +0100
Subject: PSU design?
Message-ID: <19981220013604.26749.qmail@nuernberg2.pop.metronet.de>


> and Haible wrote:
> >One typical error is to make very broad GND connections
> >and connect everything just anywhere. The currents must
> >be *forced* into a certain path, or they will find the path with
> >least resistance, not least ripple.
> 
> What is the theory behind this? I've always been quite enamoured with
huge
> GND tracks; in power supplies and in just about every other circuit. It
was
> my thinking that the broader the track, the lower the impedance and
> therefore the lower the hum. What am I not considering here?

Well, the topology of a circuit sometimes is more important than the
absolute
component values. To simplify things, imagine three nodes, A, B, C.
A is where the garbage comes in, B is where the garbage will be filtered
out,
and C is where you you want to get a clean signal. It's most important that
your signal flow is from A to B to C. What you will avoid is a direct path
from
A to C (bypassing B).
This applied to the GND path of a PSU: It's not so important what absolute
resistance you have between A (transformer/rectifier) and B (capacitor),
or between B and C (output/reference pin of regulator). But you don't want 
a direct path from A to C around B. A broad copper plane for GND will
provide
a lot of "paths" around the capacitor.

JH.



From aschrock at cs.brandeis.edu  Sun Dec 20 09:49:33 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Sun, 20 Dec 1998 03:49:33 -0500 (EST)
Subject: log pots? 
In-Reply-To: <000601be2b82$4ab56fa0$2a38883e@default>
Message-ID: <Pine.HPP.3.95.981220034258.28767A-100000@bay.cs.brandeis.edu>

Hey all, 

Has anybody found a good US source for PCB mount log pots in the US?
Perferrably for fairly cheap? (also the same dual-ganged) Good ol' Mouser
and Digikey don't seem to be able to help me, and I'd rather not have to
special order them from somewhere. I only need a few. 

thanks, 
Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|





From per.mattsson at mkv.mh.se  Sun Dec 20 11:06:37 1998
From: per.mattsson at mkv.mh.se (Per Mattsson)
Date: Sun, 20 Dec 1998 11:06:37 +0100
Subject: Re(2): PSU design?
Message-ID: <fc.000f49240037d3d03b9aca009abda3e8.37d3d3@mkv.mh.se>

Thanx everybody for the thoughts and help on my new PSU.

---Per M




From travis at it.net.au  Sun Dec 20 11:32:19 1998
From: travis at it.net.au (Travis Endersby)
Date: Sun, 20 Dec 1998 18:32:19 +0800 (WST)
Subject: ok more silly questions
In-Reply-To: <Pine.HPP.3.95.981220034258.28767A-100000@bay.cs.brandeis.edu>
Message-ID: <Pine.LNX.3.96.981220182936.30597B-100000@belgarion.it.net.au>

if u have a low tollerencve for beginners press delete...if not:

1.) how should i go about replacing the snapped hs60 key i have with the
new one kindly sent by phillip

2.) my poly 800 appears to be (without my assistance) randomly going into
vco without my permission...kind of annoying really.
What might the problem be?

thankyou in anticipation and merry christmas to u all

trav





From chordman at flash.net  Sun Dec 20 15:08:02 1998
From: chordman at flash.net (Scott Gravenhorst)
Date: Sun, 20 Dec 98 15:08:02
Subject: H11F1 Analog Fet Optocoupler
Message-ID: <199812202308.RAA03721@endeavor.flash.net>

Right off the bat, I'd like to play with this as the VC resonance pot
in a VC-SVF (a al FatMan).

-- Scott Gravenhorst
-- RedWebMail by RedStarWare
-- FatMan Site: www.teklab.com/~chordman
-- Linux Rex, Linux Vobiscum





From oakley at techrepairs.freeserve.co.uk  Sun Dec 20 20:18:41 1998
From: oakley at techrepairs.freeserve.co.uk (Tony Allgood)
Date: Sun, 20 Dec 1998 19:18:41 -0000
Subject: Clone is nearly done
Message-ID: <001d01be2c4d$bc5a6fe0$5b35883e@default>

Hi,

Nearly finished the TB clone. A few things remaining:
1. To try out the CA3046 array in place of the 2291 (obsolete) and 1583
pairs in the filter.
2. To reduce the amount of CV feedthrough in the VCA. I am hoping a trim
type adjustment will work here, like on a 3080.
3. To put the lot into a nice box, and rack it up and play for a bit.
That why I can find any niggles that need ironing out.

To those who have been following. I have kept the VCA chip. It appears
to add some clipping distortion to the signal. I have had many mails
relating to the fact that the VCA cannot be subbed with a 13700 or 3080.
Too much like a black art that one. The BA662A stays. Anyhow, Roland
seem to have plenty spare. I can supply these with the boards if people
want.

The EG trigger signal is now always connected to trigger the slide
circuit. This adds a 1mS slide to every new note. I can't really say I
noticed the difference, but it was easy to add and might go someway to
simulate what is going on in the TB.

The mixer section is staying too. I have put it after my own overdrive
circuit. The mixer actually clips asymmetrically. It has an interesting
affect on the sound, when the accent is fired. It will also have a
'servo' balanced output. The problem with using CV convertors, you can
easily get ground loops.

I am using the velocity CV to control accent and slide. It works very,
very well with Cubase and the MC303 step time sequencer/arpegiator. I
spent a good hour just playing with the MC's arp. Amazing. Accent and
trigger inputs are also provided if users want to use them. Mind you it
makes for a very interesting playing technique when using a keyboard. I
got the hang of it after a while. But it was like having four synths on
one keyboard. Weird, but useful.

The power supply is a 723. GREAT. With a 7912 doing the stuff for the
op-amps. Current consumption is very low. About 30mA for the positive
and 10mA for the negative.

Tony C has OK'd the schem to go on the archive. It should be up sometime
in the new year.

Best wishes to you all,

Tony Allgood, Cumbria, UK





From edusilva at bahianet.com.br  Sun Dec 20 21:25:31 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sun, 20 Dec 1998 18:25:31 -0200
Subject: H11F1 Analog Fet Optocoupler
Message-ID: <199812202026.SAA11568@postman.bahianet.com.br>

Hi all!

Has anyone used these chips from QT Technologies? I found it while flipping
through my Farnell catalog, and it appears very interesting to me.

It's an optocoupler with bilateral analog FET output, designed for
distortion-free control of low-level AC and DC signals.

Some nice features:

As a remote variable resistor:

	<200ohms to >300M
	>99.9% linearity
	15pf shunt capacitance
	>100G I/O isolation resistance

As an analog switch:

	extremely low offset voltage
	60V pk-pk signal capability
	no charge injection or latchup
	t.on t.off < 25us

It can be used instead of the LED+LDR pair with lots of advantages, like
faster on/off times, better linearity, and well matched characteristics,
just to name a few. Not only VCA's and phasers, but any voltage-controlled
synth module can be built with one or more of these guys!

More info at:

http://www.qtopto.com/oi/o0801.htm

Can any of you give me suggestions/ideas/opinions, etc...?

Cheers,
Edu

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From don at till.com  Sun Dec 20 22:56:09 1998
From: don at till.com (Don Tillman)
Date: Sun, 20 Dec 1998 13:56:09 -0800 (PST)
Subject: AW: Osc reset time
In-Reply-To: 	<1BF5E20E0C4DD111BBAB00805FE2D582010E73DB@nbgm336a.nbgm.siemens.de>
	(message from Haible Juergen on Fri, 18 Dec 1998 12:12:19 +0100)
Message-ID: <199812202156.NAA11651@shell9.ba.best.com>

   From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
   Date: Fri, 18 Dec 1998 12:12:19 +0100

   > Don:
   >As Colin pointed out, a simultaneous triangle output would be an
   >octave below.  It would also have glitches at the peaks. 

   Why would the triangle have glitches ?

Man, what was I thinking?  I've got to remember not to post things
when I'm in a hurry.  No, no glitches at all, it's fine.

   I'd expect the *saw* wave to have a glitch, as the current source
   will make the voltage shhot up when both sides of the cap are
   momentarily disconnected. 

Right, but there's a real fast transition happening at that point on a
sawtooth wave anyway, so a glitch during at that time would, at worst,
be hard to spot.

Also, when I said that I thought that Colin's approach was how the
Exar function generator chip worked, I was wrong, but *close*!  It is
in fact very similiar to how the 4046 PLL chip works.  Most 4046 data
sheets don't show the VCO schematic, but one exception is from
National (now Fairchild):
http://www.fairchildsemi.com/ds/MM/MM74HC4046.pdf

The 4046 VCO has a positive current source, an FET switch to ground,
and a Schmitt trigger for each side of the cap.  It's a slightly
different than Colin's design -- the 4046 doesn't need the sawtooth
wave so they don't bother selecting each side of the cap and buffering
-- but it's functionally equivalent.  Alternate sides of the cap are
grounded with an FET switch, the opposite side is charged positive
with a current source, and that voltage is sampled with a comparator.

  -- Don





From uzs159 at uni-bonn.de  Mon Dec 21 01:15:19 1998
From: uzs159 at uni-bonn.de (Rene Schmitz)
Date: Mon, 21 Dec 1998 01:15:19 +0100
Subject: H11F1 Analog Fet Optocoupler
In-Reply-To: <199812202026.SAA11568@postman.bahianet.com.br>
Message-ID: <3.0.5.32.19981221011519.0087c870@ibm.rhrz.uni-bonn.de>

At 18:25 20.12.98 -0200, you wrote:
>Hi all!
>
>Has anyone used these chips from QT Technologies? I found it while flipping
>through my Farnell catalog, and it appears very interesting to me.
>
>It's an optocoupler with bilateral analog FET output, designed for
>distortion-free control of low-level AC and DC signals.

I did not check this but I think these could be used in 
VCO reset circuits, these nasty spikes could be avoided since 
theres no capacitive coupling. 

Bye
-Rene


             ,   : (uzs159 at uni-bonn.de)
|") [" |\ | ["   : (http://www.uni-bonn.de/~uzs159)
|"\ [_ | \| [_   : (http://members.xoom.com/Rene_Schmitz)
                       




From jhaible at primus-online.de  Mon Dec 21 02:40:41 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 21 Dec 1998 02:40:41 +0100
Subject: Thought I should mention this
Message-ID: <19981221020844.16127.qmail@nuernberg2.pop.metronet.de>


> >and Haible wrote:

I see quotes like this more ond more often recently, and I just wanted to
remind you that my first name is Juergen. (I know my old email adress 
had the order reversed, so that's where the confusion originates.)

JH.




From theremin1 at worldnet.att.net  Mon Dec 21 03:49:10 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 20 Dec 1998 18:49:10 -0800
Subject: PSU design?
Message-ID: <003c01be2c8c$7d7955e0$ce774e0c@hpcustomer>


-----Original Message-----
From: Paul Eccles <pae at ar.com.au>
To: synth diy <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 19, 1998 3:42 PM
Subject: Re: PSU design?


>Tony wrote:

>>Don't use large ground conductors in any psu. Use carefully thought out
>>traces to give a star point grounding system. The amount of Guitar amps
>>that use wodges of copper for the ground supply, and they hum like
>>terrible.

>and Haible wrote:

>>One typical error is to make very broad GND connections
>>and connect everything just anywhere. The currents must
>>be *forced* into a certain path, or they will find the path with
>>least resistance, not least ripple.

Paul Eccles wrote:

>What is the theory behind this? I've always been quite enamoured with huge
>GND tracks; in power supplies and in just about every other circuit. It was
>my thinking that the broader the track, the lower the impedance and
>therefore the lower the hum. What am I not considering here?

AH writes:

In a majority of cases, the use of wide printed circuit tracks is NOT a
detriment to circuit performance.  The fact is that _every_ circuit node
needs to be considered on its own merits.

Haible is correct; the arbitrary connection of multiple currents to a single
return path will usually cause undesirable "cross-talk."
The use of a large conductor will mitigate, but not entirely eliminate,
this condition.

Hence, "star" wiring, advocated by Tony, in which each return current is
brought to a central node called "ground," is a good practice in precision
analog design. However, star topologies do not preclude the use of wide
tracks, which will, in fact, keep voltage drops to a minimum.

In short, (bad pun!) neither wide conductors nor star wiring preclude each
other.  The calculated combination of both techniques is the best approach.

>From a manufacturing perspective, large-width printed conductors are often
more reliable than very narrow traces, as a hedge against tiny "hairline"
cracks.  On the other hand, if solder masking is not employed (rare, these
days)
the solder consumption will increase proportionally with land area.

Unfortunately, from a service perspective, it is quite difficult to remove
an IC
lead from a multiple-layer board that includes a wide track or ground plane!

-Art




From theremin1 at worldnet.att.net  Mon Dec 21 04:10:15 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 20 Dec 1998 19:10:15 -0800
Subject: log pots? 
Message-ID: <004701be2c8f$6f239160$ce774e0c@hpcustomer>

These days, the words "good pots" and "cheap" can't seem to come together!
I noticed Newark advertising a deal on log pots, though, and you may want to
look into this:

Clarostat 580SX4Q25F103ZP,10k, single gang, CW log, conductive plastic, for
$3.09.

It is TINY, 9.5mm.  And, it has 90 degree terminals, so I don't know if you
can use them
for your PCB application.

Newark's stock number 83F4486.  I just tried the Clarostat P/N on their
on-line search
engine (http://www.newark.com/) and it looks to be a good number.

Perhaps you can get an evaluation sample from:
http://www.clarostat.com/Prods.htm
(click on "Sample Request.")

-Art


-----Original Message-----
From: Andrew Schrock <aschrock at cs.brandeis.edu>
To: synth diy <synth-diy at mailhost.bpa.nl>
Date: Sunday, December 20, 1998 2:13 AM
Subject: log pots?


>Hey all,
>
>Has anybody found a good US source for PCB mount log pots in the US?
>Perferrably for fairly cheap? (also the same dual-ganged) Good ol' Mouser
>and Digikey don't seem to be able to help me, and I'd rather not have to
>special order them from somewhere. I only need a few.
>
>thanks,
>Andrew
>
>| Andrew Schrock |
>| Network Programmer, Synthesizer and electronic music enthusiast |
>| aschrock at cs.brandeis.edu |





From theremin1 at worldnet.att.net  Mon Dec 21 04:24:32 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 20 Dec 1998 19:24:32 -0800
Subject: H11F1 Analog Fet Optocoupler
Message-ID: <005801be2c91$6e368760$ce774e0c@hpcustomer>

The H11F1 is an old General Electric part.
You have to be VERY careful about Vds limits to achieve decent
linearity from these devices.  In most cases, they can not substitute
Gilbert core (OTAs), Frey cores (SSM2018s), or photoresistive
technologies, due to severe dynamic range limitations.

One must ask, "99.9% linearity under what conditions?"
Graphs 2 and 5 at http://208.152.152.149/oi/H11FX.pdf
are worth examining carefully.

-Art

-----Original Message-----
From: Edu Silva <edusilva at bahianet.com.br>
To: DIY <synth-diy at mailhost.bpa.nl>
Date: Sunday, December 20, 1998 2:26 PM
Subject: H11F1 Analog Fet Optocoupler


>Hi all!
>
>Has anyone used these chips from QT Technologies? I found it while flipping
>through my Farnell catalog, and it appears very interesting to me.
>
>It's an optocoupler with bilateral analog FET output, designed for
>distortion-free control of low-level AC and DC signals.
>
>Some nice features:
>
>As a remote variable resistor:
>
> <200ohms to >300M
> >99.9% linearity
> 15pf shunt capacitance
> >100G I/O isolation resistance
>
>As an analog switch:
>
> extremely low offset voltage
> 60V pk-pk signal capability
> no charge injection or latchup
> t.on t.off < 25us
>
>It can be used instead of the LED+LDR pair with lots of advantages, like
>faster on/off times, better linearity, and well matched characteristics,
>just to name a few. Not only VCA's and phasers, but any voltage-controlled
>synth module can be built with one or more of these guys!
>
>More info at:
>
>http://www.qtopto.com/oi/o0801.htm
>
>Can any of you give me suggestions/ideas/opinions, etc...?
>
>Cheers,
>Edu
>
>_____________________
>Edu Silva - ES2 Audio
>Salvador-Bahia-Brazil




From zzynt at swipnet.se  Mon Dec 21 07:24:41 1998
From: zzynt at swipnet.se (BJ)
Date: Sun, 20 Dec 1998 22:24:41 -0800
Subject: Bananas to the beat!
References: <852566D7.007730AD.00@galaxy.support.stream.com> <3674C047.24DE@swipnet.se> <3674E859.2372@eunet.yu>
Message-ID: <367DE9A9.40BC@swipnet.se>

Thanks to all who contributed with ansvers and 
sugestions to mp3 encoders players!

Tack f?r det!

BJ



From mx at u.washington.edu  Mon Dec 21 07:32:25 1998
From: mx at u.washington.edu (M. Wallace)
Date: Sun, 20 Dec 1998 22:32:25 -0800 (PST)
Subject: synth-diy
Message-ID: <Pine.A41.4.05.9812202229450.47364-100000@dante30.u.washington.edu>


hi
im interested in building my own synth equiptment. what is the best way to
get started? i dont have experience with this sort of thing but am very
curious...
	thank you 
	max




From cyborg0 at GlobalEyes.net  Mon Dec 21 08:15:12 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Mon, 21 Dec 1998 01:15:12 -0600
Subject: psuedo-random timing generator
Message-ID: <367DF580.92423ADF@globaleyes.net>

For all the ppl who believe that perhaps much of the feel of the 303
sequencer is due to the random timing slag of the uPD, I had a real
revelation, and, although I presented my idea in this forum earlier, I
thought that perhaps no one understood my reasoning behind it..

Ok, my first idea was to take the clock circuit of the uPD and AND it
with a variable frequency.. this would induce random errors at random
points as the timing signal would be delayed occasionally. The clock
signal itself could only be delayed from 0 to n, n being 1/2 the
wavelength variable frequency. This would be interesting. But it has a
problem: most uPD are somewhat specific with how wide the pulse is...So,
what happens if the pulse cut off too early by the variable frequency? I
wouldnt think this too much of a problem, but.. Since I really only care
about delaying the onset of a note, I guess I could use a scheme whereby
once the clock circuit is hi, it is enabled until it sees the neg edge
of the clock... I guess just reset on the negative edge from the
original clock circuit would do it..So thats possible.

So, my other idea was to use this variable frequency to randomize the
timing of the gate, DAC latch, and accent line of the 303 clone..The way
I had it set up, by varying the frequency of the randomizer, you could
achieve a maximum of a few uS to a max of 10mS of delay. Of course, for
any given step, the randomizer might not have any delay, or a big delay,
depending on the max delay amount setting.

But, another idea I had is, what if you could allow it to randomize the
timing only on certain steps? Say, using a mux, allow it to randomize
only steps 1, 5, 7, and 9. Would this be more useful or musical? Really,
in a way, one could program in theyre own psuedorandom groove and limit
the occurence to a particular step. I guess, with a little extra
circuitry and by hijacking the 555 I was using to generate the
frequency, I could add a switch to put the 555 into one-shot mode and
allow ppl to use the frequency pot for a delay pot...
wow!

Things are getting interesting!

Rob



From aschrock at cs.brandeis.edu  Mon Dec 21 08:37:25 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Mon, 21 Dec 1998 02:37:25 -0500 (EST)
Subject: quick 3320 filter Q
In-Reply-To: <004701be2c8f$6f239160$ce774e0c@hpcustomer>
Message-ID: <Pine.HPP.3.95.981221022552.130B-100000@bay.cs.brandeis.edu>

All, 

After liking the paia filter I acquired quite a bit, I built a 3320
filter, and am getting some odd results with applying c/v to the input.
The c/v seems to be inverted, ie if I take c/v out from my sh-101 I get
(approximately) a descending scale as I go down the keyboard, or if I take
an output from an envelope generator it is reversed. The schematics and
CEM notes seem to dictate I'm doing everything kosher, and the VC res
works as normally expected. (not inverted response; 0 to 5v gives min to
max res) 

The circuit is basically straight out of the CEM 3320 notes 'LP filter
with VC res.' on p.2, done with a bit of consulting of tomg's 3320 LP 
filter design. Anybody know off the top of their heads if theres
anything obvious I'm missing? 

Sorry for the rather lame question, but this has been irking me all night. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|






From Juergen.Haible at nbgm.siemens.de  Mon Dec 21 12:36:37 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Mon, 21 Dec 1998 12:36:37 +0100
Subject: AW: Capacitive loading of op-amps
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D582011085F6@nbgm336a.nbgm.siemens.de>



	>While inventorying some Analog Devices ICs today, I came 
	>across AD688 precision references.  The data sheet addresses
	>capacitive loading of the part's on-board op-amps. The technique
	>described is readily applicable to output-bypassed applications
	>such as that in Joachim's schematic.
	>
	>FWIW, see page 8 of 8 in the .pdf file at:
> http://www.analog.com/pdf/ad688.pdf
> 
Fig. 14b - yes, that's the way to drive cap values that
are inside the "forbidden" range. Overkill for buffering
an auxilliary voltage like in Joachim's oscillator, but
very helpful for audio outputs. (Where most people just
add a series resistor.)

JH.




From hallgeir at ovation.musicpower.net  Mon Dec 21 17:21:45 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Mon, 21 Dec 1998 17:21:45 +0100
Subject: synth-diy
Message-ID: <199812211641.RAA05869@louise.netpower.no>


> im interested in building my own synth equiptment. what is the best way
to
> get started? i dont have experience with this sort of thing but am very
> curious...

Hullo, Max

I think I'd recommend "Music Synthesizers - a manual of design
and construction" by Delton T. Horn. It covers a lot of starting
ground. Lotsa simple example circuits.

Dunno if it's still in print, BTW. Good librarys ought to carry it.

Hallgeir



From hallgeir at ovation.musicpower.net  Mon Dec 21 17:32:23 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Mon, 21 Dec 1998 17:32:23 +0100
Subject: ASM-1 funny-bug-mod
Message-ID: <199812211641.RAA05873@louise.netpower.no>

Hi all,

When I was assembling my ASM-1, I discovered, quite by accident,
a strange thing in the VCF. I put the two CA3080 OTA's in the wrong
way (by accident, I tell you!), an whaddayaknow, the VCF acts more 
like a VCO, with the Q pot blending in a screaming noise signal! 

umm... I think I fried the OTAs. Don't know. :-)

Hallgeir

BTW thanks for info on ny Sequential question



From b.layer at vikingelectronics.com  Mon Dec 21 20:19:56 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Mon, 21 Dec 1998 13:19:56 -0600
Subject: Delton T. Horn's books
In-Reply-To: <199812211641.RAA05869@louise.netpower.no>
Message-ID: <3.0.6.32.19981221131956.007d1960@192.168.210.18>

Hi Max and all,

 
>I think I'd recommend "Music Synthesizers - a manual of design
>and construction" by Delton T. Horn. It covers a lot of starting
>ground. Lotsa simple example circuits.
>
>Dunno if it's still in print, BTW. Good librarys ought to carry it.
 
I happen to own one of Delton Horn's books on synthesizers, I beleive it is
on the topic of troubleshooting and repair. Sorry to say, but it has to be
the most useless, insipient text on the subject that I own. The section on
analog basics is not *too* bad, but the digital section is a real joke.
Basic info on poking around aimlessly, moving dust, looking quickly at
things etc. 

Nothing is worse for a beginner than an author who contradicts himself...
Maybe that it's just that my copy is an early edition, but in light of the
content, I can't believe they even bothered to print it. 

My 2 cents.

Hey, guess what? President Gore!

 
Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From aschrock at cs.brandeis.edu  Mon Dec 21 20:32:54 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Mon, 21 Dec 1998 14:32:54 -0500 (EST)
Subject: quick 3320 filter Q
In-Reply-To: <Pine.HPP.3.95.981221022552.130B-100000@bay.cs.brandeis.edu>
Message-ID: <Pine.HPP.3.95.981221143238.788A-100000@bay.cs.brandeis.edu>

Nevermind.. figured it out already. Thanks to those who replied. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|




From moxie at idonex.se  Mon Dec 21 23:29:00 1998
From: moxie at idonex.se (Johan Gustavsson)
Date: Mon, 21 Dec 1998 23:29:00 +0100 (MET)
Subject: synth-diy
Message-ID: <199812212229.XAA10582@jolt.idonex.se>

> im interested in building my own synth equiptment. what is the best way
to
> get started? i dont have experience with this sort of thing but am very
> curious...

I'd recommend, as I always do, TomGs "Electronics for music" site for
actual, practical circuits. http://www.mindspring.com/~vco

Work is now finally underway on the Moxie Maxx Modular, and so far (as
of today) we've built one ordinary boring dual LFO and one simple VCO
(the LFO-1A and the VCO-5A). Tomorrow we'll do the VCF-8b (the dual
KLM one) and go looking for a good box to put it all in, as well as
finish the PSU. Now, the point of this is that both I and my building
friend are relatively new to this building thing, and have access to a
good soldering pencil, a couple of multimeters, a scope and nothing
more. We etch circuit boards one by one, using layouts made in MS Word
of all amazing programs transfered to plastic film. Can you say
"budget"? And they both worked first thing when we plugged them
in. Sure, they are both relatively simple constructs, and I haven't
yet tried the vco with a proper 1v/oct CV source, but still - We
turned on the power and got nice squares and triangles on the scope,
reacting the way they ought when we turned the pots. Amazing enough
for me :-)

My initial meterings seems to indicate that the VCO isn't responding
in quite as linear-ish fashion as I'd like -

-11  v from the pot	-   90 hz
- 7.5v			-  180 hz
- 4  v			-  352 hz


...and so on, which doesn't bode well - Any hints? Then again, this is
when just plugged in, lying flat copper side down on the
(nonconductive, silly!) workbench, with an amazing juryrigging of test
cables and little croc clips providing power and connecting to scope
and meters, with no input except the tuning pot connected, so perhaps
the conditions aren't quite ideal...:-) We might scrub the solder side
with a toothbrush to get of solder flux goo tomorrow, as well as maybe
scrounge up some heat conductive paste and press the expo trannies
together - Think that would help? My plans for this one isn't
acutually to be a "voice" osc, but rather a modulation oscillator in
the higher frequency range, so in the end I probably won't mind too
much. I'm planning on building the VCO-2s as main voices. and started
off with the simpler stuff just to get a feel for it. Make it up as
you go along, y'know. :-)

At the same time, whilst waiting for the photoresist to dry, I opened
up the broken filter env amount slider on my CS-01, cleaned it, put it
back together and - Whoo! It is a whole new instrument! Now I only
wish that the amp env amount would fade between an envelope shape and
something gateish instead of just acting as a second volume control...

Anyway, today has been a good DIY day. Hear from you again tomorrow
:-)

/Moxie (Happy builder)




From aschrock at cs.brandeis.edu  Tue Dec 22 01:15:23 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Mon, 21 Dec 1998 19:15:23 -0500 (EST)
Subject: synth-diy
In-Reply-To: <199812212229.XAA10582@jolt.idonex.se>
Message-ID: <Pine.HPP.3.95.981221190353.909D-100000@bay.cs.brandeis.edu>

On Mon, 21 Dec 1998, Johan Gustavsson wrote:
> > im interested in building my own synth equiptment. what is the best way
> to
> > get started? i dont have experience with this sort of thing but am very
> > curious...
> 
> I'd recommend, as I always do, TomGs "Electronics for music" site for
> actual, practical circuits. http://www.mindspring.com/~vco

One thing I'll toss in here as pure opinion from personal experience.. I
had real problems using 3-pad-per-hole rat shack vectorboard. I mean, my
filters had awful hum, my envelope generators had problems, etc. etc...
after I switched to doing circuits off breadboard (w/no solder pads), they
all went away. Perhaps it's because I can focus more on layout on
breadboard, or that I take a little more care with how I construct the
modules. I'm sure capacitance between power rails and parts was reduced
as well. The breadboarded modules are quite sturdy, however, and I use 
them all the time. 

> Work is now finally underway on the Moxie Maxx Modular, and so far (as
> of today) we've built one ordinary boring dual LFO and one simple VCO
> (the LFO-1A and the VCO-5A). Tomorrow we'll do the VCF-8b (the dual
> KLM one) and go looking for a good box to put it all in, as well as
> finish the PSU. Now, the point of this is that both I and my building
> friend are relatively new to this building thing, and have access to a
> good soldering pencil, a couple of multimeters, a scope and nothing
> more. We etch circuit boards one by one, using layouts made in MS Word
> of all amazing programs transfered to plastic film. Can you say
> "budget"? And they both worked first thing when we plugged them
> in. Sure, they are both relatively simple constructs, and I haven't
> yet tried the vco with a proper 1v/oct CV source, but still - We
> turned on the power and got nice squares and triangles on the scope,
> reacting the way they ought when we turned the pots. Amazing enough
> for me :-)
> 
> My initial meterings seems to indicate that the VCO isn't responding
> in quite as linear-ish fashion as I'd like -
> 
> -11  v from the pot	-   90 hz
> - 7.5v			-  180 hz
> - 4  v			-  352 hz

These readings are confusing.. I don't have the schematic for the 1a in
front of me, so I won't embarass myself with trying to diagnose the
problem. 

> much. I'm planning on building the VCO-2s as main voices. and started
> off with the simpler stuff just to get a feel for it. Make it up as
> you go along, y'know. :-)

I've found the 2a's to be quite nice. There are two of them in my main
modular. There are a few mods you can do to make it more user-friendly
(esp. w/PWM) but overall a _very_ nice VCO once it warms up. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|







From lbupp at eagle.ycp.edu  Tue Dec 22 02:23:38 1998
From: lbupp at eagle.ycp.edu (Lewis Bupp)
Date: Mon, 21 Dec 1998 20:23:38 -0500 (EST)
Subject: Delton T. Horn's books
In-Reply-To: <3.0.6.32.19981221131956.007d1960@192.168.210.18>
Message-ID: <Pine.SOL.3.96.981221201313.12656A-100000@goose.ycp.edu>

I agree with Bill. I have a copy of D.Horn's "Troubleshooting and
Repairing Music Synths". My copy is a newer edition, not many changes if
any. In fact, after I read it I thought to myself, why did I buy this? It
is filled with contradictions and to be honest... useless information
especially on digitals. I didn't even care for the section on analogs. The
info he covered in that section I learned 25 years ago reading Paia,
Aries, arp and Moog literature.

So there.... Big Lew has spoken.

Happy Holliday's everyone!  

