From yrrab at well.com  Sun Sep  1 19:20:59 1996
From: yrrab at well.com (Barry Bernard)
Date: Sun, 1 Sep 1996 10:20:59 -0700 (PDT)
Subject: Electronotes and Mr. Hutchins
Message-ID: <v01510100ae4f021310da@[153.36.53.35]>

Hi,
   Recently have recieved some mail from Mr. Hutchins regarding the copying
of the Electronotes PCC. In my response, I explained that some people on
this list have written that they have had difficulty obtaining this
information from him and that that's these reason for this unauthorized
copying of his material. I volunteered to pay him for the information I've
recieved, even though I did not get it from him. He seemed to like this
suggestion and said that $15.00 seemed fair to him and that he'd like to
recieve that amount from the other people who'd recieved a copy of the PCC.
(The current price for the PCC through him is $25.00).
Since this material does belong to him, I believe that he deserves to be
compensated for it's distribution. It's not like this is some big
corporation ripping people off, it's just one guy providing information,
making copies. It would be really great if the people who have recieved the
PCC would voluntarily send $15.00 to Bernie Hutchins for the use of the
information. That would show that we are not a bunch of deadbeats trying to
rip him off but people who are simply interested in building analog who
very much want the information.
Bernie's messages may sound angry to people who have recieved them, and may
be putting people on the defensive. It is in my nature to try to make peace
whenever possible, and I do still think that it's possible in this
circumstance.      It would be a shame if there were a rift between the
online building community and Mr. Hutchins. I think we should try to work
this out somehow. In my response to Mr. Hutchins I suggested that he
subscribe to this list and communicate with the people here, if that was
true in the first place then this misunderstanding would have never come to
pass. I don't think that we should create an environment here on synth-diy
that makes that impossible.

  Here is the address and phone for Bernie Hutchins/Electronotes:

Bernie Hutchins
Electronotes
1 Pheasant Lane
Ithaca, NY 14850 USA
(607)-273-8030

  I strongly suggest than anyone who has recieved the Electronotes PCC send
$15.00 to Mr. Hutchins for the use of the information which, after all DOES
belong to him. I wouldn't want him to have the wrong impression about the
dwellers of this corner of the net. $15.00 isn't much to ask considering the
utility of having this information.
   If I can, I'm going to order a new copy of Electronotes from Bernie (you
never know there could be something interesting that I'm missing). When/if
I get a copy from him, I report the successful transaction on this list.



regards,

-Barry







From erik.gronberg at mbox300.swipnet.se  Sun Sep  1 23:40:14 1996
From: erik.gronberg at mbox300.swipnet.se (Erik Gronberg)
Date: Sun, 01 Sep 1996 16:40:14 -0500
Subject: Svenska DIY:are?
Message-ID: <199609011533.RAA28423@mailbox.swip.net>

Hej!

Finns det nagra svenskar som ?r intresserade av
att diskutera, kopa/salja/byta, utbyta DIY-tips,
kort sagt allt om *** ANALOG *** -syntar, lokalt i Sverige??

Att handla med syntar med USA eller England ?r knepigt 
och dyrt. Skulle vara bra mycket b?ttre med Sverige...

N?gon av er kanske har resurser att fixa en brutal
svensk DIY/AH-sajt???

Jag vet att ni finns, maila (privat)!

(Om du redan svarat p? AH-mailet s? strunta i detta)

Erik



From bah13 at cornell.edu  Mon Sep  2 19:54:55 1996
From: bah13 at cornell.edu (Bernard Hutchins)
Date: Mon, 2 Sep 1996 13:54:55 -0400 (EDT)
Subject: Bernie himself defending himself
Message-ID: <2.2.16.19960902135501.1c474950@postoffice4.mail.cornell.edu>

Hi - It's me, Bernie Hutchins

This email and net stuff is new to me.  I've only had it since early August,
1996.  It's Cornell's actually, so it certainly can't and won't be used for
routine Electronotes work.

Most of you know that we started publishing in 1972.  We are still
publishing, although the issues are larger and less frequent than in the
early days.  The latest issue is Vol. 19, No. 187, August 1996, and has a
feature article on sampling and recovery based
on an average sampling rate (Shannon apparently never said the samples had
to be equally spaced!), as well as a review of Curt Roads' astounding book
THE COMPUTER MUSIC TUTORIAL, (MIT Press) and a page or so (of paper!) on Bob
Moog's Cornell visit last November.

Mentioning Bob's visit above is propitious since he said that there were two
questions he was always asked.  The first was "Are you still alive?"  (He
was.)  I mention
this because it appears I too need to make a Mark Twain statement.  I find
that much of the net has apparently decided that since I was not on the net,
I couldn't be around at all.

So, kicking and screaming, I let Cornell put the net on my computer.   (In
truth, I came into my office and saw some yellow lights blinking on a board
in the back.)  The tech shop guy showed me how to use a web searcher, and
typed in my name.  I found I had a web page I didn't even suspect.
[Incidentally, I have apparently had some sort of default email address for
a year or more.  If you knew this, and mailed me before about Aug. 10, 1996,
I didn't get it, and have no idea if it's still around.]

OK, so we punch in "electronotes" and follow some other links, and in fewer
than five minutes, we click on "analog synthesizers" and then
"voltage-controlled filter," and then "schematic."    GOSH THIS WEB IS GOOD,
I thought.  I just logged on five minutes ago, and already, they have one of
my VCF schematics installed for me, exactly as I drew it years ago!

Well, that was the beginning, and there was much more; and frankly, things
became more disturbing as I went along.   In the course of a couple of
weeks, sending emails, and just learning how to use the web, I found that in
addition to the unauthorized and (in most cases) totally unattributed
posting of my schematics, there was some sort of distribution by which
copies of my Preferred Circuits Collection was being circulated and copied
in large numbers, and most disturbing of all, that there was a general
perception that I was no longer providing this information.  [Why am I
telling you this - you probably have all read it.]

Now, I have had some very nice and helpful email, and also some relatively
unpleasant exchanges.  The latter I attribute to individuals who were - how
shall I put this: "caught with their hand in the cookie jar and were trying
desperately to rationalize their actions." Even as they were being pleasant
to me by email, they were plotting to continue their activities with such
flimflam as attaching to personal email, hidden links, redrawn
schematics, and surface mail.  These facts I found when a student of mine
showed me how to find posted messages.   I even found my personal email to
one individual posted.  I didn't know this was proper.

For the moment, no one is authorized, or ever has been, to post my
schematics on the web.  My objection is first, the general lack of
attribution (to me and to the original
designers).  Secondly, dispite what some people would like you to believe,
all the schematics that I saw were scanned from a copy of the Preferred
Circuits Collection dated somewhere from 1983 to 1986, and are copyrighted
material.  Copyright claims, and related claims of intellectual and/or
commercial property are something that we all need to take seriously, and
rigorously defend if necessary, particularly on this web
where things are often so chaotic.  When everyone is in agreement as to who
it was that originated the material, and if the originators still want to
retain their interest, can any person of good conscience endorse the
appropriation of this material by those who
suppose that they have found some loophole, or who just profess disdain for
any such rights, claiming a public's right to all information?
[Rhetorical (?)]

But there is still an additional problem here.  When you get a schematic off
the web, you are getting it instantaneously and largely, for free
(truthfully - how many of you are
actually paying for your web access - not many heavy users I bet), or at
least very cheaply.  If you get the schematic from Electronotes, you have to
order it and wait (NOT wait and wait and wait - more on this below), and you
have to pay for it.  My prices are not excessive, essentially what we
charged years ago, allowing a bit for inflation.  But,
they are very expensive, compared to free!  You people on the net,
accustomed to getting information free, are likely to be disappointed from
the start.  Does anyone have an idea how to deal with this problem?

I guess the next issue to deal with is the much rumored problem of
(supposed) bad service.  Now, if I make a list of the principle players that
I have been dealing with on
the net in the last weeks, I would have seven names.  Most of these have
expressed the opinion that we give bad service, do not respond to requests
for information, and in perhaps one case, cashed a check and did not send
any material.  What is the basis of these ideas?

Well, it's certainly not first hand.  Of the seven people I have in mind,
only one requested information.  He got the ordering information, chose not
to order (ostensibly,
because of the rumors of poor service) and FAXed the forms on to someone
else (who did not order - but whom, it seems FAXed my answering machine but
never left a message by voice.)  The other six never wrote or called to ask
for information, and I think they will (several have) admit that they never
even tried.   Yet, they were keen to pass along the general scuttlebutt of
bad service.

We do not keep records of who requests information, so I can never say for
sure (but most names I do remember, and some I could not forget).  We are
not perfect.  We probably loose a few things.  At one time, my answering
machine died and would not respond except by pushing the reset.  I lost four
messages last December, but they may have been for Marty anyway.  (Marty is
the state assemblyman who has phone number 277-8030 and 277 is a virtually
unused exchange here in Ithaca.)   A fair amount of mail that is apparently
addressed properly comes back.

Now, to continue on, it is simply untrue that we do not respond to requests
for ordering information.  I have asked those who think this is true to give
me examples.  It seems
to be always "a friend of a friend" type of assertion, or someone thinks
they saw something "posted" about it.  My student looked pretty carefully
through your various archives.  One guy got only 2/3 of his order.  What he
does not ever add later is that he
got a full refund and kept both the refund and the 2/3 of the material.  One
had a problem in 1985.  Someone felt that "Mr. Hutchins is no longer
interested in analog synthesis."   Is there anything of substance here?  If
there are any real complaints,
let's hear them.  I think this is something that started out as a half-truth
of minor significance and rumored itself into what some of you thought to be
fact - after all, you read it on the net!  One person asks a question,
another offers an opinion in response, and pretty soon, it's fact.  People
writing on the web need to be more careful what they say in the first place,
and people reading it need to be much more skeptical (also applies off the
web, of course).

Alas, it is true that I am no longer interested in doing any more work in
analog synthesis. This remark is hopefully understood as being distinct from
saying that I am not interested in selling you people my back materials
and/or that anyone else can provide
them to you, free or otherwise.   I do still very much love that circuitry.
[Incidentally, and truthfully, I do at times get too much credit for these.
I did a few creative things that I am somewhat proud of, but so many of the
really good ideas came from others.  You will see this if you read the text
material that accompanies the diagrams, as I always tried to acknowledge
them.]  What I did was mainly refinements, testing, standardization, and
presentation.

[And, you people really need to look at digital more.  It is SO convenient
for experimentation.  Make one digital equivalent of a VCO for example.
Want 5 more in parallel with slightly different parameters?  Essentially cut
and paste an assembly language file.  Rosin smoke is pleasant, but....!]

OK.  So I have to get around to talking about the PCC.  I've been putting it
off.   It is
evident to all that there are a lot of pirated copies of the PCC out there,
some on elaborate distribution (copy and mail on) schemes.  [I see that some
of these have crashed.  Welcome, guys, to the wonderful world of mail order
to unknown people!  Gosh, these things never happen to us!]   The
rationalization for launching these seems to have been the idea that I was
not (would not) provide these, that everyone had an inalienable right to
them, and that they were not copyrighted.  None of these three is
true.  Requesting information (not just clicking), ordering (not just
filling out an on-screen form), and particularly paying for them (ouch) is
an idea some have trouble with.   It is my intention to collect a fee for
each of these pirated PCC's that
I can, so some of you may be hearing from the people who sent the PCC to you
asking you to chip in your share (three people already have contacted me and
asked to pay).  This is the easiest way to handle this I think.

For any of you who want to get in contact with Electronotes, the address and
phone are the same as they have been for 20 years:

          Electronotes
          1 Pheasant Lane
          Ithaca, NY  14850-6399
          (607)-273-8030

Please do not request information by, or to be sent by, email.  We do not
have the information except in printed form, and anyway, Cornell of course
does not allow commercial activities over email (If anyone asks, what I'm
doing here is defending
my reputation!)

Oh, and when we ask for your address, that means REGULAR mail, i.e., what
you call snail mail.

Bernie Hutchins

PS:     Thanks SC for the suggestion and for information on
           how I could post messages of my own here. 




From sscpwww  Mon Sep  2 21:52:28 1996
From: sscpwww (WWW Test Server)
Date: Mon, 2 Sep 1996 21:52:28 +0200
Subject: test
Message-ID: <9609021952.AA37680@horus.sara.nl>

test
test



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep  3 00:05:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 02 Sep 96 15:05:00 PDT
Subject: AW:Re: Voltage control
Message-ID: <322B5A85@MSMGATE.M30X.NBG.SCN.DE>


> The spec sheet for the LM13600 has 2 or 3 example schematics.

As Gene already pointed out: these circuits are too complicated.
For envelope generators, you don't really need general floating resistors.
A simple 1pole LP will do, which is easy with OTAs.

JH.



From yrrab at well.com  Tue Sep  3 06:04:33 1996
From: yrrab at well.com (Barry Bernard)
Date: Mon, 2 Sep 1996 21:04:33 -0700 (PDT)
Subject: Bernie himself defending himself
Message-ID: <v01510101ae50e9c8477c@[153.36.54.15]>

>>Hi - It's me, Bernie Hutchins
>
>Thanx Bernie,for so thoroughly AND eloquently stating your case here!
>(Eloquence seems to be a bit of a rareity these days.) It is very sad &
>disturbing that there are some kreepy little guys (and gals too,I suppose)
>on the Net who sit around scheming up ways to scam people and feel SO
>pleased with themselves,at being SO clever(?) to do such things. Alot like
>non-virtual life,eh? Usually,somewhere in life,people who practice these
>ways end up meeting their "Waterloos." (Sooner the better,for everyone!) I
>do hope this all works out for you.
>
>Keep up the good work!
>
>PS-I wonder *who* we'd hear from if the "shoe was on the other foot,"eh?
>
>PPS-Pay up,deadbeats!
>
> Greetings from the Alien Community!
>
                                               Rev.Fever,CMNC



   Well, I guess that makes me a deadbeat. There may have been a
misunderstanding about the availability of Electronotes and Bernie's
interest in selling them. Anyway I don't really think of myself as a
deadbeat and I had some part in coordinating the copying of the PCC.
So did some of the most informative and helpful people I've come across
on synth-diy and analogue. What in the world could anyone gain from copying
the PCC or posting schematics on a web page ? There's no profit in either,
so where's the scamming part ? It costs  almost as much money to copy and
send the PCC as it would to buy it from Bernie. I myself am happy to pay
Bernie for the use of the PCC and I'm sure that most everyone else involved
will follow suit.
I hope that we misunderstood about availability of Electronotes information
and that people on synth-diy will have no trouble ordering what they need
from him in the future.
   Anyway I think there are a few sets of ruffled feathers around here and
I don't believe that public name calling is going to help heal this
situation.
I suggested to Bernie that he subscribe to synth-diy and communicate with us
fellers here once in a while. Now that might help. Anyway, I'm going to order
a new copy of the PCC from Bernie Hutchins and will report back to the list
when I recieve my legit copy.
   By the way Bernie's message was to synth-diy not to analogue heaven to which
you posted your comments.

regards,

-Barry





From johns at oei.com  Tue Sep  3 12:41:16 1996
From: johns at oei.com (johns at oei.com)
Date: Tue, 03 Sep 96 12:41:16 
Subject: Electronotes and Mr. Hutchins
Message-ID: <9608038417.AA841779676@oei.oei.com>


     Barry suggests that everybody who has received the PCC give montetary 
     credit to Hutchins where credit is due and send in $15.
     
     I say "yeah" but respond in kind with the same kind of treatment that 
     Bernie Hutchins has given us.  This means, wait maybe 15 months to 
     send in the money.  Send $6 then, maybe $3 four months later and 
     possibly don't even send in the balance, ever.  If he asks for the 
     balance, just ignore him; he can ask again later.  When he does, 
     ignore him again.
     
     Mr Hutchins has, time and again, failed us and I see no reason to 
     leave him in the dust.
     
     JJS



From rsholmes at mailbox.syr.edu  Tue Sep  3 16:22:41 1996
From: rsholmes at mailbox.syr.edu (Rich Holmes)
Date: Tue, 03 Sep 1996 10:22:41 -0400
Subject: Bernie himself defending himself 
In-Reply-To: Message from yrrab@well.com (Barry Bernard)
   of "Mon, 02 Sep 1996 21:04:33 PDT." <v01510101ae50e9c8477c@[153.36.54.15]>
Message-ID: <199609031422.KAA12257@hydra.syr.edu>

First point: Given that Mr. Hutchins has gone on record as saying my
money is indeed welcome, I intend to send him some.  I think my
unauthorized copy of the PCC has some pages missing and some loss from
the photocopying process -- a new copy certainly isn't likely to be
worse and may be better.  In any case I owe Mr. Hutchins for the
material.  I assume he didn't post prices, etc. for legal reasons
(Cornell email address and all that) so I'll ask for them by snail
mail.

Second point: You can catch more flies with honey than with vinegar.
Mr Hutchins's insinuations regarding the motives and credulity of the
people who've circulated the PCC are for the most part unfounded.  It
was no "friend of a friend" who reported non-responsiveness; it was
several people who reported to the list their firsthand experience in
trying and failing to get a copy of the PCC from Mr. Hutchins -- and
NO people who reported success in same.

Getting it "for free" isn't the issue.  The cost of photocopying is
comparable to the cost of buying -- especially if you figure how much
the time you spend arguing with the photocopier is worth.

The few who've advocated keeping this material in "free" circulation
by covert and dishonest means deserve Mr. Hutchins's contempt; the
majority who simply acted under what he claims is a misconception do
not. 

Third point: My feeling is that having a selection of Electronotes
circuits freely available on the web is about the best and cheapest
advertising Mr Hutchins could get.  If he can't put up a web page of
his own, he could do worse than to give permission for a few circuits
to be put up on someone else's page along with information about
ordering the PCC.

-- 
- Rich Holmes              
  "I'm not dissing them, man, but they're seriously well different"
                  - Sidmouth native critiques the Brittania Nutters



From gstopp at fibermux.com  Tue Sep  3 20:00:22 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Tue, 03 Sep 96 11:00:22 PDT
Subject: Bernie himself defending himself
Message-ID: <9608038417.AA841773813@ccrelay.fibermux.com>

     I consider myself to be a major contibutor to the proliferation of 
     "underground" Electronotes materials over the last year or so. 
     Therefore in the context of the current discussions on this topic I'd 
     like to apologize to Bernie Hutchins for participating in something 
     that he is opposed to. Fortunately (if at least for my own moral 
     sensibilities) I can safely say that a large percentage of the 
     Electronotes-related materials that I did distribute were faxed copies 
     of the 1995 price list and order form for Electronotes. Whether or not 
     these got used I cannot say.
     
     As things stand perhaps we can look at the optimistic side of things - 
     it may be that Electronotes has finally reached a level of awareness 
     on the Internet lists such that the appetites of many more synthesizer 
     builders than before have been whetted, and perhaps they want more. If 
     somebody is serious about building their own modular analog system, 
     then they really should pop for the $265 and get *the* definitive 
     collection of schematics, theory, and background information provided 
     by the package deal from Electronotes. Of particular interest to 
     analog synthesizer enthusiasts is the fact that at the time of the big 
     developments in synthesizer history, anything that took place pretty 
     much did so in the pages of Electronotes, and in the real world soon 
     after. If you're truly bitten by the modular analog bug, then $265 
     will be a minor expenditure in your adventures, believe me. Of course 
     there's a lot of digital theory and DSP discussions later on - 
     actually my collection stops at #134 so maybe I should act on that 
     myself...
     
     Just a thought, but if you do want to recompense Bernie by sending in 
     the $15, you may want to just add a few bucks to that and actually buy 
     more materials.
     
     I did just now take a look into my own (personal) email archives, back 
     to about a year ago, and I did find the discussions warning against any 
     dealings with Electronotes. Perhaps we were too quick to judge?
     
     - Gene
     gstopp at fibermux.com
     
     p.s. also I'd like to say that it *is* possible to read Electronotes 
     over and over again, and teach yourself electronics, and then "grow 
     up" to be an EE.
     
     
______________________________ Reply Separator _________________________________
Subject: Bernie himself defending himself
Author:  Bernard Hutchins <bah13 at cornell.edu> at ccrelayout 
Date:    9/2/96 11:18 AM
     
     




From rga at es.rti.org  Tue Sep  3 20:58:37 1996
From: rga at es.rti.org (Randy Alley)
Date: Tue, 3 Sep 1996 14:58:37 -0400 (EDT)
Subject: SEM Help !
Message-ID: <Pine.ULT.3.90.960903144505.8113A-100000@shrike>


AH folks ignore the following :
Hello to all on the synth-diy list ! I guess I qualify to participate 
since I'm too cheap to farm out work on my synths ;>}

Concerning my topic, I've got a 4-Voice needing TLC. I've got the SEM-1A 
Schematic, but no trouble-shooting instructions or component layout. 
(Unfortunately, I require such hand-holding when it comes to circuits. 
I'm a software guy by trade.) 
Do these exist ? How about the original SEM manual, any thing useful in that ?
If anyone could supply copies, I would happily pay expenses, and trade 
Memorymoog+ or ARP 2600 service docs if any one might need them.