Lew Bupp II
Audio/Video Technician
York College of Pa.
York, Pa. 17403
717-815-1395
717-852-8543

On Mon, 21 Dec 1998, Bill Layer wrote:

> Hi Max and all,
> 
>  
> >I think I'd recommend "Music Synthesizers - a manual of design
> >and construction" by Delton T. Horn. It covers a lot of starting
> >ground. Lotsa simple example circuits.
> >
> >Dunno if it's still in print, BTW. Good librarys ought to carry it.
>  
> I happen to own one of Delton Horn's books on synthesizers, I beleive it is
> on the topic of troubleshooting and repair. Sorry to say, but it has to be
> the most useless, insipient text on the subject that I own. The section on
> analog basics is not *too* bad, but the digital section is a real joke.
> Basic info on poking around aimlessly, moving dust, looking quickly at
> things etc. 
> 
> Nothing is worse for a beginner than an author who contradicts himself...
> Maybe that it's just that my copy is an early edition, but in light of the
> content, I can't believe they even bothered to print it. 
> 
> My 2 cents.
> 
> Hey, guess what? President Gore!
> 
>  
> Bill Layer
> Sales Technician
> <b.layer at vikingelectronics.com>
> 
> +----------------------------------+
>      Viking Electronics, Inc.
>        1531 Industrial St.
>     Hudson, WI. 54016 - U.S.A
>       715.386.8861 ext. 210
>  <http://www.vikingelectronics.com>
> +----------------------------------+
> 
> "Telecom Solutions for the 21st Century"
> 




From theremin1 at worldnet.att.net  Tue Dec 22 06:51:00 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Mon, 21 Dec 1998 21:51:00 -0800
Subject: Capacitive loading of op-amps
Message-ID: <000e01be2d6f$0ec40620$68754e0c@hpcustomer>


AH:

> >While inventorying some Analog Devices ICs today, I came
> >across AD688 precision references.  The data sheet addresses
> >capacitive loading of the part's on-board op-amps. The technique
> >described is readily applicable to output-bypassed applications
> >such as that in Joachim's schematic.
> >
> >FWIW, see page 8 of 8 in the .pdf file at:
> >http://www.analog.com/pdf/ad688.pdf


JH:

>Fig. 14b - yes, that's the way to drive cap values that
>are inside the "forbidden" range. Overkill for buffering
>an auxilliary voltage like in Joachim's oscillator, but
>very helpful for audio outputs. (Where most people just
>add a series resistor.)

AH:

It also occurs to me that adding a large capacitor directly to the
output of an op amp will essentially cancel much of the loop's AC
gain, sort of rendering the circuit as a precision emitter follower
without a Vbe offset.  In such a case, the bulk of the load transient
rejection is furnished mainly by the capacitor itself. That is probably
fine in many cases, as Juergen stated.

For this simpler approach, however, another consideration is that a
huge slug of current will be drawn through the op amp's output transistors
upon power-up.  Most op-amps are capable of withstanding an
intermittent surge such as this, although it may cause a failure in some
cases when the capacitor is large, has an exceptionally low ESR
(e.g., tantalum), and the supply' s rate of rise is high.

The referenced circuit preserves the desired loop dynamics by
incorporating feedback comprised of the 1uF capacitor between the
op amp's negative input and output.

It would be interesting to compare each circuit's response to transient
loads.

-Art




From cyborg0 at GlobalEyes.net  Tue Dec 22 07:24:45 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Tue, 22 Dec 1998 00:24:45 -0600
Subject: synth-diy (Real Beginners vs. Advanced Beginners... GREAT Books)
References: <367F415E.45A0@interpath.com>
Message-ID: <367F3B2D.7B6ABF7B@globaleyes.net>

inman at interpath.com wrote:
> 

> 
> Along the same lines, Forrest Mims sells some mini-books on the rack
> at Radio Shack, including one on Op-amps and another on digital circuits.
> Both offer some interesting, musically-related circuits.  The books feature
> parts you can find on the next rack over at Radio Shack, usually the 741
> OP-AMP or 555 Timer, both classics.  At Radio Shack, these parts are
> relatively inexpensive, although you should know that bought in bulk
> from DIGIKEY or MOUSER, you can get the same parts for much less....
> The Mims Op-Amp book actually includes circuits for low-pass and
> high-pass filters.  The problem with these Forrest Mims books is that
> they offer very little explanation of the circuits.

Forrest Mims is god! :) he has a huge compilation of circuits WITH
explanations at Barnes and Noble. I want it for christmas..

> 
egular
> introductory columns (recently good stuff on flip-flops and gates and, in
> December... PICs!)

Hooo boy! I need that one..

BTW, I second that bit about Bob Moog.. but, how EVER did he get his Phd
with soooo much common sense?!? He prlly had a hell of a time, like
Stephen Hawking did.. I heard he basically had to beg for his undergrad
diploma..

Rob



From inman at interpath.com  Tue Dec 22 07:51:10 1998
From: inman at interpath.com (inman at interpath.com)
Date: Mon, 21 Dec 1998 22:51:10 -0800
Subject: synth-diy (Real Beginners vs. Advanced Beginners... GREAT Books) 
Message-ID: <367F415E.45A0@interpath.com>

TRUE BEGINNER BOOKS

The question of where to begin could only be answered if we knew what you
meant by beginner.  Are you a beginner in electronics, or a beginner in
music, or a beginner in both?  If you are a beginner in electronics, I
am going to differ with the majority here and suggest a Delton Horn book.
I agree that his manual on synthesizer repair is not very helpful.  
Horn is a generalist who has written countless electronics books; he
is not a synthesizer expert at all.  But books of his like "49 Electronic
6-Volt Projects" TAB Books, Inc. 1990 (REAL BEGINNER stuff) offer a few
oscillator circuits that, for an absolute beginner, are good because they
use easy to find cheap parts, are fun, and are relatively idiot-proof.  
BTW, "Music Synthesizers:  A Manual of Design and Construction" TAB 1984
is not the same as Horn's repair guide, which is notoriously useless.  
"MS:a M of D and C" actually has some interesting circuits and a good, 
low-level introduction to electronics and music and even AD / DA conversion.

Along the same lines, Forrest Mims sells some mini-books on the rack
at Radio Shack, including one on Op-amps and another on digital circuits.
Both offer some interesting, musically-related circuits.  The books feature
parts you can find on the next rack over at Radio Shack, usually the 741
OP-AMP or 555 Timer, both classics.  At Radio Shack, these parts are
relatively inexpensive, although you should know that bought in bulk
from DIGIKEY or MOUSER, you can get the same parts for much less....
The Mims Op-Amp book actually includes circuits for low-pass and
high-pass filters.  The problem with these Forrest Mims books is that
they offer very little explanation of the circuits.
  
For guitarists, another great book is Craig Anderton's "Projects for
Guitarists" (Miller Freeman Books, 1995) which begins with a section on
basic parts and their function, soldering, and reading schematics.
The best part of this book is that it includes detailed explanations
of every aspect of the designs, plus many, many great useful tips
hidden in the middle of projects.  Anderton is the Anti-Mims!
On the other hand, his "Digital Projects for Musicians"
(Anderton, Moses, and Bartlett, Amsco Publications, 1994) is
a massive book with some useful introduction to electronics and MIDI, but
it is more of an assembly manual for the MIDITOOLS computer, parts sold by
www.pavo.com.  (I've never built one, so I cannot comment, although it
looks very interesting.)  Overall, not a beginner book.

All of these authors:  Horn, Mims, and Anderton are very understandable,
even if you know little about electronics, although only Anderton is a
"real" electronic musician writer.  Also, in general, if you are searching
at a library, just look up TAB books.  They are the big publisher of
electronics and electronic music books.

Also check out this magazine:  Nuts and Volts.  (www.nutsvolts.com).  
N & V seems to have at least one or two musically-useful circuits
in every issue -- sometimes a special issue of music stuff.  A great
magazine for a true electronics beginner because they have regular
introductory columns (recently good stuff on flip-flops and gates and, in
December... PICs!)



THE NEXT LEVEL BEGINNER

At the next higher level, read anything by Bob Moog.  The great secret
about Bob Moog that I never hear anyone mention is how great a writer
he is.  He could teach a gorilla to build a voltage controlled filter.
Keyboard Magazine republished many of his articles in a book called,
"Synthesizer Basics" (1984).  Moog explains all:  not necessarily the
circuits, but the science.  See if you can find it at a library.

However, none of the above will get you to higher ground:  real
electronic schematics for a sophisticated synthesizer.  For that, I
suggest (all of which may only be available through a local
public or university library):


THE CLASSICS  (both available as reprints from the authors... check out
        the www.paia.com website and select the Friends page.  Both
        authors below are listed as friends.)

Chamberlin, Hal.  (1984)  Musical Applications of Microprocessors.
        [Fantastic book.  Worth its weight in gold.  Great circuits,
        exceptionally clear.  Covers the history and design of
        everything from analog synthesizers to digital samplers.
	Plus, Chamberlin's 1984 predictions for the future make him
	the Nostradamus of synth design -- except for the part about
	MIDI.  This book goes from absolute beginner to EE major,
        but is written so concisely that any intelligent person
        could understand it.  If you could memorize this book, you
        would know 99% of everything worth knowing about electronic
        music circuits.  If I thought I could absorb every word by
        sleeping with the book beside me, I would ask my wife to
        move over.]

Klein, Barry T.  (1982).  Electronic Music Circuits.  Howard W. Sams
        and Co., Inc.  [The Mac Daddy of Electronic Music Books...
        Barry Klein provides an example for virtually every useful
        electronic music circuit known to man or woman... Circuit
        corrections noted on the www.hyperreal.org/music/machines/
        website.  Check before you build.]


SOME OTHERS I LIKE

Paturzo, Bonaventura Anthony.  (1984)  Making Music with
        Microprocessors.  TAB BOOKS, INC.  [First half is
        useful information, second half is directly related
        to a microchip now discontinued... a gamble the
        author admitted.  Still interesting if you can find it,
        especially for a very simplified, but accurate description
        of DA / AD processes with a computer.]

Brown, Robert and Olsen, Mark.  (1984)  Experimenting with
        Electronic Music.  TAB BOOKS, INC.  [Very solid
        introduction although the circuits use older
        approaches -- few modern IC's].

Ward, Brice.  (1975).  Electronic Music Circuit Guidebook.
        TAB BOOKS, INC.  [Great introduction and circuits,
        some older parts, but some newer.  Very detailed
        description of PAIA GNOME, a classic DIY synth --
        thanks to John Simonton, who is to SYNTH DIY
        design what Linus Torvalds is to Operating Systems.]


WARNINGS:

WARNING ONE:  Older books are great as background and some of the
classic circuits live on, but often the parts are hard or impossible
to find and techniques used are potentially outdated, replaced by
easier, cheaper, more effective methods.  Still, these older books
are often the only written history of analog or early digital designs.

WARNING TWO:  Is there a book of electronic circuits published that
does not include some error?  I doubt it.  So, if at all possible
look for a second printing book or one that has "been around the
block" electronically.  There are probably people on this list who
could tell you the location of three incorrectly spelled words in 
Barry Klein's book, without opening it.  


Finally, two Cool History Books, off topic, but which should never be
forgotten for their singular, important contributions...
Just for the record...

Hiller, Lejaren A. and Issacson, Leonard.  1959.  Experimental
        Music:  Composition with an Electronic Computer.  McGraw-Hill
        Book Company, Inc.  [Sit back and watch, dear friends, as
        two men teach a computer to compose... Fascinating to retrace
        the mental footprints of Hiller, a true genius.]

Matthews, Max et. al. (1969) The Technology of Computer Music.
        The M.I.T. Press.  [Go along with Matthews as he invents
        digital music.  Learn about programming C Sound when people
        could actually learn to program C Sound.  Matthews is even
        gentle on the math-phobic, promising to keep the numbers round.]

Both of the above prove that really brilliant people are brilliant
communicators -- like Bob Moog, Hal Chamberlin, and Barry Klein.  If you
can't write it, you don't know it.

Hope this proves useful.  As always, I welcome any second opinions or
criticisms.  


Elliot "Never Read a Book until the 12th Grade and Haven't Stopped Since"



From FENATIC at aol.com  Tue Dec 22 08:20:06 1998
From: FENATIC at aol.com (FENATIC at aol.com)
Date: Tue, 22 Dec 1998 02:20:06 EST
Subject: Delton T. Horn's books
Message-ID: <6656fcab.367f4826@aol.com>


In a message dated 12/22/98 1:46:59AM, b.layer at vikingelectronics.com wrote:

<<Hey, guess what? President Gore!
>>

guess again!



From Juergen.Haible at nbgm.siemens.de  Tue Dec 22 12:29:29 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 22 Dec 1998 12:29:29 +0100
Subject: AW: Capacitive loading of op-amps
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D5820112E088@nbgm336a.nbgm.siemens.de>

	>It also occurs to me that adding a large capacitor directly to the
	>output of an op amp will essentially cancel much of the loop's AC
	>gain, 

Yes. Loop gain being more or less a LP function, it will
shift the cutoff frequency downward, i.e. less loop gain
at a certain frequency.
Now, loop gain (or let's speak about loop bandwidth, as
the DC gain is not affected by the capacitor on the
output !) isn't a benefit by itself. Why build a buffer with
high loop gain / bandwidth and tight feedback at all ?
(1) It will help for a well defined closed loop gain (i.e. relative
wide band voltage buffer), and
(2) it will also reduce the output resistance of the buffer.

You need (1) and (2) for amplifiers. But for a buffered
auxiliary voltage, you don't need (1), as the "amplifier
input" doesn't change at all. You still want (2), i.e. a stiff
voltage with low internal impedance over a wide frequency
range. The opamp with reduced loop gain (because of the
cap) will not provide such a good wide band low impedance
anymore. But who cares - that part is taken by the cap.
The opamp takes care of the DC and low frequency part.
So, for high frequencies, all is ok. (It even would be ok
with just a resistor divider and capacitor, no opamp)
For DC, everything's fine too. (cap is irrelevant here)
If there is no resonance peak in the closed loop gain
(i.e. external pole and internal pole from compensation
wide apart), everything should be nice and smooth  in 
between, too.

	>sort of rendering the circuit as a precision emitter follower
	>without a Vbe offset.  

Emitter follower is different. You don't have an external feedback
loop and no high output impedance of the "open loop" either.
Can't see how this would fit together.

	>For this simpler approach, however, another consideration is that a
	>huge slug of current will be drawn through the op amp's output
transistors
	>upon power-up.  Most op-amps are capable of withstanding an
	>intermittent surge such as this, although it may cause a failure in
some
	>cases when the capacitor is large, has an exceptionally low ESR
	>(e.g., tantalum), and the supply' s rate of rise is high.

The current will be limited by the internal current limiting that's
build into most opamps. It's not like a single transistor, where
you must take care how long a certain high current can last
without burning something. The opamp will simply go into
limiting, and behave like a current source rather than a voltage
source until the cap is charged.
The only thing I'd worry about is what happens when the circuit
is switched *off*, i.e. supply voltage goes down, but the capacitor
is still charged. I never had problems with 10u caps and the usual
cheap opamps myself, but I think that there is some limit.

	JH.



From peake at pacificnet.net  Tue Dec 22 13:08:05 1998
From: peake at pacificnet.net (Peake)
Date: Tue, 22 Dec 98 12:08:05 -0000
Subject: [AH] Eventide Instant Phaser Docs
Message-ID: <199812222000.MAA28461@polaris.pacificnet.net>

>
>If anyone has docs & schematics for the Eventide PS101 Instant Phaser I would
>be happy to pay for a copy. Thanks.

I was just at Eventide's site last night; they seem to have docs for most 
everything they've ever made. Phone 201-641-1200 and tell the 
operator you want to buy PS101 documentation/schematics. 

Easier,

Mike


________________
Specifications:

Signs and Portents/Buh Bye Newt ya Hump/Evolution in Action

         This holiday season, don't go around caroling; get 
some woodwind and steel drum players, dress up as the Mos Eisley
Cantina band, and play those classic Star Wars tunes when people 
answer the door. Remember not to say a word, just play. This 
would be most effective in areas with snow. Lag behind some 
real carolers to add to the fun. 




From Juergen.Haible at nbgm.siemens.de  Tue Dec 22 13:11:40 1998
From: Juergen.Haible at nbgm.siemens.de (Haible Juergen)
Date: Tue, 22 Dec 1998 13:11:40 +0100
Subject: RAP's book (was: AW: Delton T. Horn's books)
Message-ID: <1BF5E20E0C4DD111BBAB00805FE2D5820112E116@nbgm336a.nbgm.siemens.de>

	>And, if you really want to buy a book, get "Troubleshooting Analog
Circuits" by
	>Robert Pease. You'll need it one day, trust me. It isn't
specifically on synths,
	>but it is THE GOODS. It's the only book people regularly steal from
me.

It *is* a brilliant book, no doubt. Lots of valuable information
that you won't find too often, and some good ideas what to
do with Spice printouts. I really enjoyed reading it.

Nevertheless, I don't share the common enthusiasm about it
being such a comprehensive beginner's book. I'd recommend something like
Tietze / Schenk, "Electronic Circuits : Design and Applications"
for a profound overview. If you're familiar with that (or a similar one),
you will appreciate the additional insight of RAP's "Troubleshooting".

Once again, the Pease book is highly recommended. (And I trust
him on all but the section on Spice, which is quite outdated, IMO.
You can clearly see this when he refers to the Saber level 2 opamp models.)

JH.



From fuzztone at jpq.com  Tue Dec 22 17:34:05 1998
From: fuzztone at jpq.com (fuzz)
Date: 22 Dec 1998 11:34:05 -0500
Subject: Eventide Instant Phaser Docs
Message-ID: <n1297796071.49986@smtp.directmedia.com>

If anyone has docs & schematics for the Eventide PS101 Instant Phaser I would
be happy to pay for a copy. Thanks.




From buchanan at qualcomm.com  Tue Dec 22 18:48:54 1998
From: buchanan at qualcomm.com (Buck Buchanan)
Date: Tue, 22 Dec 1998 09:48:54 -0800
Subject: Delton T. Horn's books
In-Reply-To: <1.5.4.32.19970317043352.006dfd64@popa.melbpc.org.au>
Message-ID: <3.0.3.32.19981222094854.01542940@mage.qualcomm.com>

At 02:33 PM 3/17/97 +1000, Paul Perry wrote:
>At 01:19 PM 21/12/98 -0600, Bill Layer wrote:
>
>>I happen to own one of Delton Horn's books on synthesizers, I beleive it is
>>on the topic of troubleshooting and repair. Sorry to say, but it has to be
>>the most useless, insipient text on the subject that I own. The section on
>>analog basics is not *too* bad, but the digital section is a real joke.

Fraid I gotta throw in a "me too" here as well.

I've got one of the beginner books on buying and building your own synth
and the only thing usefull is his decription of individual modules from
Moog, Arp, etc (to give you ideas!).  

But the circuits are a joke.  Most are kinda stupid and almost every one I
built didn't work.  I know they were put together right.....  If you're
ganna write a beginner books, you gotta a least include circuits that ALL
work even with basic parts substitutions - a la Forest Mimms (evertying
works in his books - very simple!)

Somebody gave me a large text by him - kind of like an Art of Electronics
thing.  Unfortunately, I'm suspsect of the information given what this
synth book is like.  

Oh well,

Happy Holidays!!!!

Buck



From hallgeir at ovation.musicpower.net  Tue Dec 22 19:15:32 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Tue, 22 Dec 1998 19:15:32 +0100
Subject: The book I mentioned...
Message-ID: <199812221904.UAA28433@louise.netpower.no>

Yes. Sorry.

Indeed, the "Music Synthesizers - a manual of design
and construction" by Delton T. Horn was rather blurry.
In fact, at times it was downright bad. Lots of the 
illustrations are confusing to say the least. 

I had not read it too much when I wrote the last mess-age
(hence the "I think"), because most of the topics was very
basic, I didn't care reading things I knew. I'll probably turn
it back to the library again immediatly when school starts 
again after new-year.

So, on second thought, NOT recommended.

Hallgeir



From fuzztone at jpq.com  Tue Dec 22 21:27:47 1998
From: fuzztone at jpq.com (fuzz)
Date: 22 Dec 1998 15:27:47 -0500
Subject: [AH] Eventide Instant Phaser Docs
Message-ID: <n1297781995.93454@smtp.directmedia.com>

Nope, I called Eventide first and they do not have any more, or even a copy.
That is why I am putting the call out... if anyone has them... thanks.

_______________________________________________________________________________
From: Peake on Tue, Dec 22, 1998 3:04 PM
Subject: Re: [AH] Eventide Instant Phaser Docs
To: fuzz; Analogue Heaven; Synth-DIY

>
>If anyone has docs & schematics for the Eventide PS101 Instant Phaser I would
>be happy to pay for a copy. Thanks.

I was just at Eventide's site last night; they seem to have docs for most 
everything they've ever made. Phone 201-641-1200 and tell the 
operator you want to buy PS101 documentation/schematics. 

Easier,

Mike





From ka4hjh at gte.net  Tue Dec 22 21:43:14 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Tue, 22 Dec 1998 15:43:14 -0500
Subject: Delton T. Horn's books
In-Reply-To: <3.0.6.32.19981221131956.007d1960@192.168.210.18>
References: <199812211641.RAA05869@louise.netpower.no>
Message-ID: <v04011701b2a5b4b46a46@[208.252.40.229]>

>Nothing is worse for a beginner than an author who contradicts himself...
>Maybe that it's just that my copy is an early edition, but in light of the
>content, I can't believe they even bothered to print it.

I could say the same thing about at least 90% of all the books published by
Tab. They have absolutely no editorial dept., and while some of the authors
actually seem to know what they're talking about, they have no idea how to
write a book. This is where the publisher is supposed to step in but...

A local book fair had a large number of their books about ten years ago and
finally decided to get rid of them once and for all. They donated them to a
local church and they had a "pay what you don't feel guilty about" sale. My
brother and I filled two big boxes, 1 copy of everything. Most titles were
by Tab. We got home and starting looking through, them and it was quite a
mixed bag. Many of them had useful info but it was so sloppily prepared
that reading it was like walking through a quagmire. My personal favorites
are the partial reprints of schematics and plans from Information
Unlimited, the place with the overpriced plans and kits for Tesla coils and
lasers. The book is just a come-on. There are unlabeled parts on the
schematics! The worst was a "new age" electronics books with things like a
UFO detector, Kirlian photography. Not too long ago I saw this one still
for sale. I doubt if you can build a single functional project from it.

There are a couple of decent ones. Anything by Gordon McComb is
interesting, if a bit dated. Synthesizers?. Haven't seen it.

I also have a nice one on oxyacetylene welding.

Terry Bowman, KA4HJH
"The Mac Doctor"



From synth1 at airmail.net  Tue Dec 22 22:46:15 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Tue, 22 Dec 1998 15:46:15 -0600
Subject: Delton's a dodo: buy Henry!!
Message-ID: <001301be2df4$80bd1ca0$f91588cf@paults>

If you want easy, TESTED circuits from an old fart like me, then
get Thomas Henry's "Electronic music circuits: reprints".

www.prairie.lakes.com/~map

Most circuits can be built for UNDER $25. They all WORK!!!

There are some needed updates in terms of part selection
(he favors some bizarre quad op amps that were like 12 cents
in 1981). See an op amp? Shove a TL072 in there.

Want to know how the MOTM-110 Ring Mod works?? There is a 5 page
description! Want cheap filters?? Get some 3320s from me (shameless plug)
and build the P.A.L. filter.

What is nice about this book is EVERY circuit is EXPLAINED and not just
presented
"as-is".

Plus, he has neat pictures of his old monster-sized DIY synth in there.

Paul Schreiber
Synthesis Technology





From synth1 at airmail.net  Tue Dec 22 22:51:31 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Tue, 22 Dec 1998 15:51:31 -0600
Subject: Hmmm...Thomas Henry has vanished
Message-ID: <001901be2df5$3ce17ac0$f91588cf@paults>

Well, he WAS at prairie.lakes.com/~map!!!

I will try and find him. I do know that he took a full-time teaching job
at a local college and so maybe he went off-line for a while!!

Paul Schreiber





From aschrock at cs.brandeis.edu  Tue Dec 22 22:54:22 1998
From: aschrock at cs.brandeis.edu (Andrew Schrock)
Date: Tue, 22 Dec 1998 16:54:22 -0500 (EST)
Subject: The book I mentioned...
In-Reply-To: <199812221904.UAA28433@louise.netpower.no>
Message-ID: <Pine.HPP.3.95.981222164938.2426B-100000@bay.cs.brandeis.edu>

One book that I'm rather surprised isn't mentioned more is Joel Chadabe's
"Electronic Sound". It gives a very good perspective of both electronic
music (from tape music to the 1990's) as well as a good overview of
synthesizers. True, it doesn't have the flashy graphics of Mark Vails
"Vintage Synthesizers", but it simply has a lot more useful information.
It also has great interviews and accounts from people who were in the
field. Perhaps it's not specifically for synth designers, but I think it's
a book everybody should read. 

I think (?) it was out of print until recently, but Amazon has copies now.

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|




From costello at seanet.com  Wed Dec 23 00:11:50 1998
From: costello at seanet.com (Sean Costello)
Date: Tue, 22 Dec 1998 15:11:50 -0800
Subject: Hmmm...Thomas Henry has vanished
References: <001901be2df5$3ce17ac0$f91588cf@paults>
Message-ID: <36802735.E77AD535@seanet.com>

Paul Schreiber wrote:
> 
> Well, he WAS at prairie.lakes.com/~map!!!
> 
> I will try and find him. I do know that he took a full-time teaching job
> at a local college and so maybe he went off-line for a while!!

Try http://techno5.lakes.com/~map/ - he's still around.

BTW, "Electronic Music Circuits: The Reprints" is a very nice little
book. It reprints many of the articles that were the basis for Henry's
excellent book "Build a Better Music Synthesizer," which was actually
published by the infamous TAB books. And wasn't Barry Klein's book
originally on TAB?

Sean Costello (who likes the album "25...tab" by Monster Magnet quite a
bit. Good super nasty Big Muff acid rock.)



From costello at seanet.com  Wed Dec 23 00:14:19 1998
From: costello at seanet.com (Sean Costello)
Date: Tue, 22 Dec 1998 15:14:19 -0800
Subject: The book I mentioned...
References: <Pine.HPP.3.95.981222164938.2426B-100000@bay.cs.brandeis.edu>
Message-ID: <368027CB.2F378497@seanet.com>

Andrew Schrock wrote:
> 
> One book that I'm rather surprised isn't mentioned more is Joel Chadabe's
> "Electronic Sound". It gives a very good perspective of both electronic
> music (from tape music to the 1990's) as well as a good overview of
> synthesizers. True, it doesn't have the flashy graphics of Mark Vails
> "Vintage Synthesizers", but it simply has a lot more useful information.
> It also has great interviews and accounts from people who were in the
> field. Perhaps it's not specifically for synth designers, but I think it's
> a book everybody should read.

Definitely a nice book.  Not all that great for the analog stuff,
unfortuately (although there is quite a bit on Moog, as Chadabe worked
closely with Moog in the late 1960's).  Plenty of good digital music
info (Max Mathews, IRCAM, CCRMA, all the good stuff).  No real in-depth
discussion of Serge Tcherepnin's work in the 1970's, even though Ivan
Tcherepnin is pictured.

Sean Costello



From moxie at idonex.se  Wed Dec 23 01:12:48 1998
From: moxie at idonex.se (Johan Gustavsson)
Date: Wed, 23 Dec 1998 01:12:48 +0100 (MET)
Subject: Hmmm...Thomas Henry has vanished
In-Reply-To: <001901be2df5$3ce17ac0$f91588cf@paults> (synth1@airmail.net)
Message-ID: <199812230012.BAA23181@jolt.idonex.se>

Well, I did the same discovery a week or so back, and managed to find
MAP again. He's here:

http://techno5.lakes.com/~map/

/Moxie (Net sleuth)




From olleromo at ix.netcom.com  Wed Dec 23 01:32:12 1998
From: olleromo at ix.netcom.com (Olle Romo)
Date: Tue, 22 Dec 1998 16:32:12 -0800
Subject: Delton's a dodo: buy Henry!!
In-Reply-To: <001301be2df4$80bd1ca0$f91588cf@paults>
Message-ID: <v04011704b2a5e9e92f09@[205.187.202.143]>

Paul Schreiber wrote:
>If you want easy, TESTED circuits from an old fart like me, then
>get Thomas Henry's "Electronic music circuits: reprints".
>
>www.prairie.lakes.com/~map

I get a "File not found" on that link. Any other place I can find it?

Regards, Olle





From ka4hjh at gte.net  Wed Dec 23 02:09:20 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Tue, 22 Dec 1998 20:09:20 -0500
Subject: Hmmm...Thomas Henry has vanished
In-Reply-To: <36802735.E77AD535@seanet.com>
References: <001901be2df5$3ce17ac0$f91588cf@paults>
Message-ID: <v04011701b2a5f2a34d56@[208.252.40.229]>

>BTW, "Electronic Music Circuits: The Reprints" is a very nice little
>book. It reprints many of the articles that were the basis for Henry's
>excellent book "Build a Better Music Synthesizer," which was actually
>published by the infamous TAB books.

Oh yeah, that's the best book from them I've ever seen (an author who knows
his subject and how to write--what a concept). The book fair I went to had
dozens of copies for about $1.50 apiece.

I think Tab got bought up by a major publisher a while back, I forget who.

Terry Bowman, KA4HJH
"The Mac Doctor"



From mswilson at julian.uwo.ca  Wed Dec 23 02:59:32 1998
From: mswilson at julian.uwo.ca (Michael Wilson)
Date: Tue, 22 Dec 1998 20:59:32 -0500
Subject: The book I mentioned...
Message-ID: <002901be2e17$e251f4e0$3cd26481@juicy.uwo.ca>

Please take me off you're mailing list
-----Original Message-----
From: Sean Costello <costello at seanet.com>
To: Andrew Schrock <aschrock at cs.brandeis.edu>
Cc: DIY <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 22, 1998 8:12 PM
Subject: Re: The book I mentioned...


>Andrew Schrock wrote:
>>
>> One book that I'm rather surprised isn't mentioned more is Joel Chadabe's
>> "Electronic Sound". It gives a very good perspective of both electronic
>> music (from tape music to the 1990's) as well as a good overview of
>> synthesizers. True, it doesn't have the flashy graphics of Mark Vails
>> "Vintage Synthesizers", but it simply has a lot more useful information.
>> It also has great interviews and accounts from people who were in the
>> field. Perhaps it's not specifically for synth designers, but I think
it's
>> a book everybody should read.
>
>Definitely a nice book.  Not all that great for the analog stuff,
>unfortuately (although there is quite a bit on Moog, as Chadabe worked
>closely with Moog in the late 1960's).  Plenty of good digital music
>info (Max Mathews, IRCAM, CCRMA, all the good stuff).  No real in-depth
>discussion of Serge Tcherepnin's work in the 1970's, even though Ivan
>Tcherepnin is pictured.
>
>Sean Costello




From roytate at ionet.net  Wed Dec 23 03:59:04 1998
From: roytate at ionet.net (Roy Tate)
Date: Tue, 22 Dec 1998 20:59:04 -0600
Subject: Hmmm...Thomas Henry has vanished
References: <001901be2df5$3ce17ac0$f91588cf@paults>
Message-ID: <36805C78.94AF1D22@ionet.net>

Paul Schreiber wrote:
> 
> Well, he WAS at prairie.lakes.com/~map!!!
 
I haven't updated the link on my site, but
you should try ...

http://techno5.lakes.com/~map/

Regards,
 
Roy Tate
roytate at ionet.net
http://www.ionet.net/~roytate



From rob at secret-secret.com  Wed Dec 23 10:20:57 1998
From: rob at secret-secret.com (Rob)
Date: Wed, 23 Dec 1998 01:20:57 -0800
Subject: The Expressionist, a review
Message-ID: <v04003a02b2a6526da64b@[208.255.84.142]>

For years now my old CV synths were used for sample fodder.  But no longer,
and I'm one happy camper about it. I finally got myself a midi to CV box.
I've waited all too long to get one, but by doing so I really lucked out. I
got an Expressionist.

There are many fine midi to CV boxes out there I understand the Kenton
products are suppose to be very good, but I still opted for Encore's
Expressionist. I've been hearing many good things about the box. It's price
seems a bit steep and that's what kept me from getting it right away.  I
kept getting other things.  I mean for the price of this box it's not hard
to find something else that seems more useful or glitzy at the time. That
said, the 600 frog skins that the Expressionist will set you back are well
worth it, and here's why.

Hardware

It comes in a single space 19" rack mount.  Powered with a wall wart (the
only real issue I have with the machine, but it's understandable once you
know a little bit about the company). On the front you'll find a huge back
lit display, five buttons and a power switch. On the back are 16 1/4' jacks
for CVs and Gates, midi in and out, din sync, 1/4" foot switch jack and the
power connector. Pretty straight forward, but with some nice touches.

One of the nice things is that all of the 1/4" jacks are secured with
fasteners.  Most machines made these days slime out and just mount the
jacks on the circuit board and expect them to hold up. Which they don't.
With the Expressionist they are properly mounted and I'd expect them to
last a very long time.

The power switch on the front is a big deal too.  Who enjoys reaching
behind your rack, or not even having one?  Both of which tend to save the
manufacture money and keep the price down, but both are a royal pain in the
back side for the user. The Expressionist has a power switch and it's in
the right place.

Inside there's a 68k of some sort controlling the whole machine.  A great
choice for such a box. It's got power for days for this job and isn't
likely to ever be bogged down by the requests of the user.  Many boxes made
these days put the cheepest processor in the box that they can get away
with and that is fine for 80% of the uses of the box.  The manufacture
saves money and the box is cheeper.  But then when you push those boxes you
get timing errors.  Timing errors are the bane of beat oriented musician.
With the 68k the Expressionist wont have this problem.

The mother board is layed out with separate power supplies for the
processor and the analogue circuits.  This is important because it keeps
processor noise from effecting your CVs.  Again this costs more and most
manufactures wont include this on their machines.  What effect does this
have on using the box?  Well you don't have to worry about sending a
command to the box that will cause a voice that you are holding to go out
of tune.

The D/A convertor on the Expressionist is 16 bit. This allows for smooth
control of your voltages from -3 to +10 volts, more then 32,000 steps. I
don't know what the other midi to CV boxes are using (I'm sure you can find
out though), but this seems to be yet another place where the Expressionist
has done the job right.

The code for this machine is all in an FPGA, meaning that you can down
load, from Encore's website (http://www.encoreelectronics.com), the latest
version and lode it in via Sysex. They've already done two updates this
way, and I understand that a 3rd is in the works.

I could go on about the hardware, but I'm sure you are getting the picture.
This thing is built right. It's made to be a quality product.

Software

Yeah there's a whole mess of software in this box and I'm just going to
touch on a few things real quick.

The whole user interface has been given a lot of thought. For instance the
buttons have great debounce code. This means that they don't double trigger
when you press them. After many years of use this becomes even more
important as the switches start to fail, and yes all switches wear out.

The buttons also repeat as you hold them and will speed up if you hold them
for a moment.  Very nice indeed, but there's more too.  Hold one button and
tap another will take you to the end of the allowable values.  Very trick.
There's more here too, but you get the idea. Somebody though about using
this box.

There are cool things like setting up a poly synth. CV offset and
rescaling, for those old machines that you don't have time to recalibrate
or fix. Split modes. Support for both Arp and Moog style gates.
Programmable LFO's that can be modulated on the fly. Various continuous
controller support. 100 programmable presets. Two modes of glides with
different timing features. I mean this box has a lot going for it.

Gripes

OK, yeah I like this box a lot.  That said there are a few things I'd like
to see.  I hate values that don't use real world units.  If there is a
value that takes 30 seconds then say so.  Don't tell me it's value 99. This
is a small issue, but it makes things a lot easier to use in the real
world.  One that can also be added pretty easy once the machine is working.
So this is on my wish list for this machine.

Pitch bend only goes 1 octave.  This seems a bit arbitrary to me.  One of
the great things about a CV synth is that there is no real difference from
a voltage received from a pitch bend or a new note.  So you can have some
really wild pitch bending going on. This would require some boundry code,
but it's something that could be implemented.

The wall wart, I hate, but Encore is a one person shop.  Every thing is
done by one guy.  The hardware, software, testing, shipping - every thing!
So taking the wall wart rout saved him lots of FCC and UL hassle.  So I can
deal with it. Everything else about this box screams out quality so I can
cut him some slack here.  Slack I wouldn't cut say an Alesis or Roland box.

Conclusion

Would I buy one? Yeah I already did. Encore is known for making quality
products.  The Expressionist does them proud. If you are serious about what
you are doing and want some serious control over your CV machines then this
is the box.

-Rob-

Secret Secret
http://secret-secret.com





From theremin1 at worldnet.att.net  Wed Dec 23 12:41:09 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 23 Dec 1998 03:41:09 -0800
Subject: Capacitive loading of op-amps
Message-ID: <009401be2e69$24cb4e60$67754e0c@hpcustomer>

AH:


> >It also occurs to me that adding a large capacitor directly to the
> >output of an op amp will essentially cancel much of the loop's AC
> >gain,

JH:

>Yes. Loop gain being more or less a LP function, it will
>shift the cutoff frequency downward, i.e. less loop gain
>at a certain frequency.
>Now, loop gain (or let's speak about loop bandwidth, as
>the DC gain is not affected by the capacitor on the
>output !) isn't a benefit by itself. Why build a buffer with
>high loop gain / bandwidth and tight feedback at all ?
>(1) It will help for a well defined closed loop gain (i.e. relative
>wide band voltage buffer), and
>(2) it will also reduce the output resistance of the buffer.
>
>You need (1) and (2) for amplifiers. But for a buffered
>auxiliary voltage, you don't need (1), as the "amplifier
>input" doesn't change at all. You still want (2), i.e. a stiff
>voltage with low internal impedance over a wide frequency
>range. The opamp with reduced loop gain (because of the
>cap) will not provide such a good wide band low impedance
>anymore. But who cares - that part is taken by the cap.
>The opamp takes care of the DC and low frequency part.
>So, for high frequencies, all is ok. (It even would be ok
>with just a resistor divider and capacitor, no opamp)
>For DC, everything's fine too. (cap is irrelevant here)
>If there is no resonance peak in the closed loop gain
>(i.e. external pole and internal pole from compensation
>wide apart), everything should be nice and smooth  in
>between, too.

AH:

> >sort of rendering the circuit as a precision emitter follower
> >without a Vbe offset.

JH:

>Emitter follower is different. You don't have an external feedback
>loop and no high output impedance of the "open loop" either.
>Can't see how this would fit together.
>
> >For this simpler approach, however, another consideration is that a
> >huge slug of current will be drawn through the op amp's output
>transistors
> >upon power-up.  Most op-amps are capable of withstanding an
> >intermittent surge such as this, although it may cause a failure in
>some
> >cases when the capacitor is large, has an exceptionally low ESR
> >(e.g., tantalum), and the supply' s rate of rise is high.
>
>The current will be limited by the internal current limiting that's
>build into most opamps. It's not like a single transistor, where
>you must take care how long a certain high current can last
>without burning something. The opamp will simply go into
>limiting, and behave like a current source rather than a voltage
>source until the cap is charged.
>The only thing I'd worry about is what happens when the circuit
>is switched *off*, i.e. supply voltage goes down, but the capacitor
>is still charged. I never had problems with 10u caps and the usual
>cheap opamps myself, but I think that there is some limit.

AH:

All points well taken.  From a reliability standpoint, I still prefer output
protection for the op amp during power-on and power-off.
(You never know when a synthesizer will be used in a life-saving
capacity!)

I suspect that loop dynamics for all transient load conditions really
would benefit from the high AC gain, but admittedly, would have to
do a physical comparison to be sure.

I suppose a Hg relay to switch a load and a storage scope would be
the way to tell.

-Art






From honcho at paia.com  Wed Dec 23 20:47:48 1998
From: honcho at paia.com (honcho at paia.com)
Date: Wed, 23 Dec 1998 13:47:48 -0600 (CST)
Subject: http://209.52.185.39
Message-ID: <199812231947.NAA10572@qns1.qns.net>


Hi all- 

After weeks of ongoing server problems (site down completely, mail 
problems that lost mail without notification and so on) I had to put 
other things aside temporarily and shop for a new web host. 

We'll be propogating the DNS for the new host between 
Christmas and New Year. I'd like to ask anyone who has the time to 
help me test the new site for missing (probably mis-named) art, broken 
links and so on. In particular, please try the the search tool linked 
at "what's new" and let me know what you think. This is "search.pl" 
from Matt's and _real_ simple so I don't know how useful it is 
altogether. Also when I searched for "fatman", one of the references 
it gave was the MS Mic page and I can't for the life of me find the 
term "fatman" anywhere on the page.

Go in at http://209.52.185.39 and then click on "what's new".

The change will produce a lot of benefits long-term. More space means 
more goodies can go up (for instance, at "what's new"  you'll find a 
.pdf of the OZ article from Jan '77 Radio Electronics that's not 
presently at paia.com) and over time we'll have lots more wav files, 
e.g. the entire demo CD from Electronic Projects for Musicians rather 
than the limited selection put up a few weeks ago. And lots of space 
for the really cool demo material that users send from time to time.

So, thanks for any help you can give and season's grettings to all.

-John

---------------------------------------------------------
John Simonton                  PAiA Electronics, Inc
3200 Teakwood Ln.              honcho at paia.com
Edmond OK 73013                http://www.paia.com
405-340-6300                   fax 405-340-6378



From zzynt at swipnet.se  Wed Dec 23 23:50:46 1998
From: zzynt at swipnet.se (BJ)
Date: Wed, 23 Dec 1998 14:50:46 -0800
Subject: Test
References: <009401be2e69$24cb4e60$67754e0c@hpcustomer>
Message-ID: <368173C6.20C5@swipnet.se>

Test
BJ



From hekovala at lyseolukio2.kajaani.fi  Thu Dec 24 00:01:30 1998
From: hekovala at lyseolukio2.kajaani.fi (Henri Kovalainen)
Date: Thu, 24 Dec 1998 01:01:30 +0200 (EET)
Subject: Hmmm...Thomas Henry has vanished
In-Reply-To: <36802735.E77AD535@seanet.com>
Message-ID: <Pine.LNX.3.96.981224004738.8511A-100000@lyseolukio2.kajaani.fi>

On Tue, 22 Dec 1998, Sean Costello wrote:
> BTW, "Electronic Music Circuits: The Reprints" is a very nice little
> book. It reprints many of the articles that were the basis for Henry's
> excellent book "Build a Better Music Synthesizer," which was actually
> published by the infamous TAB books. And wasn't Barry Klein's book
> originally on TAB?

 I would like to emphasize that the book is really useful *only if* you
 have a source/money/time for all those CEMs and SSMs. Just about every
 circuit in Henry's book uses them... I mean, come on, an ADSR eg that
 utilizes a specific ADSR chip? Wouldn't have needed a book to built this
 type of stuff, rather a data sheet. So, if you don't want to use a crap
 load of custom chips, the book is a big disapponitment.

 ------------------.                  
 theadvancementand |  henri kovalainen    hoikankatu 19
 diffusionofknowle |  phone: +08-626555   87100 kajaani
 dgeistheonlyguard |  irc: AcidRain       finland
 ianoftrueliberty. |  http://lyseolukio2.kajaani.fi/~dh
                   '-




From synth1 at airmail.net  Thu Dec 24 01:37:01 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Wed, 23 Dec 1998 18:37:01 -0600
Subject: Henry's book and DIY flaming
Message-ID: <000e01be2ed5$966d2680$a91388cf@paults>

Perhaps a little TOO harsh. There are 35 articles in the book.
Only 9 use SSM or CEM chips. Of those, 4 use CEM3330
or CEM3320 which are still available (especially the 3320!!)

5 out of 35 is a good ratio to me!

There are a couple of SAD-1024 BBD articles, but you can use the
MN3xxx series BBDs from Panasonic (from www.digikey.com).

Paul Schreiber






From camotse at france-mail.com  Thu Dec 24 01:42:44 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Thu, 24 Dec 1998 01:42:44 +0100
Subject: Midi2cv8 connection
Message-ID: <005601be2ed8$f3ec0ee0$0213eec3@lisa>

Hi list,


Me and a friend are currently building our midi2cv's, and a question raised:
"Is there any way to use only 8 connectors (ie bananas) instead of those 16
1/8"jacks?" - in other words: "Is there a correct gate signal at the tip
output when the midi2cv is supposed to output gates?" We understand that
there is always a gate at the ring of the jack, but what when there should
already be one at the tip? Can we use the tip connections only?


Hope someone can help or direct us,
thanks

Arno & Greg.





From Barry.L.Klein at wdc.com  Thu Dec 24 01:51:29 1998
From: Barry.L.Klein at wdc.com (Barry L Klein)
Date: Wed, 23 Dec 1998 16:51:29 -0800 (Pacific Standard Time)
Subject: EMC Book
Message-ID: <ISSMTP.1.3(1).19981223165129.4294010067B@Corp.wdc.com>

BTW, my Electronic Music Circuits book is still available (from me).  $30
and $5 shipping to US.  It was originally published by SAMS.  TAB never
got it.  

Unfortunate that Thomas Henry chose to use my title somewhat.  Just
confuses things.

Barry Klein
32041 Pleasant Glen Rd.
Trabuco Canyon, CA   92679





From magnus at analogue.org  Thu Dec 24 03:01:04 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Thu, 24 Dec 1998 03:01:04 +0100
Subject: Hmmm...Thomas Henry has vanished
In-Reply-To: Your message of "Thu, 24 Dec 1998 01:50:29 -0800"
References: <36820E65.3ABB@swipnet.se>
Message-ID: <199812240201.DAA14499@mail2.it.kth.se>

>>>>> "B" == BJ  <zzynt at swipnet.se> writes:

Hi Fellas...

 B> May i have a word here please ladies and gentlemen!

... and BJ!

 B> Anyone can infact buy all the shematics and building descriptions
 B> for the A100 system from Doepfer for approx 75 usd!

 B> It contain all of the modules, approx 600 to 700 pages!

Well, that really seems interesting.

Hmm, I got this little organising-mania hitting me from time to time,
and I have noticed that this issue keeps poping up all the time. So, I
sugest that maybe we aught to compile a page with books which is
usefull for the DIYer. There is a AH FAQ, so one could have it
associated with that possibly. Every now and then we see how people
comment on this or that book, I know books (like "The Art of
Electronics" for instance) that keep surfacing.

Theres general books on synths (like Mark Vails "Vintage
Synthesizers").

Theres books on basic theory of synths (timbre and stuff).

Theres books on synthesizer cursuits.

Theres books on general electronics.

etc. etc.

All these form a suite of material that one might like to have. Theres
really so many books out there, so you need to have some
guidance. Also, as we end up buying stuff more and more remote we
don't have the option of browsing the book before bying it.

Giving directions on where the book may be acquired might also be a
good idea.

Hints like where to get Doepfer schematics, Electronotes etc kind of
fits the picture as well.

Just an idea...

I really missed a good source for this information as I have tried to
extend my library with such books, since I don't know what is good and
what is bad I don't know if I want to spend my money on them.

Cheers,
Magnus



From jhaible at primus-online.de  Thu Dec 24 03:04:26 1998
From: jhaible at primus-online.de (jhaible)
Date: Thu, 24 Dec 1998 03:04:26 +0100
Subject: EMC Book
Message-ID: <19981224022929.12207.qmail@nuernberg2.pop.metronet.de>

> BTW, my Electronic Music Circuits book is still available (from me).  $30
> and $5 shipping to US.  It was originally published by SAMS.  TAB never
> got it.  
[...]
> Barry Klein
> 32041 Pleasant Glen Rd.
> Trabuco Canyon, CA   92679

Highly recommended !

JH.



From wils0450 at itlabs.umn.edu  Thu Dec 24 05:22:28 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Wed, 23 Dec 1998 22:22:28 -0600 (CST)
Subject: Books and things (had something to do with T.H.)
Message-ID: <Pine.GSO.4.05.9812232221480.5214-100000@beluga.itlabs.umn.edu>

> Hmm, I got this little organising-mania hitting me from time to time,
> and I have noticed that this issue keeps poping up all the time. So, I
> sugest that maybe we aught to compile a page with books which is
> usefull for the DIYer. There is a AH FAQ, so one could have it
> associated with that possibly. Every now and then we see how people
> comment on this or that book, I know books (like "The Art of
> Electronics" for instance) that keep surfacing.

For those who want to put in thier two nects worth, There will be a a list
of *beginners* and more advanced books on the Midwest Synthesis COmbine
wesite. Unfortunately, everyone at University is on vacation, so it
probably won't be up until January (next month). I will post the addy as
soon as the page is up. This isn't one of those "when I get around to it
things," this is a for sure deal - the page is even done, I just don't
have my URL yet. Damn. For those who are interested, there will also be a
list server catering specifically to beginners. Thanks for the Bandwidth.


                 "There always lies so near to us a realm
        in which we have escaped entirely from all our affliction..."






From varner at k-online.com  Thu Dec 24 05:56:22 1998
From: varner at k-online.com (Steve Varner)
Date: Wed, 23 Dec 1998 20:56:22 -0800
Subject: Hmmm...Thomas Henry has vanished
References: <Pine.LNX.3.96.981224004738.8511A-100000@lyseolukio2.kajaani.fi> <36820E65.3ABB@swipnet.se>
Message-ID: <3681C974.D4F6963A@k-online.com>

I have the book "Build a better music synthesizer" by Henry. I agree about the
chips being expensive and scarce, but I find the book very useful in that he
gives the clearest instructions I've read on building 19" rack panels, wiring
the modules, hooking everything together, and generally setting up a DIY
synth. Some of the modules do not use specialty chips and are interesting
modules.

Steve Varner
varner at k-online.com

BJ wrote:

> Henri Kovalainen wrote:
> >
> > On Tue, 22 Dec 1998, Sean Costello wrote:
> > > BTW, "Electronic Music Circuits: The Reprints" is a very nice little
> > > book. It reprints many of the articles that were the basis for Henry's
> > > excellent book "Build a Better Music Synthesizer," which was actually
> > > published by the infamous TAB books. And wasn't Barry Klein's book
> > > originally on TAB?
> >
> >  I would like to emphasize that the book is really useful *only if* you
> >  have a source/money/time for all those CEMs and SSMs. Just about every
> >  circuit in Henry's book uses them... I mean, come on, an ADSR eg that
> >  utilizes a specific ADSR chip? Wouldn't have needed a book to built this
> >  type of stuff, rather a data sheet. So, if you don't want to use a crap
> >  load of custom chips, the book is a big disapponitment.
> >
> >  ------------------.
> >  theadvancementand |  henri kovalainen    hoikankatu 19
> >  diffusionofknowle |  phone: +08-626555   87100 kajaani
> >  dgeistheonlyguard |  irc: AcidRain       finland
> >  ianoftrueliberty. |  http://lyseolukio2.kajaani.fi/~dh
> >                    '-
>
> May i have a word here please ladies and gentlemen!
>
> Anyone can infact buy all the shematics and building descriptions
> for the A100 system from Doepfer for approx 75 usd!
>
> It contain all of the modules, approx 600 to 700 pages!
>
> BJ






From zzynt at swipnet.se  Thu Dec 24 10:37:55 1998
From: zzynt at swipnet.se (BJ)
Date: Thu, 24 Dec 1998 01:37:55 -0800
Subject: http://209.52.185.39
References: <199812231947.NAA10572@qns1.qns.net>
Message-ID: <36820B73.629C@swipnet.se>

honcho at paia.com wrote:

> So, thanks for any help you can give and season's grettings to all.
> 
> -John


It sounds to me that PAIA is runing a Microsoft product as a server!
If so i strongly suggest you to put the junk in the garbage bin and 
set up a nice trustly working LINUX server instead!

I think you are in about 2 seconds from now are a target of a hell of 
suport and fixing suggestions from this list!!!

BJ
[in the land of small sugesstions and a insane jobb market]



From zzynt at swipnet.se  Thu Dec 24 10:50:29 1998
From: zzynt at swipnet.se (BJ)
Date: Thu, 24 Dec 1998 01:50:29 -0800
Subject: Hmmm...Thomas Henry has vanished
References: <Pine.LNX.3.96.981224004738.8511A-100000@lyseolukio2.kajaani.fi>
Message-ID: <36820E65.3ABB@swipnet.se>

Henri Kovalainen wrote:
> 
> On Tue, 22 Dec 1998, Sean Costello wrote:
> > BTW, "Electronic Music Circuits: The Reprints" is a very nice little
> > book. It reprints many of the articles that were the basis for Henry's
> > excellent book "Build a Better Music Synthesizer," which was actually
> > published by the infamous TAB books. And wasn't Barry Klein's book
> > originally on TAB?
> 
>  I would like to emphasize that the book is really useful *only if* you
>  have a source/money/time for all those CEMs and SSMs. Just about every
>  circuit in Henry's book uses them... I mean, come on, an ADSR eg that
>  utilizes a specific ADSR chip? Wouldn't have needed a book to built this
>  type of stuff, rather a data sheet. So, if you don't want to use a crap
>  load of custom chips, the book is a big disapponitment.
> 
>  ------------------.
>  theadvancementand |  henri kovalainen    hoikankatu 19
>  diffusionofknowle |  phone: +08-626555   87100 kajaani
>  dgeistheonlyguard |  irc: AcidRain       finland
>  ianoftrueliberty. |  http://lyseolukio2.kajaani.fi/~dh
>                    '-

May i have a word here please ladies and gentlemen!

Anyone can infact buy all the shematics and building descriptions
for the A100 system from Doepfer for approx 75 usd!

It contain all of the modules, approx 600 to 700 pages!

BJ



From jlarryh at iquest.net  Thu Dec 24 11:16:04 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Thu, 24 Dec 1998 04:16:04 -0600
Subject: Thomas Henry's "reprints" book
Message-ID: <199812240910.KAA23718@mailhost.bpa.nl>

Since we are dealing with opinions here, I would like to respectfully
disagree.  What you have said is true that some of the circuits use the CEM
and SSM chips.  for example, there are 3 EG circuits, one CEM, one SSM, and
one discrete.  The real value in the book for me is the explanations that
accompany the circuits.  And, many of the chips used in the circuits are
still indeed available.  So far, I have felt like I got my moneys worth
from the book.  Perhaps, it might be a disappointment to some of you guys
experienced enough to design your own circuits.  For a non-engineer like
myself, it is full of good info.

My $.02
Larry Hendry

----------
> From: Henri Kovalainen <hekovala at lyseolukio2.kajaani.fi>
> To: synth-diy at mailhost.bpa.nl
> Subject: Re: Hmmm...Thomas Henry has vanished
> Date: Wednesday, December 23, 1998 5:01 PM
>  I would like to emphasize that the book is really useful *only if* you
>  have a source/money/time for all those CEMs and SSMs. Just about every
>  circuit in Henry's book uses them... I mean, come on, an ADSR eg that
>  utilizes a specific ADSR chip? Wouldn't have needed a book to built this
>  type of stuff, rather a data sheet. So, if you don't want to use a crap
>  load of custom chips, the book is a big disapponitment.




From jlarryh at iquest.net  Thu Dec 24 11:27:49 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Thu, 24 Dec 1998 04:27:49 -0600
Subject: list - o - books
Message-ID: <199812240922.KAA24031@mailhost.bpa.nl>

Great idea !!

----------
> From: Magnus Danielson <magnus at analogue.org>
> Cc: synth-diy at mailhost.bpa.nl
> Hmm, I got this little organising-mania hitting me from time to time,
> and I have noticed that this issue keeps poping up all the time. So, I
> sugest that maybe we aught to compile a page with books which is
> usefull for the DIYer....<<<..snip..>>>...



From chordman at flash.net  Thu Dec 24 11:23:07 1998
From: chordman at flash.net (Scott Gravenhorst)
Date: Thu, 24 Dec 98 11:23:07
Subject: FatMan Pic (cheesey) Online
Message-ID: <199812241922.NAA22991@endeavor.flash.net>

The FatMan list appears to be down...

Anyway, I took a quick vid cap to produce a cheesey shot of my FatMan's
front panel.  I will post more of the back of it where the "hairball"
lives sometime over the weekend.

Have a look if you like at:

www.teklab.com/~chordman/frontpanel.jpg

-- Scott Gravenhorst
-- RedWebMail by RedStarWare
-- FatMan Site: www.teklab.com/~chordman
-- Linux Rex, Linux Vobiscum

	





From hallgeir at ovation.musicpower.net  Thu Dec 24 17:58:46 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Thu, 24 Dec 1998 17:58:46 +0100
Subject: Merry Christmas!
Message-ID: <199812241709.SAA18311@louise.netpower.no>

Hi,

A short note from me saying:
Merry Christmas and best of wishes!

Hallgeir



From mark at spooky-solutions.co.uk  Thu Dec 24 19:08:47 1998
From: mark at spooky-solutions.co.uk (Mark Havard-Brown)
Date: Thu, 24 Dec 1998 18:08:47 -0000
Subject: Mixer opamp, which one?
Message-ID: <000501be2f68$8c282ce0$1b8e93c3@spookymb>

All,

I'm planning to add an 8 (or more) channel stereo mixer to my modular and
have been going throught the various schematics I have. In many of them the
designer has used a TL071 as the opamp of choice. On checking a 4-channel
mixer I presently have, the builder has used a TL081. The datasheet I have
on the TL071 specifys the devices noise distortion, whereas there is no
mention of the subject on the TL081 datasheet, (both sheets are from
Motorola). Question, which is the better to use?

Additionally, the designs I have do not use more than six inputs. Are there
any issues with the number of channels one just "bolts" onto the input of
the opamp"?

Any advise would be welcome.

Merry Chrismas to you all.



Mark.




From magnus at analogue.org  Fri Dec 25 00:54:04 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Fri, 25 Dec 1998 00:54:04 +0100
Subject: The Expressionist, a review
In-Reply-To: Your message of "Thu, 24 Dec 1998 18:52:18 -0800"
References: <3682FDE2.3563@swipnet.se>
Message-ID: <199812242354.AAA20104@mail2.it.kth.se>

>>>>> "B" == BJ  <zzynt at swipnet.se> writes:
  
 >> The code for this machine is all in an FPGA, meaning that you can down
 >> load, from Encore's website (http://www.encoreelectronics.com),

 B> In a FPGA?????
 B> That is strange , are you sure on this , perhaps you ment "Flash" or
 B> EEPROM!!

That would be Flash, this is what Encore's webpage says.

Cheers,
Magnus



From zzynt at swipnet.se  Fri Dec 25 03:03:06 1998
From: zzynt at swipnet.se (BJ)
Date: Thu, 24 Dec 1998 18:03:06 -0800
Subject: Henry's book and DIY flaming
References: <000e01be2ed5$966d2680$a91388cf@paults>
Message-ID: <3682F25A.6899@swipnet.se>

Paul Schreiber wrote:
> 
> Perhaps a little TOO harsh. There are 35 articles in the book.
> Only 9 use SSM or CEM chips. Of those, 4 use CEM3330
> or CEM3320 which are still available (especially the 3320!!)
> 
> 5 out of 35 is a good ratio to me!
> 
> There are a couple of SAD-1024 BBD articles, but you can use the
> MN3xxx series BBDs from Panasonic (from www.digikey.com).
> 
> Paul Schreiber

Regarding to books back in 82/84 when i purcased Barrys book
it was the only one proffesional writen and in fact the only
books about music synthesis available here in scandinavia.

The only other books was those dreadful "non working things"
from bernard babbani and its writer, M K Berry!!

One of the wery few other sources among magazines was ETI.

Therefore i think we shall be greatful that any one take the 
effort to write a  book, even a porly written (M K,Berry)one.

At least you can put it under your wobbling desk!! 

BJ



From zzynt at swipnet.se  Fri Dec 25 03:52:18 1998
From: zzynt at swipnet.se (BJ)
Date: Thu, 24 Dec 1998 18:52:18 -0800
Subject: The Expressionist, a review
References: <v04003a02b2a6526da64b@[208.255.84.142]>
Message-ID: <3682FDE2.3563@swipnet.se>

Rob wrote:

> 
> Inside there's a 68k of some sort controlling the whole machine. 

Which one , a 68302,68332,68HC12 etc ???



> choice for such a box. It's got power for days for this job and isn't
> likely to ever be bogged down by the requests of the user.  Many boxes made
> these days put the cheepest processor in the box that they can get away
> with and that is fine for 80% of the uses of the box.  The manufacture
> saves money and the box is cheeper.  But then when you push those boxes you
> get timing errors.  Timing errors are the bane of beat oriented musician.
> With the 68k the Expressionist wont have this problem.

Thats not all of the truth, it depends on what the box have to do,
LFO's,HZ/volt etc
and it depends on how well written the code is.
 