I've got two SEMs a on the fritz:

One has a dead VCO1 and VCO2. On it I can't find a audio frequency signal 
anywhere. Proper supply voltages are present. Maybe I should suspect the 
CA3086 Transconductance Amp ? Where does the initial oscillationing 
signal first appear in the circuit ?

The other SEM has signals that I can trace to one side of the VCA section 
resistor R174, but nothing on the other. Seems like a dead resistor.

Please bear with me as I learn basic electronic trouble-shooting :>}

Any help or suggestions appreciated.

Sincerely,
Randy

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Randy Alley MSEE - Research Engineer
Research Triangle Institute - Center for Semiconductor Research
rga at es.rti.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep  3 21:39:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Tue, 03 Sep 96 12:39:00 PDT
Subject: SSM2024 experiments
Message-ID: <322C89A3@MSMGATE.M30X.NBG.SCN.DE>


Hi!

Recently, I did some experiments with the output voltage
range of a SSM2024.

Background:
As I have posted some time ago, the famous SSM2040 filter
sound is partly due to its nonsymmetrical clipping, when the
ota output (!) is overdriven. This is because it has a very simple
internal stucture that saves two current mirrors in comparison
with a 3080. The output of a 2040's gm cell covers a range
of -0.5V to +14V (with +/-15V supply)

Now the simplified schematic of the SSM2024 quad VCA shows
a similar structure. This brought up two questions:

(1) Could we build a good replacement of a 2040 with the 2024
and external darlington buffers?

(2) Could we use the 2024 with a voltage output (instead of current
into virtual gnd summing node), by just introducing a positive
dc offset at the output (as in the CEM3320 filters)?

I was eager to find these answers, but only recently I found the time
to try it out.
And, alas, it does *not* work. The output stage of the 2024 must be
more complicated than the simplified schematic in the data book
would suggest. The (measured) output range is from -0.5V to
+2V only. Might be good for some unsymmetrical clipping
experiments, or for a *slight* dc offset if you want to use ordinary
polarized elkos, but that's it.

Well, at least now I know (and hope you found it interesting).

JH.



From gstopp at fibermux.com  Wed Sep  4 00:10:00 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Tue, 03 Sep 96 15:10:00 PDT
Subject: More on this Electronotes topic...
Message-ID: <9608038417.AA841788742@ccrelay.fibermux.com>

     Well recent events have triggered me into action on something I've 
     been meaning to do for a while - I've just ordered the "everything 
     package" from Electronotes for $265. If the reports of 
     unresponsiveness from this business are unfounded, then I stand to 
     loose nothing. If they are true, I do believe in giving someone a 
     second chance. I know the quality of the material that I do have so 
     far, and I'd like to see the rest of it. (Anyone familiar with the 
     game theory topics as discussed in "Scientific American" will know 
     that cooperation is the best way to behave in situations where mutual 
     trust may be in doubt.)
     
     - Gene
     gstopp at fibermux.com




From hdan at charybdis.com  Wed Sep  4 00:54:27 1996
From: hdan at charybdis.com (Dan Higdon)
Date: Tue, 3 Sep 1996 17:54:27 -0500
Subject: Barry Klein
Message-ID: <01BB99C0.F692B180@hyperion.charybdis.com>

Damn, damn, damn!  I lost his email/post address, and I want to
order one of his books.  Is he still selling them?  (Are you out there
Barry?)

hdan




From wizrad at ix.netcom.com  Wed Sep  4 01:21:37 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Tue, 03 Sep 1996 19:21:37 -0400
Subject: Barry Klein
References: <01BB99C0.F692B180@hyperion.charybdis.com>
Message-ID: <322CBD81.5934CCD8@ix.netcom.com>

Dan Higdon wrote:
> 
> Damn, damn, damn!  I lost his email/post address, and I want to
> order one of his books.  Is he still selling them?  (Are you out there
> Barry?)
> 
> hdan
8-18-95

I saved Barry's message, I was just getting ready to order it myself:
Barry wrote:

FINALLY!!
I have finally found a copy center to copy my books!  Should be 
ready to ship next week.

Electronic Music Circuits
This is a complete copy of the original book (published by Sams in 1982).  It
contains circuits for most every type of module you would want to make for
a modular analog synthesizer.  Some circuits are my own, some slightly modified
from the Digisound series, many Electronotes circuits.  There were a few
errors in the original printing and I have made the corrections in this copy.
Also, this copy is enlarged up to 8 1/2" x 11" - lots easier to read!  I 
include a 32 page update booklet that suggests alternative approaches, parts 
substitutions, an updated source list, etc.  There are no new circuits (in case 
you have the original book already).  Many of the circuits use CEM/SSM chips 
that are no longer available, but these circuits may serve as examples for 
repairing analog synths using these IC's.  There are discrete examples of VCO's, 
VCF's, envelope generators, etc. many of which you have seen discussed on this 
list.  Page count is around 335 pages.

Electronic Music IC Databook
This is a collection of all SSM and Curtis Electromusic (CEM) IC datasheets
as well as volume 1 and 2 of the Curtis Synthesource shortlived newsletter/
applications bulletin.  As the majority of these IC's are no longer 
manufactured, this manual serves as a one source reference databook for all of 
them.  The written material in these datasheets is surprisingly detailed 
as to how the IC's work internally, and how they should be applied.  The
Synthesource material is especially cool.  I also include some material 
from Linear Integrated Systems, a source for matched transistor pairs.  
Page count is around 230 pages (8 1/2" x 11").  

Both books are printed both sides, 8 1/2" x 11", with a comb binding, clear
cover.  The books should be able to lay flat on the bench, but will not fold
completely around like a spiral binding would do.

Pricing:
Electronic Music Circuits.....................  $30  plus shipping/handling
Electronic Music IC Databook..................  $20  plus shipping/handling

Shipping:
These things are quite massive/heavy, probably will run several pounds
for both together.  I think $5 each should cover US mail 3rd/4th class 
plus the purchase of the mailer, for delivery in North America.  But for
those of you outside the US continent, shipping can get quite expensive,
depending on the method chosen.  I'll have a better handle on shipping 
costs after I get the first copies back.  

Method of Payment
I don't have a charge card account so all transactions will be by money 
order.  But for those of you outside the US, I really don't know how
best to do it because there apparently are major bank charges for transferring
foriegn funds into US currency.  If you have any suggestions - let me know!

Ordering Procedure
I'd like it if you would contact me first by email with your intention to
purchase any of the books.  I then know to expect a letter from you, and
you know that I am expecting it, etc.  I can then notify you by email when
your package goes out.  Also, I should have a handle on how to handle overseas
shipments and cash transfers in a couple weeks, after suggestions come in.

My address:

Barry Klein
32041 Pleasant Glen Rd.
Trabuco Canyon, CA   92679
714-932-7493 wk phone

klein_b at a1.wdc.com    -    work address, fastest response back
barry.klein at solar.org   -   through a BBS, takes a while sometimes 


So that's about it, any questions just pass em on.  Buy a book and
start building!



From wizrad at ix.netcom.com  Wed Sep  4 01:23:24 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Tue, 03 Sep 1996 19:23:24 -0400
Subject: Oops
Message-ID: <322CBDEC.5B55B23B@ix.netcom.com>

Sorry for the waste of bandwidth. I meant to send solely to Dan.

Tomy



From wizrad at ix.netcom.com  Wed Sep  4 03:35:09 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Tue, 03 Sep 1996 21:35:09 -0400
Subject: Bernie himself defending himself
Message-ID: <322CDCCC.3506F45@ix.netcom.com>

Sorry guys, I seem to be email-impaired today. I accidentally posted
the full copy of Barry's original post, which I meant to send only to
Dan, to the entire list. Then I sent an apology meant for the list,
which I think may have only went to Dan?!

I just received the PCC. Yes I'm last in the list of "kreepy little 
guys" (or gal too, if I ever get a sex change). And yes I will send
$15 to BH. I'll even purchase the full package, if satisfied with
BH's responsiveness to Gene's order. 

I agree w/ Gene, "cooperation is the best way to behave in situations
where mutual trust may be in doubt." I've seen it proven in life as
well as in simulations. I should have relied on my own experience
rather than jump to conclusions.

I have a tendency to trust those I have respect for, and the quality
of postings and helpfulness of those of whom frequent synth-diy have
instilled such trust. I also get the impression most are professionals
who, like me, could make considerably more than $25 in the time required
to stand in front of a copier and pirate a copy of PCC at more "clever"
occupations.

I build for the love of building, for the desire of increasing my
understanding, and the unmatched joy of tinkering w/ modulars.
BH is right that I could sit down with something like Csound and model
things my current modular (and lack of modules) could produce, and
sometimes I do (still haven't figured out how to model a frequency
shifter though). But after a day of programming for a living, the last
thing I want is to schedule my inspiration around another
"edit/compile/run" cycle.

I would hope that we could overcome our shakey start w/ BH. His
experience would be a wonderful addition to synth-diy. Perhaps our
love of building, experimentation, and modulars could rekindle
old loves in him,  if not of modulars, then perhaps of informing,
which from my cursory reading of PCC, he did quite well.

I don't want to "Stoke" the fire, excuse my lack of eloquence (I 
didn't figure out a way to meander through "Waterloo" :-).

Sorry for the soapbox.

Tomy



From lcedar at worldscope.net  Wed Sep  4 08:33:34 1996
From: lcedar at worldscope.net (Laurence Cedar)
Date: Wed, 04 Sep 1996 15:33:34 +0900
Subject: How do I sign Up ?
Message-ID: <322D22BE.1767@worldscope.net>

Hi

I was wondering how I connect to your list

Laurence Cedar
lcedar at worldsope.net
tel&fax: +44 171 221 2214




From thierry.rochebois at ief-paris-sud.fr  Wed Sep  4 11:12:34 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Wed, 4 Sep 1996 11:12:34 +0200
Subject: Bernie himself defending himself
Message-ID: <9609040912.AA03361@zeus.ief-paris-sud.fr>

Hello,

I just would like to ask a silly question:
What is so interesting in "Electronotes" ?
Is that worth its price ?

I am particularly interested in knowing what are the contents:
- old fashioned low-cost low quality transistor circuits
or
- hard to find Curtis and SSM chips based circuits
or
- Original and interesting circuits ?


Thierry Rochebois



From thierry.rochebois at ief-paris-sud.fr  Wed Sep  4 11:22:26 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Wed, 4 Sep 1996 11:22:26 +0200
Subject: Patents
Message-ID: <9609040922.AA03365@zeus.ief-paris-sud.fr>

Hello,

I have ordered and received a few patents from the US Patent & Trademark Office.

Amongst them, there is the patent 580.035:
Art of and Apparatus for Generating and Distributing Music Electrically
By Thaddeus Cahill 1897.
This is really stunning : it discribes a 6 partial/voice additive organ
having velocity sensitive keyboard !


I also received patent 4.018.121 ... John Chowning's patent.
It fully describes the TTL circuits for building a two operator
FM generator...


I think that patents are really an interesting data ressource for synth-DIY.
Maybe, we can list patent references and comments on a Web page so that
people can order interesting stuff from USPTO (3$ per patent copy including
US postage...).


Thierry Rochebois



From e93_mda at drum.it.kth.se  Wed Sep  4 12:28:50 1996
From: e93_mda at drum.it.kth.se (Magnus Danielson)
Date: Wed, 04 Sep 1996 12:28:50 +0200
Subject: More on this Electronotes topic... 
In-Reply-To: Your message of "Tue, 03 Sep 1996 15:10:00 MET DST."
             <9608038417.AA841788742@ccrelay.fibermux.com>
Message-ID: <199609041028.MAA07399@piraya.electrum.kth.se>

> Well recent events have triggered me into action on something I've been
> meaning to do for a while - I've just ordered the "everything package" from
> Electronotes for $265. If the reports of unresponsiveness from this business
> are unfounded, then I stand to loose nothing. If they are true, I do believe
> in giving someone a second chance.

Good that you volunteer to do the test. I have personally no experience of
dealing with Electronotes, but if you get succesfull I think this could 
certainly kill this rather nonproductive discussion. I am certainly on my way
to do the same...

As Bernie is working as a teacher and the new term just begun I think that some
slowness must be accepted...

> (Anyone familiar with the game theory topics as discussed in "Scientific
> American" will know that cooperation is the best way to behave in situations
> where mutual trust may be in doubt.)

Didn't that turn out to be a Nobel Price winner? In economics :)

Could we also take some lessons from the Noble Price winners here?

Magnus




From sscprick at horus.sara.nl  Wed Sep  4 13:01:00 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Wed, 04 Sep 1996 13:01:00 +0200
Subject: Electronotes and Mr. Hutchins
Message-ID: <9609041101.AA38284@horus.sara.nl>


Dear readers,

Synth-diy is a non-moderated list, but would like to request 
the discussions on the Electronotes to be closed. We've heard 
from Mr. Hutchins, and as soon as it's clear what people with
a copy of the PCC in their possession owe I suggest they make
up with him or the Electronotes organisation.

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From joef at roland.co.uk  Wed Sep  4 13:06:26 1996
From: joef at roland.co.uk (Joe Farler)
Date: Wed, 4 Sep 96 11:06:26 GMT
Subject: Bernie Hutchins
Message-ID: <9609041106.ZM3126@pro1.roland.co.uk>

It's interesting to see that Bernie Hutchins has discovered the delights of the
Internet.  It must have been quite a shock to find his schematics posted.
He really stands to do very well out of it, though, if he can cope with the new
demand for all these copies of the PCC at $25 and the Electronotes sets at
$265.
The point is that I had never heard of or seen Electronotes before I found the
synth-diy list but now I would certainly want to order up the full set.
So if Bernie can supply ( from stock? ) then he will do all right.
I wait with bated breath for a reply from him and also to see if Gene gets his
set  ( didn't Bernie say around forty days ).

Joe.
-- 
Joe Farler
joef at roland.co.uk



From wbf at aloft.att.com  Wed Sep  4 14:33:25 1996
From: wbf at aloft.att.com (william.b.fox)
Date: Wed, 4 Sep 96 08:33:25 EDT
Subject: I Met Bernie
Message-ID: <9609041233.AA01123@acropolis>

Hello AHers and synth-diyers,

Over the holiday weekend, I went to the Ithaca area to visit family.  As
a side venture, I dropped in (pre-announced, of course) on Bernie
Hutchins at his Cornell office.  We spent one of the swiftest 2.5 hours
of my life talking about things analog, digital, electronotes, academic,
musical, commercial, and on and on!  Bernie, I am pleased to announce,
exists, is alive, continues to service snail-mail orders for
Electronotes materials, continues to publish Electronotes, and is
generally a very interesting guy.  He was nice enough to see me, a total
stranger, and seems to be a reasonable sort.  If you think you may have
ruffled his feathers or he yours, I'd like to recommend putting forth
the effort to smooth things over.  It will be a fruitfull venture, IMHO.
Not wanting to speak for Bernie, and not asking him outright, I did get
the impression that if certain conditions were met, it might be possible
to get his blessing to display schematic diagrams on selected web sites.
If credit is given, (? la the References sections found in Electronotes)
and the need to purchase Electronotes from Bernie is increased, not
decreased, then I think that he would be more open to web publishing of
Electronotes schematics.  As I said, I don't wish to speak for Bernie.
These are just my impressions.  I implore you, do NOT construe my
impressions to be permission.  Please, do not publish Electronotes
material on your web sites without Bernie's express permission.  Having
said all that, I'd also like to add that my impression of the members of
these two lists is that most, if not all, would rather pay Bernie for
their pirate copies of the PCC or order a copy direct from him rather
than rip him off.

I had a great time meeting Bernie and found him to be very approachable.

Bill Fox



From gstopp at fibermux.com  Wed Sep  4 18:20:56 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Wed, 04 Sep 96 09:20:56 PDT
Subject: Bernie himself defending himself
Message-ID: <9608048418.AA841854267@ccrelay.fibermux.com>

     Rick Jansen asked that we stop this thread, so here's one last post 
     from me, in response to Thierry's question:
     
     If you want to build an analog synthesizer, Electronotes is essential. 
     It is definitely worth the price. It contains old-fashioned low-cost 
     low-quality transistor circuits, just for curiosity value. It contains 
     hard-to-find Curtis and SSM chip based circuits, because Curtis and 
     SSM started in Electronotes. Above all it contains original and 
     interesting circuits, that are as professional as Serge modules and 
     maybe even better (oooh strong words I know...). In other words, it 
     contains all types of circuits. It also contains a lot of theory of 
     design, and of other related topics like psychoacoustics, interviews, 
     and even record reviews.
     
     Probably I should mention that my original distribution of the PCC was 
     verbally authorized by Bernie via telephone over one year ago. Perhaps 
     he doesn't remember, and to be honest I don't really remember the 
     actual verbage used. I do remember mentioning an "email list" which 
     didn't seem to have a big impression at the time. However he is 
     perfectly proper in his requests, so let honor be our guide here. This 
     thing may have well gotten out of control beyond his or my 
     expectations.
     
     And I do think that there is something to the idea that email list 
     discussions, and maybe even web site tidbits, could be his best 
     advertising ever....
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Re: Bernie himself defending himself
Author:  thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois) at ccrelayout
Date:    9/4/96 4:00 AM


Hello,
     
I just would like to ask a silly question: 
What is so interesting in "Electronotes" ? 
Is that worth its price ?
     
I am particularly interested in knowing what are the contents: 
- old fashioned low-cost low quality transistor circuits
or
- hard to find Curtis and SSM chips based circuits 
or
- Original and interesting circuits ?
     
     
Thierry Rochebois




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Wed Sep  4 21:24:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Wed, 04 Sep 96 12:24:00 PDT
Subject: AW: Re: Bernie himself defending himself
Message-ID: <322DD7C3@MSMGATE.M30X.NBG.SCN.DE>


Gene wrote:

>     I did just now take a look into my own (personal) email archives, back 

>     to about a year ago, and I did find the discussions warning against 
any
>     dealings with Electronotes. Perhaps we were too quick to judge?

First I have to say that I am also happy that Bernie Hutchkins has 
"returned".
I did express this in a letter to him, and I am also willing to pay him for 
my
PCC, if he insists, although this means that I will pay for it twice. (The 
copy shop
did not copy it for free! I think I have payed at least as much as if I 
could (!)
have bought it from Bernie Hutchkins !!)
So, again, I am really happy, and willing to pay for the PCC a second time,
BUT I still believe that what we have done was the only thing we could.

Bernie Hutchkins wrote:

> Most of these have
> expressed the opinion that we give bad service, do not respond to requests
> for information, and in perhaps one case, cashed a check and did not send
> any material.  What is the basis of these ideas?
> Well, it's certainly not first hand.  Of the seven people I have in mind,
> only one requested information.

Well, in my case it *is* first hand. I sent a letter (not just a FAX or 
email ...),
asking for an offer for several parts of EN, and was never ever answered.
Can't speak for others - this is *my* first-hand experience.

JJS wrote:

>      Barry suggests that everybody who has received the PCC give montetary 

>     credit to Hutchins where credit is due and send in $15.
>     I say "yeah" but respond in kind with the same kind of treatment that
>     Bernie Hutchins has given us.  This means, wait maybe 15 months to
>     send in the money.  Send $6 then, maybe $3 four months later and
>     possibly don't even send in the balance, ever.  If he asks for the
>     balance, just ignore him; he can ask again later.  When he does,
>     ignore him again.

(;->) (;->) (;->)
No, we wouldn't do this, would we? Anyway, I laughed a lot! I hope Bernie
Hutchkins can also laugh with us now. As others said, we owe him a lot
for the great work he has done in the past.

JH.