> The mother board is layed out with separate power supplies for the
> processor and the analogue circuits.  This is important because it keeps
> processor noise from effecting your CVs.  Again this costs more and most
> manufactures wont include this on their machines. 

Ouch!! costly!!
But there is up to the PCB designer to do a good power layout if
mixed technology are used, usally a +/-1 mV of power noise 
are not causing any problems ! :)

> What effect does this
> have on using the box?  Well you don't have to worry about sending a
> command to the box that will cause a voice that you are holding to go out
> of tune.

> The D/A convertor on the Expressionist is 16 bit. 

Wich one??

> This allows for smooth
> control of your voltages from -3 to +10 volts, more then 32,000 steps. I
> don't know what the other midi to CV boxes are using (I'm sure you can find
> out though), but this seems to be yet another place where the Expressionist
> has done the job right.

Many boxes uses 8 bitters infact,and then you have to use multiturn
pots to set the scaling of the CV. many boxes uses 12bitters (as mine
does).
Most 12 bitters uses software scaling of the CV's, depending on the
range
the DAC has to work at, 0 to + 8volt as a example. 
And as you say some uses 16 bitters. 

For any modular or regular synths using 1/v oct 12 bit is more then
enough
for any unit using HZ/v then 12 bits will do up to a sertain voltage
range.
If software scaling is still to be used. 16 bits is of course the best
solution
but then you have to do a very good powersupply (ground path) for not to
lose 
any bits in the converter due to noise.
  
> The code for this machine is all in an FPGA, meaning that you can down
> load, from Encore's website (http://www.encoreelectronics.com),

In a FPGA?????
That is strange , are you sure on this , perhaps you ment "Flash" or
EEPROM!!

> The whole user interface has been given a lot of thought. For instance the
> buttons have great debounce code. This means that they don't double trigger
> when you press them. After many years of use this becomes even more
> important as the switches start to fail, and yes all switches wear out.

Hmm, any synth and for that matter Midi to CV converters who uses 
momentary buttoms has debounch code applied in the software in some
form so that i dont think this is a reference for "qualiy factor" to
use.
And how can you know that the debounce code is great?? Have you
dissasemble the code???
 
> The buttons also repeat as you hold them and will speed up if you hold them
> for a moment.  Very nice indeed, but there's more too.  Hold one button and
> tap another will take you to the end of the allowable values.  Very trick.
> There's more here too, but you get the idea. Somebody though about using
> this box.

Nice function implemented!
 
> Pitch bend only goes 1 octave.  This seems a bit arbitrary to me. 

Most converters use this range ,due to the fact that most manufacturers
only decode the 7 bits of the pitch bend midi code.

> the great things about a CV synth is that there is no real difference from
> a voltage received from a pitch bend or a new note.  So you can have some
> really wild pitch bending going on. This would require some boundry code,
> but it's something that could be implemented.
 
> The wall wart, I hate, but Encore is a one person shop.  Every thing is
> done by one guy.  The hardware, software, testing, shipping - every thing!
> So taking the wall wart rout saved him lots of FCC and UL hassle.

Keep on the good work!!
 
>Would I buy one? Yeah I already did. Encore is known for making quality
>products.  The Expressionist does them proud. If you are serious about what
>you are doing and want some serious control over your CV machines then this
>is the box.

Thanks for the review!
I to think Encores CV converter is among the best, sad its "wery"
expensive here!

BJ



From jhaible at primus-online.de  Fri Dec 25 04:40:01 1998
From: jhaible at primus-online.de (jhaible)
Date: Fri, 25 Dec 1998 04:40:01 +0100
Subject: VP330 human voice
Message-ID: <19981225034000.1452.qmail@nuernberg2.pop.metronet.de>

Hi,

I hope you have a nice Christmas !

I have just finished the filter bank of the Roland Vocoder Plus
"Human Voice" section.

I haven't built the divider circuit, nor the chorus section. So I tested
with
a 1-VCO /w vibrato sound from the OB-8 and my clone of the JX3P chorus.
It really sounds impressive. (And I thought my Lambda was good in choir
sounds already !)

The VP330 has special waveforms to feed the filter bank: The 8' is an
exponential saw wave, and the 4' is a truncated expo saw wave. I couldn't
exactly duplicate this yet. But I got good results with slightly
LP-filtered
saw wave and pulse wave with 1/4 ... 1/5 pulse width. (quite critical. More
narrow, or broader pw's sound bad.)

JH.



From theremin1 at worldnet.att.net  Fri Dec 25 06:29:22 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Thu, 24 Dec 1998 21:29:22 -0800
Subject: Fw: Mixer opamp, which one?
Message-ID: <004201be2fc7$882b77a0$e1744e0c@hpcustomer>



>MH:
>
>>All,
>>
>>I'm planning to add an 8 (or more) channel stereo mixer to my modular and
>>have been going throught the various schematics I have. In many of them
the
>>designer has used a TL071 as the opamp of choice. On checking a 4-channel
>>mixer I presently have, the builder has used a TL081. The datasheet I have
>>on the TL071 specifys the devices noise distortion, whereas there is no
>>mention of the subject on the TL081 datasheet, (both sheets are from
>>Motorola). Question, which is the better to use?
>
>AH:
>
>According to the original manufacturer, Texas Instruments, "The JFET-input
>operational amplifiers in the TL07x series are designed as low-noise
>versions
>of the TL08x series amplifiers."
>Typically, Vn=18 nV/Hz at f =1kHz for the TL07x parts.
>
>http://www-s.ti.com/sc/psheets/slos080d/slos080d.pdf,
>page 7 has table data for TL07x noise characteristics
>page 13 has a graph of "Equivalent input noise voltage vs Frequency"
>
>http://www-s.ti.com/sc/psheets/slos081d/slos081d.pdf,
>page 9 has table data for TL08x noise characteristics
>page 17 has a graph of "Equivalent input noise voltage vs Frequency"
>
>The chart and graph data is the same for both parts, so I do not know
>why TI claims that the TL07x parts are better for noise.
>
>I conjecture that these are identical die, perhaps tested for different
>criteria.  (There are some types of specifications given for one part,
>and not the other.)
>
>If you breadboard a channel with a socket, you may want to compare several
>different op amps for noise.  There are some parts with better noise
>specifications
>than the TL07x available, these days.  For example, see:
>http://products.analog.com/products/info.asp?product=AD797 for the AD797.
>Keep in mind that circuit impedances have a direct impact on noise
>performance
>for op amps, and that the actual design, not just the op amp type, must be
>optimized
>for obtaining the lowest noise.
>
>MH:
>
>>Additionally, the designs I have do not use more than six inputs. Are
there
>>any issues with the number of channels one just "bolts" onto the input of
>>the opamp"?
>
>>Any advise would be welcome.
>
>AH:
>
>Good layout in important.  A PCB with planes for ground, Vcc and Vee is
>ideal.
>
>Merry Christmas to all!
>
>-Art
>




From zzynt at swipnet.se  Fri Dec 25 09:37:02 1998
From: zzynt at swipnet.se (BJ)
Date: Fri, 25 Dec 1998 00:37:02 -0800
Subject: The Expressionist, a review
References: <368297B8.64E7D2B8@usa.net>
Message-ID: <36834EAE.763C@swipnet.se>

Cary Roberts wrote:
> 
> >Which one , a 68302,68332,68HC12 etc ???
> 
> 68000
> 
> >Thats not all of the truth, it depends on what the box have to do,
> >LFO's,HZ/volt etc and it depends on how well written the code is.
> 
> I think the 68000 was a good choice.  It's no more costly than a 6811
> or Z80 or 8051.

It may and may not be a good choice because you would need  
separate UART IC, a buss ACK/ready cirquit, and some extras additionals.

And you canot compare a Z80 to a 6811 to a 68K,its completely
in different ballparks in the price range for example.

The 6811 is a MCU the Z80 and 68k is CPU's.
The Z80 lacks many instructions and adress modes who makes it
slow compared to a 6811,8051, 68k.

The 6811 is wery efficent for controll things.
 
> >Ouch!! costly!!
> >But there is up to the PCB designer to do a good power layout if
> >mixed technology are used, usally a +/-1 mV of power noise
> >are not causing any problems ! :)
> 
> The power supply section has separate voltage regulators and filter
> caps.  That's good practice, the orginal poster made it sound like
> they were totally separate, they are not.

It doesn't matter, if the power and ground layout of the PCB is laid out
in the wrong way so the return currents (as discussed erlier on this
list)
takes the wrong path to the summing node.
 
> >> The D/A convertor on the Expressionist is 16 bit.
> >Which one??
> 
> I can't remember off the top of my head, but it was either a Sony or
> a Burr Brown.

OK!
 
> >Many boxes uses 8 bitters infact,and then you have to use multiturn
> >pots to set the scaling of the CV. many boxes uses 12bitters (as mine
> >does).
> >Most 12 bitters uses software scaling of the CV's, depending on the
> >range
> >the DAC has to work at, 0 to + 8volt as a example.
> >And as you say some uses 16 bitters.
> 
> It takes at least six bits to do a 64 note 1v/oct scale.  8 bit only
> leaves .25 semitone accuracy.  That is pathetic at best. 

No i dissagree, it depends on the linearity of the DAC too, both PAIA
and Roland MPU401 and others uses 8 bit with exelent results.
 
> 12 bit ups
> that to 1/64 semitone accuracy, which while good, can still cause beats
> between identically tuned voices.  With a 16 bit D/A Tony Karavidas
> (the designer) was able to handle note, pitchbend, modulation, and
> scale adjust with just one D/A conversion. 

Still, it depends on the voltage range the converter has to cope with.
My Midi CV converter do that to in just one D/A mux update conversion.
It depends how well the code is written too.

With a 16 bitter for a 10 volt range we are down to 0.152mV
a DA stept, this is far below the offsett voltage on a high quality
OP amp. 

I would arugmenting that its extremely difficult to get this kinda
low AC noise voltage in a odinary power supply as a 16 bit DA are
kapable of!

> Older boxes (and some  current  ones too) use separate D/A cycles
> for both note and modulation.  That
> can induce error in the summing amp and allows for more droop error
> due to the extra demux/S&H channel.

??? I dont understand what you are talking about here??
Usually you do all the calculations in the CPU and then output a
"complete" CV voltage to the mux cannel who has to be uppdated.
This CV voltage contains all MIDI information selected to this
specific CV channel, then its just up to the CPU to keep
the CV channel refreshed so it would not lose the voltage and start
drifting. 

I dont see the picture where you have a summing amp?
A 68k 8Mhz CPU has the power to uppdate more then 128 CV channels
and do some heavy syntheis callculations at the same time without any
Mux doppouts.
 
> >In a FPGA?????
> >That is strange , are you sure on this , perhaps you ment "Flash" or
> >EEPROM!!
> 
> There's a PIC in there, I don't remember an FPGA.  I could be wrong.
> It definitely stores the operating system and parameters in
> FLASH/EEPROM.

What does the PIC doing in there?
 
> >Thanks for the review!
> >I to think Encores CV converter is among the best, sad its "wery"
> >expensive here!
> 
> Not only is Encore's CV box an exceptional product, the MIDI retrofits
> are outstanding too.  They replace the original processor and ROM with
> a new board, (relocated) processor, ROM, RAM, and UART.  This
> is a FAR BETTER route than Kenton takes.  I highly recommend the kits.

Kenton uses loads of electronics to do the things to be done(at least in
the older models)

BJ



From edusilva at bahianet.com.br  Fri Dec 25 15:02:17 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Fri, 25 Dec 1998 12:02:17 -0200
Subject: IL300 Linear Optocoupler
Message-ID: <199812251517.NAA18964@postman.bahianet.com.br>

Thanks to all the replies about the H11F1. Maybe I should try another one:
how about the Siemens IL300 Linear Optocoupler (one LED and two
photodiodes)? The synth apllications are not obvious, but seems to be
interesting.

Any ideas?

Datasheet:
http://www.siemens.de/semiconductor/products/37/pdf/il300.pdf

Tips:
http://www.siemens.de/semiconductor/products/37/pdf/app50.pdf
http://www.siemens.de/semiconductor/products/37/pdf/app54.pdf

Happy New Year!

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From ben at stuyts.nl  Fri Dec 25 19:00:47 1998
From: ben at stuyts.nl (Ben Stuyts)
Date: Fri, 25 Dec 98 19:00:47 +0100
Subject: Where to get keyboard/controller mech. parts?
Message-ID: <199812251800.TAA00252@daneel.stuyts.nl>

Hello,

My first post here. Very interesting list!

I need some additional modulation controls for my setup, and I thought it  
might be fun to make something like that myself. Might even add a simple  
keyboard, so that it becomes sort of a master keyboard.

I was wondering if there is a place (preferable in the Netherlands or close)  
where one can get modulation wheels, ribbon controls, and other mechanical  
keyboard parts. I did a search on the web, but couldn't find anything. Only  
complete master keyboards, etc.

Thanks,
Ben



From hallgeir at ovation.musicpower.net  Fri Dec 25 19:29:09 1998
From: hallgeir at ovation.musicpower.net (Hallgeir Helland)
Date: Fri, 25 Dec 1998 19:29:09 +0100
Subject: Keyboard scanner hints
Message-ID: <199812251838.TAA25499@louise.netpower.no>

Hello everyone,

Can someone direct me towards a brief explanation
of the principle of the type of polyphonic digitally
scanned keyboard controller found in for example 
the Prophet 5 and the eight-voice?

Thanks,
Hallgeir



From synth1 at airmail.net  Sat Dec 26 00:26:16 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Fri, 25 Dec 1998 17:26:16 -0600
Subject: Keyboard scanner hints
Message-ID: <000c01be305e$0a8fae00$971488cf@paults>

Here is an GENERAL overview.

First, you have to figure out which keys are up & which are
down. There are 2 ways of doing this.

The first way is "serially". (this is done on the Synergy, for example).
The keyboard MUST have a common busbar for key DOWN and
individual switches for each key. You attach a 'pullup' resistor to each key
(A 10K SIP pack is perfect for this) and attach the bussbar to GROUND.

Next, you get say 9ea 74HC151 8:1 muxes (about 50 cents each). These parts
act like a 8 position
rotary switch, based on a 3-bit digital input. Assuming a 61-note keyboard,
you
take 8 of the '151s (8x8=64, 3 left over) and attach 1 key to 1 mux input.
All of
the select inputs (A, B, C) are bussed together. Lastly, you take the 8 mux
outputs,
and tied each one of THOSE to the 8 mux inputs of the 9th '151. Whew!!!!

OK, now we are cooking! we have a 2-tier scanner, that needs 6 bits of
"address"
to "look" at each key, ONE AT A TIME. You can scan with a uP, you can scan
with 2ea 74HC161
counters (50 cents each). You connect the 3 LOWER address bits to the 8
bussed selects, and the 3 UPPER
address bits the the 9th '151.

So to "look" at a key, all you have to do is "address" it (000000 is the
leftmost key, 000001 the next one, 111111 the
rightmost) and if the output of the 9th '151 is a LOW, that key is DOWN.
(otherwise, it's a HIGH because
we pulled it up, remember???)

Now, if we want to get REAL clever, we can add velocity sensing in BOTH key
down & key up. How??
What you do is have 2 bussbars: one common for keys UP and 1 common for keys
DOWN. Then you
attach BOTH busbars to ground!!! So, what happens is that the "addressed"
keys start by reading a '1',
then they read a '0' AS THEY ARE TRAVELLING BETWEEN BUSBARS, then they read
a '1' again!!!
So, all your uP or circuitry has to do is TIME how long it read a '0' for
each key. Of course, you have to
assume that on power-up initialization, you don't freak out the logic by
HOLDING KEYS DOWN!! That of
course will read the scans 'backwards' for velocity.

I built a monophonic keyboard with low-note priority (ie Moog) using this
scheme. No uP: about $7 worth of
TTL chips. It used a 6-bit counter, that was latched in a 74LS273 when the
key down signal arrived. A 10-bit
DAC was used to for the CV. The GATE output was a simple flip-flop, and the
TRIGGER was a 555 timer
that "stretched" the key down signal. I scanned EACH key about 28 times a
second with another 555 timer.

The second way (what you would do today, most likely) is use a MARTIX SCAN.
The surplus keyboards
(like the Panasonic rubber dome types) are pre-wired in an 8 x 8 matrix with
blocking diodes.
A uP sets up 1 8-bit OUT port and 1 8-bit IN port. You then output a
"walking 1" pattern
(00000001, 00000010, 00000100, etc) that "scans" a set of 8 common keys. If
a '1' shows up at the IN port,
that key is DOWN.

Again velocity is a matter of keeping a table of "hey, the key changed
states for N scan times, then it stopped".
If you can each "column" every 1ms then you can quantize the velocity in 8ms
steps.

Hope this sheds some light!!

Paul Schreiber
Synthesis Technology
www.synthtech.com







From jhaible at primus-online.de  Sat Dec 26 02:08:43 1998
From: jhaible at primus-online.de (jhaible)
Date: Sat, 26 Dec 1998 02:08:43 +0100
Subject: Keyboard scanner hints
Message-ID: <19981226011154.17519.qmail@nuernberg2.pop.metronet.de>

> Now, if we want to get REAL clever, we can add velocity sensing in BOTH
key
> down & key up. How??
> What you do is have 2 bussbars: one common for keys UP and 1 common for
keys
> DOWN. Then you
> attach BOTH busbars to ground!!! So, what happens is that the "addressed"
> keys start by reading a '1',
> then they read a '0' AS THEY ARE TRAVELLING BETWEEN BUSBARS, then they
read
> a '1' again!!!
> So, all your uP or circuitry has to do is TIME how long it read a '0' for
> each key. Of course, you have to
> assume that on power-up initialization, you don't freak out the logic by
> HOLDING KEYS DOWN!! That of
> course will read the scans 'backwards' for velocity.

But what if one key is not completely pressed down, and then released again
??
Why not use the scanner to *feed* a "high" into the keys, one by one, and
then
use the two bus bars to *read out* the value ?

JH.



From magnus at analogue.org  Sat Dec 26 05:29:43 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Sat, 26 Dec 1998 05:29:43 +0100
Subject: Books relating to Synth-DIY etc.
Message-ID: <199812260429.FAA06306@mail2.it.kth.se>

Hi!

I have now put some work into compiling a web-page with reference to a
number of books.

This list is the joint effort of friendly Synth-DIYers and
Jerry Federspiel (a newcommer to the list) for compiling a summary of
the thread on books that appeared lately.

I throwed in a number of books that I throught where missing but in one
way or another could be usefull.

You can find this page on:
http://www.it.kth.se/~e93_mda/synths/books.html

Any more details on a book in there is needed, any more hints on books
to include, comments on books etc. is as allways very wellcome.

One VERY good way to get a book in there is to send me a copy ;^)
(OK, it was a shameless try, but you can't blame me for trying)

I am considering grouping books together into some categories.

Enjoy,
Magnus



From theremin1 at worldnet.att.net  Sat Dec 26 07:17:07 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Fri, 25 Dec 1998 22:17:07 -0800
Subject: IL300 Linear Optocoupler
Message-ID: <001201be3097$5e8015c0$11764e0c@hpcustomer>

The linearization method shown in the Siemens data sheet is very effective
for many applications.  A similar technique may be employed with the two
matched sections of a LM13600 to make all kinds of precision filters and
VCAs.

-Art

-----Original Message-----
From: Edu Silva <edusilva at bahianet.com.br>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Friday, December 25, 1998 8:34 AM
Subject: IL300 Linear Optocoupler


>Thanks to all the replies about the H11F1. Maybe I should try another one:
>how about the Siemens IL300 Linear Optocoupler (one LED and two
>photodiodes)? The synth apllications are not obvious, but seems to be
>interesting.
>
>Any ideas?
>
>Datasheet:
>http://www.siemens.de/semiconductor/products/37/pdf/il300.pdf
>
>Tips:
>http://www.siemens.de/semiconductor/products/37/pdf/app50.pdf
>http://www.siemens.de/semiconductor/products/37/pdf/app54.pdf
>
>Happy New Year!
>
>_____________________
>Edu Silva - ES2 Audio
>Salvador-Bahia-Brazil
>




From Aranakin at aol.com  Sat Dec 26 07:23:36 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Sat, 26 Dec 1998 01:23:36 EST
Subject: a good book that i have enjoyed...
Message-ID: <d15821e0.368480e8@aol.com>

i've been reading this book as a text book in my PCB fabrication class at
school (Cal Poly Pomona) and i find that it gives a ton on the making of
PCB's,chassis building, etc... anything in that realm is covered in great
amounts of detail...
it's called "Electronic Techniques - Shop Practices and Construction (Sixth
Edition)"
by Villanucci, Avtgis, and Megow


for more info, the publishers have a site : www.prenhall.com

Merry CHRISTmas
anthony



From IXQY at aol.com  Sat Dec 26 12:22:07 1998
From: IXQY at aol.com (IXQY at aol.com)
Date: Sat, 26 Dec 1998 06:22:07 EST
Subject: Keyboard scanner hints
Message-ID: <4ab4f4c0.3684c6df@aol.com>

In a message dated 98-12-25 18:29:30 EST, synth1 at airmail.net writes:

<< I built a monophonic keyboard with low-note priority (ie Moog) using this
 scheme.   >> 

 Hello,
  I was wondering if it is possible (without too much modification) to convert
a poly synth like the Oberheim OBXa (in unison mode) or a mono Moog Source to
respond to high or last note priority instead of low note priority.
 I'm more accustomed to either last-note or high note triggering schemes and
would be interested in changing this aspect of these two synths. Is this a
difficult thing to do?
 Thank you very much for any input you may give.

 Happy holidays,
 Andrew Sanchez



From mark at spooky-solutions.co.uk  Sat Dec 26 13:57:01 1998
From: mark at spooky-solutions.co.uk (Mark Havard-Brown)
Date: Sat, 26 Dec 1998 12:57:01 -0000
Subject: Headphone amp
Message-ID: <000301be30cf$3b95f740$708d93c3@spookymb>

All,

Does anyone have a stereo headphone module circuit?

I'd like to put one into the modular and not have to keep powering up the
mixing desk and amp every time I won't to "tweek".



Mark.




From djblue at asu.edu  Sat Dec 26 15:33:56 1998
From: djblue at asu.edu (Reverend bluE)
Date: Sat, 26 Dec 1998 07:33:56 -0700 (MST)
Subject: newbie with some questions.
In-Reply-To: <000301be30cf$3b95f740$708d93c3@spookymb>
Message-ID: <Pine.GSO.3.96.981226072845.611D-100000@general1.asu.edu>


Hi, I'm totally new to building circuits, let alone building synths, so I have
some questions.  

I'm trying to build a modular type system, ground up.
I've finished my power supply (-+15vDC) and it works great (except I blew out
the LED's).  

I've been trying to find schematics for simple VCO's that don't need hard to
find parts (or at least parts that I have to order).  I'm in Phoenix AZ, so
there are a lot of shops that sell components, but I'm not sure of what to
get.  Every schematic that I've found has at least one or two parts that I
can't locate yet.  well.  I dunno.  

I guess I'm just looking for some tips and pointers, and maybe some easy VCO
schematics...

By the way, my name is ben, and I'm glad that this list exists.  It seems cool
so far..

:)
-ben




From hhelland at usa.net  Sat Dec 26 16:20:14 1998
From: hhelland at usa.net (Hallgeir Helland)
Date: Sat, 26 Dec 1998 16:20:14 +0100
Subject: The Digital Keyboard Scanner....
Message-ID: <3684FEAD.14DBE663@usa.net>

Hello all,

Thanks for a lot of keyboard info.
However, I obviously missed the long, deep ones.
My e-mail account was having a bad day.
Got a new one. I'm much happier now.
Praps someone will care to send me the replys
over again (pleeease....), maybe privately?
Here's the new one, see...

hhelland at usa.net

Thanx-a-lot,
Hallgeir





From edusilva at bahianet.com.br  Sat Dec 26 17:29:30 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sat, 26 Dec 1998 14:29:30 -0200
Subject: Headphone amp
Message-ID: <199812261648.OAA06579@postman.bahianet.com.br>

> De: Mark Havard-Brown <mark at spooky-solutions.co.uk>
> Para: Synth-DIY <synth-diy at mailhost.bpa.nl>
> Assunto: Headphone amp
> Data: S?bado, 26 de Dezembro de 1998 10:57
> 
> All,

Hi!
 
> Does anyone have a stereo headphone module circuit?
 
Yes.

> I'd like to put one into the modular and not have to keep powering up the
> mixing desk and amp every time I won't to "tweek".
> 
> Mark.

Try this:
http://www.paia.com./headbuff.htm

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From edusilva at bahianet.com.br  Sat Dec 26 18:29:30 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sat, 26 Dec 1998 15:29:30 -0200
Subject: The Digital Keyboard Scanner....
Message-ID: <199812261731.PAA00696@postman.bahianet.com.br>

I'm sending privately the replies from Paul Schreiber, Juergen Haible and
Andrew Sanchez.

There's a copy of an article from Elektor with a schem of a digital
keyboard at Anders Sponton page:
http://www.tellus.vallentuna.se/gymninfo/personal/anders/andersus.html
It's the Elektor Polysynth, think it can be useful.

Bye,
Edu

_____________________
Edu Silva = ES2 Audio
Salvador-Bahia-Brazil

----------
> De: Hallgeir Helland <hhelland at usa.net>
> Para: DIY <synth-diy at mailhost.bpa.nl>
> Assunto: The Digital Keyboard Scanner....
> Data: S?bado, 26 de Dezembro de 1998 13:20
> 
> Hello all,
> 
> Thanks for a lot of keyboard info.
> However, I obviously missed the long, deep ones.
> My e-mail account was having a bad day.
> Got a new one. I'm much happier now.
> Praps someone will care to send me the replys
> over again (pleeease....), maybe privately?
> Here's the new one, see...
> 
> hhelland at usa.net
> 
> Thanx-a-lot,
> Hallgeir
> 



From pjson at pacbell.net  Sat Dec 26 18:52:48 1998
From: pjson at pacbell.net (Kirke Sonnichsen)
Date: Sat, 26 Dec 1998 09:52:48 -0800
Subject: VP330 human voice
Message-ID: <v02130501b2aad28c29a1@[206.170.3.7]>

Is there a site I could go to download some examples
of this impressive DIY feat?

- Kirke
(what about the korg ks)


>Hi,
>
>I hope you have a nice Christmas !
>
>I have just finished the filter bank of the Roland Vocoder Plus
>"Human Voice" section.
>
>I haven't built the divider circuit, nor the chorus section. So I tested
>with
>a 1-VCO /w vibrato sound from the OB-8 and my clone of the JX3P chorus.
>It really sounds impressive. (And I thought my Lambda was good in choir
>sounds already !)
>
>The VP330 has special waveforms to feed the filter bank: The 8' is an
>exponential saw wave, and the 4' is a truncated expo saw wave. I couldn't
>exactly duplicate this yet. But I got good results with slightly
>LP-filtered
>saw wave and pulse wave with 1/4 ... 1/5 pulse width. (quite critical. More
>narrow, or broader pw's sound bad.)
>
>JH.





From theremin1 at worldnet.att.net  Sat Dec 26 19:15:25 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 26 Dec 1998 10:15:25 -0800
Subject: Headphone amp
Message-ID: <004001be30fb$b6af0300$bc744e0c@hpcustomer>

http://www.national.com/krkDir/parametric_table/0,1817,799-c2-1,00.html
has a table of National Semiconductor's audio amplifier offerings.  Most of
these parts are designed for low voltage, and are in microscopic packages.

In some cases, a dual op-amp such as the National LM833N or Phillips NE5532N
is adequate as a stereo headphone driver, if you don't require very high
volumes.
They're compatible with +/-15v supplies, and easy to apply.

For high-loudness applications, I've used the Apex PA26 dual power amp in a
SIP
package to drive low-Z headphones with good results.
See:  http://www.theriver.com/apexmicrotech/pdf/power_op_amps/pa212526.pdf

BTW, I recommend building in at least two output jacks, preferably with
independent
volume and balance controls.  That makes it easy to share your sounds with
friends.

-Art

-----Original Message-----
From: Mark Havard-Brown <mark at spooky-solutions.co.uk>
To: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 26, 1998 5:56 AM
Subject: Headphone amp


>All,
>
>Does anyone have a stereo headphone module circuit?
>
>I'd like to put one into the modular and not have to keep powering up the
>mixing desk and amp every time I won't to "tweek".
>
>
>
>Mark.
>
>




From varner at k-online.com  Sat Dec 26 19:17:19 1998
From: varner at k-online.com (Steve Varner)
Date: Sat, 26 Dec 1998 10:17:19 -0800
Subject: Books relating to Synth-DIY etc.
References: <199812260429.FAA06306@mail2.it.kth.se>
Message-ID: <3685282E.A91D235@k-online.com>

There are some DIY bibliographies on the Music Machines web site. You may
want to check these out for more info on the books you listed (publisher,
dates, etc.) as well as to find additional books.

http://www.hyperreal.org/music/machines/categories/DIY/books/

SV

Magnus Danielson wrote:

> Hi!
>
> I have now put some work into compiling a web-page with reference to a
> number of books.
>
> This list is the joint effort of friendly Synth-DIYers and
> Jerry Federspiel (a newcommer to the list) for compiling a summary of
> the thread on books that appeared lately.
>
> I throwed in a number of books that I throught where missing but in one
> way or another could be usefull.
>
> You can find this page on:
> http://www.it.kth.se/~e93_mda/synths/books.html
>
> Any more details on a book in there is needed, any more hints on books
> to include, comments on books etc. is as allways very wellcome.
>
> One VERY good way to get a book in there is to send me a copy ;^)
> (OK, it was a shameless try, but you can't blame me for trying)
>
> I am considering grouping books together into some categories.
>
> Enjoy,
> Magnus






From jlarryh at iquest.net  Sat Dec 26 19:34:14 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Sat, 26 Dec 1998 12:34:14 -0600
Subject: Books relating to Synth-DIY etc.
Message-ID: <199812261728.SAA06248@mailhost.bpa.nl>

> Magnus wrote:
> You can find this page on:
> http://www.it.kth.se/~e93_mda/synths/books.html
> 
> Any more details on a book in there is needed, any more hints on books
> to include, comments on books etc. is as allways very wellcome.
> 
> One VERY good way to get a book in there is to send me a copy ;^)
> (OK, it was a shameless try, but you can't blame me for trying)

Thanks Magnus !  I will plan to check it out.  As far as your "shameless
try," it
was good for the best chuckle for me so far today :)

Larry Hendry



From varner at k-online.com  Sat Dec 26 19:43:10 1998
From: varner at k-online.com (Steve Varner)
Date: Sat, 26 Dec 1998 10:43:10 -0800
Subject: Bypass cap's
Message-ID: <36852E3B.7B2321D7@k-online.com>

How many of you use bypass capacitors on your circuit designs?

Where do you put these in the circuit and what size caps do you use?
(5-10 microfarad?)

Is noise to and from the board via suply lines really that much of a
problem?

SV




From varner at k-online.com  Sat Dec 26 19:48:16 1998
From: varner at k-online.com (Steve Varner)
Date: Sat, 26 Dec 1998 10:48:16 -0800
Subject: Output of final signal
Message-ID: <36852F6D.280FD33F@k-online.com>

Survey question number 2:

After your signal goes out of a VCA, where do you all channel it? Do you
have an audio amp on your synth rack? Do you send the signal directly to
a home stereo receiver? Is is a good idea to have a master attenuator on
your system (the signals are generally +5V to -5V, which is pretty
"hot", not really audio levels!) Anyone have built in speakers as an
option?

SV




From Aranakin at aol.com  Sat Dec 26 19:55:13 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Sat, 26 Dec 1998 13:55:13 EST
Subject: Where can I get DPDT footswitches?
Message-ID: <7461399b.36853111@aol.com>

please, I can't find anywhere that has a phone number that sells heavy duty
DPDT footswitches.
I'm quite amazed at this, being that i would think that electronic stores that
have everything thing else in the world, don't have this....
as well as jameco and the likes...
gees...
please halp me out if you can..
anthony



From WeAreAs1 at aol.com  Sat Dec 26 20:05:39 1998
From: WeAreAs1 at aol.com (WeAreAs1 at aol.com)
Date: Sat, 26 Dec 1998 14:05:39 EST
Subject: Headphone amp
Message-ID: <7080bb94.36853383@aol.com>


In a message dated 12/26/98 5:01:21 AM, you wrote:

<<Does anyone have a stereo headphone module circuit?>>

There are several very nice headphone amp circuits to be found at 
Rane's most excellent website:     http://www.rane.com

Their entire schematics directory:    http://bsd.rane.com/pdf/

For their excellent six (stereo) channel studio headphone amp, the HC6:
	Owner's manual:  hc6man.pdf
	The schematic:  hc6sch.pdf    

Also, you could check out any of their DJ mixer products, all of which have
robust headphone amps built in.

Lots of other great stuff there, too.

Happy soldering,
Michael Bacich



From cyborg0 at GlobalEyes.net  Sat Dec 26 21:23:23 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sat, 26 Dec 1998 14:23:23 -0600
Subject: Where can I get DPDT footswitches?
References: <7461399b.36853111@aol.com>
Message-ID: <368545BB.587DC8A5@globaleyes.net>

Aranakin at aol.com wrote:
> 
> please, I can't find anywhere that has a phone number that sells heavy duty
> DPDT footswitches.
> I'm quite amazed at this, being that i would think that electronic stores that
> have everything thing else in the world, don't have this....
> as well as jameco and the likes...
> gees...
> please halp me out if you can..
> anthony

look at your average guitar pedal: it has a footswitch (SPST) that
triggers a flip-flop (well, not really a flip-flop but a discrete
transistor based flip-flop) this flip-flop feeds a couple of different
circuits that turn on or off the various elements of the pedal..
I would say you would be better off with the spst (cheaper) and using a
d-flop or something rigged up with the QNOT fed back into D, and the
switch switching CLK.. This would turn on Q with one hit of the pedal,
then the next hit will turn Q off, then next hit turn on Q, etc.. 

Rob (who has worked on more stupid gee-tar pedals than he wants to
admit)



From ka4hjh at gte.net  Sat Dec 26 21:32:43 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Sat, 26 Dec 1998 15:32:43 -0500
Subject: Keyboard scanner hints
In-Reply-To: <19981226011154.17519.qmail@nuernberg2.pop.metronet.de>
Message-ID: <v04011700b2aaf85e7b22@[208.255.152.139]>

>> Now, if we want to get REAL clever, we can add velocity sensing in BOTH
>key
>> down & key up. How??
>
>But what if one key is not completely pressed down, and then released again
>??

It'll just start trouble I'll say it anyway: this cries out for a
microcontroller. In fact, this is probably the one thing in an analog synth
that really would be easier and more elegant that way. And please, don't
ask me how. I'm up to my ears in development and troubleshooting right now.
I wish I could get to my HC11.

Terry Bowman, KA4HJH
"The Mac Doctor"



From cyborg0 at GlobalEyes.net  Sat Dec 26 21:42:55 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sat, 26 Dec 1998 14:42:55 -0600
Subject: Bypass cap's
References: <36852E3B.7B2321D7@k-online.com> <3685B5DA.4684@swipnet.se>
Message-ID: <36854A4F.61425082@globaleyes.net>

BJ wrote:
> 
> Steve Varner wrote:
> >
> > How many of you use bypass capacitors on your circuit designs?
> 
> All do!
> 
> > Where do you put these in the circuit and what size caps do you use?
> > (5-10 microfarad?)
> 
They need to be MUCH smaller than this, otherwise they will find a way
to oscillate using the leads of the cap..
rob



From magnus at analogue.org  Sat Dec 26 21:49:32 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Sat, 26 Dec 1998 21:49:32 +0100
Subject: Books relating to Synth-DIY etc.
In-Reply-To: Your message of "Sat, 26 Dec 1998 12:34:14 -0600"
References: <199812261728.SAA06248@mailhost.bpa.nl>
Message-ID: <199812262049.VAA09951@mail2.it.kth.se>

>>>>> "JLH" == J Larry Hendry <jlarryh at iquest.net> writes:

Hey, Larry!

 >> One VERY good way to get a book in there is to send me a copy ;^)
 >> (OK, it was a shameless try, but you can't blame me for trying)

 JLH> Thanks Magnus !  I will plan to check it out.  As far as your "shameless
 JLH> try," it
 JLH> was good for the best chuckle for me so far today :)

Happy to spread some joy ;)

Cheers,
Magnus




From edusilva at bahianet.com.br  Sat Dec 26 21:57:04 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sat, 26 Dec 1998 18:57:04 -0200
Subject: Where can I get DPDT footswitches?
Message-ID: <199812262141.TAA05680@postman.bahianet.com.br>

Do you know this?
http://www.stewmac.com/index.htm

Edu

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil

----------
> De: Aranakin at aol.com
> Para: synth-diy at mailhost.bpa.nl
> Assunto: Where can I get DPDT footswitches?
> Data: S?bado, 26 de Dezembro de 1998 16:55
> 
> please, I can't find anywhere that has a phone number that sells heavy
duty
> DPDT footswitches.
> I'm quite amazed at this, being that i would think that electronic stores
that
> have everything thing else in the world, don't have this....
> as well as jameco and the likes...
> gees...
> please halp me out if you can..
> anthony



From edusilva at bahianet.com.br  Sat Dec 26 23:59:37 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sat, 26 Dec 1998 20:59:37 -0200
Subject: Bypass cap's
Message-ID: <199812262301.VAA22091@postman.bahianet.com.br>

Steve Varner wrote:

> Where do you put these in the circuit and what size caps do you use?
> (5-10 microfarad?)

I do like this...

>From
power  (+)
supply >----100R----+---> to the
board               |     circuit (+)
                    |+
                  100uF
                    |-
                    |
                  ground

..... at the supply inputs of the PCB, and this...

>-----+------> IC supply
(+)   |        pin (+)
      |
    0.1uF
      |
      |
    ground

..... near each IC. Invert the polarity for the negative rail.

>Is noise to and from the board via suply lines really that much of a
>problem?

Sometimes. To be safe, (isn't an overkill...) place regulator IC's (7815
and 7915) at the supply rails of each circuit board. The main supply should
be at least 18 volts, to make things work.

You can find datasheets at:
http://www.national.com/catalog/AnalogRegulators.html

Have fun!
Edu

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From zzynt at swipnet.se  Sun Dec 27 00:08:11 1998
From: zzynt at swipnet.se (BJ)
Date: Sat, 26 Dec 1998 15:08:11 -0800
Subject: Headphone amp
References: <000301be30cf$3b95f740$708d93c3@spookymb>
Message-ID: <36856C5B.6033@swipnet.se>

Mark Havard-Brown wrote:
> 
> All,
> 
> Does anyone have a stereo headphone module circuit?
> 
> I'd like to put one into the modular and not have to keep powering up the
> mixing desk and amp every time I won't to "tweek".
> 
> Mark.

Have a look at :
http://home8.swipnet.se/~w-88660/schpcb.htm

And the headphone shemo and pcb , pdf files there!

BJ



From theremin1 at worldnet.att.net  Sun Dec 27 03:28:10 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 26 Dec 1998 18:28:10 -0800
Subject: newbie with some questions.
Message-ID: <000801be3140$8cdfd5a0$44794e0c@hpcustomer>

Hi Ben,

The often-referenced National Semiconductor AN-299 is viewable at:
http://www.national.com/an/AN/AN-299.pdf and has an exponential-response
VCO on page 1.  This is just be one possible starting point for VCO designs.
The list's members have quite a few designs of their own.

-Art


-----Original Message-----
From: Reverend bluE <djblue at asu.edu>
To: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 26, 1998 7:57 AM
Subject: newbie with some questions.


>
>Hi, I'm totally new to building circuits, let alone building synths, so I
have
>some questions.
>
>I'm trying to build a modular type system, ground up.
>I've finished my power supply (-+15vDC) and it works great (except I blew
out
>the LED's).
>
>I've been trying to find schematics for simple VCO's that don't need hard
to
>find parts (or at least parts that I have to order).  I'm in Phoenix AZ, so
>there are a lot of shops that sell components, but I'm not sure of what to
>get.  Every schematic that I've found has at least one or two parts that I
>can't locate yet.  well.  I dunno.
>
>I guess I'm just looking for some tips and pointers, and maybe some easy
VCO
>schematics...
>
>By the way, my name is ben, and I'm glad that this list exists.  It seems
cool
>so far..
>
>:)
>-ben
>




From mamundso at mr.net  Sun Dec 27 03:35:36 1998
From: mamundso at mr.net (Mark Amundson)
Date: Sat, 26 Dec 1998 18:35:36 -0800
Subject: Bypass cap's
References: <199812262301.VAA22091@postman.bahianet.com.br>
Message-ID: <36859CF8.6F2D@mr.net>

> Steve Varner wrote:
> > Where do you put these in the circuit and what size caps do you use?
> > (5-10 microfarad?)

That question is way easier asked than answered. Even analog engineers
get ruffled by proper use of bypass caps and supply layout issues
(especially ground loops). Here is a couple of my rules of thumb for
circuits a few inches or more from thier power supplies.

1. A cap of about 0.1uf (X7R or Z5U ceramic) is a good choice of analog
IC power supply decoupling (power to ground).

2. If you are dealing with higher frequency stuff as well (like radios,
D/A coverters, etc.) reduce this value to 0.01uf and keep the leads
short and layout tight.

3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
issues. Do not use these caps if you have regulated supplies and good
beefy wiring as they may cause more power supply hum than their curative
effects.

Mark Amundson,



From mamundso at mr.net  Sun Dec 27 03:48:13 1998
From: mamundso at mr.net (Mark Amundson)
Date: Sat, 26 Dec 1998 18:48:13 -0800
Subject: Headphone amp
References: <000301be30cf$3b95f740$708d93c3@spookymb> <36856C5B.6033@swipnet.se>
Message-ID: <36859FED.4366@mr.net>

> Mark Havard-Brown wrote:
> > All,
> > Does anyone have a stereo headphone module circuit?
> >
> > I'd like to put one into the modular and not have to keep powering up the
> > mixing desk and amp every time I won't to "tweek". Mark.

Consider using two of National Semiconductor's (www.natsemi.com) LM1875
Audio Power Amp ICs for driving one or more headphones from a +/- 15v
supply setup. With the modern recording style headphones with 30 or more
ohms of impedance, the extra watts (about 10) per channel can drive
several pairs or one pair of home audio headphones (8 ohms).

I built a dedicated one rack space headphone amp for a friend
demonstrating studio mics at the last AES show using the above idea, and
was a hit for great audio headroom. It bettered the Rane, Furman, and
Behringer type units for transient response and low noise.

The NE5532 idea is also good for 30 ohm or greater headphone
applications if critical listening is not needed.

Mark Amundson,



From theremin1 at worldnet.att.net  Sun Dec 27 04:01:52 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 26 Dec 1998 19:01:52 -0800
Subject: Bypass cap's
Message-ID: <002301be3145$418b3860$44794e0c@hpcustomer>

SV:

>How many of you use bypass capacitors on your circuit designs?

AH:

Used when needed, but their application must be evaluated for each case.

SV:

>Where do you put these in the circuit and what size caps do you use?
>(5-10 microfarad?)

AH:

Again, this depends on the circuit.  A typical 10uF aluminum electrolytic
may do
little to reduce supply transients or ringing at certain frequencies, due to
its inductance.
Often, a parallel combination of different capacitors are needed.  High
frequency
designs may require the use of ceramic chip caps connected as close as
possible
to both the IC's supply pin and a ground plane.  It is wise to consider the
capacitor's
self-resonant frequency to ensure that it acts like a capacitor at the
frequencies of
interest.  Generally, it doesn't hurt to incorporate a 0.01uF to 0.1uF
ceramic capacitor(s)
in each device socket, and a 10uF tantalum capacitor(s) at the board's power
entry.

SV:

>Is noise to and from the board via suply lines really that much of a
>problem?

AH:

Noise may be conducted or radiated, and must be evaluated not just in terms
of
the power supply currents in supply lines, but also within a circuit itself.
Decoupling
capacitors are never a cure-all for noise problems.
You must also consider proper load distribution, ground currents, and
shielding to
prevent noise problems.  Beside noise, bypass capacitors also address
requirements
for stability (i.e., preventing oscillations).

-Art




From cyborg0 at GlobalEyes.net  Sun Dec 27 04:10:46 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sat, 26 Dec 1998 21:10:46 -0600
Subject: Bypass cap's
References: <199812262301.VAA22091@postman.bahianet.com.br>
Message-ID: <3685A536.4556A0AF@globaleyes.net>

Edu Silva wrote:

> >Is noise to and from the board via suply lines really that much of a
> >problem?
> 
> Sometimes. To be safe, (isn't an overkill...) place regulator IC's (7815
> and 7915) at the supply rails of each circuit board. The main supply should
> be at least 18 volts, to make things work.
> 

The regulators are so cheap now, its really no problem to do this and
may save you many problems..

Rob



From cyborg0 at GlobalEyes.net  Sun Dec 27 04:15:19 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sat, 26 Dec 1998 21:15:19 -0600
Subject: PCM=PWM?
Message-ID: <3685A647.7E380E4C@globaleyes.net>

Is it true that pulse code modulation is the SAME as pulse width
modulation?
I always thought this was true, that the pulse code modulation just took
a simple square wave, and by shaping the pulse very quickly was able to
churn out sampled sounds..Basically, radically and quickly modulating
the pulse width of an existing wave form to generate all the needed
harmonics and such.

Rob



From zzynt at swipnet.se  Sun Dec 27 05:21:47 1998
From: zzynt at swipnet.se (BJ)
Date: Sat, 26 Dec 1998 20:21:47 -0800
Subject: Bypass cap's
References: <36852E3B.7B2321D7@k-online.com>
Message-ID: <3685B5DA.4684@swipnet.se>

Steve Varner wrote:
> 
> How many of you use bypass capacitors on your circuit designs?

All do! 
 
> Where do you put these in the circuit and what size caps do you use?
> (5-10 microfarad?)

As close to the "supply pin" as possible at the IC that needs to be
bypassed!
 
> Is noise to and from the board via suply lines really that much of a
> problem?

Regulary analogue designs "no", but in a mixed tech design "yes".




BJ



From jlarryh at iquest.net  Sun Dec 27 06:07:17 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Sat, 26 Dec 1998 23:07:17 -0600
Subject: LM317 question
Message-ID: <199812270401.FAA13740@mailhost.bpa.nl>

I am wanting to supply 9 +VDC @ 1 amp from a 12 VDC supply.  Would a LM317
be a good choice for this application?  All the schematics I have found
using a LM317 to supply an adjustable output voltage use more than 12 VDC
as the source voltage to the LM317.

Thanks,
Larry Hendry




From zzynt at swipnet.se  Sun Dec 27 08:00:37 1998
From: zzynt at swipnet.se (BJ)
Date: Sat, 26 Dec 1998 23:00:37 -0800
Subject: Books relating to Synth-DIY etc.
References: <199812260429.FAA06306@mail2.it.kth.se>
Message-ID: <3685DB15.789B@swipnet.se>

Magnus Danielson wrote:
> 
> Hi!
> 
> I have now put some work into compiling a web-page with reference to a
> number of books.
> 
> This list is the joint effort of friendly Synth-DIYers and
> Jerry Federspiel (a newcommer to the list) for compiling a summary of
> the thread on books that appeared lately.
> 
> I throwed in a number of books that I throught where missing but in one
> way or another could be usefull.
> 
> You can find this page on:
> http://www.it.kth.se/~e93_mda/synths/books.html
> 
> Any more details on a book in there is needed, any more hints on books
> to include, comments on books etc. is as allways very wellcome.
> 
> One VERY good way to get a book in there is to send me a copy ;^)
> (OK, it was a shameless try, but you can't blame me for trying)
> 
> I am considering grouping books together into some categories.
> 
> Enjoy,
> Magnus

Good work!

BJ



From zzynt at swipnet.se  Sun Dec 27 08:11:07 1998
From: zzynt at swipnet.se (BJ)
Date: Sat, 26 Dec 1998 23:11:07 -0800
Subject: http://209.52.185.39
References: <199812231947.NAA10572@qns1.qns.net> <36820B73.629C@swipnet.se> <3681A760.BC19D605@obv-records.com>
Message-ID: <3685DD8B.7EC3@swipnet.se>

> BJ wrote:
> 
> > honcho at paia.com wrote:
> >
> > > So, thanks for any help you can give and season's grettings to all.
> > >
> > > -John
> >
> > It sounds to me that PAIA is runing a Microsoft product as a server!
> > If so i strongly suggest you to put the junk in the garbage bin and
> > set up a nice trustly working LINUX server instead!
> >
> > I think you are in about 2 seconds from now are a target of a hell of
> > suport and fixing suggestions from this list!!!
> >
> > BJ
> > [in the land of small sugesstions and a insane jobb market]

Sorry if this seemed aggresive against PAIA, it was surely not my
intention
i was mixing up the words a bit , im wery sorry! 
Its was porly written in fact,late night ,and wery sleepy if 
this can be some sort of a excuse for a clumsey email!

It was supposed to be seen in a positively way to be
"2 sec from being a target for good and informative support
and good sugestions from the nice people on this list"

Im wey sorry again, if it looked wery attacking and 
agressive against John and PAIA.

BJ



From theremin1 at worldnet.att.net  Sun Dec 27 08:55:00 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sat, 26 Dec 1998 23:55:00 -0800
Subject: Where can I get DPDT footswitches?
Message-ID: <000c01be316e$3570c8a0$cc744e0c@hpcustomer>

FWIW, you can try Linemaster:
http://www.linemaster.com/catalog.html
They manufacture industrial foot switches.

Push-on, push-off ("maintained") DPDT foot switches can be hard to find.
In many cases, it is better to use a SPST momentary foot switch and a
circuit
(flip-flop with analog switches or a relay) to provide the latching and
signal-routing functions.

-Art


-----Original Message-----
From: Aranakin at aol.com <Aranakin at aol.com>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 26, 1998 12:17 PM
Subject: Where can I get DPDT footswitches?


>please, I can't find anywhere that has a phone number that sells heavy duty
>DPDT footswitches.
>I'm quite amazed at this, being that i would think that electronic stores
that
>have everything thing else in the world, don't have this....
>as well as jameco and the likes...
>gees...
>please halp me out if you can..
>anthony
>




From theremin1 at worldnet.att.net  Sun Dec 27 09:22:06 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 27 Dec 1998 00:22:06 -0800
Subject: LM317 question
Message-ID: <004a01be3171$feb087c0$cc744e0c@hpcustomer>

The critical specification here is "dropout voltage.  
See the graph on page 4 of the .pdf file at:
http://www.national.com/ds/LM/LM117.pdf

It indicates that for a 1A load at 25 degrees C, the LM317 
requires a minimum input-output difference of about 2v, based 
on a maximum allowable sag of 100mV at the output.  
Since you have a 3v difference available, you should be okay 
with this part.  You will be dissipating 3W of heat in the regulator, 
so be sure to provide an adequate radiator.

-----Original Message-----
From: J. Larry Hendry <jlarryh at iquest.net>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Saturday, December 26, 1998 9:10 PM
Subject: LM317 question


>I am wanting to supply 9 +VDC @ 1 amp from a 12 VDC supply.  Would a LM317
>be a good choice for this application?  All the schematics I have found
>using a LM317 to supply an adjustable output voltage use more than 12 VDC
>as the source voltage to the LM317.
>
>Thanks,
>Larry Hendry
>
>




From hhelland at usa.net  Sun Dec 27 12:03:16 1998
From: hhelland at usa.net (Hallgeir Helland)
Date: Sun, 27 Dec 1998 12:03:16 +0100
Subject: The Digital Keyboard Scanner....
References: <3684FEAD.14DBE663@usa.net>
Message-ID: <368613F4.C920138C@usa.net>

I wrote:

> blah blah blah.... <snip>
> Praps someone will care to send me the replys
> over again (pleeease....), maybe privately?

Thank you Edu Silva & J. Harry Hendry for filling
me in. :-)

Here's a follow-up:

Paul Schreiber mentioned using 74HC151's and a clock.
This is <g> exactly what I did on my first 13-note basspedal
thingy that I now use together with the ASM-1 as a bass-
pedal-synth. Works fine except it got bugs: when key (pedal)
was released sometimes one bit of the binary code feeding the
R/2R ladder D/A would change, so I got a different note on
the Release. Annoying. Not bothering to debug, I wanted to
make one *without* any clock and counter. So I found the
4532 8-input priority encoder, and now I've designed a nice
circuit with this chip. Haven't built it yet, but I belive it'll be OK.

But, being an adventurus chap, I now hoped to be able to make
a polyphonic one...... I'm not shure anymore. The idea was to
use an analog MUX and make a sort of arpeggiator by cycling
thru the different CV outputs..... and maybe later make a complete
polysynth (maybe with CEM chips) ... but still I haven't settled on
anything yet.     I have two 44-note keyboards from an old Solina
organ, so maybe I'll start off with the mono keyboard, and prehaps
try and stuff together a ploly keyboard later.

But are the schems for, say, the P5 or the eight-voice keyboards
available anywhere? (Just *had* to end with a question, right :-) )

Thanx,
Hallgeir

BTW: I'll be checking out the Elektor Polysynth on Sponton's page.




From debus at cityweb.de  Sun Dec 27 14:29:57 1998
From: debus at cityweb.de (Ingo Debus)
Date: Sun, 27 Dec 1998 14:29:57 +0100
Subject: Mixer opamp, which one?
References: <000501be2f68$8c282ce0$1b8e93c3@spookymb>
Message-ID: <36863653.6E03@cityweb.de>

Mark Havard-Brown wrote:
> mixer I presently have, the builder has used a TL081. The datasheet I have
> on the TL071 specifys the devices noise distortion, whereas there is no
> mention of the subject on the TL081 datasheet, (both sheets are from
> Motorola). Question, which is the better to use?

TL071. Less noise, almost the same price.

> Additionally, the designs I have do not use more than six inputs. Are there
> any issues with the number of channels one just "bolts" onto the input of
> the opamp"?

In my mixer there are 12 inputs summed with one standard summing opamp
circuit, no prob at all. I use resistor arrays (one common pin for
several resistors) for the summing resistors, they are handy for PCB
layout.
But: although the gain from one input to the output of the summing amp
is low (1 in my mixer) the noise gain is pretty high when there are many
inputs. It makes a difference if a TL072 or a NE5532 (less noise) is
used here.

Ingo




From Mischerr at silyn-tek.de  Sun Dec 27 17:11:48 1998
From: Mischerr at silyn-tek.de (Michael Scherr)
Date: Sun, 27 Dec 1998 17:11:48 +0100
Subject: S: 8x8 MIDI interface for PC schematic/service manual
Message-ID: <000f01be31b3$cfde1e20$75a619c2@ICT00121>

I'm thinking about building a 8x8 MIDI-interface like the MOTU 'MIDI express
XT'.

Is there anybody who can give me a hint where to find a schematics, a
service manual or something else on the web?

regards,
   M.S.
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From varner at k-online.com  Sun Dec 27 17:19:30 1998
From: varner at k-online.com (Steve Varner)
Date: Sun, 27 Dec 1998 08:19:30 -0800
Subject: Bypass cap's
References: <199812262301.VAA22091@postman.bahianet.com.br> <36859CF8.6F2D@mr.net>
Message-ID: <36865E0F.2EA1E0C5@k-online.com>

Well, it seems you guys all read the same bypass cap book  ;-)
I'm mainly using analog synth modules and have a regulated power supply
with a bipolar +15/-15 and a +5V power output. I'm using a design that is
the same as the Electronotes PCC and Thomas Henry's power supply. I run 4
wires (18 awg) up through the synth and tap in using those blue tap-in
connectors. The 4 lines (+15 / -15 / +5 / Gnd) that were tapped out then
run to a hard-drive-type power connector and clip into to a connector
mounted on the board.
Sooo... Mark got me a bit worried when he said:

Mark Amundson wrote:

> 3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
> issues. Do not use these caps if you have regulated supplies and good
> beefy wiring as they may cause more power supply hum than their curative
> effects.

Exactly how do these "larger" caps on the power supply inputs to the module
cause power supply hum?

It seems that a lot of other people on this list are using this size cap on
the power lines and smaller ones into each IC. I was under the impression
that the caps on the ICs were usually only necessary for digital circuits
and for op-amps that handle low-level signals.

SV




From grichter at execpc.com  Sun Dec 27 17:29:25 1998
From: grichter at execpc.com (Grant Richter)
Date: Sun, 27 Dec 1998 10:29:25 -0600
Subject: Output of final signal
Message-ID: <199812271634.KAA25351@pop02.execpc.com>

I generally go to a rack mount effects unit. A Lexicon Reflex for instance.
It has input and output level controls and allows you to match the synth to
the
effect and the effect to the output amp.

----------
> From: Steve Varner <varner at k-online.com>
> To: synth-diy <synth-diy at mailhost.bpa.nl>
> Subject: Output of final signal
> Date: Saturday, December 26, 1998 12:48 PM
> 
> Survey question number 2:
> 
> After your signal goes out of a VCA, where do you all channel it? Do you
> have an audio amp on your synth rack? Do you send the signal directly to
> a home stereo receiver? Is is a good idea to have a master attenuator on
> your system (the signals are generally +5V to -5V, which is pretty
> "hot", not really audio levels!) Anyone have built in speakers as an
> option?
> 
> SV



From blayer at uswest.net  Sun Dec 27 18:36:45 1998
From: blayer at uswest.net (Bill Layer)
Date: Sun, 27 Dec 1998 11:36:45 -0600
Subject: Bypass cap - why is big not better?
In-Reply-To: <36865E0F.2EA1E0C5@k-online.com>
References: <199812262301.VAA22091@postman.bahianet.com.br>
 <36859CF8.6F2D@mr.net>
Message-ID: <3.0.6.32.19981227113645.007a77a0@192.168.0.1>

Hi All,

(Bill chiming in)

>Sooo... Mark got me a bit worried when he said:
>
>Mark Amundson wrote:
>
>> 3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
>> issues. Do not use these caps if you have regulated supplies and good
>> beefy wiring as they may cause more power supply hum than their curative
>> effects.
>
>Exactly how do these "larger" caps on the power supply inputs to the module
>cause power supply hum?

Large power supply caps create a saturation issue for the transformer, as
well as putting more pressure on the rectifier (which creates diode noise
and EMF).

Imagine a powersupply filter cap hooked to a rectifer, but under no load.
The voltage across the cap rises to (1.4)(Vrms) and stays there. As a load
is applied, the voltage across the cap begins to sag to (1.2)(Vrms). Now as
the power waveform approaches the crest, it suddenly overcomes the resting
voltage of the cap. At this precise moment, the rectifier switches on very
hard, and the cap now looks like an dead short to that small difference in
voltage. Dead short or not, the power waveform is now cresting and trying
vainly to raise the cap voltage.

Unfortunately, our theoretical dead short now draws (theoretical) INFINITE
current... Since our transformer cannot supply infinite current, it
saturates and quickly corrupts it's power waveform. This creates harmonic
distortion and noise, as well as harms the power factor for the whole AC
side. Meanwhile, the saturation generates heat, which may also in turn
damage the transformer.

Nice, eh?



  / /  (_)__  __ ____  __     
 / /__/ / _ \/ // /\ \/ /  
/____/_/_//_/\_,_/ /_/\_\  The choice of a GNU generation.  



From jhaible at primus-online.de  Sun Dec 27 20:58:12 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 20:58:12 +0100
Subject: Headphone amp
Message-ID: <19981227214341.21121.qmail@nuernberg2.pop.metronet.de>

Does anybody have a circuit for a good tube headphone amp ?
Should be easier to build one without a transformer than  a full
power amp. 

JH.




From jhaible at primus-online.de  Sun Dec 27 21:02:16 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 21:02:16 +0100
Subject: Bypass cap's
Message-ID: <19981227214342.21121.qmail@nuernberg2.pop.metronet.de>

> > >Is noise to and from the board via suply lines really that much of a
> > >problem?
> > 
> > Sometimes. To be safe, (isn't an overkill...) place regulator IC's
(7815
> > and 7915) at the supply rails of each circuit board. The main supply
should
> > be at least 18 volts, to make things work.
> > 
> 
> The regulators are so cheap now, its really no problem to do this and
> may save you many problems..
> 
> Rob
> 

I had a lot of problems with 7815 / 7915 on board regulators, and 7818 /
7918
pre-stabilized PSU. Don't ask me why, but they failed all the time. (no
destruction,
but latching up in protection mode). I switched to RC4195's and all was
fine.

JH.



From jhaible at primus-online.de  Sun Dec 27 21:04:43 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 21:04:43 +0100
Subject: PCM=PWM?
Message-ID: <19981227214344.21121.qmail@nuernberg2.pop.metronet.de>

> Is it true that pulse code modulation is the SAME as pulse width
> modulation?

Of course not. But you can transform a PCM'ed information into a
stream of 1's and 0's at a higher sampling rate, which is at least
*similar* to PWM.

JH.