 



From djmaytag at terracom.net  Thu Sep  5 03:35:12 1996
From: djmaytag at terracom.net (DJMaytag)
Date: Wed, 4 Sep 1996 20:35:12 -0500 (CDT)
Subject: analog drum theory?
Message-ID: <199609050135.UAA21066@mendota.terracom.net>

i've been wondering about making up some simple analog drum circuits after
studying the schems of the 606, 808, and cr-8000. i'm more interested in
things like kicks, congas, and toms and things like that that use the
"bridged T filter" network thing, rather than cymbals and hi-hats (which
seem WAY beyond my technical ability, even with the schems from roland).

anyway, are there any books or articles that might provide some more detail
about analog drum building? how about that electronotes thing i've heard
about lately? or is that more for just synths?

any info would be appreciated,
mitch

djmaytag at terracom.net

three things to remember about me:
1) i'm not a dj, (but i play one on TV)
2) i have no intentions of becoming a dj (or an actor)
3) i'm not a washer and dryer repairman either

http://www.washerndryer.net/djmaytag/DJM/
"home of DJMaytag's Bass Tone(TM)"




From costello at costello.seanet.com  Thu Sep  5 05:11:49 1996
From: costello at costello.seanet.com (Sean Costello)
Date: Wed, 4 Sep 1996 20:11:49 -0700 (PDT)
Subject: analog drum theory?
Message-ID: <199609050311.UAA11493@mx.seanet.com>

At 08:35 PM 9/4/96 -0500, you wrote:

>anyway, are there any books or articles that might provide some more detail
>about analog drum building? how about that electronotes thing i've heard
>about lately? or is that more for just synths?

Check out Midwest Analog Products' web site, at
http://prairie.lakes.com/~map/.  They offer for sale "The Electronic Drum
Cookbook" by Tom Henry, one of those Synth-DIY types that has been around
forever.  

Sean






From barry.klein at solar.org  Thu Sep  5 13:09:31 1996
From: barry.klein at solar.org (Barry Klein)
Date: Thu, 05 Sep 1996 11:09:31 +0000
Subject: Barry Klein
Message-ID: <96090423291740339@solar.org>

Hey, I'm still here!
Be sure to note that the EM IC Databook is now $25 because the
I neglected to include a bunch of datasheets in the first version.
I had to add over 50 pages if I remember right.  I think I managed
to send those pages to all the original purchasers.

SHIPPING
I am now shipping domestically by Priority Mail at a cost of $5 for one
book or $7 for both.

Out of the US orders - please contact me for a shipping estimate before
you order.

Also, Global Priority shipping is now available from the postal service
for $6.95 to Europe and $8.95 to the "Pacific Rim".  The EM IC Databook
fits fine but the EMC book has to ship without the plastic GBC binding.
The shipper envelope is real thin cardboard and may get damaged in 
shipping (what can they do in a couple days...) but they will allow me
to place tape all around the edges, which may help.  My "normal" 
shipper bag is the best I could find and I haven't heard of any
complaints with it.

For faster response you might want to email me at:

klein_b at a1.wdc.com


Barry




... Elect. Music, Photography, Bubble Machines, Stunt Kites, Elect. Design

___ Blue Wave/QWK v2.20 [NR]



From s0176326 at cc.ysu.edu  Thu Sep  5 23:15:15 1996
From: s0176326 at cc.ysu.edu (Pope TROUT SOUP XXIII)
Date: Thu, 5 Sep 1996 17:15:15 -0400
Subject: analog drum theory?
Message-ID: <199609052115.RAA25029@unix1.cc.ysu.edu>

At 08:35 PM 9/4/96 -0500, DJMaytag wrote:
>i've been wondering about making up some simple analog drum circuits after
>studying the schems of the 606, 808, and cr-8000. i'm more interested in
>things like kicks, congas, and toms and things like that that use the
>"bridged T filter" network thing, rather than cymbals and hi-hats (which
>seem WAY beyond my technical ability, even with the schems from roland).

>anyway, are there any books or articles that might provide some more detail
>about analog drum building? how about that electronotes thing i've heard
>about lately? or is that more for just synths?

The Electronic Drum Cookbook
"18 practical electronic drum circuits for the do-it-yourselfer"
"- with 23 illustrations -"
by thomas henry

published by midwest analog products:
email - map at prairie.lakes.com
web   - http://prairie.lakes.com/~map

it ran me 12$ and covers alot.  the only drawback is there is _actual_thinking_
involved! thomas lays out the basic circuits you need as modules and nudges
you in the direction to assemble them in.  there is a layout of the snare
getup and it looks like a doozey.  midwest analog sells a kit called the ADV
Snare.  looks good, i've been pondering wheter to get it ...  

  trouty.

--------------------------------------------------------------------------------
        "To Kung Fu, Thanks For Everything, David Carridine" - HANNiBAL
          Trout Soup's home page of doom: http://cc.ysu.edu/~s0176326/
                 PB-CLE raves / AWE32 / MIDI / Links to odd stuff
--------------------------------------------------------------------------------




From kdok at gower.net  Fri Sep  6 00:16:00 1996
From: kdok at gower.net (kdok at gower.net)
Date: Thu, 5 Sep 96 17:16 CDT
Subject: Pro-1 Problem
Message-ID: <m0uymjK-0006RDC@ns.gower.net>

        My Pro-1 is getting on my nerves. I have to clean the key contacts
constantly. I have never had this problem with any of the other analogs. I
will clean them, and they will work fine for a week or so. Then they start
acting up again. I clean the contacts with a can of York TF i have left
over. I try to put a little something under the contacts to prop them
up....then i scrub them with the Freon cotton swabs (the long ones you know,
like the ones they use in Doctor's offices) making sure that no cotton is
left on the contacts when i am done.
        Is there a better way? I use the Freon and swabs on all my other
synths, but as you know the contacts on a Pro-1 are quite different from a
Prophet600 or whatever..much less reliable. I just cannot believe that there
is not a better way. Can anyone offer a little advice? I would appreciate
any advice. 

Matt Logan  




From walters at digidesign.com  Fri Sep  6 00:48:26 1996
From: walters at digidesign.com (Tim Walters)
Date: Thu, 5 Sep 1996 15:48:26 -0700
Subject: Pro-1 Problem
Message-ID: <v01530501ae5507dad3a2@[204.31.105.81]>

At 5:16 PM 9/5/96, kdok at gower.net wrote:
>        My Pro-1 is getting on my nerves. I have to clean the key contacts
>constantly. (etc.)

I'm assuming you have a J-wire Pro-One like mine...

One thing that can happen (according to a friend of mine who used to be a
synth tech) is that the bar that all the J-wires touch when played can
become corroded and uneven, causing the J-wires to make lousy contact.  I'm
trying to remember his solution; I think it was something like sanding the
busbar very gently with fine sandpaper (but don't try anything until I ask
him again!).

My Pro-One takes quite a bit longer to get crummy, but it does need
cleaning every once in a while.  In fact it needs one right now.


-----------------------------
"Ever wonder what it sounds like *inside* that trash can icon on your
desktop?  Tim Walters knows."  -Jim Aikin, _Keyboard_

Tim Walters  --  walters at digidesign.com  --  http://www.slip.net/~coredump





From walters at digidesign.com  Fri Sep  6 00:51:51 1996
From: walters at digidesign.com (Tim Walters)
Date: Thu, 5 Sep 1996 15:51:51 -0700
Subject: Pro-1 Problem
Message-ID: <v01530502ae55099d3db3@[204.31.105.81]>

I said:

>I'm trying to remember his solution; I think it was something like sanding
>the busbar very gently with fine sandpaper (but don't try anything until I
>ask >him again!).

Now that I think about it, this is only for drastic cases.  Probably all
you have to do is turn the busbar so that a different "side" faces the
J-wires.


-----------------------------
"Ever wonder what it sounds like *inside* that trash can icon on your
desktop?  Tim Walters knows."  -Jim Aikin, _Keyboard_

Tim Walters  --  walters at digidesign.com  --  http://www.slip.net/~coredump





From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Fri Sep  6 01:06:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Thu, 05 Sep 96 16:06:00 PDT
Subject: AW: Barry Klein
Message-ID: <322F5DA0@MSMGATE.M30X.NBG.SCN.DE>


> I had to add over 50 pages if I remember right.  I think I managed
> to send those pages to all the original purchasers.

Yes, I was very pleased with this "update service"!

I had many SSM and CEM data sheets before, and originally I just bought
Barrys IC book for "completist" reasons. But now I find myself using this 
Book
all the time, while my loose paper data sheets collect dust.
I highly recommend to buy Barry's book to anybody who has to service,
or wants to experiment with these chips.
(So much to the requests about specific data sheets that come up on AH and
DIY every now and then)

JH.



From majmoog at synthfool.com  Fri Sep  6 01:21:44 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Thu, 5 Sep 1996 17:21:44 -0600
Subject: Pro-1 Problem
Message-ID: <v02140b04ae550ffd580b@[206.171.253.88]>

On really bad units, I've resorted to even desoldering and removing the
keyboard buss bars completely and either use a very gnarly solvent  (like
MEK or Trichlorethane 1,1,1) OR in VERY bad cases, take a piece of
scotchbrite scouring pad and draw the buss bar through it... ONCE. (You
want to try and keep the gold plating on the bar!)

This always works for me.]

The separate J wires or springs can be cleaned in similar way, but you have
to be super careful not to bend or damage them.

My two cents....

Kevin





From wizrad at ix.netcom.com  Fri Sep  6 01:36:32 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Thu, 05 Sep 1996 19:36:32 -0400
Subject: analog drum theory?
References: <199609050135.UAA21066@mendota.terracom.net>
Message-ID: <322F6400.6F78812F@ix.netcom.com>

DJMaytag wrote:
> 
> i've been wondering about making up some simple analog drum circuits 

There are quite a few good articles in Polyphony. In particular,
the Oct '83 issue has an article by Craig Anderton, "Build The Hip
Bass Drum". This is on my to-build list. The design uses a single
op-amp and has a lot of control to go from slap to thud. Thomas
Henry gave it a good review.

The Aug '84 issue has a Thomas Henry article "The High-Hat and
Percussive voice"

And the Sep/Oct '82 issue has another Thomas Henry article "The Snare
+ Drum Voice".

PAiA still sells back issues. http://www.paia.com

The Thomas Henry book mentioned in a previous post would probably be
the end-all of the subject. As you can see from his articles, he was
in to this a long time ago, he's probably massed quite a collection
of circuits.

Tomy



From rob at secret-secret.com  Fri Sep  6 01:46:11 1996
From: rob at secret-secret.com (Rob)
Date: Thu, 5 Sep 1996 16:46:11 -0700
Subject: Pro-1 Problem
Message-ID: <v02140b07ae54b3317f01@[204.31.105.176]>

Tim Posted:

>One thing that can happen (according to a friend of mine who used to be a
>synth tech) is that the bar that all the J-wires touch when played can
>become corroded and uneven, causing the J-wires to make lousy contact.  I'm
>trying to remember his solution; I think it was something like sanding the
>busbar very gently with fine sandpaper (but don't try anything until I ask
>him again!).

What Chris says to do, if you can't clean the bar, is to rotate it a bit
and get a fresh surface for the j wires to contact.  This soultion works
pretty well, and you can do it a few times.

A good point to remember with all of these old boxes is to keep the tronics
clean.  So every so often go through each machine and give it a good
cleaning.  They work better and are more fun then too.  Well, ok I'll admit
that a messed up machine can sometimes come up with really fun sounds.  8.)

-Rob-





From honcho at paia.com  Fri Sep  6 05:34:07 1996
From: honcho at paia.com (honcho at paia.com)
Date: Thu, 5 Sep 96 22:34:07 CDT
Subject: analog drum theory?
Message-ID: <9609060334.AA11811@qns1.qns.net>


Hi Mitch-

www.paia.com/syndrum.htm has a schematic for a bridged T filter with 
some voltage control capability that I've used for drum tone 
oscillators. There's some discussion of component value selections 
too. If you have any questions, let me know.

-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 jdm at synthcom.com  Fri Sep  6 09:18:41 1996
From: jdm at synthcom.com (J.D. McEachin)
Date: Fri, 06 Sep 1996 00:18:41 -0700
Subject: Bernie himself defending himself
Message-ID: <1.5.4.32.19960906071841.006cdd28@synthcom.com>

At 01:54 PM 9/2/96 -0400, Bernard Hutchins wrote:

>I find
>that much of the net has apparently decided that since I was not on the net,
>I couldn't be around at all.

I'd guess much of the net doesn't know who your are, or care if you're on
the net or not.

>Now, I have had some very nice and helpful email, and also some relatively
>unpleasant exchanges.

Given your tone of discourse, I'm not surprised you've had some unpleasant
exchanges.

>The latter I attribute to individuals who were - how
>shall I put this: "caught with their hand in the cookie jar and were trying
>desperately to rationalize their actions." Even as they were being pleasant
>to me by email, they were plotting to continue their activities with such
>flimflam as attaching to personal email, hidden links, redrawn
>schematics, and surface mail.  These facts I found when a student of mine
>showed me how to find posted messages.   I even found my personal email to
>one individual posted.  I didn't know this was proper.

Since I wasn't in on this "flimflam", and have not participated in any PCC
distribution "schemes", I'll attribute the unpleasantness of this email to
my irritation with your display of hubris.

>For the moment, no one is authorized, or ever has been, to post my
>schematics on the web.  My objection is first, the general lack of
>attribution (to me and to the original designers).  

You have a valid objection.  Credit should be given where credit's due.
However, if given proper credit, you should look upon the posted schematics
as a free advertisement.

>Secondly, dispite what some people would like you to believe,
>all the schematics that I saw were scanned from a copy of the Preferred
>Circuits Collection dated somewhere from 1983 to 1986, and are copyrighted
>material.  Copyright claims, and related claims of intellectual and/or
>commercial property are something that we all need to take seriously, and
>rigorously defend if necessary, particularly on this web
>where things are often so chaotic.  

In that case, let's seriously consider your claim.  As I understand it, the
material in the PCC was previously printed in NON-COPYRIGHTED issues of
ElectroNotes.  If the material was previously published unprotected, then
you had no LEGAL right to try to retroactively assert your claim to
copyright.  Therefore, the copyright on the PCC would appear to be null and
void.

As Sean Costello wrote previously:

>Concerning copyrights on Electronotes material:

>I did some browsing on the web, and found some informative material at
>gopher://marvel.loc.gov:70/00/.ftppub/copyright/circs/circ01.  Here's some
>of the relevant information:

>>NOTE: Before 1978, statutory copyright was generally secured by 
>>the act of publication with notice of copyright, assuming 
>>compliance with all other relevant statutory conditions.  Works in 
>>the public domain on January 1, 1978 ( for example, works published
>without satisfying all conditions for securing statutory copyright
>>under the Copyright Act of 1909) remain in the public domain under
>>the current act.
>
>And:
>
>>For works first published on and after March 1, 1989, use of the
>>copyright notice is optional, though highly recommended. Before
>>March 1, 1989, the use of the notice was mandatory on all published
>>works, and any work first published before that date must bear a
>>notice or risk loss of copyright protection.

I'm not an intellectual property lawyer, but you may want to consider
consulting one before you go flouting your questionable PCC copyright.

Ric, if you want a copy of the schematics as they originally appeared in
ElectroNotes, let me know.  Since they're not copyrighted you can scan and
post them on your web site with impunity.  I think you'll find them to be
identical to the schematics in the PCC.

>When everyone is in agreement as to who
>it was that originated the material, and if the originators still want to
>retain their interest, can any person of good conscience endorse the
>appropriation of this material by those who
>suppose that they have found some loophole, or who just profess disdain for
>any such rights, claiming a public's right to all information?
>[Rhetorical (?)]

I've got a copy of the first 130 or so ElectroNotes, but I can't find a
copyright notice on them, so I'm not losing any sleep since I'm within the
letter of the law.  FWIW, putting a copyright notice on material was not a
mere loophole, but pretty much the cornerstone of copyright law until 1989.

>But there is still an additional problem here.  When you get a schematic off
>the web, you are getting it instantaneously and largely, for free
>(truthfully - how many of you are
>actually paying for your web access - not many heavy users I bet), or at
>least very cheaply.  If you get the schematic from Electronotes, you have to
>order it and wait (NOT wait and wait and wait - more on this below), and you
>have to pay for it.  My prices are not excessive, essentially what we
>charged years ago, allowing a bit for inflation.  But,
>they are very expensive, compared to free!  

Uh yeah, it doesn't cost me anything to pay US$240/year for net access and
then tie up my $3000 computer for hours and hours and hours downloading
schematics [sarcasm mode is ON, for all who can't detect written sarcasm].

I think it will be a while before people can afford the "free" download of
such a vast quantity of information as the entire ElectroNotes collection
over the Net.  

Say, why don't you OCR/Scan the complete ElectroNotes and put it all on
CD-ROM? I'd buy a copy.  I'm sure others would too.  You'd also save a lot
of trees.

>You people on the net,
>accustomed to getting information free, are likely to be disappointed from
>the start.  Does anyone have an idea how to deal with this problem?

"You people"?  I haven't heard such prejudicial language since I left my
(sadly) racist family down South.  You're on the Net too now - like it or
not, you're one of us.

>I guess the next issue to deal with is the much rumored problem of
>(supposed) bad service.  Now, if I make a list of the principle players that
>I have been dealing with on
>the net in the last weeks, I would have seven names.  Most of these have
>expressed the opinion that we give bad service, do not respond to requests
>for information, and in perhaps one case, cashed a check and did not send
>any material.  What is the basis of these ideas?

Ideas?  Facts would be a better choice of words.  If Juergen says that he
sent you a letter requesting pricing information and he got no response,
then it must be so.  Juergen is one of the kindest, and certainly the most
helpful person I've encountered on the Net.

>Well, it's certainly not first hand.

Bzzzt! Of the four people I mentioned, one of them told me verbally about
his experiences, two have come forward on this maillist, and the fourth you
aparently know about.

>Of the seven people I have in mind,
>only one requested information.  He got the ordering information, chose not
>to order (ostensibly,
>because of the rumors of poor service) and FAXed the forms on to someone
>else (who did not order - but whom, it seems FAXed my answering machine but
>never left a message by voice.)  The other six never wrote or called to ask
>for information, and I think they will (several have) admit that they never
>even tried.   Yet, they were keen to pass along the general scuttlebutt of
>bad service.

Well, where there's smoke there's usually fire.  My personal belief is that
you've been very slack and you're now trying to weasel out of it (but that's
just my belief).

>We do not keep records of who requests information, so I can never say for
>sure (but most names I do remember, and some I could not forget).  We are
>not perfect.  We probably loose a few things.  At one time, my answering
>machine died and would not respond except by pushing the reset.  I lost four
>messages last December, but they may have been for Marty anyway.  (Marty is
>the state assemblyman who has phone number 277-8030 and 277 is a virtually
>unused exchange here in Ithaca.)   A fair amount of mail that is apparently
>addressed properly comes back.

Excuses, excuses.

>Now, to continue on, it is simply untrue that we do not respond to requests
>for ordering information.  

...but this seems to have been true in the past.

>I have asked those who think this is true to give me examples.  

As one of those persons you asked, I have to say that I don't keep records
of who says they requested ElectroNotes information and didn't receive it.
I've read or scanned about 100,000 email messages since I got on the Net
(100 a day for 3 years), and the names weren't what my brain remembered -
what was remembered was that no one said they had successfully obtained
ElectroNotes from Bernie Hutchins.

Just to put your request in perspective, hopefully in terms you can relate
to - if I asked you to name the authors of every article or paper you've
seen in the last 3 years on a subject (say, improved Fast Fourier
Transforms), could you do it?

Given that I've been able to come up with 3 out of 4, I'd say I'm doing
pretty well.

>It seems
>to be always "a friend of a friend" type of assertion, or someone thinks
>they saw something "posted" about it.  

Actually, a very good personal friend of mine told me that he spoke with you
over the phone about obtaining ElectroNotes copies a few years ago.  He said
that you didn't want to talk about old ElectroNotes and reluctantly agreed
to send him a price list - which you never did.  Given the genuine
disappointment he demonstrated, I can hardly call this a rumor.

Before you demand to know who he is, I'll say that he's on this list and has
chosen to stay out of this.

>My student looked pretty carefully through your various archives.  

Which are finite and only go back so far.

>One guy got only 2/3 of his order.  What he
>does not ever add later is that he
>got a full refund and kept both the refund and the 2/3 of the material.  One
>had a problem in 1985.  Someone felt that "Mr. Hutchins is no longer
>interested in analog synthesis."   Is there anything of substance here?  

Just out of curiosity, when WAS the last time you published something on
analog synthesis?

>Alas, it is true that I am no longer interested in doing any more work in
>analog synthesis. This remark is hopefully understood as being distinct from
>saying that I am not interested in selling you people my back materials
>and/or that anyone else can provide
>them to you, free or otherwise.   I do still very much love that circuitry.
>[Incidentally, and truthfully, I do at times get too much credit for these.
>I did a few creative things that I am somewhat proud of, but so many of the
>really good ideas came from others.  You will see this if you read the text
>material that accompanies the diagrams, as I always tried to acknowledge
>them.]  What I did was mainly refinements, testing, standardization, and
>presentation.