From jhaible at primus-online.de  Sun Dec 27 21:08:43 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 21:08:43 +0100
Subject: Mixer opamp, which one?
Message-ID: <19981227214345.21121.qmail@nuernberg2.pop.metronet.de>

There's an interesting application for using the SSM2017 as mixer
on the data sheet. I haven't tried it, but I am very fond of this chip
for other amplification aplications. It isn't that expensive anymore,
and you could even have a balanced mixing bus ...

JH.



From jhaible at primus-online.de  Sun Dec 27 21:19:37 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 21:19:37 +0100
Subject: Output of final signal
Message-ID: <19981227214346.21121.qmail@nuernberg2.pop.metronet.de>

I have built a special input / output module for my JH-3 Modular.
Two balanced stereo input channels with variable gain to get the
5V amplitude for the synth from any line level signals. "Signal"
and "Overload" LED (green / red).
Two balanced stereo outputs with variable attenuation from
the 5V synth amplitude to any line level amplitude.
Then I have two 4p2t switches that will optionally connect
the first and second input pair to the 1st and 2nd output pair.
This is to connect two external synthesizers to the Modular
if I want to run them thru certain modules. I can switch Modular
on or bypass with a single switch, and input / output level
adjustment will provide seamless integration.
My OB-8 is connected to the JH-3 Modular all the time, and
it's important to get it thru in stereo when on bypass. For
the Modular, there is just a mono signal extracted, however.
Four 1/4" jacks in parallel to feed enough modules without
an extra Multiple.
The second stereo output is mostly used for straight Modular 
synth stuff, but it's built identically to the first channel.

JH.



From THEKn0TiS at aol.com  Sun Dec 27 21:23:01 1998
From: THEKn0TiS at aol.com (THEKn0TiS at aol.com)
Date: Sun, 27 Dec 1998 15:23:01 EST
Subject: 4 voice keyboard scanner
Message-ID: <119418bf.36869725@aol.com>

at www.synthfool.com thier are schamatics for an oberhiem 4 voice keyboard
just thought you might want to know if you didnt already
peace
shawn



From magnus at analogue.org  Sun Dec 27 22:16:04 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Sun, 27 Dec 1998 22:16:04 +0100
Subject: PCM=PWM?
In-Reply-To: Your message of "Sat, 26 Dec 1998 21:15:19 -0600"
References: <3685A647.7E380E4C@globaleyes.net>
Message-ID: <199812272116.WAA28084@mail2.it.kth.se>

>>>>> "R" == Rob  <cyborg0 at GlobalEyes.net> writes:

 R> Is it true that pulse code modulation is the SAME as pulse width
 R> modulation?

No.

 R> I always thought this was true, that the pulse code modulation just took
 R> a simple square wave, and by shaping the pulse very quickly was able to
 R> churn out sampled sounds..Basically, radically and quickly modulating
 R> the pulse width of an existing wave form to generate all the needed
 R> harmonics and such.

Way off... PCM is the somewhat confusing name for what usually is
called sampling (which BTW is a incorrect term, because more is really
happening).

PCM really means a form of modulation where the waveform is encoded
for every sampling pulse. The encoding is being done in a binary
system.

Sampling is really when sample the contious time waveform into a
discrete time waveform (with a Sample and Hold cursuit). This discrete
time waveform is then encoded into binary code (with a Analog to
Digital Converter cursuit). What you have in the end of this
transformation is the PCM encoded waveform. It should be noted that
due to the frequency wrapping inherent of the sampling process will
usually a frequency selection filter (usually a lowpass filter) be
used to treat the signal prior sent into the S/H.

Cheers,
Magnus



From cyborg0 at GlobalEyes.net  Sun Dec 27 22:36:46 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sun, 27 Dec 1998 15:36:46 -0600
Subject: rotary decoder synth mod AGAIN! Glitch-free version :)
Message-ID: <3686A86E.FFCF7C8E@globaleyes.net>

Well, I now have a NEW and REVISED (read: glitch-free) version of my
rotary decoder..This one uses a 4013 instead of the quirky data latch..
I think the data latch/nand gate combo was oscillating, making the whole
system glitch a lot.
Got the chip count down to 3 for the whole deal!
:))
BTW, this came after reading the TTL cookbook over and over again..What
a good no bull informative book.

email me if any are interested in it.. it also has a parts list
included..
Im sooo happy it no longer glitches.. that prob was really driving me
nutty..
Rob



From jhaible at primus-online.de  Sun Dec 27 22:48:08 1998
From: jhaible at primus-online.de (jhaible)
Date: Sun, 27 Dec 1998 22:48:08 +0100
Subject: Bypass cap's
Message-ID: <19981228003107.23499.qmail@nuernberg2.pop.metronet.de>

> Ironically, some digital circuits built on power/ground plane boards need
no
> bypass
> caps at all.  I was informed that the stored energy exists due to the
> topology of
> the planes.  Something about the "H" field, but I'm no expert in these
> matters, so
> perhaps a lurking physicist may care to comment.

Make that "E-Field", and it makes sense.
C = epsilon * A / d,
epsilon being the dielectric constant of the PCB material,
A being the area, and d being the distance between the planes.
This only makes sense when you have two planes in close
proximity - surely not with the 1mm or more of a double sided board.

JH.



From edusilva at bahianet.com.br  Sun Dec 27 22:51:05 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sun, 27 Dec 1998 19:51:05 -0200
Subject: Bypass cap's (a long one)
Message-ID: <199812272152.TAA02212@postman.bahianet.com.br>

I found the following text about bypass caps at Dan Hildebrand's page:
http://www.qnx.com/~danh/tubenote4.html

Well, it's not my opinion, but makes some sense. However, I'm still doing
the old way...

**********

Tube Amp Design Notes

This series of postings, by Henry Pasternack, is a discussion on the design
of a tube power amp.

From: "henry (h.) pasternack" 
Subject:  Tube Note 4. 

My design effort was temporarily stalled for a couple of weeks while I
mulled over some issues of component philosophy. For years, I have
reflexively paralleled all electrolytics with small film caps under the
audiophile assumption that these capacitors would augment the performance
of the electrolytics at high frequencies. 

The problems with using these caps are several-fold. They take up space;
they cost money; they require careful grounding if they are to be
effective; they have the potential to cause high-frequency ringing; they
may be ineffective; some people have reported that bypassing actually
increases audible coloration. 

In my last amplifier, I took the approach of treating the driver circuit as
a unit, with its own ground system and all power rails bypassed at high
frequency by 0.1uf film caps. The input signal ground and the bypass cap
ground were run separately back to the star ground in the power supply.
While the presence of those pretty red and blue gumdrops is very pleasing
to the eye and soothing to the conscience, I wonder if they really do any
good. 

Let's suppose there is some high-frequency noise riding on the power supply
rails. At 100kHz, the impedance of a 0.1uF cap is about 15 Ohms. At 20kHz,
it's five times higher. What is the benefit? 

I did some simple tests with a couple of capacitors, a 100 Ohm film
resistor, and a 10-10MHz signal generator. What I found is that the
impedance of even a lowly Sprague computer-grade electro- lytic is in the
range of tenths or hundredths of an Ohm out to frequencies in the hundreds
of kilohertz. The effect of a 0.1uF film bypass was entirely negligible.
The frequency response of the film motor-run caps I'm using in this amp was
even better. The bypass had no beneficial effect on the film cap, but did
result in resonances at medium RF frequencies. 

On the other hand, putting a 10uF SCR polypropylene cap in parallel with
the electrolytic resulted in a uniform and very low impedance right across
the audio band and out to AM radio frequencies. Modern electrolytic caps
are a lot better than those built two decades ago. It's probably time to
rethink the wisdom of automatically bypassing every electrolytic with a
small film cap. 

The wavelength of a radio wave in free space at 1MHz is three hundred
meters. The length of the wire carrying B+ from the filter caps to my
driver circuit is about three inches. This is also food for thought. 

Most solid-state power amplifiers are littered with bypass caps. A good
designer will consider using tantalums or ceramics because these types,
although they aren't that linear, have very low impedance and wide
bandwidth compared to films. Far from being superfluous, the bypass
capacitors keep the supply rail impedance low at frequencies in the tens of
Megahertz. This is necessary because the open-loop bandwidth of a
solid-state amp is often this high. As well, solid-state devices are more
prone to producing distortion in the presence of RF noise than tubes. 

On the other hand, the open-loop bandwidth of a typical tube amplifier is
only a couple of hundred kilohertz at best. They don't suffer from junction
rectification problems. 

Finally, I surveyed many schematics of classic tube amplifiers, vintage and
modern, and found that there were very few gratuitous bypass caps in them.
Of course, it costs money to install these parts. But I suspect there'd be
more of them if they really made a big sonic difference. 

The "underground" DIY literature was inconsistent. Some tweak articles
mandated elaborate networks bypasses-upon-bypasses. Others said the
bypasses screwed up the sound. Not much help there. 

I am sure there are many cases where changing a cap here and there can make
a significant difference in the sound in spite of objective predictions to
the contrary. The problem is, if we never build amplifiers without these
parts, we will never have a standard of comparison for tweaked-out designs.

So, I am using quality film filter caps in my power supply, and I am going
to forego most of the bypass caps unless I can convince myself there is a
good engineering reason for having them in the circuit. This makes the
circuit board layout much easier and keeps the cost down, as well. We'll
see how it sounds. 

**********

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From tom.verheyden at village.uunet.be  Sun Dec 27 23:01:57 1998
From: tom.verheyden at village.uunet.be (be053520)
Date: Sun, 27 Dec 1998 23:01:57 +0100
Subject: BACK & Re: PCM=PWM?
Message-ID: <008e01be31e5$912a68a0$9a2907c2@be053520>


-----Original Message-----
From: Rob <cyborg0 at GlobalEyes.net>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: zondag 27 december 1998 5:18
Subject: PCM=PWM?


First:

After 2 years I'm finally back,... Hi everybody, I'm very happy to be
back!!!!!!!!!!

Rob wrote:

>Is it true that pulse code modulation is the SAME as pulse width
>modulation?

No,

Normally, pulse code modulation is often used to generate a specific
data(communication) pattern (no synth-use :-)), for example in
telecommunications.
However some years ago the PCM-technology was used in synths.
I don't really know how it exactly works but I always thought that the PCM
was used to control an IC which outputs a sampled sound??

I thought that:

In a PCM signal the timebase is not divided in HZ, but rather in timeslots.
Each timeslot at his turn represents a number of bits.
So, when you create a PCM signal with  32 timeslots (channels) for example,
your synth can/will be 32-voice polyphonic.

a PCM signal can be:

1_  _     ___ _    _  _      ____
                                                           the period marked
with *
0  --  ----       -  ---  --  -----         ------  represents one timeslot
of 8 bits
  *************
      !!!!!!!
to create this same signal with PWM
you should have a square-wave wich starts with a '1', duty-cycle
(=pulse-width) is aproximatly 50% for the first 2 bits...OK, that couldn't
be hard to generate :-)
BUT NOW, the next 2 bits (marked with ! )  have as duty-cycle value 1/3th
and a larger period (slower frequency) as the previous 2 bits.

So while a PCM controller would say: the signal read is 10100111,
a PWM controller says 1;50%;1 33,3%;1 99%.

Bye

Tom Verheyden,




From theremin1 at worldnet.att.net  Sun Dec 27 23:49:32 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 27 Dec 1998 14:49:32 -0800
Subject: Bypass cap's
Message-ID: <002601be31eb$2c9217c0$69754e0c@hpcustomer>


Steve Varner:


>Well, it seems you guys all read the same bypass cap book  ;-)
>I'm mainly using analog synth modules and have a regulated power supply
>with a bipolar +15/-15 and a +5V power output. I'm using a design that is
>the same as the Electronotes PCC and Thomas Henry's power supply. I run 4
>wires (18 awg) up through the synth and tap in using those blue tap-in
>connectors. The 4 lines (+15 / -15 / +5 / Gnd) that were tapped out then
>run to a hard-drive-type power connector and clip into to a connector
>mounted on the board.
>Sooo... Mark got me a bit worried when he said:

Mark Amundson:

>> 3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
>> issues. Do not use these caps if you have regulated supplies and good
>> beefy wiring as they may cause more power supply hum than their curative
>> effects.

Steve Varner:

>Exactly how do these "larger" caps on the power supply inputs to the module
>cause power supply hum?

Art Harrison:

Bill Layer had a though-provoking post last month in this regard, in which
he responded
to a comment from J. Larry Hendry. I've been meaning to do some tests to
investigate
the relationship of PS capacitance to line-frequency noise, and specifically
see if a
real-world example of  "more is worse" could be created.  Keep in mind that
the
capacitor at issue in the following post is the pre-regulator "bulk" filter,
not the capacitor
at the regulator output.

Anyway, I am taking the liberty of reposting Larry's question and Bill's
response
(I hope y'all don't mind):

Bill Layer:

Hi Larry, All,

J. Larry Hendry:

>I was having trouble following the logic that a linear power supply using
>solid state diodes would cause distortion of this type.  Then the obvious
>hit me like a brick --  the diode does not start conducting until the
>voltage magnitude of the sine wave overcomes the voltage required to cause
>the diode to connect.  So, at each zero crossing, you have a shut off
>period on both sides where neither diode is connecting.

Bill Layer:

This is true, but the zero-crossing is not always the ugliest hour for the
SS rectfier. Imagine a simple single-wave rectified supply, with a single
diode feeding a single filter cap. Assume that this supply is unloaded, the
voltage across the capacitor now rises to the peak of the AC waveform,
about 1.414 x RMS. Assuming that no current is drawn (not the case, for a
real cap) the voltage remains constant AND the diode never conducts again.

But when current is drawn, something else ocurrs. The voltage across the
cap falls, and now the diode wants to conduct, BUT ONLY at the peak of the
waveform. Now, the filter cap tends oppose that change in voltage (the
bigger the cap - the bigger the opposition... read on), and when that diode
does switch on - look out. The AC waveform is at the near peak of it's
power cycle, and when the diode switches on, the instantanious current is
large. If the supply voltage now falls to 1.2 X peak, this means that for
over 10% of the waveform, the transformer and rectifier are pushing against
a brick wall.

To an extent, this also relates to the fact that given two otherwise
identical power supplies, more current may be drawn from an inductive 1st
filter than a capacative 1st filter design. Peak currents are lower in the
inductive filter.

What this means to me, is that the guidelines for filter cap size in power
design may need to be re-thougt, on the basis of 'bigger is not better'.
How would you like to find out that that ultra-quiet 10X overfiltered
supply you built is doing more harm to the overall sound of your system,
than good for the device it is powering! Obviously the extreme case, but
the logical end nonetheless.

Any thoughts?

Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>


--------end archived post---------

Steve Varner:

>It seems that a lot of other people on this list are using this size cap on
>the power lines and smaller ones into each IC. I was under the impression
>that the caps on the ICs were usually only necessary for digital circuits
>and for op-amps that handle low-level signals.

Art Harrison:

Ironically, some digital circuits built on power/ground plane boards need no
bypass
caps at all.  I was informed that the stored energy exists due to the
topology of
the planes.  Something about the "H" field, but I'm no expert in these
matters, so
perhaps a lurking physicist may care to comment.

In some instances, the use of bypass capacitors for linear integrated
circuits is
desirable for stability, regardless of power supply noise.

Last thought:  In many instances, large output capacitors can actually cause
instabilities
in a regulator.  !00uF of tantalum loading a 7812, for example, has cause
oscillations,
in my experience.







From edusilva at bahianet.com.br  Mon Dec 28 00:12:21 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sun, 27 Dec 1998 21:12:21 -0200
Subject: Headphone amp
Message-ID: <199812272314.VAA20560@postman.bahianet.com.br>

Juergen Haible (not Haible Juergen...) wrote:
 
> Does anybody have a circuit for a good tube headphone amp ?

Visit Andrea Ciuffoli at
http://www.geocities.com/ResearchTriangle/8231/my/index.html#MY_HEAD

> Should be easier to build one without a transformer than  a full
> power amp. 

Well, I've seen lots of OTL tube apms. The first I have notice was a design
by RCA, aka the "Dickie-Mackovisky" amp, (or something like) by the middle
50's. Lotsa info about OTL's at the italian guy page!

BTW, one can say (and I'm tempted to agree) that most of the "magic" in
tube sound comes from the xformers...

Edu

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From jlarryh at iquest.net  Mon Dec 28 00:17:04 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Sun, 27 Dec 1998 17:17:04 -0600
Subject: Filter caps  WAS: bypass caps?
Message-ID: <199812272211.XAA28231@mailhost.bpa.nl>

Us mind?  Why heck no !!  Any light shed on this issue on the load side of
the power transformer would be enlightening.  Bill's well thought out
comments got me to thinking about things I never before considered. 
However, I have changed the subject line since this thread has somewhat
broken loose from the original post concerning bypass caps  Go for it Art !

My area of capacitor expertise lies in their high voltage AC application. 
Since that is OT to this list, I shall leave any questions concerning that
to private e-mail.

Thanks to all for making this such a great list.
Larry

----------
> From: Arthur Harrison <theremin1 at worldnet.att.net>
> Bill Layer had a though-provoking post last month in this regard, in
which
> he responded to a comment from J. Larry Hendry. I've been meaning to
> do some tests to investigate the relationship of PS capacitance to
> line-frequency noise, and specifically see if a real-world example of
> "more is worse" could be created.  Keep in mind that the capacitor
> at issue in the following post is the pre-regulator "bulk" filter, not
the
> capacitor at the regulator output.
> 
> Anyway, I am taking the liberty of reposting Larry's question and Bill's
> response.  (I hope y'all don't mind):
> 
> Bill Layer:
> 
> Hi Larry, All,
> 
> J. Larry Hendry:
> 
> >I was having trouble following the logic that a linear power supply
using
> >solid state diodes would cause distortion of this type.  Then the
obvious
> >hit me like a brick --  the diode does not start conducting until the
> >voltage magnitude of the sine wave overcomes the voltage required to
cause
> >the diode to connect.  So, at each zero crossing, you have a shut off
> >period on both sides where neither diode is connecting.
> 
> Bill Layer:
> 
> This is true, but the zero-crossing is not always the ugliest hour for
the
> SS rectfier. Imagine a simple single-wave rectified supply, with a single
> diode feeding a single filter cap. Assume that this supply is unloaded,
the
> voltage across the capacitor now rises to the peak of the AC waveform,
> about 1.414 x RMS. Assuming that no current is drawn (not the case, for a
> real cap) the voltage remains constant AND the diode never conducts
again.
> 
> But when current is drawn, something else ocurrs. The voltage across the
> cap falls, and now the diode wants to conduct, BUT ONLY at the peak of
the
> waveform. Now, the filter cap tends oppose that change in voltage (the
> bigger the cap - the bigger the opposition... read on), and when that
diode
> does switch on - look out. The AC waveform is at the near peak of it's
> power cycle, and when the diode switches on, the instantanious current is
> large. If the supply voltage now falls to 1.2 X peak, this means that for
> over 10% of the waveform, the transformer and rectifier are pushing
against
> a brick wall.
> 
> To an extent, this also relates to the fact that given two otherwise
> identical power supplies, more current may be drawn from an inductive 1st
> filter than a capacative 1st filter design. Peak currents are lower in
the
> inductive filter.
> 
> What this means to me, is that the guidelines for filter cap size in
power
> design may need to be re-thougt, on the basis of 'bigger is not better'.
> How would you like to find out that that ultra-quiet 10X overfiltered
> supply you built is doing more harm to the overall sound of your system,
> than good for the device it is powering! Obviously the extreme case, but
> the logical end nonetheless.
> 
> Any thoughts?
> 
> Bill Layer
> Sales Technician
> <b.layer at vikingelectronics.com>
> 
> 
> --------end archived post---------
> 
> Steve Varner:
> 
> >It seems that a lot of other people on this list are using this size cap
on
> >the power lines and smaller ones into each IC. I was under the
impression
> >that the caps on the ICs were usually only necessary for digital
circuits
> >and for op-amps that handle low-level signals.
> 
> Art Harrison:
> 
> Ironically, some digital circuits built on power/ground plane boards need
no
> bypass
> caps at all.  I was informed that the stored energy exists due to the
> topology of
> the planes.  Something about the "H" field, but I'm no expert in these
> matters, so
> perhaps a lurking physicist may care to comment.
> 
> In some instances, the use of bypass capacitors for linear integrated
> circuits is
> desirable for stability, regardless of power supply noise.
> 
> Last thought:  In many instances, large output capacitors can actually
cause
> instabilities
> in a regulator.  !00uF of tantalum loading a 7812, for example, has cause
> oscillations,
> in my experience.
> 
> 
> 
> 




From jlarryh at iquest.net  Mon Dec 28 00:21:30 1998
From: jlarryh at iquest.net (J. Larry Hendry)
Date: Sun, 27 Dec 1998 17:21:30 -0600
Subject: PCM=PWM?
Message-ID: <199812272215.XAA28359@mailhost.bpa.nl>

Magnus wrote:
> Way off... PCM is the somewhat confusing name for what usually is
> called sampling (which BTW is a incorrect term, because more is really
> happening).
> PCM really means a form of modulation where the waveform is encoded
> for every sampling pulse. The encoding is being done in a binary
> system.

Korg used this term extensively to refer to their sampled data both in
their samplers in the M1 (and those thereafter) ROM and external RAM cards.
 They even called them PCM data cards.

Larry





From cyborg0 at GlobalEyes.net  Mon Dec 28 00:35:15 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Sun, 27 Dec 1998 17:35:15 -0600
Subject: PCM=PWM?
References: <19981227214344.21121.qmail@nuernberg2.pop.metronet.de>
Message-ID: <3686C433.C154CFB8@globaleyes.net>

jhaible wrote:
> 
> > Is it true that pulse code modulation is the SAME as pulse width
> > modulation?
> 
> Of course not. But you can transform a PCM'ed information into a
> stream of 1's and 0's at a higher sampling rate, which is at least
> *similar* to PWM.
> 
> JH.

AHa! ok.. this is what was going on.. the circuit in question is the
hi-hat circuit of the 909.. just by increasing the freq of the input
clock, the samples play faster..
rob



From blayer at uswest.net  Mon Dec 28 00:36:45 1998
From: blayer at uswest.net (Bill Layer)
Date: Sun, 27 Dec 1998 17:36:45 -0600
Subject: Bypass cap - why is big not better?
In-Reply-To: <36865E0F.2EA1E0C5@k-online.com>
References: <199812262301.VAA22091@postman.bahianet.com.br>
 <36859CF8.6F2D@mr.net>
Message-ID: <3.0.6.32.19981227173645.007aa1b0@192.168.0.1>

Hi All,

(Bill chiming in)

>Sooo... Mark got me a bit worried when he said:
>
>Mark Amundson wrote:
>
>> 3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
>> issues. Do not use these caps if you have regulated supplies and good
>> beefy wiring as they may cause more power supply hum than their curative
>> effects.
>
>Exactly how do these "larger" caps on the power supply inputs to the module
>cause power supply hum?

Large power supply caps create a saturation issue for the transformer, as
well as putting more pressure on the rectifier (which creates diode noise
and EMF).

Imagine a powersupply filter cap hooked to a rectifer, but under no load.
The voltage across the cap rises to (1.4)(Vrms) and stays there. As a load
is applied, the voltage across the cap begins to sag to (1.2)(Vrms). Now as
the power waveform approaches the crest, it suddenly overcomes the resting
voltage of the cap. At this precise moment, the rectifier switches on very
hard, and the cap now looks like an dead short to that small difference in
voltage. Dead short or not, the power waveform is now cresting and trying
vainly to raise the cap voltage.

Unfortunately, our theoretical dead short now draws (theoretical) INFINITE
current... Since our transformer cannot supply infinite current, it
saturates and quickly corrupts it's power waveform. This creates harmonic
distortion and noise, as well as harms the power factor for the whole AC
side. Meanwhile, the saturation generates heat, which may also in turn
damage the transformer.

Nice, eh?



  / /  (_)__  __ ____  __     
 / /__/ / _ \/ // /\ \/ /  
/____/_/_//_/\_,_/ /_/\_\  The choice of a GNU generation.  



From edusilva at bahianet.com.br  Mon Dec 28 00:43:33 1998
From: edusilva at bahianet.com.br (Edu Silva)
Date: Sun, 27 Dec 1998 21:43:33 -0200
Subject: Bypass cap's
Message-ID: <199812272345.VAA19356@postman.bahianet.com.br>

Juergen wrote:

> I had a lot of problems with 7815 / 7915 on board regulators, and 7818 /
> 7918
> pre-stabilized PSU. Don't ask me why, but they failed all the time. (no
> destruction,
> but latching up in protection mode). I switched to RC4195's and all was
> fine.
> 
> JH.

You know, some devices, like the 555, have the annoyng habit of inducing
little glitches in supply lines, when changing states. The 78/79
regulators, sensible as they are, may be interpreting this as a short, and
bravely saving your beloved gear...

Just a thought...

Edu

_____________________
Edu Silva - ES2 Audio
Salvador-Bahia-Brazil



From jhaible at primus-online.de  Mon Dec 28 01:46:20 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 28 Dec 1998 01:46:20 +0100
Subject: Bypass cap's
Message-ID: <19981228005956.23846.qmail@nuernberg2.pop.metronet.de>

> You know, some devices, like the 555, have the annoyng habit of inducing
> little glitches in supply lines, when changing states.

... as does any CMOS logic gate.

> The 78/79
> regulators, sensible as they are, may be interpreting this as a short,
and
> bravely saving your beloved gear...

No, this surely wasn't the case.

JH.



From magnus at analogue.org  Mon Dec 28 02:23:18 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Mon, 28 Dec 1998 02:23:18 +0100
Subject: PCM=PWM?
In-Reply-To: Your message of "Sun, 27 Dec 1998 17:21:30 -0600"
References: <199812272215.XAA28359@mailhost.bpa.nl>
Message-ID: <199812280123.CAA29860@mail2.it.kth.se>

>>>>> "JLH" == J Larry Hendry <jlarryh at iquest.net> writes:

 JLH> Magnus wrote:
 >> Way off... PCM is the somewhat confusing name for what usually is
 >> called sampling (which BTW is a incorrect term, because more is really
 >> happening).
 >> PCM really means a form of modulation where the waveform is encoded
 >> for every sampling pulse. The encoding is being done in a binary
 >> system.

 JLH> Korg used this term extensively to refer to their sampled data both in
 JLH> their samplers in the M1 (and those thereafter) ROM and external RAM cards.
 JLH>  They even called them PCM data cards.

Not only them, Philips used it alot back in the days when they
promoted the first (14-bit) CD-player.

Cheers,
Magnus





From mamundso at mr.net  Mon Dec 28 04:33:01 1998
From: mamundso at mr.net (Mark Amundson)
Date: Sun, 27 Dec 1998 19:33:01 -0800
Subject: LM317 question
References: <004a01be3171$feb087c0$cc744e0c@hpcustomer>
Message-ID: <3686FBED.26FA@mr.net>

Arthur Harrison wrote:
> The critical specification here is "dropout voltage....
> ..Since you have a 3v difference available, you should be okay
> with this part.  

J. Larry Hendry wrote:
> >I am wanting to supply 9 +VDC @ 1 amp from a 12 VDC supply.  Would a LM317
> >be a good choice for this application?  All the schematics I have found
> >using a LM317 to supply an adjustable output voltage use more than 12 VDC
> >as the source voltage to the LM317. Thanks, Larry Hendry

The 3 volt difference between supplied and regulated output is
acceptable under conditions Mr. Harrison and others mentioned. If it
were me, I always allocate at least a 3 volt margin for early regulators
like the 78XX/79XX, and 317/337 types. Thus I would choose if possible,
a more modern low dropout version of the LM317.

Things like AC supply sags (brownouts) and wall wart supplies always
make me pad the worst case input voltage number on the supply. Unless
battery powered, I am more than willing to deal with the extra heat
dissipation on the regulator.

Mark Amundson,



From mamundso at mr.net  Mon Dec 28 04:50:11 1998
From: mamundso at mr.net (Mark Amundson)
Date: Sun, 27 Dec 1998 19:50:11 -0800
Subject: Bypass cap's
References: <199812262301.VAA22091@postman.bahianet.com.br> <36859CF8.6F2D@mr.net> <36865E0F.2EA1E0C5@k-online.com>
Message-ID: <3686FFF3.1A47@mr.net>

Steve Varner wrote:
> Sooo... Mark got me a bit worried when he said:
> 
> Mark Amundson wrote:
> > 3. Use 10uf to 100uf tantalum or electrolytic caps for local supply sag
> > issues. Do not use these caps if you have regulated supplies and good
> > beefy wiring as they may cause more power supply hum than their curative
> > effects.

> Exactly how do these "larger" caps on the power supply inputs to the module
> cause power supply hum? SV

Bill Layer's comments about over-doing the total capacitance should be
heeded. My biggest concern is that return (ground) wire. Since you are
already planning on using the +5 volt supply, all that current returns
on the ground wire (bus) back to the supply. Problems do occur if the
return currents bounce around in value to digital and analog demands.
Any modest wire resistance (more than tens of milli-ohms) will cause
"ground bounce" and milli-amperes of current swing covert to milli-volts
of noise on the ground wire. That is why I like separate digital and
analog ground buses and split supplies (+/- 15v) for analog circuits.

The point to be made is that large caps absorb/provide current changes
to maintain supply voltages, but those currents may also bounce the
ground a bit. That is why I like the larger caps close to the power
supply.

A return wire to ground is not always a good ground wire if there is
significant current flowing through it.

Mark Amundson,



From djblue at asu.edu  Mon Dec 28 06:33:57 1998
From: djblue at asu.edu (Reverend bluE)
Date: Sun, 27 Dec 1998 22:33:57 -0700 (MST)
Subject: More Questions.
Message-ID: <Pine.GSO.3.96.981227215948.22680E-100000@general1.asu.edu>


Okay.   I have a VCO chip, and a schematic for a logarithmic amplifier.

The chip is the (Phillips) ECG864 Precision Waveform Generator.
It's a 14pin DIP  the pin-outs are as follows:
1  SINE WAV ADJ
2  SINE WAV OUT
3  TRIANGLE OUT
4,5  DUTY CYCLE FREQUENCY ADJ
6  V+
7  FM BIAS
8  FM/SWEEP INPUT
9  SQUARE WAVE OUT
10  TIMING CAP
11  V-/GROUND
12  SINE WAVE ADJ
13  NC
14  NC

As far as I can tell, this is a linear VCO (true/false?), but I can get them
from TechAmerica (right down the street from me) for 4-5 dollars.  