Do any of the other contributors get a share of the proceeds when you sell a
copy of the PCC?

>[And, you people really need to look at digital more.  It is SO convenient
>for experimentation.  Make one digital equivalent of a VCO for example.
>Want 5 more in parallel with slightly different parameters?  Essentially cut
>and paste an assembly language file.  Rosin smoke is pleasant, but....!]

I have nothing against digital (digital control of analog circuits is my
main interest). It's just much easier for most people to experiment with
analog.  For instance, a friend of mine wanted to build his own synth, but
barely knew the hot end of a soldering iron. I showed him how to read a
schematic, buy the parts needed and build a circuit.  I also taught him a
little about breaking down a circuit into functional modules. NO MATH
WHATSOEVER.  He went on to build a pretty big modular, and got to the point
where he could mix and match parts of circuits.  He's very keen on
experimenting, and probably more inventive than someone who knows
theoretically what they're doing.

I just can't imagine sitting down with him and a DSP evaluation board and
going "here's the code for a VCO, here's the code for a VCF - go for it!".

>OK.  So I have to get around to talking about the PCC.  I've been putting it
>off.   It is
>evident to all that there are a lot of pirated copies of the PCC out there,
>some on elaborate distribution (copy and mail on) schemes. 

What's so elaborate about making a copy and mailing to the next guy on the list?

> [I see that some
>of these have crashed.  Welcome, guys, to the wonderful world of mail order
>to unknown people!  Gosh, these things never happen to us!]

The distribution lists seem to have had a higher success rate than the list
of people mailing to Bernie Hutchins for information!

>The
>rationalization for launching these seems to have been the idea that I was
>not (would not) provide these,

And all evidence we have so far says this is still true.  When someone
writes "I've actually received something from Bernie Hutchins" (heaven
forbid!), then our evidence will begin to tip in the other direction.

> that everyone had an inalienable right to them,

People just wanted to build their own synths to make music with, and the PCC
is a great place to start.  That's what pisses me off - this wasn't about
"Gee, let's rip off Bernie Hutchins for a few bucks" (which is what you seem
to think), it was about getting information to build synthesizers to make
music with.

> and that they were not copyrighted.  

The validity of that copyright is questionable.

>None of these three is true.  

Sounds like your batting average is worse than the Mets'.

>Requesting information (not just clicking), ordering (not just
>filling out an on-screen form), and particularly paying for them (ouch) is
>an idea some have trouble with. 

Have you ever gone into Kinko's with a stack of papers to copy?  Believe me,
you definitely pay.

>It is my intention to collect a fee for
>each of these pirated PCC's that
>I can, so some of you may be hearing from the people who sent the PCC to you
>asking you to chip in your share (three people already have contacted me and
>asked to pay).  This is the easiest way to handle this I think.

As Gene Stopp wrote:

>     Probably I should mention that my original distribution of the PCC was 
>     verbally authorized by Bernie via telephone over one year ago. Perhaps 
>     he doesn't remember, and to be honest I don't really remember the 
>     actual verbage used. I do remember mentioning an "email list" which 
>     didn't seem to have a big impression at the time. However he is 
>     perfectly proper in his requests, so let honor be our guide here. This 
>     thing may have well gotten out of control beyond his or my 
>     expectations.

Gee, thanks Bernie!

>For any of you who want to get in contact with Electronotes, the address and
>phone are the same as they have been for 20 years:
>
>          Electronotes
>          1 Pheasant Lane
>          Ithaca, NY  14850-6399
>          (607)-273-8030
>
>Please do not request information by, or to be sent by, email.  We do not
>have the information except in printed form, and anyway, Cornell of course
>does not allow commercial activities over email 

What were you saying about the Net being "free"?  If you were serious about
selling ElectroNotes, it seems that a Net account would be a justifiable
expense.

>(If anyone asks, what I'm
>doing here is defending
>my reputation!)

What reputation there is left to defend...

You know, this whole exchange just amazes me.  It seems like you've
essentially accused everyone on this maillist of stealing, spewed a lot of
venom, and made a lot of enemies in the process.  Several people here
worshipped you, one to the point of naming his modular after you.  I don't
think anyone's going to be worshipping you now.  You've burned a lot of
bridges with what is probably the best source of customers for ElectroNotes
you're going to find.  Whatever respect I may have for your electrical
engineering skills certainly doesn't extend to your social skills.

I'd like to contrast your actions with those of Barry Klein, also publisher
of a near legendary book of electronic music circuits, who got on the Net,
took the time to get to find out what the analogue heaven maillist was
about, asked if there was interest in an updated version of his book, and
then spent time revising his book and making copies available at a very
reasonable price.  He also did a great job of telling those of us who bought
the first edition what the errors were.  A tip of the hat to Barry. Bernie,
I hope you've figured out how I feel about you.

Now, can we PLEASE get back to analog circuitry?

JDM - channeling Mr.808 ...




From majmoog at synthfool.com  Fri Sep  6 09:38:24 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Fri, 6 Sep 1996 01:38:24 -0600
Subject: myself defending himself
Message-ID: <v02140b01ae5580dbb25f@[198.147.97.119]>


>I have asked for this kind of thing to stop on synth-diy,
>the message I quote from above really is going too far.
>Keep in mind that you're a guest on mailing lists and should
>behave accordingly. I have removed you from synth-diy.
>
>Rick Jansen
>__


I personally have no problem with any of the Hutchin's thread and JD has
contributed well to DIY and has  even requested himself at one point, that
x0x messages not be on the list.

Considering the problems that are constantly occuring within the Internet,
and that in my rather cursory overview of JD's last email I saw no mention
of Rick's post regarding ending this thread, might it not be a little
premature silencing him when one cannot even be certain he has received the
warning?

I left Analog Heaven because of a similar action and considering that this
is an incredibly small and specialized group here on DIY, wouldn't it be
better to approach this problem via personal email and keep some sort of
"family" environment here.

I personally refuse to be part of any group that silences it members due to
their own point of view and usage of free speech. If I don't want to read
Mr. McEachin's opinions, I can choose to do so.

The reason a mailing list exists is to share information, experiences and
resources with individuals with like interests. The diversity of the
individuals is what is important here and as soon as this criteria is
manipulated by personal feelings of the moderator, I cease to even have an
interest contributing freely myself for fear of finding a sore spot.


-Kevin





From sscprick at horus.sara.nl  Fri Sep  6 10:01:26 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Fri, 06 Sep 1996 10:01:26 +0200
Subject: Bernie himself defending himself 
In-Reply-To: Your message of Fri, 06 Sep 1996 00:18:41 MET DST.
             <1.5.4.32.19960906071841.006cdd28@synthcom.com>
Message-ID: <9609060801.AA23134@horus.sara.nl>


In message <1.5.4.32.19960906071841.006cdd28 at synthcom.com> you write:

> I'd guess much of the net doesn't know who your are, or care if you're on
> the net or not.

> Given your tone of discourse, I'm not surprised you've had some unpleasant
> exchanges.

> You have a valid objection.  Credit should be given where credit's due.
> However, if given proper credit, you should look upon the posted schematics
> as a free advertisement.

> In that case, let's seriously consider your claim.  As I understand it, the
> material in the PCC was previously printed in NON-COPYRIGHTED issues of
> ElectroNotes.  If the material was previously published unprotected, then
> you had no LEGAL right to try to retroactively assert your claim to
> copyright.  Therefore, the copyright on the PCC would appear to be null and
> void.
 
> JDM - channeling Mr.808 ...

etc etc.

I have asked for this kind of thing to stop on synth-diy,
the message I quote from above really is going too far.
Keep in mind that you're a guest on mailing lists and should
behave accordingly. I have removed you from synth-diy.

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From Christopher_List at sonymusic.com  Fri Sep  6 10:38:31 1996
From: Christopher_List at sonymusic.com (Christopher List)
Date: 6 Sep 96 10:38:31 
Subject: FM of Tri-Square VCO
Message-ID: <9609061444.AA4636@worldcom-37.worldcom.com>

Howdy DIYers - 

It was mentioned a while back that the Tri-Square VCO (of 
Electronotes/Elctronic Music Circuits) couldn't do "through zero FM". I have a 
vague notion of what this limitation implies - just from looking at the FM'ed 
waveforms on a scope, but I'm 100% sure. 

1. Could someone describe this limitation (or rather, this capablility)?
2. Does anyone know if it would be possible to modify the circuit so that it 
could do through-zero FM? 
3. How? 
- Perhaps Bernie has a suggestion?

- Thanks,
CList



From sscprick at horus.sara.nl  Fri Sep  6 14:00:35 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Fri, 06 Sep 1996 14:00:35 +0200
Subject: Bernie himself defending himself
Message-ID: <9609061200.AA19298@horus.sara.nl>


Dear list,

Already I have received some mails frowning at my removing
J.D. McEachin from the list. 

If you've been on some mailing lists you will find shit eventually
happens to any list. Frankly, synth-diy has been quite free of it
until now. I started synth-diy for the exchange of technical info,
and that has worked quite well. I cannot, however, be responsible
for a list where people's rights (Mr. Hutchin's in this case) are
questioned.

Regard diy as a room in my employer's office, not even mine, that 
I offer free and where you are welcome to visit and talk about 
synthesizer-related subjects. If, however, people and their behaviour 
and or reputations become the topic I feel I must stop that, for your 
and my sake. J.D. McEachin is very welcome back to talk electronics.

Please, enough about this. Let's keep our emotions on a linear
instead of an exponential scale. (Yes, I plead guilty too.)

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's not feeling too well




From frosty at mail.net-connect.net  Fri Sep  6 14:57:26 1996
From: frosty at mail.net-connect.net (Paul D'Amato)
Date: Fri, 6 Sep 1996 07:57:26 -0500
Subject: Bernie himself defending himself
Message-ID: <199609061257.HAA25606@dns1.net-connect.net>

>
>Since I wasn't in on this "flimflam", and have not participated in any PCC
>distribution "schemes", I'll attribute the unpleasantness of this email to
>my irritation with your display of hubris.


You know, I have been watching this shit for well over a week now and I have
one pretty stupid (maybe) qustion to ask...WHAT THE FUCK IS PCC AND WHY HAS
IT ATTRACTED SO MUCH ATTENTION ?!?!?

                        Thank you for your time............>


_________________________________________________________________________

*   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   * 
  *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   
Paul D'Amato..........frosty at net-connect.net..........(318) 856.9813.....
*   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   * 
  *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   
_________________________________________________________________________




From jdm at synthcom.com  Fri Sep  6 15:05:34 1996
From: jdm at synthcom.com (J.D. McEachin)
Date: Fri, 6 Sep 1996 13:05:34 +0000 ()
Subject: Bernie himself defending himself
In-Reply-To: <199609061257.HAA25606@dns1.net-connect.net>
Message-ID: <Pine.BSD.3.91.960906124652.18442C-100000@beacon.synthcom.com>

I apologize to Rick for the lengthy email I posted earlier.  His cease 
and desist order and my flame passed each other when I hit "Check Mail".
Rick has not deleted me from the list, so please don't quit over this.

I know I was ruffling some feathers, given Mr. Hutchin's legendary 
status, but I felt that what I wrote needed to be said.  Apologies to 
those who were offended, and thanks to those who wrote supportive private 
emails.  Great thanks to those who supported me publicly.

Synth-diy has the highest signal/noise ratio of any maillist I'm on, and 
I'd like to keep it that way.  No more flames from me!  If anyone is 
interested in my response to Bernie's inevitable response, then privately 
email me.  Now, back to DIY.

On Fri, 6 Sep 1996, Paul D'Amato wrote:

> You know, I have been watching this shit for well over a week now and I have
> one pretty stupid (maybe) qustion to ask...WHAT THE FUCK IS PCC AND WHY HAS
> IT ATTRACTED SO MUCH ATTENTION ?!?!?

PCC is the Preferred Circuits Collection.  It is a reprinting of the best 
schematics from ElectroNotes published prior to (I believe) 1983.  THink 
of it as ElectroNotes Lite.

ElectroNotes has much more on circuit theory, but also more filler, such 
as record reviews by Craig Anderton, humorous classifieds (Wanted: 
Electronic Percussion Circuits - Jim Mothersbaugh (circa 1976)), etc.

If you're really interested in electronic music circuits and want to know 
more about how to design and build them, ElectroNotes is an invaluable 
resource.  If you're just looking for a source of schematics to build a 
modular from, then PCC is a good introduction.  Remember, you can learn a 
lot about what goes into building a modular right here on synth-diy!

A complete set of ElectroNotes is pretty massive, and would probably cost 
$150-250 to copy at Kinko's, as well as costing time.  If Mr. Hutchins 
demonstrates himself to be responsive to orders, you should definitely 
consider ordering a set from him, as it is a hassle copying them yourself.

JDM




From mpulver at wwa.com  Fri Sep  6 15:59:17 1996
From: mpulver at wwa.com (Mark Pulver)
Date: Fri, 06 Sep 1996 08:59:17 -0500
Subject: Pro-1 Problem
Message-ID: <3.0b15.32.19960906081803.0068096c@pop.wwa.com>


>My Pro-1 is getting on my nerves. I have to clean the key contacts
>constantly. I have never had this problem with any of the other analogs. I
>will clean them, and they will work fine for a week or so. Then they start
>acting up again.

If they're grunging up that bad/that quick, it sounds like the plating may
of worn off. Is it the bus bars or the key contacts that are grunging? I
this though elsewhere in the thread, but if it's the buss bar, then turning
it 180 degrees may help.

mark

------------------------------------------------------------------------
 Mark Pulver/Chicagoish, IL          The home of "Son of The MIDI Wall"
 mpulver at wwa.com                        http://shoga.wwa.com/~mpulver
    Check out the EMP CD -->>> http://soli.inav.net/~kent/emp.html




From keen at austin.ibm.com  Fri Sep  6 17:34:32 1996
From: keen at austin.ibm.com (R.G. Keen)
Date: Fri, 06 Sep 96 09:34:32 -0600
Subject: Drilling PCB's
Message-ID: <9609061434.AA26935@keen.austin.ibm.com>

Over the weekend I wandered into a local sporting goods store and 
bought a Tasco 4power x 20mm objective rifle scope for $14. I took 
this home and taped my 3 power jeweler's loupe onto the non-eyepiece 
end of the scope and bango! I now have a 12 power drill microscope 
that focuses 2" from the end of the scope and has crosshairs for 
alignment. 

For those of you who missed the original post, you use this by
making a stand with a PCB drill setup like a Dremel tool on its
drill press accessory stand, but rearranged to drill UP through 
the table from the bottom. The drill microscope is arranged to focus 
on the place where the drill bit comes up through the table, with
the crosshairs centered on the center of the drill bit. You can then
manually move the board around, centering the pads in the crosshairs 
and then activating the drill to drill a perfectly aligned hole
from the bottom. 

The optics make alignment very easy, and humans are a very efficient
CNC controlled positioning system...



From bzimmer at voicenet.com  Fri Sep  6 19:01:23 1996
From: bzimmer at voicenet.com (Bob Zimmer)
Date: Fri, 6 Sep 1996 13:01:23 -0400 (EDT)
Subject: Where can I buy 1 and 2 space rackmount chassis?
Message-ID: <1.5.4.16.19960906130006.4757ee40@voicenet.com>

At 08:46 AM 9/6/96 -0400, you wrote:
>Can anyone recommend places to buy 1 and 2 space rackmount chassis?
>
>Does chassis have a plural or am I stuck sounding like I'm learning english?
>
>Thank you,
>James Trammell

James,

I know of two sources of reasonably prices rackmount chassis.  The first is
PAiA Electronic (www.paia.com) who lists panels and chassis separately in
their 1996 catalog.  They offer the following:

        BP-1    Single Height Rack Panel        $7.95 (4.00 S/H)
        BP-2    Double Height Rack Panel        $9.95 (4.50 S/H)

        RCE-1   Single Height Chassis           $19.95 (4.50 S/H)
        RCE-2   Double Height Chassis           $21.95 (4.50 S/H)

Note that a complete unit requires two separate items.

Another supplier is the current catalog from Jameco Electronics
(www.jameco.com) who offers offers complete units from 1 to I think 4 RUs.

Bob

  >=== Bob Zimmer -- Philadelphia PA ===<
  >=== bzimmer at voicenet.com          ===<





From rsholmes at MailBox.Syr.Edu  Fri Sep  6 19:28:09 1996
From: rsholmes at MailBox.Syr.Edu (Rich Holmes)
Date: Fri, 06 Sep 1996 13:28:09 -0400
Subject: Bernie himself defending himself 
In-Reply-To: Message from Rick Jansen <rick@sara.nl>
   of "Fri, 06 Sep 1996 14:00:35 +0200." <9609061200.AA19298@horus.sara.nl>
Message-ID: <199609061728.NAA00340@hydra.syr.edu>

Rick Jansen <rick at sara.nl> writes:
>Already I have received some mails frowning at my removing
>J.D. McEachin from the list. 
>
>If you've been on some mailing lists you will find shit eventually
>happens to any list. Frankly, synth-diy has been quite free of it
>until now. I started synth-diy for the exchange of technical info,
>and that has worked quite well. I cannot, however, be responsible
>for a list where people's rights (Mr. Hutchin's in this case) are
>questioned.
>
>Regard diy as a room in my employer's office, not even mine, that 
>I offer free and where you are welcome to visit and talk about 
>synthesizer-related subjects. If, however, people and their behaviour 
>and or reputations become the topic I feel I must stop that, for your 
>and my sake. J.D. McEachin is very welcome back to talk electronics.

No, sir.  Within twenty-four hours either Mr McEachin is back on
Synth-DIY with an apology from you, or I'm gone.

I don't expect you to miss me.  I haven't been much of a contributor,
because I have far more to learn than to expound on this subject.  I
will miss this list, badly.

But I *will not* participate in a list that will kick off a member for
posting one statement of his own opinions on a relevant subject.

Yes, I thought Mr McEachin was out of line in his choice of words.
No, I do not agree with his opinions in general about Bernie Hutchins.
But I will defend his right to speak his mind.

Of course, you run the list and there's no law that says you can't
kick off whoever you like.  That doesn't mean I have to like it when
you do.

I dislike Mr McEachin's attitude toward Bernie Hutchins, but I dislike
your attitude toward the list even more.

-- 
- Rich Holmes              
  "I'm not dissing them, man, but they're seriously well different"
                  - Sidmouth native critiques the Brittania Nutters



From gstopp at fibermux.com  Fri Sep  6 20:08:56 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Fri, 06 Sep 96 11:08:56 PDT
Subject: FM of Tri-Square VCO
Message-ID: <9608068420.AA842033540@ccrelay.fibermux.com>

     I haven't any experience with through-zero FM VCO's, so I can only 
     share what I have gleaned from reading materials.
     
     My understanding is that through-zero FM on a VCO is when a descending 
     CV into the VCO FM input causes the VCO to drop in frequency until it 
     hits zero hertz, and then as the CV keeps going more negative the VCO 
     starts up again in the reverse direction and begins increasing its 
     frequency of operation.
     
     Of course the "normal" VCOs we are probably familiar with (integrator 
     schmidt-trigger, sawtooth reset, Curtis chip, etc.) don't do this but 
     merely drop to a lower and lower frequency without ever even reaching 
     zero hertz. Therefore one may consider approximating the through-zero 
     behaviour described above by building a VCO whose minimum frequency is 
     achieved at zero volts CV sum in (rather than the minus supply) and 
     putting a full-wave rectifier on the CV input. This way a decreasing 
     CV input will cause the VCO to stop (actually just get real slow) at 
     zero volts and as it goes more negative it gets inverted by the FWR 
     and goes positive again, starting up the VCO into increasing 
     frequency.
     
     Now the important bit here is that apparently this doesn't sound quite 
     the same as a true through-zero FM effect. See a true through-zero VCO 
     will go down to zero hertz and stop dead and then back up and reverse 
     its cycle. Okay I don't feel like drawing an ASCII waveform at the 
     moment so here's a number string representing a non-modulated 
     triangle's voltage in time:
     
     -5 -4 -3 -2 -1 0 1 2 3 4 5 4 3 2 1 0
     
     and here's a "fake" through-zero FM'ed triangle:
     
     -5 -4 -3 -2 -1 0 1 2 2 2 2 2 2 2 3 4 5 4 3 2 1 0
     
                        ^^^^^^^^^^^^^
                    (CV going thru zero here)
     
     and here's a real through-zero FM'ed triangle:
     
     -5 -4 -3 -2 -1 0 1 2 1 0 -1 -2 -3 -4 -5 -4 -3 -2 -1 0
     
                       ^^^
                   (CV thru zero here)
     
     Notice how the "fake" through-zero effect just stops and then picks up 
     where it left off. From what I understand, the "back up the waveform 
     and go the other way" type of FM has a sound that is noticeably more 
     profound or harmonically interesting than using the FWR method. It may 
     seem that it is a little trivial waveform anomaly but this has a 
     drastic effect anyway - enough to justify scads of complicated 
     through-zero FM VCO designs.
     
     Anyway like I said I never played with this so I can't provide a 
     critique of the sonic ramifications of true through-zero VCO FM. I 
     guess I kind of skipped over the whole issue when I built a 
     through-zero frequency shifter, which I suspect can give similar 
     harmonic results, only better, because it involves live signals as 
     well.
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: FM of Tri-Square VCO
Author:  Christopher List <Christopher_List at sonymusic.com> at ccrelayout
Date:    9/6/96 10:24 AM


Howdy DIYers - 
     
It was mentioned a while back that the Tri-Square VCO (of 
Electronotes/Elctronic Music Circuits) couldn't do "through zero FM". I have a 
vague notion of what this limitation implies - just from looking at the FM'ed 
waveforms on a scope, but I'm 100% sure. 
     
1. Could someone describe this limitation (or rather, this capablility)?
2. Does anyone know if it would be possible to modify the circuit so that it 
could do through-zero FM? 
3. How? 
- Perhaps Bernie has a suggestion?
     
- Thanks,
CList




From ms20 at itchy.serv.net  Fri Sep  6 20:56:28 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Fri, 6 Sep 1996 11:56:28 -0700 (PDT)
Subject: FM of Tri-Square VCO
In-Reply-To: <9609061444.AA4636@worldcom-37.worldcom.com>
Message-ID: <Pine.BSD.3.91.960906115214.11430A-100000@itchy.serv.net>



On 6 Sep 1996, Christopher List wrote:

> Howdy DIYers - 
> 
> It was mentioned a while back that the Tri-Square VCO (of 
> Electronotes/Elctronic Music Circuits) couldn't do "through zero FM". I have a 
> vague notion of what this limitation implies - just from looking at the FM'ed 
> waveforms on a scope, but I'm 100% sure. 
> 
> 1. Could someone describe this limitation (or rather, this capablility)?
> 2. Does anyone know if it would be possible to modify the circuit so that it 
> could do through-zero FM? 
> 3. How? 

Wouldn't that be the through zero VCO in Option 4? (I'm assuming you're 
asking about the Option 3 tri/square VCO.)  Note that the two have the 
same output circuitry.


R.




From mugen at spacelab.net  Fri Sep  6 21:46:40 1996
From: mugen at spacelab.net (J P M)
Date: Fri, 06 Sep 1996 19:46:40 +0000
Subject: Where can I buy 1 and 2 space rackmount chassis?
References: <1.5.4.16.19960906130006.4757ee40@voicenet.com>
Message-ID: <32307FA0.324A@spacelab.net>

Those PAIA tin cans are crap (Sorry PAIA).There is a company called 
SAS ? they make VERY NICE good quality racks for very little money (in 
reference to racks anyway). I'll give info on the company Sat Night(the 
Catalog is at work)....


Jason 
Vocod'o'rama
http://www.spacelab.net/~mugen/vocolist.html




From majmoog at synthfool.com  Fri Sep  6 21:51:45 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Fri, 6 Sep 1996 13:51:45 -0600
Subject: Where can I buy 1 and 2 space rackmount chassis?
Message-ID: <v02140b03ae562fa2629b@[206.171.253.91]>

Also, try Sescom, Inc. at 1-800-634-3457. They are in Henderson, Nevada.

They basically make two lines of rack enclosures, one that is good and one
that is VERY good and they come in  a variety of depths, heights and
finishes. The prices are very reasonable too.

I've used their enclosures for years and have built SCSI patchbays and
other devices for years with them.
(In fact, the big Zimmer modulars I did, use their cases for the external
power supplies!)

They also  make micro rack enclosures and sell punches, etc.

-Kevin








From ctodish at cisco.com  Fri Sep  6 22:20:13 1996
From: ctodish at cisco.com (Clint Todish)
Date: Fri, 06 Sep 1996 13:20:13 -0700
Subject: Where can I buy 1 and 2 space rackmount chassis?
Message-ID: <2.2.32.19960906202013.009ca868@lint>


Middle Atlantic Audio has by far the most extensive collection of
rack hardware around...I don't think they have a site, but most
pro audio companies carry their stuff...

-C

At 01:01 PM 9/6/96 -0400, Bob Zimmer wrote:
>At 08:46 AM 9/6/96 -0400, you wrote:
>>Can anyone recommend places to buy 1 and 2 space rackmount chassis?
>>
>>Does chassis have a plural or am I stuck sounding like I'm learning english?
>>
>>Thank you,
>>James Trammell
>
>James,
>
>I know of two sources of reasonably prices rackmount chassis.  The first is
>PAiA Electronic (www.paia.com) who lists panels and chassis separately in
>their 1996 catalog.  They offer the following:
>
>        BP-1    Single Height Rack Panel        $7.95 (4.00 S/H)
>        BP-2    Double Height Rack Panel        $9.95 (4.50 S/H)
>
>        RCE-1   Single Height Chassis           $19.95 (4.50 S/H)
>        RCE-2   Double Height Chassis           $21.95 (4.50 S/H)
>
>Note that a complete unit requires two separate items.
>
>Another supplier is the current catalog from Jameco Electronics
>(www.jameco.com) who offers offers complete units from 1 to I think 4 RUs.
>
>Bob
>
>  >=== Bob Zimmer -- Philadelphia PA ===<
>  >=== bzimmer at voicenet.com          ===<
>
>
>
>




From Kjarger at aol.com  Sat Sep  7 07:35:47 1996
From: Kjarger at aol.com (Kjarger at aol.com)
Date: Sat, 7 Sep 1996 01:35:47 -0400
Subject: FM of Tri-Square VCO
Message-ID: <960907013545_279316573@emout17.mail.aol.com>

Gene Stopp:
>My understanding is that through-zero FM on a VCO is when...

Thanks for a great description!

Were you implying that it would be really hard to build a "real" tzFM
oscillator, and it's only feasible (due to ckt cost and/or complexity) to
fake it in analog ckts?  Has anyone really done it in analog yet?

Kyle Jarger

JKJ Electronics



From honcho at paia.com  Sat Sep  7 23:26:59 1996
From: honcho at paia.com (honcho at paia.com)
Date: Sat, 7 Sep 96 16:26:59 CDT
Subject: Where can I buy 1 and 2 space rackmount chassis?
Message-ID: <9609072127.AA28396@qns1.qns.net>


>Those PAIA tin cans are crap (Sorry PAIA).
>>>
No offense taken, but let me at least point out that we don't have 
anything that we sell as a Rack Case. We have 1U and 2U blank panels 
and "backs" for folks who absolutely must have an enclosure for some 
of our "panels only" kits. Some people have put these two together to 
make a rack case despite our trying to talk the out of it (yes, we 
really do advise against a purchase if it's our feeling that there 
will be an unpleasant surprise for the purchaser). I don't like the 
result too much either.

I don't think your remark applies to cases for specific products, such 
as the TubeHead or the new Stereo Compressor, but I don't think you 
intended it to, either. Similarly, the Fractional Rack Packaging 
system (fracrak) is pretty good in my opinion - particularly 
considering the price of the alternatives.

My personal favorite for low cost Rack Cases is sescom. I wish there 
was some way to get into them without taking them completely apart.

-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 BDermody at aol.com  Sun Sep  8 06:35:16 1996
From: BDermody at aol.com (BDermody at aol.com)
Date: Sun, 8 Sep 1996 00:35:16 -0400
Subject: some catching up
Message-ID: <960908003455_303781777@emout15.mail.aol.com>



  Well, I leave for awhile and all hell breaks loose!! I'll be sending B.H.
the $15.00
for my bootleg copy of the PCC. I've been quite busy since may and have been 
neglecting my e-mail, as well as my synth building, I hope to amend both.
Back in may I offered to trade schematics I had for whathave you. (Joe Farler
and Erik the Viking  e-mail me if you each still need the source drawings.)
(Gene I am still looking for those Moog drawings, let me know)

I currently need the drawings for the ARP OMNI MK1. A friend at work has a
dead
one. Any help would be appreciated


 Thanks 

    Brian Dermody 
    Levittown,NY
BDermody at aol.com



From don at till.com  Mon Sep  9 09:04:12 1996
From: don at till.com (Don Tillman)
Date: Mon, 9 Sep 1996 00:04:12 -0700
Subject: Is this thing the coolest, or what?
Message-ID: <199609090704.AAA14686@shellx.best.com>

Anybody tried out the new Tek 'scope yet that came about about a week
ago?  Take a look:

  http://www.testequity.com/new-tektronix/TDS-200-Series.html

This thing seems completely bitchin'!  It's a digital 'scope with an
LCD display, and unlike the handheld LCD 'scopettes, this one has a
proper full-sized front panel.  And the 60MHz version is only $1K.
And optionally it's got a serial port to make pretty web pages from
scope traces.  And it's only a little over 4-inches deep.

  -- Don









From jocke at netcontrol.fi  Mon Sep  9 10:53:40 1996
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Mon, 9 Sep 1996 11:53:40 +0300 (EET DST)
Subject: Epoxy Block Phasers
In-Reply-To: <Chameleon.4.01.3B.960909025315.grichter@execpc.com>
Message-ID: <Pine.LNX.3.91.960909114643.29441A-100000@netcontrol.netcontrol.fi>

On Mon, 9 Sep 1996, Grant Richter wrote:

> I have two phasers that are based on epoxy blocks. The blocks
> must be some kind of ladder structure because they are modulated
> by exponential current sinks and have differential
> input and output drives like a Moog ladder filter.

ARP used an all-pass ladder design for the phaser that was built
into the Quadra synth. The schematics may be available at the
Music Machines site, not sure. Let me know if you can't find them.

-joachim




From grichter at execpc.com  Mon Sep  9 11:45:03 1996
From: grichter at execpc.com (Grant Richter)
Date: Mon,  9 Sep 96 02:45:03 PDT
Subject: Epoxy Block Phasers
Message-ID: <Chameleon.4.01.3B.960909025315.grichter@execpc.com>


I have two phasers that are based on epoxy blocks. The blocks
must be some kind of ladder structure because they are modulated
by exponential current sinks and have differential
input and output drives like a Moog ladder filter. But these
are phase shifters. One is "The Pipe" by Taurus and the other is the
Aries Model AR-329 Phase/Flange.

Question: Does anyone know the structure of the circuitry in the
blocks? They must be similar in design since they are both modulated
the same way. Any help is appreciated, thanks.

Grant







From Christopher_List at sonymusic.com  Mon Sep  9 10:07:25 1996
From: Christopher_List at sonymusic.com (Christopher List)
Date: 9 Sep 96 10:07:25 
Subject: Is this thing the coolest, or what?
Message-ID: <9609091419.AA4125@worldcom-37.worldcom.com>

> This thing seems completely bitchin'!  It's a digital 'scope with an
> LCD display, and unlike the handheld LCD 'scopettes, this one has a
> proper full-sized front panel.  And the 60MHz version is only $1K.
> And optionally it's got a serial port to make pretty web pages from
> scope traces.  And it's only a little over 4-inches deep.

...and to think I just upgraded my tempermental old Dumont for a tempermental 
old Tek-564 storage scope that weighs about 50lbs and is 24" deep! 

Well, the price was right :). 

Actually, any of you old-time EE types know anything about the 3A3 dual trace 
plug-in? Seems one of my channels is reading way in the negative zone (like off 
the screen). I tried swapping all the transistors between the two channels and 
it didn't help (they're plug-ins, transistors were a big deal back then!). I 
have all the schems but don't know enough about transistor circuits to be 
capable of figuring out the problem - I should probably just look for another 
used plug-in somewhere, but I figured I give a try here first. 
I figure,  maybe, by some miracle, someone has a long-standing personal 
relationship with the 3A3 plug-in and can give me a quick answer (ha). Then 
again, even if I get an answer, I've got those silver-soldered ceramic things 
to deal with - yikes what'd I get myself into!

- CList



From scott at mprgate.mpr.ca  Mon Sep  9 12:32:59 1996
From: scott at mprgate.mpr.ca (scott at mprgate.mpr.ca)
Date: Mon,  9 Sep 96 03:32:59 PDT
Subject: Moog 902 module question
Message-ID: <9609091032.3B3F54@scott.mpr.ca>

Hi guys
Does anyone know what the  part number is for the diode bridge DB1 on the Moog 902 Voltage Controller Amplifier?
Thanks
Ron




From mpulver at wwa.com  Mon Sep  9 15:56:21 1996
From: mpulver at wwa.com (Mark Pulver)
Date: Mon, 09 Sep 1996 08:56:21 -0500
Subject: Is this thing the coolest, or what?
Message-ID: <3.0b15.32.19960909085614.006a0344@pop.wwa.com>


>Anybody tried out the new Tek 'scope yet that came about about a week
>ago?  Take a look:

I'm curious Don... I'm completely naive in this, and have never used one,
but I would think that an LCD based 'scope would be quite ugly... Wouldn't
you get a lot of trails, especially if the LCD get's busy, like watching a
pair of fairly complex waveforms?

Like I say, I'm naive as hell on hi-tech LCD panels, my only experience has
been with a boatload of laptops of varying types.

mark

------------------------------------------------------------------------
 Mark Pulver/Chicagoish, IL          The home of "Son of The MIDI Wall"
 mpulver at wwa.com                        http://shoga.wwa.com/~mpulver
    Check out the EMP CD -->>> http://soli.inav.net/~kent/emp.html




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Mon Sep  9 20:56:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 09 Sep 96 11:56:00 PDT
Subject: AW: Re: FM of Tri-Square VCO
Message-ID: <32346851@MSMGATE.M30X.NBG.SCN.DE>


 > Has anyone really done it in analog yet?

I have. I think I have even posted about it to DIY, so you
could find the details in the archives.
But I try to write it again in short form, which is easy as Gene
already has given a great description:

>     My understanding is that through-zero FM on a VCO is when a descending 

>     CV into the VCO FM input causes the VCO to drop in frequency until it
>     hits zero hertz, and then as the CV keeps going more negative the VCO
>     starts up again in the reverse direction and begins increasing its
>     frequency of operation.

That's it all. Keep in mind, that "reverse direction" means phase inversion
of the triangle output signal.

>     rop to a lower and lower frequency without ever even reaching
>     zero hertz. Therefore one may consider approximating the through-zero
>     behaviour described above by building a VCO whose minimum frequency is 

>     achieved at zero volts CV sum in (rather than the minus supply) and
>     putting a full-wave rectifier on the CV input. This way a decreasing
>     CV input will cause the VCO to stop (actually just get real slow) at
>     zero volts and as it goes more negative it gets inverted by the FWR
>     and goes positive again, starting up the VCO into increasing
>     frequency.

The resistor that sets the reference current in the expo generator is
the right place to start, as it usually goes to a virtual GND summing node.
Instead of connecting this to VCC, connect it to the output of the FWR.
The FWR gets two inputs: one for the initial frequency (i.e. resistor to
VCC ...), and one for tzFM input.

>     Now the important bit here is that apparently this doesn't sound quite 

>     the same as a true through-zero FM effect. See a true through-zero VCO 

>     will go down to zero hertz and stop dead and then back up and reverse
>     its cycle.

Now the only thing that is left to do, is changing the phase of the VCO
output signal just at the same time as the FWR's input changes sign.
This is easy, because the diode drops in a opamp/diode-based
FWR cause the opamp output to make a little "jump" anyway, when
it passes thru zero. Connect a comparator to this point, and toggle
the direction of the capacitor charging with the comparator !
A possible way to do this would be using a D-flipflop in the triangle
VCO. In normal operation, an upper threshold SETs the flipflop,
and a lower threshold RESETs the flipflop. Tri/Square VCO as usual;
every 555 timer works this way.
But now for Thru Zero FM: Connect Qbar to D, and use the clock
input of the flipflop to toggle the phase.

>      enough to justify scads of complicated
>     through-zero FM VCO designs.

I don't think it's too complicated. I built an add-on to a CEM3340
VCO within a few hours. (And the 3340 makes things more
difficult here, compared with a discrete tri/square VCO!)
You can find the circuit in an old Curtis newsletter, which is part
of Barry's book on CEM/SSM chips.

How does it sound?

I wouldn't describe tzFM as a dramatic new effect. In contrary, it sounds
like linear FM should sound like - only that ordinary linear FM stops
at a small modulation index (well, when you reach zero hertz ...),
so that the effect is still rather "tame". TzFM just gives a larger 
modulation
index, and thus enters the more interesting regions.

A little problem:

The FWR does not work perfect (even with offset trimming). The result
is a *very slight*  irregularity when you just cross the border between
FM and tzFM. But you can live with that. There is also, for the same reason,
a *slight* frequency shift between very small and very large modulation
strength. "Slight" is a few cents - not the annoying shift which you know 
from
expo FM.

Hope this helped - if you want to know the details, it's in Barry's book.

JH.




From majortom at muc.de  Mon Sep  9 22:46:03 1996
From: majortom at muc.de (Michael Wesemann)
Date: Mon, 9 Sep 1996 22:46:03 +0200
Subject: Nonsymmetrical Clipping
In-Reply-To: <322C89A3@MSMGATE.M30X.NBG.SCN.DE>
References: <322C89A3@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <32347dd2.5265893@mail.muc.de>

JH wrote:

>Background:
>As I have posted some time ago, the famous SSM2040 filter
>sound is partly due to its nonsymmetrical clipping, when the
>ota output (!) is overdriven. 

Thank you for this insight!

Do i take it nonsymmetrical clipping means that either the lower or
the higher halfwave clips earlier than the other?

If so, my question is are there differences in sound depending on
whether the high or low halfwave clips first?

Is it right that nonsymmetrical clipping is detected later by the ear
as such than symmetrical clipping at equal level?

Would it be generally desireable to have the option of nonsymmetrical
clipping as an effect?

Thanks!

___________________________________________________________________
         (I could be wrong)



From janhee at lokki.edutec.pori.fi  Mon Sep  9 23:23:19 1996
From: janhee at lokki.edutec.pori.fi (Janne Heikkarainen)
Date: Mon, 9 Sep 1996 23:23:19 +0200 (EET)
Subject: noise...aaar
Message-ID: <Pine.HPP.3.93.960909232121.24668A-100000@lokki.edutec.pori.fi>

i recently made a vcf and i noticed the annoying noise...hmm how could you
suppress noise? shielding wires? or what :) (also notice that i am a
newbie so...you know ;) )

   - bIOTEK of dAMONEs -





From costello at costello.seanet.com  Tue Sep 10 01:22:05 1996
From: costello at costello.seanet.com (Sean Costello)
Date: Mon, 9 Sep 1996 16:22:05 -0700 (PDT)
Subject: Nonsymmetrical Clipping
Message-ID: <199609092322.QAA09876@mx.seanet.com>

At 10:46 PM 9/9/96 +0200, you wrote:
>JH wrote:
>
>>Background:
>>As I have posted some time ago, the famous SSM2040 filter
>>sound is partly due to its nonsymmetrical clipping, when the
>>ota output (!) is overdriven. 
>
>Thank you for this insight!
>
>Do i take it nonsymmetrical clipping means that either the lower or
>the higher halfwave clips earlier than the other?

Nonsymmetrical clipping implies that the clipping of the waveform halfves
are not equal; one half may be clipped more than the other half, or the type
of clipping may differ between the halves.  For example, a typical fuzz box
circuit uses back-to-back diodes to achieve the "fuzz" sound (these diodes
are usually either in the feedback loop of an op-amp, or simply connected
between the signal and ground).  If only one diode is present, only one half
of the waveform will be clipped; this waveform will have more even harmonics
present than the waveform clipped by back-to-back diodes (which will sound
more or less like a square wave, depending on the input signal and the type
of diodes).  Silicon and germanium diodes clip differently, with the onset
of clipping in a germanium diode being "softer" (more gradual); thus, having
a silicon diode back-to-back with a germanium diode will result in
nonsymmetrical clipping.

>If so, my question is are there differences in sound depending on
>whether the high or low halfwave clips first?

Depends on the input signal, I guess. 

>Would it be generally desireable to have the option of nonsymmetrical
>clipping as an effect?