I was wondering if this chip would work in a synth design.  I would plan to
use it with the logarithmic amplifier design from "The Master Handbook of IC
Circuit Applications 3rd Edition" by Delton T. Horn.
Sorry for the crudeness, but this is my first try at ascii-matics...
		
			   0.1
		|------|---||---|-----|
		|      |        |     |
		|      |---|<---|     |
		|         1N914       |
		|		      |
		|-------[2N2222]------|
		|		      |
Vin	100k	|   2	|---V+        |
-------/\/\/----|----|\ |	      |
		     | \|7	      |	
		     |  \ 6	      |    Vout
		    3|   \____________|________
		|----|741/   	      
		|    |  /4|
		|    | /  |
		|    |/2| |--|
	        \   1|  |    |
	     82k/    \  |-|  |
		\    /330 |  |
		/    \    |  |
		|    /    |  |
		|    |10k |  |
	      -----  -/\/\-  |
	       ---      ^    |
		-       |    |
			|----|
			|
		       -V


Now, I expect that this will take my Keyboard voltage (which is linear) and
make it logarithmic so I can have a 1v/Octave synth.  Is this true?  

Or...should I just give up on these, and order some decent "music" chips?

thanks in advance... 
-ben




From theremin1 at worldnet.att.net  Mon Dec 28 07:13:17 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 27 Dec 1998 22:13:17 -0800
Subject: Bypass cap's (a long one)
Message-ID: <002101be3229$29e56520$d97a4e0c@hpcustomer>

Yeah, these seem pretty sane comments, surprisingly objective for an
audiophile type! (;
.

-Art


-----Original Message-----
From: Edu Silva <edusilva at bahianet.com.br>
To: DIY <synth-diy at mailhost.bpa.nl>
Date: Sunday, December 27, 1998 4:34 PM
Subject: Re: Bypass cap's (a long one)


>I found the following text about bypass caps at Dan Hildebrand's page:
>http://www.qnx.com/~danh/tubenote4.html
>
>Well, it's not my opinion, but makes some sense. However, I'm still doing
>the old way...
>
>**********
>
>Tube Amp Design Notes
>
>This series of postings, by Henry Pasternack, is a discussion on the design
>of a tube power amp.
>
>From: "henry (h.) pasternack"
>Subject:  Tube Note 4.
>
>My design effort was temporarily stalled for a couple of weeks while I
>mulled over some issues of component philosophy. For years, I have
>reflexively paralleled all electrolytics with small film caps under the
>audiophile assumption that these capacitors would augment the performance
>of the electrolytics at high frequencies.
>
>The problems with using these caps are several-fold. They take up space;
>they cost money; they require careful grounding if they are to be
>effective; they have the potential to cause high-frequency ringing; they
>may be ineffective; some people have reported that bypassing actually
>increases audible coloration.
>
>In my last amplifier, I took the approach of treating the driver circuit as
>a unit, with its own ground system and all power rails bypassed at high
>frequency by 0.1uf film caps. The input signal ground and the bypass cap
>ground were run separately back to the star ground in the power supply.
>While the presence of those pretty red and blue gumdrops is very pleasing
>to the eye and soothing to the conscience, I wonder if they really do any
>good.
>
>Let's suppose there is some high-frequency noise riding on the power supply
>rails. At 100kHz, the impedance of a 0.1uF cap is about 15 Ohms. At 20kHz,
>it's five times higher. What is the benefit?
>
>I did some simple tests with a couple of capacitors, a 100 Ohm film
>resistor, and a 10-10MHz signal generator. What I found is that the
>impedance of even a lowly Sprague computer-grade electro- lytic is in the
>range of tenths or hundredths of an Ohm out to frequencies in the hundreds
>of kilohertz. The effect of a 0.1uF film bypass was entirely negligible.
>The frequency response of the film motor-run caps I'm using in this amp was
>even better. The bypass had no beneficial effect on the film cap, but did
>result in resonances at medium RF frequencies.
>
>On the other hand, putting a 10uF SCR polypropylene cap in parallel with
>the electrolytic resulted in a uniform and very low impedance right across
>the audio band and out to AM radio frequencies. Modern electrolytic caps
>are a lot better than those built two decades ago. It's probably time to
>rethink the wisdom of automatically bypassing every electrolytic with a
>small film cap.
>
>The wavelength of a radio wave in free space at 1MHz is three hundred
>meters. The length of the wire carrying B+ from the filter caps to my
>driver circuit is about three inches. This is also food for thought.
>
>Most solid-state power amplifiers are littered with bypass caps. A good
>designer will consider using tantalums or ceramics because these types,
>although they aren't that linear, have very low impedance and wide
>bandwidth compared to films. Far from being superfluous, the bypass
>capacitors keep the supply rail impedance low at frequencies in the tens of
>Megahertz. This is necessary because the open-loop bandwidth of a
>solid-state amp is often this high. As well, solid-state devices are more
>prone to producing distortion in the presence of RF noise than tubes.
>
>On the other hand, the open-loop bandwidth of a typical tube amplifier is
>only a couple of hundred kilohertz at best. They don't suffer from junction
>rectification problems.
>
>Finally, I surveyed many schematics of classic tube amplifiers, vintage and

>modern, and found that there were very few gratuitous bypass caps in them.
>Of course, it costs money to install these parts. But I suspect there'd be
>more of them if they really made a big sonic difference.
>
>The "underground" DIY literature was inconsistent. Some tweak articles
>mandated elaborate networks bypasses-upon-bypasses. Others said the
>bypasses screwed up the sound. Not much help there.
>
>I am sure there are many cases where changing a cap here and there can make
>a significant difference in the sound in spite of objective predictions to
>the contrary. The problem is, if we never build amplifiers without these
>parts, we will never have a standard of comparison for tweaked-out designs.
>
>So, I am using quality film filter caps in my power supply, and I am going
>to forego most of the bypass caps unless I can convince myself there is a
>good engineering reason for having them in the circuit. This makes the
>circuit board layout much easier and keeps the cost down, as well. We'll
>see how it sounds.
>
>**********
>
>_____________________
>Edu Silva - ES2 Audio
>Salvador-Bahia-Brazil
>




From theremin1 at worldnet.att.net  Mon Dec 28 07:20:25 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Sun, 27 Dec 1998 22:20:25 -0800
Subject: Bypass cap's
Message-ID: <003501be322a$290ebec0$d97a4e0c@hpcustomer>

I've always had good luck with 78xx and 79xx parts, but those little 78Lxx
and 79Lxx things have given me noise and stability problems on occasion.

-Art

-----Original Message-----
From: Edu Silva <edusilva at bahianet.com.br>
To: jhaible at metronet.de <jhaible at metronet.de>; DIY
<synth-diy at mailhost.bpa.nl>
Date: Sunday, December 27, 1998 5:36 PM
Subject: Re: Bypass cap's


>Juergen wrote:
>
>> I had a lot of problems with 7815 / 7915 on board regulators, and 7818 /
>> 7918
>> pre-stabilized PSU. Don't ask me why, but they failed all the time. (no
>> destruction,
>> but latching up in protection mode). I switched to RC4195's and all was
>> fine.
>>
>> JH.
>
>You know, some devices, like the 555, have the annoyng habit of inducing
>little glitches in supply lines, when changing states. The 78/79
>regulators, sensible as they are, may be interpreting this as a short, and
>bravely saving your beloved gear...
>
>Just a thought...
>
>Edu
>
>_____________________
>Edu Silva - ES2 Audio
>Salvador-Bahia-Brazil
>




From jhaible at primus-online.de  Mon Dec 28 14:00:03 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 28 Dec 1998 14:00:03 +0100
Subject: Headphone amp
Message-ID: <19981228225429.9815.qmail@nuernberg2.pop.metronet.de>

> Visit Andrea Ciuffoli at
> http://www.geocities.com/ResearchTriangle/8231/my/index.html#MY_HEAD

Ahh, that's what I was looking for ! Thank you !
 

> BTW, one can say (and I'm tempted to agree) that most of the "magic" in
> tube sound comes from the xformers...

For distortion no doubt. But what I'm after is a clean amplifier to connect
to my
record player with as few artifacts as possible.

JH.



From jhaible at primus-online.de  Mon Dec 28 14:37:52 1998
From: jhaible at primus-online.de (jhaible)
Date: Mon, 28 Dec 1998 14:37:52 +0100
Subject: Bypass cap's
Message-ID: <19981228225440.9815.qmail@nuernberg2.pop.metronet.de>

> I've always had good luck with 78xx and 79xx parts, but those little
78Lxx
> and 79Lxx things have given me noise and stability problems on occasion.

Hmm, yes, it may have been the "L" types which I have used.
They work normally worked fine, too. Only with the 18V pre-regulation I ran
into problems.

JH. 

> 
> -Art
> 
> -----Original Message-----
> From: Edu Silva <edusilva at bahianet.com.br>
> To: jhaible at metronet.de <jhaible at metronet.de>; DIY
> <synth-diy at mailhost.bpa.nl>
> Date: Sunday, December 27, 1998 5:36 PM
> Subject: Re: Bypass cap's
> 
> 
> >Juergen wrote:
> >
> >> I had a lot of problems with 7815 / 7915 on board regulators, and 7818
/
> >> 7918
> >> pre-stabilized PSU. Don't ask me why, but they failed all the time.
(no
> >> destruction,
> >> but latching up in protection mode). I switched to RC4195's and all
was
> >> fine.
> >>
> >> JH.
> >
> >You know, some devices, like the 555, have the annoyng habit of inducing
> >little glitches in supply lines, when changing states. The 78/79
> >regulators, sensible as they are, may be interpreting this as a short,
and
> >bravely saving your beloved gear...
> >
> >Just a thought...
> >
> >Edu
> >
> >_____________________
> >Edu Silva - ES2 Audio
> >Salvador-Bahia-Brazil
> >
> 
> 



From wils0450 at itlabs.umn.edu  Mon Dec 28 17:00:17 1998
From: wils0450 at itlabs.umn.edu (Clarissa Fragile)
Date: Mon, 28 Dec 1998 10:00:17 -0600 (CST)
Subject: Found this laying around...
In-Reply-To: <199812240201.DAA14499@mail2.it.kth.se>
Message-ID: <Pine.GSO.4.05.9812232218080.5214-100000@beluga.itlabs.umn.edu>

> Hmm, I got this little organising-mania hitting me from time to time,
> and I have noticed that this issue keeps poping up all the time. So, I
> sugest that maybe we aught to compile a page with books which is
> usefull for the DIYer. There is a AH FAQ, so one could have it
> associated with that possibly. Every now and then we see how people
> comment on this or that book, I know books (like "The Art of
> Electronics" for instance) that keep surfacing.

For those who want to put in thier two cents worth, There will be a a
list of *beginners* and more advanced books on the Midwest Synthesis
Combine website. Unfortunately, everyone at University is on vacation, so
it probably won't be up until January (next month). I will post the addy
as soon as the page is up. This isn't one of those "when I get around to
it things," this is a for sure deal - the page is even done, I just don't
have my URL yet. Damn. For those who are interested, there will also be a
list server catering specifically to beginners. Thanks for the Bandwidth.






From djblue at asu.edu  Tue Dec 29 00:46:25 1998
From: djblue at asu.edu (Reverend bluE)
Date: Mon, 28 Dec 1998 16:46:25 -0700 (MST)
Subject: cap question
Message-ID: <Pine.GSO.3.96.981228163922.28024A-100000@general1.asu.edu>


okay, I finally found a VCO design that I like (read:  I can find the parts
for it.)

It is the Maxx2 Master VCO  (VCO-4B)
http://www.mindspring.com/~vco/maxx2/page_007.html

the only problem that I have is the word "POLY" printed in red on the
schematics under the 2N4392 trans.  It would appear that this word refers to
the Cap that it is printed by.  "POLY .002"  

does this mean I need a Polyester Cap?  I find them, but the tolerance is
poor (+-20%)  the other Polys I find are the Metalized Polypropylene Film
ones, but these are physically big (32mm), and it would be the most expensive
part of the circuit (just about)...

beyond that, I can't find a .002uf CAP anywhere.  it jumps from 1 to 2.2uf.
So what is the deal here?  

I guess I have two questions.  The one about the word "POLY" and one about
.002uf CAPs.  yeah.  I think that's all.

thanks for your time.
-ben




From varner at k-online.com  Tue Dec 29 01:46:45 1998
From: varner at k-online.com (Steve Varner)
Date: Mon, 28 Dec 1998 16:46:45 -0800
Subject: LPTC 12
Message-ID: <36882674.FDB4EE0C@k-online.com>

Has anyone used the LPTC 12 in place of Tempco resistors?

Precision Film Temperature Sensor (LPTC 12):
http://www.micro-ohm.com/temperature/temprecflm.html

SV




From radiohead33 at hotmail.com  Tue Dec 29 02:03:46 1998
From: radiohead33 at hotmail.com (Radio Head)
Date: Mon, 28 Dec 1998 17:03:46 PST
Subject: Midwest Analog Products DIY Help
Message-ID: <199812290103.RAA29148@law-f99.hotmail.com>

Hi,

Does anyone know where I can get finished front panels (punched & 
silkscreened)for the Midwest Analog Products ADV-Bass, ADV-Snare, and 
ADV-MIDI.  I already have the boards assembled and i have the pots & 
knobs.  I have looked at MAP web page and have emailed them and haven't 
gotten any response from Midwest Analog Products.  Please email to 
Radiohead33 if you have any ideas.  Thanks in advance.

Alex

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com



From magnus at analogue.org  Tue Dec 29 04:24:38 1998
From: magnus at analogue.org (Magnus Danielson)
Date: Tue, 29 Dec 1998 04:24:38 +0100
Subject: [Synth-DIY] Further on the book list page.
Message-ID: <199812290324.EAA26037@mail2.it.kth.se>

Hi!

Thanks to a number of friendly contributers (Jerry Federspiel,
Anthony, BJ, Ian Fritz, Steve Varner and Jessica Piper) the page have
expanded and gotten slightly reshaped (thanks BJ for kicking my
fanny!).

There is still many loose ends both material wise, comment wise,
format wise etc. to attend to, but this thing is very quickly getting
into some sort of shape where it might be usefull. Thanks to it I have
become aware of books which looks really interesting, I have also got
more quality comments on books that have been surfacing before.
Thus, it is allready getting usefull to some degree.

Any feedback is ofcourse wellcome, especially comments on books.

Cheers,
Magnus



From djfonzi at pacbell.net  Tue Dec 29 08:03:39 1998
From: djfonzi at pacbell.net (Mikel Zwissler)
Date: Mon, 28 Dec 1998 23:03:39 -0800
Subject: MIDI pitch bend
Message-ID: <36887ECA.599E1B24@pacbell.net>

    Hello all, and happy holidays.  Just a couple of questions I need to
ask.  I need to make a custom keyboard controller, sort of a double
manual thing, and I think I'm just going to use two Fatar Studiologic
37's recased together.  Should be fine, I don't need much
features-wise.  But I do need a bender on one of the manuals.  Pitch &
mod would be cool, but if it's just pitch, I could live.  Now to the
questions:
   1.) Anybody know of a quick and dirty analog-MIDI thingy, say PC
joystick-MIDI (minus a computer, just a sort of one-shot device)
    2.) Anybody know of a way to change the output channel of one of the
keyboards? They're both CH1.
    3.) On a related note, anybody have a URL for the bloke that made
the knobs box for rebirth-MC-303?

            Any help is appreciated.  And again, happy holidays,
whichever you may choose.

                                                        Mikel Z




From blacet at metro.net  Tue Dec 29 13:51:11 1998
From: blacet at metro.net (John Blacet)
Date: Tue, 29 Dec 1998 12:51:11 +0000
Subject: Jomox lighted PB switches
Message-ID: <3688D03E.7359@metro.net>

Does anyone know who makes these switches and where to get them? They
appear on the bass station thing...

Any problems from Jomox owners?

Regards.
-------------------------
John Blacet
Blacet Research Music Electronics
-------------------------
blacet at metro.net
http://metro.net/blacet/music.html



From b.layer at vikingelectronics.com  Tue Dec 29 15:50:30 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 29 Dec 1998 08:50:30 -0600
Subject: cap question
In-Reply-To: <Pine.GSO.3.96.981228163922.28024A-100000@general1.asu.edu>
Message-ID: <3.0.6.32.19981229085030.00793ad0@192.168.210.18>

Hey hey,

>does this mean I need a Polyester Cap?  I find them, but the tolerance is
>poor (+-20%)  the other Polys I find are the Metalized Polypropylene Film
>ones, but these are physically big (32mm), and it would be the most expensive
>part of the circuit (just about)...

The vintage of the circuit, as well as the values called out, should give
some good clues about just which 'poly' we're talking about. My guess is
that they are calling for polypropylene i.e. Sprague Orange Drop. A very
stable and cheap substitute would be the Xicon line of metallized
polypropylene parts. 

I'm not sure what to say about the MPPs you are describing; they don't
sound *at all* like MPPs to me. The size for one, and the cost. MPP is the
most compact, cost effective film type around. For example, Xicon
.10uF at 630V (!) are   85 cents each in lots of 10 or more. The .002 part is
probably around 25 cents in the same quantity. The part you are describing
sounds more like film and foil (i.e. Solen) than MPP...

The value, .002 is also in keeping with that line of parts. Whenever you
see these small values, think tube amplifier. Tube amps generally use
.001-.1uF parts for coupling etc. The small values are possible thanks to
the high-impedance nature of vacuum tubes. 

>beyond that, I can't find a .002uf CAP anywhere.  it jumps from 1 to 2.2uf.
>So what is the deal here?  

Where have you looked? Try places that supply tube parts, like Antique
Electronic or New Sensor Corp. If you need to, you can put two .001 in
parallel, or two .0047 in series for roughly .002uF.

>I guess I have two questions.  The one about the word "POLY" and one about
>.002uf CAPs.  yeah.  I think that's all.
>

Hope this helped. 


Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From Chris.List at sc.siemens.com  Tue Dec 29 16:25:27 1998
From: Chris.List at sc.siemens.com (List, Christopher)
Date: Tue, 29 Dec 1998 10:25:27 -0500
Subject: cap question
Message-ID: <81A062BC5305D111A9D700805F06596801836C33@maildepo.sc.siemens.com>

This cap is the integrator for the VCO. Best bet for a VCO is
Poly"styrene" - can be found in the Mouser catalog, and they only come
in small values (I keep hearing rumors that they aren't being made
anymore - why is that?). Tolerance isn't too much of an issue - temp.
coefficients being more important.

- CList

> -----Original Message-----
> From:	Reverend bluE [SMTP:djblue at asu.edu]
> Sent:	Monday, December 28, 1998 6:46 PM
> To:	DIY
> Subject:	cap question
> 
> 
> okay, I finally found a VCO design that I like (read:  I can find the
> parts
> for it.)
> 
> It is the Maxx2 Master VCO  (VCO-4B)
> http://www.mindspring.com/~vco/maxx2/page_007.html
> 
> the only problem that I have is the word "POLY" printed in red on the
> schematics under the 2N4392 trans.  It would appear that this word
> refers to
> the Cap that it is printed by.  "POLY .002"  
> 
> does this mean I need a Polyester Cap?  I find them, but the tolerance
> is
> poor (+-20%)  the other Polys I find are the Metalized Polypropylene
> Film
> ones, but these are physically big (32mm), and it would be the most
> expensive
> part of the circuit (just about)...
> 
> beyond that, I can't find a .002uf CAP anywhere.  it jumps from 1 to
> 2.2uf.
> So what is the deal here?  
> 
> I guess I have two questions.  The one about the word "POLY" and one
> about
> .002uf CAPs.  yeah.  I think that's all.
> 
> thanks for your time.
> -ben



From b.layer at vikingelectronics.com  Tue Dec 29 18:17:24 1998
From: b.layer at vikingelectronics.com (Bill Layer)
Date: Tue, 29 Dec 1998 11:17:24 -0600
Subject: cap question
In-Reply-To: <81A062BC5305D111A9D700805F06596801836C33@maildepo.sc.sieme
 ns.com>
Message-ID: <3.0.6.32.19981229111724.007d0890@192.168.210.18>

Hi Chris, All,

>This cap is the integrator for the VCO. Best bet for a VCO is
>Poly"styrene" - can be found in the Mouser catalog, and they only come
>in small values (I keep hearing rumors that they aren't being made
>anymore - why is that?). 

The rumors stem from the closing of a major manufacturer of PS film in
Germany. Perhaps some of our German (or is that Deutsch?) friends know more
about the defunct firm. 

I heard this info from the folks at Reliable Capacitor, who gave it as the
reason that they were unable to continue supplying their *very* excellent
PS part that we used heavily at Atma-Sphere. We (now they) bought the
remaining stock on hand.

So my question is: Why the hell can't 3M make a decent PS film? Apparently,
microscopic pinholes are the enemy...


Bill Layer
Sales Technician
<b.layer at vikingelectronics.com>

+----------------------------------+
     Viking Electronics, Inc.
       1531 Industrial St.
    Hudson, WI. 54016 - U.S.A
      715.386.8861 ext. 210
 <http://www.vikingelectronics.com>
+----------------------------------+

"Telecom Solutions for the 21st Century"



From cyborg0 at GlobalEyes.net  Tue Dec 29 21:18:55 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Tue, 29 Dec 1998 14:18:55 -0600
Subject: push-button on/off switch
Message-ID: <3689392F.359A42AB@globaleyes.net>

Just wondering if anyone has had any problems using push button switches
to trigger flip-flops.. Basically, routing QNOT to D, and switching clk
on and off.. One hit is on, one hit being off..
Rob
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From uzs159 at uni-bonn.de  Tue Dec 29 23:13:42 1998
From: uzs159 at uni-bonn.de (Rene Schmitz)
Date: Tue, 29 Dec 1998 23:13:42 +0100
Subject: cap question
In-Reply-To: <3.0.6.32.19981229111724.007d0890@192.168.210.18>
References: <81A062BC5305D111A9D700805F06596801836C33@maildepo.sc.sieme ns.com>
Message-ID: <3.0.5.32.19981229231342.00886c90@ibm.rhrz.uni-bonn.de>

At 11:17 29.12.98 -0600, you wrote:
>Hi Chris, All,
>
>>This cap is the integrator for the VCO. Best bet for a VCO is
>>Poly"styrene" - can be found in the Mouser catalog, and they only come
>>in small values (I keep hearing rumors that they aren't being made
>>anymore - why is that?).
>
>The rumors stem from the closing of a major manufacturer of PS film in
>Germany. Perhaps some of our German (or is that Deutsch?) friends know more
>about the defunct firm.

I have no clue but I think SIEMENS is one of the major companies that make 
polystyrene caps, I don't think that ps-caps will become "obsolete" or "rare"
in the future.

My 0.02 Deutschmark ....

Rene


             ,   : (uzs159 at uni-bonn.de)
|") [" |\ | ["   : (http://www.uni-bonn.de/~uzs159)
|"\ [_ | \| [_   : (http://members.xoom.com/Rene_Schmitz)
                       




From vco at mindspring.com  Wed Dec 30 01:46:14 1998
From: vco at mindspring.com (tomg)
Date: Tue, 29 Dec 1998 19:46:14 -0500
Subject: kbd_2a - kbd_2d update
Message-ID: <yam7667.721.119177872@mail.mindspring.com>

Here is an update to the one-switch per key 1v/oct keyboard
controller.

I reduced the parts count a little seems to work as well as 
the 2a and it's a little easier to put together.

http://www.mindspring.com/~vco/misc/kbd_2d.html

-tg





From vco at mindspring.com  Wed Dec 30 02:00:13 1998
From: vco at mindspring.com (tomg)
Date: Tue, 29 Dec 1998 20:00:13 -0500
Subject: Mad Mouse Update #5
Message-ID: <yam7667.684.118764264@mail.mindspring.com>


Here is a new drawing and gif of the Easytrax MM pcb. I should get a 
hard quote on the boards Monday.


http://www.mindspring.com/~vco/madm/page_005.html

-tg





From vco at mindspring.com  Wed Dec 30 02:24:36 1998
From: vco at mindspring.com (tomg)
Date: Tue, 29 Dec 1998 20:24:36 -0500
Subject: cap question
In-Reply-To: <Pine.GSO.3.96.981228163922.28024A-100000@general1.asu.edu>
Message-ID: <yam7667.1817.119395248@mail.mindspring.com>

On 28-Dec-98, Reverend bluE wrote:

>okay, I finally found a VCO design that I like (read:  I can find the parts
>for it.)

>It is the Maxx2 Master VCO  (VCO-4B)
>http://www.mindspring.com/~vco/maxx2/page_007.html

>the only problem that I have is the word "POLY" printed in red on the
>schematics under the 2N4392 trans.  It would appear that this word refers to
>the Cap that it is printed by.  "POLY .002"  

>does this mean I need a Polyester Cap?  I find them, but the tolerance is
>poor (+-20%)  the other Polys I find are the Metalized Polypropylene Film
>ones, but these are physically big (32mm), and it would be the most expensive
>part of the circuit (just about)...

>beyond that, I can't find a .002uf CAP anywhere.  it jumps from 1 to 2.2uf.
>So what is the deal here?  

>I guess I have two questions.  The one about the word "POLY" and one about
>.002uf CAPs.  yeah.  I think that's all.

>thanks for your time.
>-ben


Any good .002 even a ceramic will work. A ployester film 
type will offer better stability and a +-5% tolerance. Temp
stability of +5% to -2% change @ 85'C / 0% to -5% at
40'C.

sub-mini and cheep! 

Mouser # 140-PM2A202K $.12 each.

-tg









From theremin1 at worldnet.att.net  Wed Dec 30 03:05:52 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 29 Dec 1998 18:05:52 -0800
Subject: cap question
Message-ID: <001c01be3398$eea52b00$d8754e0c@hpcustomer>

FWIW, several years ago, I heard exactly the same explanation
re: unobtainability of polystyrene film.

As far as the 2nF goes, if you can obtain a 1.8nF or 2.2nF part,
perhaps you can use it instead of 2nF, and trim the value of the
potentiometer accordingly.

BTW, a seldom considered, but superb dielectric for these
applications is mica, although a 2nF mica cap is quite expensive
(and perhaps too large for some layouts).  Cornell Dubilier makes
a 2nF, +/-5% mica job, their part number CD19FD202J03, and it's
in the Newark catalog as stock number 15F1259 for $2.42 each.
(See: http://www.newark.com/)

-Art
-----Original Message-----
From: Bill Layer <b.layer at vikingelectronics.com>
To: List, Christopher <Chris.List at sc.siemens.com>; synth-diy at mailhost.bpa.nl
<synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 29, 1998 11:55 AM
Subject: RE: cap question


>Hi Chris, All,
>
>>This cap is the integrator for the VCO. Best bet for a VCO is
>>Poly"styrene" - can be found in the Mouser catalog, and they only come
>>in small values (I keep hearing rumors that they aren't being made
>>anymore - why is that?).
>
>The rumors stem from the closing of a major manufacturer of PS film in
>Germany. Perhaps some of our German (or is that Deutsch?) friends know more
>about the defunct firm.
>
>I heard this info from the folks at Reliable Capacitor, who gave it as the
>reason that they were unable to continue supplying their *very* excellent
>PS part that we used heavily at Atma-Sphere. We (now they) bought the
>remaining stock on hand.
>
>So my question is: Why the hell can't 3M make a decent PS film? Apparently,
>microscopic pinholes are the enemy...
>
>
>Bill Layer
>Sales Technician
><b.layer at vikingelectronics.com>
>
>+----------------------------------+
>     Viking Electronics, Inc.
>       1531 Industrial St.
>    Hudson, WI. 54016 - U.S.A
>      715.386.8861 ext. 210
> <http://www.vikingelectronics.com>
>+----------------------------------+
>
>"Telecom Solutions for the 21st Century"




From cyborg0 at GlobalEyes.net  Wed Dec 30 04:04:08 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Tue, 29 Dec 1998 21:04:08 -0600
Subject: push-button on/off switch
References: <005101be33ae$ef0bb300$d8754e0c@hpcustomer>
Message-ID: <36899828.9F7AE14D@globaleyes.net>

Arthur Harrison wrote:
> 

> The CD40106BE plus three CD4013BE packages, on the other hand, provide
> six independent bounceless on-off switches with both Q and Qnot outputs.

This sounds like what Im after.. You see, the problem is that I will
have 18 pushbuttons, and it gets kinda hectic doing all the layout for
debouncing each and every switch, and I am trying to keep the parts
count low...

> 
> A typical circuit with one section of a CD40106BE and half of a CD4013BE is
> at:
> http://home.att.net/~theremin1/debounce.gif

Going to look at this...
> 
> A related circuit, specifically designed for the Big Briar "Etherwave"
> theremin is at:
> http://home.att.net/~theremin1/circuitlibrary/mute.html

hmm..
> 
> An often-ignored requirement for reliable switching is the switch contact.
> For low-level
> currents, such as in this application, it is best to use a switch with
> gold-plated contacts
> and a "snap" mechanism, 

This is the kind I am using.. the type you see on a lot of gear, like
the buttons on the akai samplers et al... the surface mount tact
switches.. Cheap, but when I look at the extra work needed, I am
starting to wonder if I am not better off with toggles. Perhaps a micro
is a good idea here..
Rob
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From synth1 at airmail.net  Wed Dec 30 04:25:31 1998
From: synth1 at airmail.net (Paul Schreiber)
Date: Tue, 29 Dec 1998 21:25:31 -0600
Subject: Debouncing alot of switches
Message-ID: <001501be33a4$0ec69120$851a88cf@paults>

Try going to

www.maxim-ic.com

and search on 'debounce'. There is like a hex or octal
debouncer in there. It is in a SSOP package, but you can
get adapters for it or CAREFULLY solder.

Aries Electronics (not the old synth company!!) makes
tons of adapters.

Paul Schreiber
Synthesis Technology





From theremin1 at worldnet.att.net  Wed Dec 30 05:43:22 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Tue, 29 Dec 1998 20:43:22 -0800
Subject: push-button on/off switch
Message-ID: <005101be33ae$ef0bb300$d8754e0c@hpcustomer>

Unless you have a "bounceless" contact in the switch (mercury, for example),
you must pre-condition the switch with a hysteretic comparator before going
to
the FF.  There are many approaches, but for metal-gate CMOS, a section of a
CD40106BE hex Schmitt inverter is handy.  The CD4013BE FF is also nice for
the storage element, but a neat one-IC trick is to use a CD4024BE counter,
which has built-in hysteresis, giving you debounce and storage in one part.
The CD40106BE plus three CD4013BE packages, on the other hand, provide
six independent bounceless on-off switches with both Q and Qnot outputs.