I think so.  I'm forwarding something I wrote in a message to A.S.P. (Romeo)
a while back:

>The SSM 2040 is reputed to have good distortion.  I wonder if the quality
of the distortion is due to the inverting gain stages.  The stuff I have
read in the diy archive suggests that each stage has asymmetrical
distortion, but that the inversion of the signal in each gain stage makes
the distortion symmetrical (as the non-clipped side of the signal would be
clipped by the next stage).  Undoubtedly both sides of the signal would be
distorted in this situation, but this does not mean that the distortion is
symmetrical.  I know that there is a tube-emulation circuit that clips one
half of the waveform, amplifies it, then clips the opposite half of the
amplified waveform; this results in asymmetrical distortion.  Asymmetrical
distortion sounds more "tube-like" than symmetrical distortion, in that more
even harmonics are found in the output signal (as opposed to the square-wave
type signal found in symmetrical distortion); even harmonics are generally
regarded as more pleasing to the ear.  Tubes run in class A mode (such as
the Vox AC-30, the Fender Champ, and the Matchless amps) have lots of even
harmonics in the output, and a very musical sound; the Fuzz Face also uses
asymmetrical clipping for an output rich in even harmonics.  It seems to me
that the inversion of each gain stage in the 2040 would result in a signal
that was clipped, amplified and otherwise modified, than clipped on the
other side repeatedly, resulting in a complex waveform rich in even
harmonics.  The 2040 emulation circuits I have seen (I am including the
Electronotes 4-pole in this category) seem to use noninverting OTA stages;
this would result in asymmetrical clipping, but of a different type than
that in a circuit that uses inverting stages.  Perhaps the ideal circuit
would use inverting OTA stages, and smaller resistor values at the imput and
between the stages to obtain higher clipping levels.  

Unfortunately, I haven't heard anything about traditional OTA op-amps (3080,
13600/13700) clipping asymmetrically.  Many other things could be wrong in
the above statement (this should be a warning on all of my messages - I was
an Anthropology major, and am learning electronics on the fly).  Anybody out
there who knows what they are talking about have any ideas?

Later,

Sean   







From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep 10 01:36:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 09 Sep 96 16:36:00 PDT
Subject: AW: Re: Is this thing the coolest, or what?
Message-ID: <3234AA0A@MSMGATE.M30X.NBG.SCN.DE>


>>Anybody tried out the new Tek 'scope yet that came about about a week
>>ago?  Take a look:
>
>I'm curious Don... I'm completely naive in this, and have never used one,
>but I would think that an LCD based 'scope would be quite ugly... Wouldn't
>you get a lot of trails, especially if the LCD get's busy, like watching a
>pair of fairly complex waveforms?

I share your feelings, Mark, though I don't know how good LCDs really
can be today, either.
Surely the screen would not be updated with 60MHz (and surely 60 MHz
would not be necessary) - but then again how often *is* the screen updated,
and is this often enough to find tiny glitches? (I am sure there is a 
*function*
in there that litterally *finds* glitches for me, but that's not the same 
...)

Am I just oldfashioned and superstitious, or *is* there some reason to
keep my good old analogue one ??

JH.



From frosty at mail.net-connect.net  Tue Sep 10 04:50:29 1996
From: frosty at mail.net-connect.net (Paul D'Amato)
Date: Mon, 9 Sep 1996 21:50:29 -0500
Subject: JX3P problem
Message-ID: <199609100250.VAA27168@dns1.net-connect.net>

I was just given a JX3P that seems to have a minor problem....it will not
make a sound!!!  When you turn it on you can hear the power come on and
static as you turn the volume knob, but none of the preset led's wil light
and no sound comes out at all when depressing any key. The only led that
will light is the LFO trig. All fuses are ok but I have no idea what to
check next. Any suggestions ???

                                Thanks................Paul


_________________________________________________________________________

*   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   * 
  *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   
Paul D'Amato..........frosty at net-connect.net..........(318) 856.9813.....
*   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   * 
  *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   
_________________________________________________________________________




From e93_mda at drum.it.kth.se  Tue Sep 10 05:20:29 1996
From: e93_mda at drum.it.kth.se (Magnus Danielson)
Date: Tue, 10 Sep 1996 05:20:29 +0200
Subject: AW: Re: Is this thing the coolest, or what? 
In-Reply-To: Your message of "Mon, 09 Sep 1996 16:36:00 MET DST."
             <3234AA0A@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <199609100320.FAA27914@piraya.electrum.kth.se>

> 
> >>Anybody tried out the new Tek 'scope yet that came about about a week
> >>ago?  Take a look:
> >
> >I'm curious Don... I'm completely naive in this, and have never used one,
> >but I would think that an LCD based 'scope would be quite ugly... Wouldn't
> >you get a lot of trails, especially if the LCD get's busy, like watching a
> >pair of fairly complex waveforms?
> 
> I share your feelings, Mark, though I don't know how good LCDs really
> can be today, either.
> Surely the screen would not be updated with 60MHz (and surely 60 MHz
> would not be necessary) - but then again how often *is* the screen updated,
> and is this often enough to find tiny glitches? (I am sure there is a 
> *function*
> in there that litterally *finds* glitches for me, but that's not the same 
> ...)
> 
> Am I just oldfashioned and superstitious, or *is* there some reason to
> keep my good old analogue one ??

A hint for you:

I have used an Tektronix oscillioscope with 16 channels of 2Gsamples/s that
have a color screen and a standard VGA outlet on the back in case you need a
bigger screen.... it also has a 3.5 inch floppy to store the waveforms at and
you can print them too.... oscillioscopes isn't what they used to be :)

Next keyword:

Sampling.

These portable LCD scopes are really usefull and certainly fill their part of
the market. You can't compare them with the real thing, but then it wouln't be
fair to compare your portable Fluke with a desktop precision multimeter either.
The LCD isn't really that big problem.

Magnus





From don at till.com  Tue Sep 10 08:45:09 1996
From: don at till.com (Don Tillman)
Date: Mon, 9 Sep 1996 23:45:09 -0700
Subject: Is this thing the coolest, or what?
In-Reply-To: <3.0b15.32.19960909085614.006a0344@pop.wwa.com> (message from
	Mark Pulver on Mon, 09 Sep 1996 08:56:21 -0500)
Message-ID: <199609100645.XAA05964@shellx.best.com>

   Date: Mon, 09 Sep 1996 08:56:21 -0500
   From: Mark Pulver <mpulver at wwa.com>

   >Anybody tried out the new Tek 'scope yet that came out about a week
   >ago?  

   I'm curious Don... I'm completely naive in this, and have never used one,
   but I would think that an LCD based 'scope would be quite ugly... Wouldn't
   you get a lot of trails, especially if the LCD get's busy, like watching a
   pair of fairly complex waveforms?

Passive LCD displays are like that.  The active LCD display on my Mac
Powerbook (a seperate transistor driver for each pixel, or so I'm lead
to believe) is fast as all hell, with none of of those annoying vapor
trails.

But you bring up a important point; I've not actually seen this scope
yet and this is a good thing to consider.

   Date: Tue, 10 Sep 1996 05:20:29 +0200
   From: Magnus Danielson <e93_mda at drum.it.kth.se>

   These portable LCD scopes are really usefull and certainly fill their 
   part of the market. You can't compare them with the real thing, but
   then it wouln't be fair to compare your portable Fluke with a
   desktop precision multimeter e ither.

Well the whole point of this particular 'scope is that it's *not* a
portable, it's a serious bench scope that happens to have an LCD
display.  How successful they are at this is still unknown.

  -- Don




From caliban at organic.com  Tue Sep 10 11:34:48 1996
From: caliban at organic.com (Rocky Mullin)
Date: Tue, 10 Sep 1996 02:34:48 -0700 (PDT)
Subject: CS-50 !!
In-Reply-To: <3235AF24@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <Pine.SGI.3.93.960910023242.3941D-100000@tempest.organic.com>


	weird blinking lights has a cs-60 in our analog aresenal,
	as well as a cs-10.  both fine, fine, amazing synths.

	btw, got the sbk-80 syncing both the old roland gear as well 
	as the r8mkII and the other midi stuff tonight.  just took 
	a little hacking, as well as some manual reading.  it's like,
	in the end, to have the r8 be the master and the rest be the
	slaves, but we'll see if that is possible.  does not look all
	that promising from this angle, however.

On Tue, 10 Sep 1996, Haible_Juergen#Tel2743 wrote:

> 
> Hi!
> 
> Played a CS-50 for the first time yesterday - what a wonderful
> instrument!
> When I came into the store, I first thought it was a CS-60, unti II found 
> that
> there was no hinged lid with presets, and no ribbon. Nevertheless
> I decided to give it a try, and man, I couldn't let go for a whole hour!
> How can a 1-VCO / 4-Voice polysynth sound so lush, and that without
> a chorus section !!
> Ok, it was quite out of tune, so I can't say how fat it sounds when
> tuned. But I think most of its richness comes from the LFO's, especially
> from the PWM section. Now what's so different with the PWM?
> I think the SINE shape of the modulation is the trick! I found that you
> can set a much higher modulation amount and rate before it becomes
> annoying. I tried it at home on the OB-8 (which has, like most synths,
> triangle instead of sine), and I didn't get the same effect. Then I tried
> it on the Modular, and voila !
> 
> I was very fond of this little synth, but I think if I ever buy one, a CS-60
> would be my choice.
> 
> A few questions to CS-synthesizer owners:
> 
> (1) I liked the feature "Sustain II" on the CS-50, which allows pseudo-
>       monophonic playing. Does this work on the CS-60 and -80 as well?
> 
> (2) The filters seem to be a cascade of 2-poles. Has anybody yet figured
>       out what architecture they have? They don't sound like state variables
>       to me ....
> 
> (3) What shape does the Ring Modulator AD-envelope have? The schematics
>       (of the CS-80) show linear slopes, but then again the VCF/VCA 
> envelopes
>       are also printed wrong, so I can't be sure.
> 
> (4) - related to (3) - the Ring Modulator VCO, is it exponential or linear?
>      (I know the main VCOs are linear)
> 
> Thanks in advance for any information !
> 
> JH.
> 
> 
> PS.: I make a crosspost to DIY, because of the technical questions.
> 

-- 
\  c   /\  a   /\  l   /\  i   /\  b   /\  a   /\  n   /\     rocky mullin
_\____/__\____/__\____/__\____/__\____/__\____/__\____/__\   san francisco
  \  /    \  /    \  /    \  /    \  /    \  /    \  /organic online, inc. 
   \/      \/      \/      \/      \/ http://www.organic.com/Staff/caliban
ninja250 - analog synthesis - chaotic good - polyamory - sleep deprivation




From pye at bluesky.net.au  Tue Sep 10 11:38:47 1996
From: pye at bluesky.net.au (christopher pye)
Date: Tue, 10 Sep 1996 19:38:47 +1000 (EST)
Subject: Korg 800DV
Message-ID: <v01540b00ae5b739d76ae@[203.21.76.33]>

I have a Korg 800 DV  (maxi korg)  and am about to try to convert to CV &
gate...  Has anyone had experience with this synth before.???   It has 2
switches to set the keyboard mode, havn't worked out excactly what they do
yet...


Thanks...


Chris...





From barry.klein at solar.org  Tue Sep 10 11:39:28 1996
From: barry.klein at solar.org (Barry Klein)
Date: Tue, 10 Sep 1996 09:39:28 +0000
Subject: Is this thing the coolest
Message-ID: <96090923182462611@solar.org>

One real bummer is that Tektronix will only be making digital scopes
in the near future.  It seems that making the CRT's is difficult due
to some kind of environmental hazards etc.  They apparently
let go most of their analog guys and had to bring some of them back
to do work on the 2467, a high intensity scope.  That scope shows things
that just can't be shown with their current line of scopes - even with
their "Insta-view" feature.  I did do things with Insta-view that their
product manager and sales guy didn't know could be done, to try and
simulate what we do with the 2467, but still, if in 5 years from now
someone were to come out with a 2467 clone it would be regarded as
revolutionary.  What short sightedness!  God, just make the CRT's in
India or Russia, or make the whole darn thing over there - don't just
give up!

Barry


... Elect. Music, Photography, Bubble Machines, Stunt Kites, Elect. Design

___ Blue Wave/QWK v2.20 [NR]



From jocke at netcontrol.fi  Tue Sep 10 13:45:15 1996
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Tue, 10 Sep 1996 14:45:15 +0300 (EET DST)
Subject: CS-50 !!
In-Reply-To: <3235AF24@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <Pine.LNX.3.91.960910134507.31156C-100000@netcontrol.netcontrol.fi>

On Tue, 10 Sep 1996, Haible_Juergen#Tel2743 wrote:

> Now what's so different with the PWM?
> I think the SINE shape of the modulation is the trick! I found that you
> can set a much higher modulation amount and rate before it becomes
> annoying. I tried it at home on the OB-8 (which has, like most synths,
> triangle instead of sine), and I didn't get the same effect. Then I tried
> it on the Modular, and voila !

Yes, that's one thing I learnt on my Maplin synth, whose LFO had sine
and square outputs but no triangular. Vibrato and cut-off modulation
usually sound better using a triangular LFO, but for PWM you've gotta
have sine.

Another thing I like about the CS-series voice architecture is that
you can high-pass (or band-pass) filter the signal, and then add the
fundamental (sine, again) at the VCA stage.

> (2) The filters seem to be a cascade of 2-poles. Has anybody yet figured
>       out what architecture they have? They don't sound like state variables
>       to me ....

Looking at the schems, the way the resistors and capacitors surronding
the filter chips are connected, I'd almost swear it's two 2-pole
state variables in cascade. I wonder what makes them sound different...
the OTAs, perhaps?

-joachim



From mpulver at wwa.com  Tue Sep 10 15:56:05 1996
From: mpulver at wwa.com (Mark Pulver)
Date: Tue, 10 Sep 1996 08:56:05 -0500
Subject: Moog 902 module question
Message-ID: <3.0b15.32.19960910085210.00679014@pop.wwa.com>


>Does anyone know what the  part number is for the diode bridge DB1 on the
Moog 
>902 Voltage Controller Amplifier?

If he doesn't see this on his own, drop a line to Kevin Lightner,
majmoog at synthfool.com


------------------------------------------------------------------------
 Mark Pulver/Chicagoish, IL          The home of "Son of The MIDI Wall"
 mpulver at wwa.com                        http://shoga.wwa.com/~mpulver
    Check out the EMP CD -->>> http://soli.inav.net/~kent/emp.html




From richard at ttech.com  Tue Sep 10 18:52:57 1996
From: richard at ttech.com (Richard Martin)
Date: Tue, 10 Sep 1996 09:52:57 -0700
Subject: CS50
Message-ID: <199609101652.JAA05300@ptm.ttech.com>


On Tue, 10 Sep 1996, Haible_Juergen#Tel2743 wrote:

> A few questions to CS-synthesizer owners:
> 
> (1) I liked the feature "Sustain II" on the CS-50, which allows pseudo-
>       monophonic playing. Does this work on the CS-60 and -80 as well?
>

Yes.
 
> (2) The filters seem to be a cascade of 2-poles. Has anybody yet figured
>       out what architecture they have? They don't sound like state variables
>       to me ....
>

>From the CS-80 schematics, they sure look like state variables. (Custom
Yamaha chip, as is most everything else).

> (3) What shape does the Ring Modulator AD-envelope have? The schematics
>       (of the CS-80) show linear slopes, but then again the VCF/VCA 
> envelopes
>       are also printed wrong, so I can't be sure.
> 

The EG circuit is the same as the one that the VCAs use, actually its a
VCA-EG combo chip.  In the ring modulator the EG controls the VCA which
attenuates a DC voltage (!).  The output of the VCA is attenuated by
the 'depth' pot which feeds the VCO input.  It's not real clear what the
transfer function of this whole mess is.

> (4) - related to (3) - the Ring Modulator VCO, is it exponential or linear?
>      (I know the main VCOs are linear)
> 

I would guess it's linear, but its not the same chip that the voice cards 
use.

> Thanks in advance for any information !
> 
> JH.
> 

The CS-80 is a great instrument and lots of fun to play.  (Not lots 
of fun to move).

Richard Martin
richard at ttech.com



From gstopp at fibermux.com  Tue Sep 10 19:04:44 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Tue, 10 Sep 96 10:04:44 PDT
Subject: Is this thing the coolest
Message-ID: <9608108423.AA842375361@ccrelay.fibermux.com>

     These days the analog scopes are pretty much sitting on the shelves in 
     the lab. If you want to troubleshoot a high-speed uP-based embedded 
     system you can't really use an analog scope - the trace just gets too 
     dim, and the trigger goes by too fast. To track down digital timing 
     problems, once you use a digitizing scope you won't go back. The 
     analog scopes are good for the audio stuff, or for looking for power 
     supply problems, but that's about it.
     
     I guess what with everything going digital, the demand for analog 
     scopes has diminished. Hand me an Ethernet bridge and tell me to fix 
     it, and I'll suck up to the nearest 16-channel 500 Msample color HP in 
     a heartbeat. But for a busted Minimoog I'd probably prefer a beat-up 
     10 Meg Heathkit with a dim trace.
     
     So I guess in the future we'll be able to look at analog signals with 
     physical-modelled analog scopes, right?
     
     - Gene


______________________________ Reply Separator _________________________________
Subject: Is this thing the coolest
Author:  barry.klein at solar.org (Barry Klein) at ccrelayout
Date:    9/10/96 2:51 AM


One real bummer is that Tektronix will only be making digital scopes 
in the near future.  It seems that making the CRT's is difficult due 
to some kind of environmental hazards etc.  They apparently
let go most of their analog guys and had to bring some of them back
to do work on the 2467, a high intensity scope.  That scope shows things 
that just can't be shown with their current line of scopes - even with 
their "Insta-view" feature.  I did do things with Insta-view that their 
product manager and sales guy didn't know could be done, to try and 
simulate what we do with the 2467, but still, if in 5 years from now 
someone were to come out with a 2467 clone it would be regarded as 
revolutionary.  What short sightedness!  God, just make the CRT's in India 
or Russia, or make the whole darn thing over there - don't just give up!
     
Barry
     
     
... Elect. Music, Photography, Bubble Machines, Stunt Kites, Elect. Design
     
___ Blue Wave/QWK v2.20 [NR]




From mpulver at wwa.com  Tue Sep 10 19:33:13 1996
From: mpulver at wwa.com (Mark Pulver)
Date: Tue, 10 Sep 1996 12:33:13 -0500
Subject: Is this thing the coolest
Message-ID: <3.0b16.32.19960910122827.00676ad4@pop.wwa.com>


>     I guess what with everything going digital, the demand for analog 
>     scopes has diminished. Hand me an Ethernet bridge and tell me to fix 
>     it, and I'll suck up to the nearest 16-channel 500 Msample color HP in 
>     a heartbeat. But for a busted Minimoog I'd probably prefer a beat-up 
>     10 Meg Heathkit with a dim trace.

heh-heh... Does that mean that there's still hope for my Eico 460? :)


------------------------------------------------------------------------
 Mark Pulver/Chicagoish, IL          The home of "Son of The MIDI Wall"
 mpulver at wwa.com                        http://shoga.wwa.com/~mpulver
    Check out the EMP CD -->>> http://soli.inav.net/~kent/emp.html




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep 10 20:10:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Tue, 10 Sep 96 11:10:00 PDT
Subject: CS-50 !!
Message-ID: <3235AF24@MSMGATE.M30X.NBG.SCN.DE>


Hi!

Played a CS-50 for the first time yesterday - what a wonderful
instrument!
When I came into the store, I first thought it was a CS-60, unti II found 
that
there was no hinged lid with presets, and no ribbon. Nevertheless
I decided to give it a try, and man, I couldn't let go for a whole hour!
How can a 1-VCO / 4-Voice polysynth sound so lush, and that without
a chorus section !!
Ok, it was quite out of tune, so I can't say how fat it sounds when
tuned. But I think most of its richness comes from the LFO's, especially
from the PWM section. Now what's so different with the PWM?
I think the SINE shape of the modulation is the trick! I found that you
can set a much higher modulation amount and rate before it becomes
annoying. I tried it at home on the OB-8 (which has, like most synths,
triangle instead of sine), and I didn't get the same effect. Then I tried
it on the Modular, and voila !

I was very fond of this little synth, but I think if I ever buy one, a CS-60
would be my choice.

A few questions to CS-synthesizer owners:

(1) I liked the feature "Sustain II" on the CS-50, which allows pseudo-
      monophonic playing. Does this work on the CS-60 and -80 as well?

(2) The filters seem to be a cascade of 2-poles. Has anybody yet figured
      out what architecture they have? They don't sound like state variables
      to me ....

(3) What shape does the Ring Modulator AD-envelope have? The schematics
      (of the CS-80) show linear slopes, but then again the VCF/VCA 
envelopes
      are also printed wrong, so I can't be sure.

(4) - related to (3) - the Ring Modulator VCO, is it exponential or linear?
     (I know the main VCOs are linear)

Thanks in advance for any information !

JH.


PS.: I make a crosspost to DIY, because of the technical questions.



From majmoog at synthfool.com  Wed Sep 11 08:22:15 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Wed, 11 Sep 1996 00:22:15 -0600
Subject: Polymoog people only...
Message-ID: <v02140b04ae5c09f4dc19@[206.171.253.86]>

I found about 30-40 of the little slider caps that go on Polymoogs (and a
few other Moogs).

They have tops of various colors with grey bodies.

I have little need for these and figured maybe someone might need 'em.

If anyone needs one or two or any reasonable amount of these (not just for
their stock, mind you),

I would be willing to send them out no charge.



-Kevin





From Zontar13 at aol.com  Wed Sep 11 22:03:35 1996
From: Zontar13 at aol.com (Zontar13 at aol.com)
Date: Wed, 11 Sep 1996 16:03:35 -0400
Subject: With this Ring Modulator, I thee wed
Message-ID: <960911160334_199346996@emout09.mail.aol.com>

I just built a Paia ring modulator. It seems to work, Im getting sounds that
I recognize as being Devo like. The things im confused about are that 
1.This thing Howls constantly (as though it had liver damage or something
else really painful). Ive adusted the internal trimpot to minimize this, but
its pretty loud. Ive never played with a Ring modulator before this. Is this
something it should be doing. The kit came with a heavy gauge Insulated wire
that wasn't (at least to my understanding) explained, I did not use it. Could
this be the problem?
Also the signal gain is massive when the effect is on, like a super pre-amp.

2. A friend of mine would like me to make one of these for him (assuming I
can stop the howling -the terrible terrible howling- ) but would like me to
replace the in/out switch with a pot that would control just how in or out
this thing is.
How would I wire that?

3. Im making modifications to a toy called A Mega Mouth Warp'r (per the
instructions posted on Analogue Heaven by Josh Brandt) It has tiny little
pots built right onto the board. I would like to replace these with full size
pots, but I do not have a clue as to determine what value pots I should
replace them with. It is a cool toy, and makes a metronome sound like a Wasp.

4. I would like to get a digest version of this list, cause my mailbox gets
mighty full. I checked the web page as I was told, but im kind of an idiot,
and was able to find no information about digesting the list.

I hope you are all well,
Johnny13



From gstopp at fibermux.com  Wed Sep 11 22:24:01 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Wed, 11 Sep 96 13:24:01 PDT
Subject: New Electronotes Order Arrival
Message-ID: <9608118424.AA842473653@ccrelay.fibermux.com>

     Hi DIY list,
     
     I have received the first portion of my recent order of the complete 
     set of Electronotes, from Bernie Hutchins. The cover sheet explains 
     that large orders (such as this one) will be broken up into a couple 
     different shipments and to expect them a few days apart.
     
     The shipment I received appears to be the most recent materials, so 
     I'll be reading alot in the near future.
     
     Just thought I'd drop a note to the list...
     
     - Gene
     gstopp at fibermux.com




From honcho at paia.com  Wed Sep 11 22:53:04 1996
From: honcho at paia.com (honcho at paia.com)
Date: Wed, 11 Sep 96 15:53:04 CDT
Subject: Nonsymmetrical Clipping
In-Reply-To: <199609092322.QAA09876@mx.seanet.com>
Message-ID: <9609112053.AA12558@qns1.qns.net>


the infinitely wise sean said:

>It seems to me
that the inversion of each gain stage in the 2040 would result in a 
signal
that was clipped, amplified and otherwise modified, than clipped on 
the
other side repeatedly, resulting in a complex waveform rich in even
harmonics.  
>>>

I can't add much to this, but here's a little something:

Cascaded assymetrical distortion stages that are capacitively coupled 
add a transient "punch" to a signal because as the first stage 
squashes the top (or bottom) the average value of the waveform changes 
- equivalently there is a DC component introduced. This DC is coupled 
as a transient to the second stage and for a short period causes it to 
squash more (or less) than it will when the capacitor charges to a 
steady-state value.

I haven't put that particularly well, but I know that you guys will 
get the drift of it.

-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 HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 12 00:08:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Wed, 11 Sep 96 15:08:00 PDT
Subject: P5 mod, AW: Re: CS-50 !!
Message-ID: <323738F9@MSMGATE.M30X.NBG.SCN.DE>


> Looking at the schems, the way the resistors and capacitors surronding
> the filter chips are connected, I'd almost swear it's two 2-pole
> state variables in cascade.

Yes, I think you are right, checked again last night.

Now this whole CS-50 thing made me think of an easy way to
implement sine shaped PWM on one of my polysynths.
(The JH-4 will have it, but I think it's a long way till this
one is finished!)
Unfortunately, the OB-8 is not the right one, here. :-(
Would have been nice, because on the CS-50 the deep PWM
in combination with rotational voice assignment was real killer.
(repeat the same note, and voices are layered on this note ...)
But now I'd rather go modding the Prophet.

Changing the LFO triangle waveform to sine would be easy:

Replace the 160k resistor between triangle level shift opamp
output and noise/lfo mix ota with a 91k and 12k series combination,
and connect two diodes to gnd (antiparallel) to form a "T"
circuit.
(Only done simulation so far, but should be easy).

Other ideas: When none of the three LFO waveform buttons is
switched on, no LFO output is produced. This is not of much use,
as you can turn off the LFO with the mod wheel anyway.
So I could easily detect this state (all three switches off), and
switch to sine wave. So I could have it as an option.
The same thing would work for the VCO's, btw. Would be nice
to have a sine here, too. Or maybe an inverted saw wave,
which is good to simulate thru-zero-PWM.

Guess I have a lot of things to solder on the weekend!

JH.



From wizrad at ix.netcom.com  Thu Sep 12 00:31:26 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Wed, 11 Sep 1996 18:31:26 -0400
Subject: Pulse Width Multipliers
Message-ID: <32373DBE.6130B347@ix.netcom.com>

Has anyone ever built or seen a circuit similar to the "Pulse Width 
Multiplier" article by Craig Anderton in Polyphony Jan/Feb '81?

For those not familiar, I quote from the article:

"The PW Multiplier uses four comparators, three of which have voltage
controllable thresholds, to turn a triangle wave into a number of
pulse waves with varying duty cycles. These pulse waves are then
mixed together digitally via EX-OR gates, resulting in a very complex
composite waveform."

I find it interesting because the typical timber modulator has only
one dimension of control. 


Tomy



From e93_mda at drum.it.kth.se  Thu Sep 12 01:52:52 1996
From: e93_mda at drum.it.kth.se (Magnus Danielson)
Date: Thu, 12 Sep 1996 01:52:52 +0200
Subject: Pulse Width Multipliers 
In-Reply-To: Your message of "Wed, 11 Sep 1996 18:31:26 MET DST."
             <32373DBE.6130B347@ix.netcom.com>
Message-ID: <199609112352.BAA14570@piraya.electrum.kth.se>

> Has anyone ever built or seen a circuit similar to the "Pulse Width 
> Multiplier" article by Craig Anderton in Polyphony Jan/Feb '81?
> 
> For those not familiar, I quote from the article:
> 
> "The PW Multiplier uses four comparators, three of which have voltage
> controllable thresholds, to turn a triangle wave into a number of
> pulse waves with varying duty cycles. These pulse waves are then
> mixed together digitally via EX-OR gates, resulting in a very complex
> composite waveform."
> 
> I find it interesting because the typical timber modulator has only
> one dimension of control. 

The ring-modulation cirsuit in a MS-20 works in a similar way even thougth
the comparator voltages is fixed. The PWM knob of OSC2 will have effect 
thougth.
It's a intresting thing.

It is trivial to do a twin PW multiplier useing one standard EXOR cursuit.
I would buffer the outputs if I built it. Maybe input knobs would be nice...

This reminds me of the distorsion effect that I had in my headphone amp when I
got it selfoscillating at about 1.3 MHz... it sounded weird. For some reason
I changed the cursuit totally later... nowdays it just eats batteries :)

Magnus




From johns at oei.com  Thu Sep 12 09:03:41 1996
From: johns at oei.com (johns at oei.com)
Date: Thu, 12 Sep 96 09:03:41 
Subject: Matchin transistors
Message-ID: <9608128425.AA842544221@oei.oei.com>


     In preparing to build an ASM-1, I am considering searching for 
     matching transistors.  I assume this means trying to find a pair of 
     transistors that show a close match of a V-be curve for an identical 
     I-b current ramp.  (Is this correct?)
     
     For anybody who has experience, who many samples will one typically 
     need to take before one finds a pretty good match?  And what is 
     considered a good match for VCO and VCF applications?
     
     John Speth - johns at oei.com



From honcho at paia.com  Thu Sep 12 15:16:52 1996
From: honcho at paia.com (honcho at paia.com)
Date: Thu, 12 Sep 96 08:16:52 CDT
Subject: AW: Re: Nonsymmetrical Clipping
Message-ID: <9609121316.AA22110@qns1.qns.net>

Juergen sayz:

>But the thing with RC-coupled stages is most interesting as well!
Might be a clue to explain some of the mystery about the good
sound of tube amplifiers.
>>>
It's one of the "secrets" of our TubeHead things (Stack-in-a-Box, Tube 
Mic Pre). There's more on this and "tube sound" on our pages at 
www.paia.com/tubesnd.htm and at www.paia.com/tubworks.htm .

-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 hbcsc349 at email.csun.edu  Thu Sep 12 19:02:14 1996
From: hbcsc349 at email.csun.edu (JunoMan)
Date: Thu, 12 Sep 1996 10:02:14 -0700 (PDT)
Subject: CS-50, Part 2 ...
In-Reply-To: <3238758E@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <Pine.HPP.3.95.960912095034.24066E-100000@csun1.csun.edu>

On Thu, 12 Sep 1996, Haible_Juergen#Tel2743 wrote:
 
> Hmm, and as soon as I carried it out of the store to my car,
> I was *happy* that it was no -60 or -80 (;->)
>
Maybe you can give a quick specs on what it's got and how it sounds?
Is it similar to CS-80?
 
> I tuned it last night, and it is really wonderful. Many people
> complain about tuning CS synths (and I really don't know
> how hard it is on a CS-80), but tuning the CS-50 was fun:
> *No* iterative adjustment of offset, scale and HFT, as I know it
> from V/oct synths, but just tuning highest note, lowest note,
> and 4 transposition switches. Easy!
> 
I am still trying to tune my CS-80.  I got some procedures now, but man
it's hell of a job.

> Also, it would be fine to have the complete User- und Service
> Manuals ...
> 
You can get these from Yamaha.  Call Kenya at (714)522-9011
She send me free photocopies of CS-20 and CS-80 user manuals, since they
were out of them.  So if you are lucky, they will be out on the CS-50 as
well, so you get free copies.  I had to pay $50 for the CS-80 service
manual tough, ouch.

Pierre
================================================================== 
      ___    ___
      |  |     /         Pierre Zarokian
      ~~~    ~/~         E-mail: pzarokian at huey.csun.edu
      |      /__         URL: http://www.csun.edu/~hbcsc349/
==================================================================




From bbrett at illuminati.heald.edu  Thu Sep 12 22:39:00 1996
From: bbrett at illuminati.heald.edu (Bill Brett)
Date: Thu, 12 Sep 1996 13:39:00 -0700
Subject: manuals
Message-ID: <9609122039.AA14820@heald.edu>

I am looking for owner manuals for a moog prodigy,roland sh-3 and a prophet
600.I also need the service manuals for the roland and prophet-I have the
moog service manual if any one is looking-
Bill




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 12 22:40:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Thu, 12 Sep 96 13:40:00 PDT
Subject: CS-50, Part 2 ...
Message-ID: <3238758E@MSMGATE.M30X.NBG.SCN.DE>


Well, "Part 2" means:

Meanwhile, I actually bought this CS-50 ! I didn't intend to,
but the price was so cheap (DM 400,-) that I could not
resist.

Hmm, and as soon as I carried it out of the store to my car,
I was *happy* that it was no -60 or -80 (;->)

I tuned it last night, and it is really wonderful. Many people
complain about tuning CS synths (and I really don't know
how hard it is on a CS-80), but tuning the CS-50 was fun:
*No* iterative adjustment of offset, scale and HFT, as I know it
from V/oct synths, but just tuning highest note, lowest note,
and 4 transposition switches. Easy!

BTW, it has a nice aftertouch action (optoelectronic).

There are a few sliders that don't work perfect. Does anybody
happen to have replacements for these ? (Should be the same
ones as in CS-60 and CS-80 ...)

Also, it would be fine to have the complete User- und Service
Manuals ...

JH.



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 12 23:07:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Thu, 12 Sep 96 14:07:00 PDT
Subject: AW: Re: Nonsymmetrical Clipping
Message-ID: <32387BAA@MSMGATE.M30X.NBG.SCN.DE>


> Cascaded assymetrical distortion stages that are capacitively coupled
> add a transient "punch" to a signal because as the first stage
> squashes the top (or bottom) the average value of the waveform changes
> - equivalently there is a DC component introduced. This DC is coupled
> as a transient to the second stage and for a short period causes it to
> squash more (or less) than it will when the capacitor charges to a
> steady-state value.
>
> I haven't put that particularly well, but I know that you guys will
> get the drift of it.

Though the 2040 is not capacitively coupled (rather the contrary,
with a LP function in each stage!), it shows the same effect. I
remember that I have done some spice simulations on this,
and have posted the results to DIY. Must be somewhere in
the archives - don't remember the details myself.

But the thing with RC-coupled stages is most interesting as well!
Might be a clue to explain some of the mystery about the good
sound of tube amplifiers. Most publications stress the effect
on the spectrum of the distortion products, but I haven't found
anything about this "punch" effect so far. And this effect must
occur even *before* you can hear much of distortion!
Imagine this: a "punch exciter" inherently build-in! Great!

JH.



From mariano-elizalde at postoffice.worldnet.att.net  Fri Sep 13 03:26:35 1996
From: mariano-elizalde at postoffice.worldnet.att.net (Mariano Elizalde)
Date: Fri, 13 Sep 1996 01:26:35 +0000
Subject: matching FETs
Message-ID: <19960913012633.AAA3460@LOCALNAME>


  Hello;

  The easiest way to match jfets is by selecting those whose Ids (drain to
source curren) is identical (or as close as possible...),  here's how you
can do that:

                ^ +15v
                |
                |
                | Drain
             ___|
            |
  Gate  --->|       jfet under test... 
       |    |
       |    |___   Source 
       |        |
       |        |<---- your meter's + lead (red)
       |        |
       |        /
       |        \ 1K 1%  place you digital volt meter
       |        /         in parallel to this resistor...
       |        \
       |        |<---- you meter's -lead (black)
      ---      ---
        (ground)

   Select the jfets that have a similar voltage reading across the 1K
resistor... 

    A quick breadboarding and three KE4392 jfets revealed.. a) 1.602 volts
b) 2.612 volts and c) 1.876 volts for each jfet... I would use a) and c) as
the closest match...

  note: let the circuit settle a minute or so with each jfet before taking
the final reading... (thermals, you know ..)

   ( I know this post is proper of synt-diy, but I found it here at AH... :]  )


  Hope this helps...
 
  bye...

 someone wrote:
   
>From: Gareth Jones <gareth at swansea.demon.co.uk>
>Date: Thu, 12 Sep 1996 10:26:41 +0100
>Subject: Re: matching FETs
>
>In article <199609120505.WAA19726 at taz.hyperreal.com>, analogue-
>owner at hyperreal.com writes
>>Does anyone know how to match FET's for phase shifters specifically the
>>Roland System 100m as it asks for the Fet's to be selected. But doesn't
say for
>>what . I can only assume that they be matched. Is there a circuit I could
build
>>like a jig for matching up Fet's and if they don't match can I alter the
>>resistors>
>
>I would have thought that the selection was just to match the gain. It
>should not be too difficult to breadboard up a little circuit to give
>you the amplification factor of each device. How many do you need? its
>been a while since I've worked with discretes, but trannys can be
>obtained in matched pairs or batches that are pre matched to be within a
>certain (closer) spec.
>It depends on the circuit, but I'd be more inclined not to fiddle with
>the other components (why not put a 3 pin socket in there and just try
>different ones untill it works to your satisfaction?)
>- -- 
>__________________________________________
><Gareth Jones>  Gareth at swansea.demon.co.uk
>                       gl.jones at sihe.ac.uk
>  "Reality sucks - go watch a Star Trek"


   mariano
   
   mariano-elizalde at worldnet.att.net
  




From johns at oei.com  Fri Sep 13 12:17:25 1996
From: johns at oei.com (johns at oei.com)
Date: Fri, 13 Sep 96 12:17:25 
Subject: Matchin transistors
Message-ID: <9608138426.AA842642245@oei.oei.com>


     joachim (and DIY) -
     
     Thanks for the techy treatment of transistor matching.  I think this 
     might cover it all.
     
     But are you saying that the term "matched transistors" really 
     indicates 2 transistors in good thermal "sync" (using come good 
     thermal coupling) rather than 2 transistors selected for closely 
     matched VI and gain characteristics?
     
     JJS


______________________________ Reply Separator _________________________________
Subject: Re: Matchin transistors
Author:  Joachim Verghese <jocke at netcontrol.fi> at Internet
Date:    9/13/96 11:24 AM


On Thu, 12 Sep 1996 johns at oei.com wrote:
     
>      In preparing to build an ASM-1, I am considering searching for 
>      matching transistors.  I assume this means trying to find a pair of 
>      transistors that show a close match of a V-be curve for an identical 
>      I-b current ramp.  (Is this correct?)
     
The problem with using a transistor (or diode) as an exponentiating 
device is that the transfer function is heavily dependent upon 
changes in temperature.
     
In a typical linear voltage-to-exponential-current converter, the 
first transistor is connected as a voltage follower, and the second
as the exponentiator. The voltage follower adds a temperature dependent 
offset to the control voltage. This compensates for the 1st order 
thermal effects of the exponantiating transistor.
     
In other words, if the two transistors have identical thermal 
responses, then you've eliminated a major part of the converter's 
thermal drift.
     
Ideally, then, the two transistors should be matched for *thermal 
tracking*. Using a dual transistor (MAT-0x, SSM22x0) obviously
is an advantage since the two transistors are on the same silicon 
substrate. If you choose to use two discrete devices (2N390x...), 
there's no easy way to guarantee thermal tracking, but in most 
cases you'll achieve good results by just using randomly selected 
devices, as long as you provide adequate thermal coupling. Some
sort of heatsink or metal clip should be used to hold the transistors 
together.
     
As far as Vbe-Ic (or Ib) matching goes, this is generally not needed 
for exponentiator applications. Any mismatch in these parameters only 
affect the tuning offset of the oscillator/filter.
     
In systems with large numbers of oscillators/filters, it might be 
desireable to Vbe-Ic match the transistors, since this allows you
to have less coarse tuning trimmers, which makes calibration easier. 
(Remember that a change of 18 mV at the base-emitter changes the 
frequency by one whole octave.)
     
-joachim
     



From honcho at paia.com  Fri Sep 13 15:18:58 1996
From: honcho at paia.com (honcho at paia.com)
Date: Fri, 13 Sep 96 08:18:58 CDT
Subject: With this Ring Modulator, I thee wed
In-Reply-To: <960911160334_199346996@emout09.mail.aol.com>
Message-ID: <9609131318.AA08255@qns1.qns.net>

Zontar13 at aol.com, said:

>I just built a Paia ring modulator. It seems to work, Im getting 
sounds that I recognize as being Devo like. The things im confused 
about are that 1.This thing Howls constantly (as though it had liver 
damage or something else really painful). Ive adusted the internal 
trimpot to minimize this, but its pretty loud. Ive never played with a 
Ring modulator before this. Is this something it should be doing. The 
kit came with a heavy gauge Insulated wire that wasn't (at least to my 
understanding) explained, I did not use it. Could this be the problem?
Also the signal gain is massive when the effect is on, like a super 
pre-amp.
>>>

I asked Scott Lee, who knows every weird thing every PAiA product has 
ever done, about this and he passed this along:
------------
High gain at the input stage of the Ring Modulator project can cause 
noise to be modulated and this would appear as excessive bleed.  The 
noise can be hum introduced through the input connection (guitar 
pick-ups/cable) or right on the circuit itself due to less than 
optimum shielding or bad ground circuits (loops/resistive).