A typical circuit with one section of a CD40106BE and half of a CD4013BE is
at:
http://home.att.net/~theremin1/debounce.gif

A related circuit, specifically designed for the Big Briar "Etherwave"
theremin is at:
http://home.att.net/~theremin1/circuitlibrary/mute.html

An often-ignored requirement for reliable switching is the switch contact.
For low-level
currents, such as in this application, it is best to use a switch with
gold-plated contacts
and a "snap" mechanism, or better yet, a magnet-actuated dry reed switch
(expensive!).
Typical silver-plated contacts used in switches rated in the ampere range
may form
resistive oxides over time which do not readily clean away with a few
milliamperes of
current, causing unreliable operation.

Another type of bounceless switch are the hybrid types which contain a
magnet,
Hall-effect transducer, and IC.  I've seen these used in some FX pedals.

-Art

-----Original Message-----
From: Rob <cyborg0 at GlobalEyes.net>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 29, 1998 2:55 PM
Subject: push-button on/off switch


>Just wondering if anyone has had any problems using push button switches
>to trigger flip-flops.. Basically, routing QNOT to D, and switching clk
>on and off.. One hit is on, one hit being off..
>Rob




From allan.houston at lineone.net  Wed Dec 30 17:10:54 1998
From: allan.houston at lineone.net (Allan)
Date: Wed, 30 Dec 1998 16:10:54 -0000
Subject: MIDI port(first time post)
Message-ID: <000201be340e$fa5ae540$463763c3@default>

I'm in my final year at Uni., Electronics degree, and for my project I'm
making a monophonic synth, which has to be MIDI controlled.  At the moment I
just want note on and note off think.  I've got a diagram of the port its
just how do I decode the info?  I want to try and convert this to a voltage
so I can feed it into a VCO.  Any advice, pointers etc would be most
welcome.

Allan




From wils0450 at itlabs.umn.edu  Wed Dec 30 17:59:53 1998
From: wils0450 at itlabs.umn.edu (Michael Tang)
Date: Wed, 30 Dec 1998 10:59:53 -0600 (CST)
Subject: Electronic Projects for Musicians
Message-ID: <Pine.GSO.4.05.9812301057500.7160-100000@urchin.itlabs.umn.edu>

While the information in this book is fantastic, DO NOT spill even the
tiniest amount of fluid on it. I was drinking a soda near mine and a
little drip fell from the lip of the bottle on to my book. It immediately
bled through two pages and obliterated the type and ate a hole in the
page. I hate it when people skimp on materials.

                 "There always lies so near to us a realm
        in which we have escaped entirely from all our affliction..."






From wils0450 at itlabs.umn.edu  Wed Dec 30 20:12:38 1998
From: wils0450 at itlabs.umn.edu (Claire F.)
Date: Wed, 30 Dec 1998 13:12:38 -0600 (CST)
Subject: Electronic Projects for Musicians
In-Reply-To: <001501be3440$9bb16c80$ce794e0c@hpcustomer>
Message-ID: <Pine.GSO.4.05.9812301311370.7160-100000@urchin.itlabs.umn.edu>

uOn Wed, 30 Dec 1998, Arthur Harrison wrote:

> What kind of soda was that?!
Minute Maid Orange.

> And, were you referring to the Anderton book?  
Yep, just got it a couple of days ago.


                 "There always lies so near to us a realm
        in which we have escaped entirely from all our affliction..."






From costello at seanet.com  Wed Dec 30 20:46:37 1998
From: costello at seanet.com (Sean Costello)
Date: Wed, 30 Dec 1998 11:46:37 -0800
Subject: Electronic Projects for Musicians
References: <001501be3440$9bb16c80$ce794e0c@hpcustomer>
Message-ID: <368A831D.68BD00E2@seanet.com>

Arthur Harrison wrote:

> Seriously, I find it very irritating that a vast majority of affordable
> ink-jet printers have water-soluble output.  I suppose I'd have to
> spend at least $500 for a decent laser/xerography printer to
> avoid that.

Yeah, that does suck.  Many a schematic has met its demise around my
desk in that manner.  The HP720 prints out schematics beautifully, but
it does suffer from water-related issues.  Also, it sometimes crashes
Windows 98, but that could be the work of the Great Satan of Redmond (I
am about .5 mile from there as I type this).

> I'd hate to think that publishers are resorting to ink-jets instead
> of offset printing presses, just to save a buck.

I recently purchased a copy of "Elements of Computer Music" by F.
Richard Moore (EXCELLENT book, btw - explains everything, including the
math, and has TONS of C code for implementing oscillators, phase
vocoding, filters, etc.).  The print on the pages has a weird raised
quality.  I have the feeling that the book is printed on demand, using
some weird technique. That would explain why the damn thing cost $64
(worth it, though).

Sean Costello



From debus at cityweb.de  Wed Dec 30 21:26:39 1998
From: debus at cityweb.de (Ingo Debus)
Date: Wed, 30 Dec 1998 21:26:39 +0100
Subject: AD8307 logarithmic amplifier
Message-ID: <368A8C7E.6F26@cityweb.de>

Hi,

did anyone have a look at the AD8307 from Analog Devices? I only had a
glance at the data sheet (www.analog.com), but I wonder if a expo
converter could be made from it?

Ingo





From jhaible at primus-online.de  Wed Dec 30 21:35:48 1998
From: jhaible at primus-online.de (jhaible)
Date: Wed, 30 Dec 1998 21:35:48 +0100
Subject: Radio Buttons (was: Debouncing alot of switches)
Message-ID: <19981231013921.16934.qmail@nuernberg2.pop.metronet.de>

Related topic to debouncing pushbuttons:

I was thinking about a set of "radio buttons" recently, i.e. an array
of electronic switches where selecting one pushbutton de-selects
all the others. The most straight forward approach would be a flip
flop for each switch, and pressing one switch would reset all flip
flops over a common "reset" line, and only set the single one that
belongs to the switch with an individual "set" signal. Or a schmitt 
trigger for each switch, with all schmitt triggers getting a "weak"
(high impedance) low signal, and only the selected one getting
a "strong" (low impedance) high signal.
Problem would be the *priority* of the two signals. The selected
flipflop or schmitt trigger would get strong high and weak low
at the same time, but you'd have to avoid the weak "low" being
active any longer than the "high" under all circumstances (bouncing
keys etc.) This sounds trivial, but it isn't. One could spend an extra
capacitor for each switch to delay the "high", but I was looking for 
ultra low component count. I experimented with *one* capicitor
to give a short common reset trigger only - the idea was that the
individual set pulse would last longer then, and I only need one capacitor
for the whole circuit. But unfortunately this wasn't very relyable.

So I am still looking for the most elegant, minimum part cound solution.

Any ideas ?

JH.

PS.: Frontpanel for HiFli Clone was in the mail today. Great work from
       Schaeffer Apparatebau, once again !



From jhaible at primus-online.de  Wed Dec 30 21:37:39 1998
From: jhaible at primus-online.de (jhaible)
Date: Wed, 30 Dec 1998 21:37:39 +0100
Subject: Electronic Projects for Musicians
Message-ID: <19981231013922.16934.qmail@nuernberg2.pop.metronet.de>

> While the information in this book is fantastic, DO NOT spill even the
> tiniest amount of fluid on it. I was drinking a soda near mine and a
> little drip fell from the lip of the bottle on to my book. It immediately
> bled through two pages and obliterated the type and ate a hole in the
> page. I hate it when people skimp on materials.

What acid stuff are you drinking ??

Sorry, couldn't resist. (;->)

Happy new year !



From jhaible at primus-online.de  Wed Dec 30 21:48:04 1998
From: jhaible at primus-online.de (jhaible)
Date: Wed, 30 Dec 1998 21:48:04 +0100
Subject: That VP330 project
Message-ID: <19981231013923.16934.qmail@nuernberg2.pop.metronet.de>

I've played along with the human voice filter bank a little, and also
ran it thru the MKS-30 - type chorus. I think I will make a 19" 1U
box with the filter and the chorus now.
I don't know if I will use the MKS-30 chorus, however. I was looking
at different Roland chorus effects (from synthesizers, not stand alone),
and I was astonished that they are all so different. At first glance, they
look much the same, but there aren't any two that are identical, or so
it seems. I consider building the Juno-6 version now.
Are the MN3101 and 3009 chips still available, btw ?

JH.



From garry at gazbar.freeserve.co.uk  Wed Dec 30 22:00:40 1998
From: garry at gazbar.freeserve.co.uk (Garry Barton)
Date: Wed, 30 Dec 1998 21:00:40 -0000
Subject: No subject
Message-ID: <002001be3437$78d31e60$8141883e@default>

Can anyone sugest a simple and cheap synth project or kit. I have just recently become interested and do ot have alot of building experince.
Thanks


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From peterc at pop.onwe.co.za  Wed Dec 30 22:15:14 1998
From: peterc at pop.onwe.co.za (peter_cornell)
Date: Wed, 30 Dec 1998 21:15:14 +0000
Subject: Headphone amps 
Message-ID: <199812301909.VAA22935@mail-intertech.onwe.co.za>

Hi list

There was a query about headphone amps valve or otherwise recently.

Check out

headwize.com

for a few interesting circuits

Peter Cornell



From james at newd.demon.co.uk  Wed Dec 30 22:26:05 1998
From: james at newd.demon.co.uk (James Jackson)
Date: Wed, 30 Dec 1998 21:26:05 +0000
Subject: Line Levels
Message-ID: <1.5.4.32.19981230212605.0067a374@pop3.demon.co.uk>

Does anybody know what voltage / current line levels and the output from
record decks are?

Also, does anybody know of any phone pre-amp circuits?

Thanks,
James.
-------------------------------------------------------------------------------
James Jackson - New Era Web Designs
          |
          ------------------- james at newd.demon.co.uk
Sales ------------------- sales at newd.demon.co.uk
Information ------------ info at newd.demon.co.uk
-------------------------------------------------------------------------------




From theremin1 at worldnet.att.net  Wed Dec 30 23:06:09 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 30 Dec 1998 14:06:09 -0800
Subject: Electronic Projects for Musicians
Message-ID: <001501be3440$9bb16c80$ce794e0c@hpcustomer>

What kind of soda was that?!

And, were you referring to the Anderton book?  
I've had one for many years, and never noticed any problems.

Seriously, I find it very irritating that a vast majority of affordable 
ink-jet printers have water-soluble output.  I suppose I'd have to 
spend at least $500 for a decent laser/xerography printer to 
avoid that.

I'd hate to think that publishers are resorting to ink-jets instead 
of offset printing presses, just to save a buck.

-Art

-----Original Message-----
From: Michael Tang <wils0450 at itlabs.umn.edu>
To: Synth-DIY <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 30, 1998 11:00 AM
Subject: Electronic Projects for Musicians


>While the information in this book is fantastic, DO NOT spill even the
>tiniest amount of fluid on it. I was drinking a soda near mine and a
>little drip fell from the lip of the bottle on to my book. It immediately
>bled through two pages and obliterated the type and ate a hole in the
>page. I hate it when people skimp on materials.
>
>                 "There always lies so near to us a realm
>        in which we have escaped entirely from all our affliction..."
>
>
>
>




From camotse at france-mail.com  Wed Dec 30 23:38:02 1998
From: camotse at france-mail.com (^cAmOtSe^)
Date: Wed, 30 Dec 1998 23:38:02 +0100
Subject: No subject
Message-ID: <002f01be3447$c9c66f60$a915eec3@lisa>

who said ASM-1 ? :o))
-----Message d'origine-----
De : Garry Barton <garry at gazbar.freeserve.co.uk>
? : synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date : mercredi 30 d?cembre 1998 23:13


Can anyone sugest a simple and cheap synth project or kit. I have just
recently become interested and do ot have alot of building experince.
Thanks







From wils0450 at itlabs.umn.edu  Wed Dec 30 23:47:38 1998
From: wils0450 at itlabs.umn.edu (Claire F.)
Date: Wed, 30 Dec 1998 16:47:38 -0600 (CST)
Subject: Sync multiplier
Message-ID: <Pine.GSO.4.05.9812301644100.29366-100000@barney.itlabs.umn.edu>

I would like to build a mult unit for din sync. I' d like to do it up as a
two in, four out unit. 

Assumption: I am going to have to amplify the input signal
Question How?


                 "There always lies so near to us a realm
        in which we have escaped entirely from all our affliction..."






From Aranakin at aol.com  Thu Dec 31 01:15:03 1998
From: Aranakin at aol.com (Aranakin at aol.com)
Date: Wed, 30 Dec 1998 19:15:03 EST
Subject: Electronic Projects for Musicians
Message-ID: <2333c1d.368ac207@aol.com>

In a message dated 12/30/98 9:04:28 AM Pacific Standard Time,
wils0450 at itlabs.umn.edu writes:

spe4aking of shoody amterials in this book, i love it, but about 5 pages
havejust ripped out from all the handeling, being that this is a book you
don't jsut readonce and put on your shelf, but rather use many times, the
publishers should haveput more consideration into it.
anthony




From cyborg0 at GlobalEyes.net  Thu Dec 31 01:25:11 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Wed, 30 Dec 1998 18:25:11 -0600
Subject: Sync multiplier
References: <Pine.GSO.4.05.9812301644100.29366-100000@barney.itlabs.umn.edu>
Message-ID: <368AC467.51E2C210@globaleyes.net>

"Claire F." wrote:
> 
> I would like to build a mult unit for din sync. I' d like to do it up as a
> two in, four out unit.
> 
> Assumption: I am going to have to amplify the input signal
> Question How?
> 
>            
Im not sure of this, but I think if you just use cmos logic you can do
this. It *might* be a good idea to isolate the sync 24 at the inputs and
outputs with, say, a MOC3010..
Whats up with the two in? Do you want to somehow merge them, or make the
two inputs switchable?
Rob



From mamundso at mr.net  Thu Dec 31 03:29:36 1998
From: mamundso at mr.net (Mark Amundson)
Date: Wed, 30 Dec 1998 18:29:36 -0800
Subject: Line Levels
References: <1.5.4.32.19981230212605.0067a374@pop3.demon.co.uk>
Message-ID: <368AE190.5733@mr.net>

James Jackson wrote:
> Does anybody know what voltage / current line levels and the output from
> record decks are? Also, does anybody know of any phone pre-amp circuits?
> Thanks, James.

The standard consumer recording deck standard (read TEAC/Tascam
standard) is -10dBV for zero VU, which equates to about the 316mV level.
More professional equipment relies on the +4dBu standard for zero VU,
which equates to the 1.23V level.

I don't have any "telephone" pre-amp circuits, but their are a few
internet resources for "phonograph" preamps.

Mark Amundson,



From don at till.com  Thu Dec 31 04:45:09 1998
From: don at till.com (Don Tillman)
Date: Wed, 30 Dec 1998 19:45:09 -0800 (PST)
Subject: Radio Buttons (was: Debouncing alot of switches)
In-Reply-To: <19981231013921.16934.qmail@nuernberg2.pop.metronet.de>
	(jhaible@primus-online.de)
Message-ID: <199812310345.TAA13986@shell9.ba.best.com>

   From: "jhaible" <jhaible at primus-online.de>
   Date: Wed, 30 Dec 1998 21:35:48 +0100

   So I am still looking for the most elegant, minimum part count solution.

How about an N-Flop?  An N-unit extrapolation of the standard RS flip
flop -- the simple one made from, say, two 2-input NAND gates.  The
inputs are active low, the outputs are active high.

To build it: use a two input NAND gate and an N-1 input OR gate for
each stage.  "I'll leave the rest as an excercise for the reader."

  -- Don






From cyborg0 at GlobalEyes.net  Thu Dec 31 04:59:34 1998
From: cyborg0 at GlobalEyes.net (Rob)
Date: Wed, 30 Dec 1998 21:59:34 -0600
Subject: Radio Buttons (was: Debouncing alot of switches)
References: <19981231013921.16934.qmail@nuernberg2.pop.metronet.de>
Message-ID: <368AF6A6.F4CD987B@globaleyes.net>

jhaible wrote:
> 
> Related topic to debouncing pushbuttons:
> 
> I was thinking about a set of "radio buttons" recently, i.e. an array
> of electronic switches where selecting one pushbutton de-selects
> all the others. The most straight forward approach would be a flip
> flop for each switch, and pressing one switch would reset all flip
> flops over a common "reset" line, and only set the single one that
> belongs to the switch with an individual "set" signal. Or a schmitt
> trigger for each switch, with all schmitt triggers getting a "weak"
> (high impedance) low signal, and only the selected one getting
> a "strong" (low impedance) high signal.

Why not just have ANY button press trigger a high edge trigger circuit
that hits ALL the clears of the flip-flops? That means that the button
you want and the one that stays on AFTER clear pulse (due to you holding
it) will be the one that will stay in the flopped state. I dont know if
it will work, but try it.. 

Rob



From ka4hjh at gte.net  Thu Dec 31 05:58:43 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Wed, 30 Dec 1998 23:58:43 -0500
Subject: Electronic Projects for Musicians
Message-ID: <v04011702b2b0b4ee3d97@[153.37.233.60]>

>When I build anything out of a book I photocopy it first.. then I can
>scribble all over it, and write rude comments if necessary before filing.

Ah, an _experienced_ hobbiest. I usually blow them up at least 44% while
I'm at it. On 11 x 17.

If you need to waterproof it, spray some workable fixative on it (expensive
but you can still write on it). The paper will now disentegrate before the
ink/toner comes loose.

Terry Bowman, KA4HJH
"The Mac Doctor"



From ka4hjh at gte.net  Thu Dec 31 06:03:29 1998
From: ka4hjh at gte.net (KA4HJH)
Date: Thu, 31 Dec 1998 00:03:29 -0500
Subject: Radio Buttons (was: Debouncing alot of switches)
In-Reply-To: <368AF6A6.F4CD987B@globaleyes.net>
References: <19981231013921.16934.qmail@nuernberg2.pop.metronet.de>
Message-ID: <v04011704b2b0b5aa6993@[153.37.233.60]>

>Why not just have ANY button press trigger a high edge trigger circuit
>that hits ALL the clears of the flip-flops? That means that the button
>you want and the one that stays on AFTER clear pulse (due to you holding
>it) will be the one that will stay in the flopped state.

Or use  SPDT pushbuttons. Pressing clears 'em all, releasing sets the
corresponding flip-flop (just AC couple it).

Terry Bowman, KA4HJH
"The Mac Doctor"



From grbridgw at facstaff.wisc.edu  Thu Dec 31 06:58:34 1998
From: grbridgw at facstaff.wisc.edu (Gary R.Bridgwater)
Date: Wed, 30 Dec 1998 23:58:34 -0600
Subject: Remove
Message-ID: <3.0.2.32.19981230235834.006f9730@facstaff.wisc.edu>

>Return-Path: owner-synth-diy at mailhost.bpa.nl
>From: "David Lee" <mymoog at ix.netcom.com>
>To: <synth-diy at mailhost.bpa.nl>
>Subject: Remove
>Date: Mon, 23 Nov 1998 13:32:48 -0600
>X-MSMail-Priority: Normal
>X-Priority: 3
>Sender: owner-synth-diy at mailhost.bpa.nl
>Precedence: bulk
>
>Remove
>



From vco at mindspring.com  Thu Dec 31 07:14:02 1998
From: vco at mindspring.com (tomg)
Date: Thu, 31 Dec 1998 01:14:02 -0500
Subject: Radio Buttons (was: Debouncing alot of switches)
In-Reply-To: <19981231013921.16934.qmail@nuernberg2.pop.metronet.de>
Message-ID: <yam7669.130.119872296@mail.mindspring.com>

On 30-Dec-98, jhaible wrote:
>Related topic to debouncing pushbuttons:

>I was thinking about a set of "radio buttons" recently, i.e. an array
>of electronic switches where selecting one pushbutton de-selects
>all the others. 

[snip]

>Any ideas ?

>JH.


Got this out of a reciever kit. I don't remember who's. I
think it was in a RE mag. The original used 2 4011's and
then inverted the output. I just replaced the second 4011
with a 4081.

Might be expanded to more than 4 outputs I never tried. You 
could build 5 and use one to select the other 4 switch banks.

http://www.mindspring.com/~vco/misc/pics/radio_s.gif

I sent this to Rob maybe someone else is interested.

Try this one. It's right out of the CMOS cookbook. The neet thing
about this is the cap remembers the last state when powered down.
So when you turn whatever it is back on the switches remember where
they were set. very cool! The 4016/66 can be omitted and a manual
PB used instead. But with the analog switch it can be voltage
controlled...also very cool!


http://www.mindspring.com/~vco/misc/pics/switch.gif




From bduggan at netcom.com  Thu Dec 31 07:29:59 1998
From: bduggan at netcom.com (Brett Duggan)
Date: Wed, 30 Dec 1998 22:29:59 -0800 (PST)
Subject: Which temperature coefficient for resistors?
Message-ID: <Pine.3.89.9812302232.A25131-0100000@netcom8>


Hi folks,

I need to buy a variety of metal film resistors for use in an ASM-1 along 
with various other synth-DIY projects.  The resistors I wanted to 
purchase come in both 50ppm and 100ppm varieties.  Are there any 
particular reasons why I should choose one kind over the other, or is 
this irrelevant?  Would it be okay to mix both kinds within the same circuit?

Thanks very much for any help,
Brett D




From theremin1 at worldnet.att.net  Thu Dec 31 08:14:58 1998
From: theremin1 at worldnet.att.net (Arthur Harrison)
Date: Wed, 30 Dec 1998 23:14:58 -0800
Subject: That VP330 project
Message-ID: <001a01be348d$4718e700$1b7a4e0c@hpcustomer>

Yup, they're both in DigiKey:
http://www.digikey.com/

-Art


-----Original Message-----
From: jhaible <jhaible at primus-online.de>
To: DIY <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 30, 1998 7:03 PM
Subject: That VP330 project


>I've played along with the human voice filter bank a little, and also
>ran it thru the MKS-30 - type chorus. I think I will make a 19" 1U
>box with the filter and the chorus now.
>I don't know if I will use the MKS-30 chorus, however. I was looking
>at different Roland chorus effects (from synthesizers, not stand alone),
>and I was astonished that they are all so different. At first glance, they
>look much the same, but there aren't any two that are identical, or so
>it seems. I consider building the Juno-6 version now.
>Are the MN3101 and 3009 chips still available, btw ?
>
>JH.
>




From MHELIN at tnclus.ntc.nokia.com  Thu Dec 31 11:27:53 1998
From: MHELIN at tnclus.ntc.nokia.com (Mikko Helin)
Date: Thu, 31 Dec 1998 12:27:53 +0200
Subject: MIDI port
Message-ID: <981231122753.53000bef@tnclus.ntc.nokia.com>

>I'm in my final year at Uni., Electronics degree, and for my project I'm
>making a monophonic synth, which has to be MIDI controlled.  At the moment I
>just want note on and note off think.  I've got a diagram of the port its
>just how do I decode the info?  I want to try and convert this to a voltage
>so I can feed it into a VCO.  Any advice, pointers etc would be most
>welcome.
>
You can order MIDI specs from www.midi.org, though every information
you'll need is on page http://www.midi.org/table1.htm

You got to receive the MIDI data with a UART, and convert the
key (not) number to analog voltage which is feeded then into VCO.
You also need to convert the note on status to gate on, and the
note off status to gate off signals.

The easiest solution is to force the MIDI sequencer or master keyboard
to use NOTE ON/NOTE OFF messages with no running status. Then use
binary comparator (74HC688) to find a note on status byte.
The following data byte, which is the key (note) value, is read 
into latch register, and from the latch output to DAC (DAC08 etc.)
to buffer and from it to the VCO. You'll need another 74HC688 for note off
status recognition. You'll need some counter (a decade counter
should work here) to count the data bytes after NOTE ON has received, 
and some logic for the latch enable control signal (short pulse after 
1st data byte after note on has received). 

The note on comparator sets a flip-flop (such as 74HC74) and note off
comparator resets it. The Q output of 7474 is the gate signal
for EG's or VCA.

This design can be simplified a little. As the difference with the
note on and note off is only one bit, just compare the other
bits, and connect bit 4 (the 5th bit) to an AND gate with
the (inverted?) output of 688, and the output of AND to /S input of 
7474 and to /RESET of counter and through an inverter to /R input.
You may need some inverters there or use NAND gate etc., but this
gives you the idea.

This kind of hardware midi2cv converter will not work with running
status, which use the second data byte (velocity) for note
off (when RS=note on, if the 2nd data byte is zero, it means
a note off status). You could use the other decade counter output
and third comparator (or other gates) to compare whether the
2nd data byte is zero or more. If it's zero, generate a pulse
to reset the 7474 (also the counter has to be reset somewhere).

An alternative and a better solution is a microcontroller 
like PIC16F84 with a DAC.

If you are not familiar with digital locigs try www.paia.com
- they have a thing called MIDI2CV8 which has everything you
need and a lot more.

Hope this helps,

-Mikko




From jhaible at primus-online.de  Thu Dec 31 14:01:20 1998
From: jhaible at primus-online.de (jhaible)
Date: Thu, 31 Dec 1998 14:01:20 +0100
Subject: Radio Buttons (was: Debouncing alot of switches)
Message-ID: <19981231135635.25321.qmail@nuernberg2.pop.metronet.de>

> Why not just have ANY button press trigger a high edge trigger circuit
> that hits ALL the clears of the flip-flops? That means that the button
> you want and the one that stays on AFTER clear pulse (due to you holding
> it) will be the one that will stay in the flopped state. I dont know if
> it will work, but try it.. 

The idea is good, but what happens when the key bounces ? The last
short "high" impulse may be long enough to perform the clear function, but
not long enough to activate the desired flip flop after that.
In some way, that's exactly what I built (but I didn't use CMOS logic. I
used
opamps with positive feedback as storage elements, because I needed 24V
swing,
and a CR high pass for the reset trigger.) Didn't work.

JH.



From patchell at teletrac.com  Thu Dec 31 19:49:09 1998
From: patchell at teletrac.com (patchell)
Date: Thu, 31 Dec 1998 10:49:09 -0800
Subject: AD8307 logarithmic amplifier
References: <368A8C7E.6F26@cityweb.de>
Message-ID: <368BC725.6AB15B80@teletrac.com>

    I would say no.  First off, this is a 500MHz part (translation,
expensive).  Also, the word logarithmic is being used in a different sense
as used in E-music circuits.  I am afraid we are still stuck with the
traditional way of making an exponential converter.

    By the way, this is my first post to this group.  I have been reading
it for about a month.  You seem like a fairly swell bunch of people.  Wish
I had known about this group sooner, but better late than never.

    -Jim

Ingo Debus wrote:

> Hi,
>
> did anyone have a look at the AD8307 from Analog Devices? I only had a
> glance at the data sheet (www.analog.com), but I wonder if a expo
> converter could be made from it?
>
> Ingo

--
-----------------------------------------------------------------
Visit:http://www.silcom.com/~patchell/
-----------------------------------------------------------------





From james at newd.demon.co.uk  Thu Dec 31 21:31:56 1998
From: james at newd.demon.co.uk (James Jackson)
Date: Thu, 31 Dec 1998 20:31:56 +0000
Subject: Sequential Circuits Prophet Scematics
Message-ID: <1.5.4.32.19981231203156.006752d8@pop3.demon.co.uk>

Doea enyone know where I can get scematics, PCB layout diagrams and so on
for the Sequential Circuits Prophet Five?

Thanks,
James.
-------------------------------------------------------------------------------
James Jackson - New Era Web Designs
          |
          ------------------- james at newd.demon.co.uk
Sales ------------------- sales at newd.demon.co.uk
Information ------------ info at newd.demon.co.uk
-------------------------------------------------------------------------------




From wils0450 at itlabs.umn.edu  Thu Dec 31 21:44:19 1998
From: wils0450 at itlabs.umn.edu (Claire F.)
Date: Thu, 31 Dec 1998 14:44:19 -0600 (CST)
Subject: No subject
Message-ID: <Pine.GSO.4.05.9812311440360.14629-100000@beluga.itlabs.umn.edu>

Hello all.
Does anyone know of a project or have suggestions for a project that would
produce warm, smooth, etheral pads? I have a few ideas for features, but
am still new to this whole deal.
 Pleasent thought for the day: Electronics aren't quite as tough as I
thought they would be. Kinda'like being a DJ...sort of.

                 "There always lies so near to us a realm
        in which we have escaped entirely from all our affliction..."






From dbalvage at ptdcs2.ra.intel.com  Thu Dec 31 22:38:24 1998
From: dbalvage at ptdcs2.ra.intel.com (Duane R Balvage)
Date: Thu, 31 Dec 1998 13:38:24 -0800
Subject: 6-pole switched capacitor filter "Q's" (literally)
Message-ID: <368BEED0.794B@ptdcs2.intel.com>

Hello all -

I have ordered some switched cap 6-pole butterworth filter chips from
National Semi... I originally got them to replace the anti-aliasing
filter and reconstruction filter in my Prophet-2000 sampler, but I got a
(strange) idea...

Can you loop the output through a VCA or variable attenuator back to the
input for a resonance control? Or will the switched-cap filter freeak
out if you do that? Anyone tried this? I don't have the chips yet, but I
was thinking of trying this.

				- Duane
-- 
   "That boy's got a mouth like a cannon ... Always shootin' it off..."
                                
                             - Foghorn Leghorn
                      ________________________________
                     / o o oo              o ooo o   /\
       -------------/ ////  Duane R. Balvage   //// / /---------
                   /    _________________________  / /
                  / // / // /// // /// // /// / / / /
                 /___ //////////////////////////_/ /
                 \____\________________________\_\/

                     Intel Corporation, RA1-303
                   Portland Technology Development
       =========================================================

              Phone: (503) 613-8055    FAX: (503) 613-8261
                   E-Mail: dbalvage at ptdcs2.intel.com



From hugo.haesaert at skynet.be  Thu Dec 31 22:46:07 1998
From: hugo.haesaert at skynet.be (Hugo Haesaert)
Date: Thu, 31 Dec 1998 22:46:07 +0100
Subject: MIDI port
In-Reply-To: <981231122753.53000bef@tnclus.ntc.nokia.com>
Message-ID: <199812312136.WAA23399@sunsoap.skynet.be>

Hi Allen and All !

Most (if not all) of the midi docs are on :

http://www.borg.com/~jglatt/

The source code for the Paia converter is to be found at ther-ir 
website .  Makes for interesting reading ;-)

Good luck .

Happy New Year !!!!!!


Keep 'em oscillating :)


Hugo
=