Resistor R12 can be selected for different amounts of amplification of 
the input signal.  We include 33K, 100K, and 330k resistors in the kit 
for R12. The higher the value of the resistor at R12, the higher the 
gain of the input stage.

If you're connecting a guitar, try turning the volume control down to 
find out if this reduces the bleed.  Single coil pickups are good hum 
senors. Grounding the input by shorting the tip and sleeve contacts of 
the RM input jack is another way of determining if it's noise from the 
input connection that's being modulated.  If the bleed stays or is not 
reduced, maybe there is a problem on the circuit board or wiring.

Our RM kit is packed with #22 insulated stranded wire and shielded 
wire for the input and other sensitive connections.  The I, E, and F 
wires could pick up noise and would benefit from shielding.  Enclosing 
the project in a metal enclosure with a connection to circuit ground 
would help shield external hum and noise.

>2. A friend of mine would like me to make one of these for him 
(assuming I can stop the howling -the terrible terrible howling- ) but 
would like me to replace the in/out switch with a pot that would 
control just how in or out this thing is.
How would I wire that?
>>>

The kit already works this way.  We don't provide a switch in the kit 
for In/Out switching.  The Ring Level and Straight Level 
potentiometers, Rs 10 and 11 provide adjustment of the wet/dry mix.

-over and out.
-Scott
-------------------

-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 jocke at netcontrol.fi  Fri Sep 13 16:40:05 1996
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Fri, 13 Sep 1996 17:40:05 +0300 (EET DST)
Subject: Matchin transistors
In-Reply-To: <9608128425.AA842544221@oei.oei.com>
Message-ID: <Pine.LNX.3.91.960913164404.3303B-100000@netcontrol.netcontrol.fi>

On Thu, 12 Sep 1996 johns at oei.com wrote:

>      In preparing to build an ASM-1, I am considering searching for 
>      matching transistors.  I assume this means trying to find a pair of 
>      transistors that show a close match of a V-be curve for an identical 
>      I-b current ramp.  (Is this correct?)

The problem with using a transistor (or diode) as an exponentiating
device is that the transfer function is heavily dependent upon
changes in temperature.

In a typical linear voltage-to-exponential-current converter, the
first transistor is connected as a voltage follower, and the second
as the exponentiator. The voltage follower adds a temperature dependent
offset to the control voltage. This compensates for the 1st order
thermal effects of the exponantiating transistor.

In other words, if the two transistors have identical thermal
responses, then you've eliminated a major part of the converter's
thermal drift.

Ideally, then, the two transistors should be matched for *thermal
tracking*. Using a dual transistor (MAT-0x, SSM22x0) obviously
is an advantage since the two transistors are on the same silicon
substrate. If you choose to use two discrete devices (2N390x...),
there's no easy way to guarantee thermal tracking, but in most
cases you'll achieve good results by just using randomly selected
devices, as long as you provide adequate thermal coupling. Some
sort of heatsink or metal clip should be used to hold the transistors
together.

As far as Vbe-Ic (or Ib) matching goes, this is generally not needed
for exponentiator applications. Any mismatch in these parameters only
affect the tuning offset of the oscillator/filter.

In systems with large numbers of oscillators/filters, it might be
desireable to Vbe-Ic match the transistors, since this allows you
to have less coarse tuning trimmers, which makes calibration easier.
(Remember that a change of 18 mV at the base-emitter changes the
frequency by one whole octave.)

-joachim




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Sat Sep 14 00:25:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Fri, 13 Sep 96 15:25:00 PDT
Subject: Another CS-50 question, and specs !
Message-ID: <3239DF51@MSMGATE.M30X.NBG.SCN.DE>


Sorry for bringing up the CS-50 thread again, but I have
another question (and maybe more to follow):

When I have Sustain 2 switched on, the portamento and
glissando work as they should.
In Sustain 1 mode, however, there is *always* a short
prtamento between notes, regardless of the portamento
slider setting. Is this a general bug, or is it just mine that
does this?

BTW, for those who asked for specs:
Think of it as a 4-voice/4octave version of the CS-60,
without the pitch ribbon (and chorus?).

In short:
(sorry if the terminology doesn't correspond exactly
to the front panel labels - don't have the beast before
me as I type ... hope I don't forget a feature ...)

1VCO/Voice, with three mixable waveforms:
  Pulse (with dedicated sine shape PWM LFO),
  Saw and
  Sine (continuously mixable *after* the VCF,
      to enhance the fundamental when you do BP
      filtering)
2 VCF/Voice (in series):
   HP with Frequency and Resonance slider,
   LP with Frequency and Resonance slider.
2 Envelopes/Voice
   VCA-ENV is ADSR type,
   VCF_ENF is also ADSR shape, but with different
      controls than usual: Instead of A, D, S, R and Amount
      you have Sustain level = zero Volt, and determine the
      amount by a (negative) Initial Value and a (positive)
      Peak Value. Weird, but not bad. Envelope works
      on both, HP and LP at the same time.
VCA: here you can mix in the Sine wave. You can also set
   the VCA level, up to a nice overdrive.

Ringmodulator: Has its own AD envelope for frequency of
  modulating VCO. Frequency goes from LFO up to the
  middle audio range. Levers for Attack, Decay, LFO frequency,
  LFO-FM amount (from AD), Mix between dry and ringmodulated.
  Levers are extremely handy to use (what sliders should be,
  but never ever are ...). Instant "Vangelis" effects at your fingertips ...

Levers for Brilliance and Resonance. Change the initial settings
  of the panel (see above) and the presets, in a way that it
  works on both HP and LP Frequency and Resonance . But
  it doesn't just add - there is a total maximum, so if you have
  lower settings on the panel or preset, effect of the levers is larger.

Preset buttons: Imaginative names that don't hold what they promise;
  nevertheless very useful for further processing with Levers ...

Aftertouch. Best Aftertouch I have seen on any synth. Comes really
  soon, and has a large usable range. Can work on:
  VCA level: Drive that VCA into distortion with aftertouch! Or just 
increase
     the volume ...
  Brilliance: Works on VCF frequencies
  LFO Mod for VCF
  LFO Mod for VCO

Main LFO: Sine, Saw up, Saw down, Noise, External (!) ...
Portamento, Glissando (semitone steps ...)
Sustain 1 / 2 switch: Sustain 2 is phantastic for solo lines with random
  chords thrown in - hard to describe!
Sustain: (actually Release time ...) another slider that also works on
  the presets.

BTW, "Presets" are just predefined rough material. If you change
Brilliance, Resonance and Sustain, a "Flute" is not at all a boring
flute anymore ...

And I just forgot: The pitch bend "ring" around the fine tune knob
lets the Roland Stick look like a luxury pitch bender (;->).

Corrections / Additions are welcome. This was just from a first
touch with my new instrument, so errors are likely. Hope you
enjoyed it nevertheless. Maye with some corrections you could
put it to Music Machines.

JH.





From jocke at netcontrol.fi  Sun Sep 15 11:59:16 1996
From: jocke at netcontrol.fi (Joachim Verghese)
Date: Sun, 15 Sep 1996 12:59:16 +0300 (EET DST)
Subject: Matchin transistors
In-Reply-To: <9608138426.AA842642245@oei.oei.com>
Message-ID: <Pine.LNX.3.91.960915123042.5662A-100000@netcontrol.netcontrol.fi>

On Fri, 13 Sep 1996 johns at oei.com wrote:

>      But are you saying that the term "matched transistors" really 
>      indicates 2 transistors in good thermal "sync" (using come good 
>      thermal coupling) rather than 2 transistors selected for closely 
>      matched VI and gain characteristics?

No. "Matched transistors" implicitly means that the devices have
closely matched Vbe-Ic characteristics. (And in order to maintain
matching over a range of temperatures, the devices need to be
thermally coupled, too).

This, I assume, is because that's what's needed to build good
differential amplifiers and current mirrors - two of the most popular
and useful transistor applications.

The exponential converter is a totally different application,
and therefore the matching requirements differ too.

-joachim



From majmoog at synthfool.com  Mon Sep 16 01:49:30 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Sun, 15 Sep 1996 17:49:30 -0600
Subject: Transistor arrays 
Message-ID: <v02140b02ae6245fe547a@[206.171.253.91]>

>Hi Kevin!
>
>While digging trougth some old mails (about 3000 before current countervalue)
>I found your question, so just in case noone answered here it is:
>
>> Does anyone know the exact differences between LM/CA 3046 and 3086's???
>> Also, SG3821's?
>>
>> They all have the same pin out and architecture (5 NPN's) and I've often
>> substituted 3046's with '86's with good results in 2600's, Moogs, etc.
>>
>> It seems VCO's are a bit more stable with the '86's, though in sine wave
>> shapers, I can't see much improvement.
>
>While looking in my Harris databook I could hardly find any major diffrence
>between the two... they seems so similar that you might miss the point.. the
>CA3046 is matched, the CA3086 ain't. Other than there is no diffrence...
>
>Magnus


Thanks.

Still, along that criteria I'm confused.
Most of the techs I know use 86's as an upgrade for a 46.

This would appear to be the opposite of what is desired, although it may
make zilch difference after actually adjusting trimmers.

In fact, I've found that Oberheim SEM's are a bit more stable with 86's,
than a Moog 921 with 46's.

So confused....!! :)


 I could see how a sine shaper might be better with it though, as far as
bipolar symetricallness goes.


Maybe I should make a VCO jig that has both arrays and do a temperature vs
freq graph or something for each.

Probably not enough difference to warrant that though.



Thanks for checking this out!

Kevin





From magda at it.kth.se  Mon Sep 16 02:31:41 1996
From: magda at it.kth.se (Magnus Danielson)
Date: Mon, 16 Sep 1996 02:31:41 +0200
Subject: Transistor arrays 
In-Reply-To: Your message of "Wed, 28 Aug 1996 13:44:32 MET DST."
             <v02140b04ae4a51057a07@[198.147.97.118]>
Message-ID: <199609160031.CAA27782@piraya.electrum.kth.se>

Hi Kevin!

While digging trougth some old mails (about 3000 before current countervalue) 
I found your question, so just in case noone answered here it is:

> Does anyone know the exact differences between LM/CA 3046 and 3086's???
> Also, SG3821's?
> 
> They all have the same pin out and architecture (5 NPN's) and I've often
> substituted 3046's with '86's with good results in 2600's, Moogs, etc.
> 
> It seems VCO's are a bit more stable with the '86's, though in sine wave
> shapers, I can't see much improvement.

While looking in my Harris databook I could hardly find any major diffrence
between the two... they seems so similar that you migt miss the point.. the
CA3046 is matched, the CA3086 ain't. Other than there is no diffrence...

Magnus



From majmoog at synthfool.com  Mon Sep 16 16:16:51 1996
From: majmoog at synthfool.com (Kevin Lightner)
Date: Mon, 16 Sep 1996 08:16:51 -0600
Subject: Today's 1st phone call....
Message-ID: <v02140b07ae631108b5ad@[206.171.253.71]>

B: Hello, is this Kevin Lightner?

K: Yes

B: Hi, you don't know me, but I just bought an Arp2500 with BOTH wing
cabinets in a NY pawn shop for $125.00. They didn't know what it was....

K: <picking the phone up off the floor>


NEED I SAY MORE?!!!!!


TRUE STORY!!!!

Deals CAN still be found!!!

-Kevin

synthfool.com





From e93_mda at drum.it.kth.se  Tue Sep 17 00:02:45 1996
From: e93_mda at drum.it.kth.se (Magnus Danielson)
Date: Tue, 17 Sep 1996 00:02:45 +0200
Subject: Today's 1st phone call.... 
In-Reply-To: Your message of "Mon, 16 Sep 1996 08:16:51 MET DST."
             <v02140b07ae631108b5ad@[206.171.253.71]>
Message-ID: <199609162202.AAA17508@piraya.electrum.kth.se>

> B: Hello, is this Kevin Lightner?
> 
> K: Yes
> 
> B: Hi, you don't know me, but I just bought an Arp2500 with BOTH wing
> cabinets in a NY pawn shop for $125.00. They didn't know what it was....
> 
> K: <picking the phone up off the floor>
> 
> 
> NEED I SAY MORE?!!!!!
> 
> 
> TRUE STORY!!!!
> 
> Deals CAN still be found!!!

Did you take this dude's name?

I can give hime the double for that box :) 10 cents times model number :)

But really.. I MIGTH go higher :) :)

Magnus




From costello at costello.seanet.com  Tue Sep 17 00:03:35 1996
From: costello at costello.seanet.com (Sean Costello)
Date: Mon, 16 Sep 1996 15:03:35 -0700 (PDT)
Subject: Interesting Paper available on Moog VCF
Message-ID: <199609162203.PAA11060@mx.seanet.com>

Hi all,

Just found an interesting paper residing in the depths of the CCRMA web site
at Stanford (my old alma mater), "Analyzing the Moog VCF with Considerations
for Digital Implementation."  Haven't had the time to do anything beyond
skimming yet, but it looks quite interesting; pretty pictures.  It is in a
similar vein to Hutchin's VCF analysis in Electronotes #41 (and the Musical
Engineer's Handbook).

Check it out at http://cmn19.stanford.edu/~stilti/papers/Welcome.html.

I do find it strange that all of this work has been put into making a very
powerful DSP system emulate a circuit that can be built with about $2 in
parts. Oh well, I guess they have to use those NeXT cubes for something. :)

Later,

Sean






From thierry.rochebois at ief-paris-sud.fr  Tue Sep 17 12:06:10 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Tue, 17 Sep 1996 12:06:10 +0200
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609171006.AA02043@zeus.ief-paris-sud.fr>

>I do find it strange that all of this work has been put into making a very
>powerful DSP system emulate a circuit that can be built with about $2 in
>parts. Oh well, I guess they have to use those NeXT cubes for something. :)

Well, when you know that the Clavia NordLead uses a Motorola 56002 DSP and
that this machine is polyphonic... and is very expensive when you compare
its price to the price of the DSP (about $30-$40). As far as I know, the price
for a DSP56002 evaluation board is about $200... If you can implement good
simulations of Moog Filters and others, it is not as stupid as it seems at first
sight.

Thierry Rochebois

+-------------------------------------------------------------+
|                                                             |\
|  Thierry Rochebois      Tel:69 41 79 39  Piece 353          | +
|  IEF   AXIS/TSA(ARCEMA)   Bat 220 UPS   91405 ORSAY Cedex   | |
|  thierry at ief-paris-sud.fr               FRANCE              | |
|  http://www.ief.u-psud.fr/~thierry/welcome.html             | |
|                                                             | |
+-------------------------------------------------------------+ |
 \                                                             \|
  +-------------------------------------------------------------+



From predo at dist.dist.unige.it  Tue Sep 17 14:36:09 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Tue, 17 Sep 1996 14:36:09 +0200 (MET DST)
Subject: bulk resistance compensation revisited
Message-ID: <199609171236.OAA02539@dist.dist.unige.it>

Hello!
This is my first posting to this mailing list.
A few days ago I downloaded Rick Jansen's sawtooth VCO. It uses a LM3046
transistor array for the lin/exp conversion and for the thermal stabilization.
The schematic has a compensation for the emitter resistance of the 3046.
At first I could not understand the explanation because the assumption
that the voltage across the diode (transistor in diode configuration) is
constant seemed not suitable for a first order compensation.
So I studied the circuit and found that the diode (transistor) can be 
eliminated yet the compensation is maintained.

I include a short GIF. It's uuencoded at the end of this message.
Please refer to it for the following discussion.

Q1 and Q2 are ideal transistors. Their Ic currents can be calculated using:
Ic = Is * exp(Vbe / Vt)
Vbe is the base-emitter voltage.
Vbe1 is referred to Q1's Vbe, Vbe2 is referred to Q2's Vbe.
Moreover Vb1 and Vb2 are the absolute voltages of Q1's and Q2's bases.

The 2 Re resistors represent the emitter resistances that can be found in
real transistors. So Q1 + Re = a real transistor (eg: LM3046)

The polarization current sets a constant Vbe1:
Vbe1 = Vt ln(Ipol / Is)

Vb1 is a linear combination of Vin and Vf:
Vb1 = k1 * Vin + k2 * Vf - c1
where:
k1 = R * R2 / (R1 * R2 + R * (R1 + R2))
k2 = R * R1 / (R1 * R2 + R * (R1 + R2))
c1 is a constant that takes into account the base current of Q1

k1 is usually 18E-03

Now:
Vf = V1 - Rf * (Iout + Ipol)
V1 = Vb1 - Vbe1 - Re * Ipol =
   = k1 * Vin + k2 * Vf - c1 - Vbe1 - Re * Ipol = 
   = k1 * Vin + k2 * Vf - c2 =
   = k1 * Vin + k2 * V1 - k2 * Rf * Iout - k2 * Rf * Ipol - c2
   
So:
V1 = k1 / (1 - k2) * Vin - k2 * Rf / (1 - k2) * Iout - c3

Now Vbe2 can be calculated:
Vbe2 = - V1 - Re * Iout
     = - k1 / (1 - k2) * Vin + k2 * Rf / (1 - k2) * Iout + c3 - Re * Iout

The two terms that depend on Iout must compensate each other.
k2 / (1 - k2) * Rf = Re

The solution is:
k2 = Re / (Re + Rf)

This final equation and the equations that define k1 and k2 should
be solved for R, R1, R2, k2 and Rf.
Since the solution is rather difficult to find, an approximated solution
is needed.
First choose Rf and R. Eg. Rf = 2k2 and R = 1k
Now calculate a course value for R1 so that 1V/oct is obtained. Eg: R1 = 54k
Calculate k2 (Eg: Re = 5.6, so k2 = 2.54E-03)
Find R2 using the formula:
 R2 = R * R1 * (1 - k2) / ((R1 + R) * k2)     (R2 = 386k)
Now R1 can be re-calculated:
 R1 = R * R2 * (1 - k1) / ((R2 + R) * k1)
but usually R1 is a constant resistor + a trimmer, so don't re-calculate
R1: use the course value and adjust the trimmer until 1V/oct conformity is
achieved.

As it can be seen from the calculation R2 is ~ 390k (standard resistor value)
which is the same value Rick Jansen found to be appropriate in his schematic.
The only difference is that a diode (transistor) is saved.

Some final notes:
-the 18mV/oct for Vbe seems not appropriate for the 3046. AN-299 uses
 21.4mV/oct. The difference may depend on different temperature condition but
 may be due to a forward current emission coefficient > 1 as well.
-The polarization current Ipol should not be set to a high value (eg: top
 octave value) because you would have to use high input voltages (~10V) to
 decrease the output current to the lower octaves. High Vin means high
 Vb1. Keep in mind that Q1's collector is at 0V so if Vbc1 > -5 * Vt the
 transistor enters the saturated region and the exponential relationship is
 lost.

I would appreciate feedback in case of any errors in my calculations.
I would like to know in what cases and why a diode is necessary. (Sorry,
I couldn' t find S. Franco's book).

I know that there are at least 2 other problems about exp conformity.
Is this compensation sufficient or should I work on the other problems?
I think the LM3046 is so cheap and available that it's worth trying to
correct its defects by means of additional circuitry.

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`
end

-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From don at till.com  Tue Sep 17 18:28:32 1996
From: don at till.com (Don Tillman)
Date: Tue, 17 Sep 1996 09:28:32 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <9609171006.AA02043@zeus.ief-paris-sud.fr>
	(thierry.rochebois@ief-paris-sud.fr)
Message-ID: <199609171628.JAA07295@shellx.best.com>

   Date: Tue, 17 Sep 1996 12:06:10 +0200
   From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)

   >I do find it strange that all of this work has been put into making a very
   >powerful DSP system emulate a circuit that can be built with about $2 in
   >parts. Oh well, I guess they have to use those NeXT cubes for something. :)

   Well, when you know that the Clavia NordLead uses a Motorola 56002 DSP and
   that this machine is polyphonic... and is very expensive when you compare
   its price to the price of the DSP (about $30-$40). As far as I
   know, the price for a DSP56002 evaluation board is about $200... If
   you can implement good simulations of Moog Filters and others, it
   is not as stupid as it seems at first sight.

You seem to be suggesting that this algorithm is used in the Nord
Lead, that the Nord Lead has a good simulation of the Moog filter, and
that a digital simulation of a filter is a good thing because a DSP
evaluation board costs $200 (huh?).

Please note that Stilson & Smith's paper is very recent original
research; this is *not* the algorithm used in the Nord Lead.

The interesting thing about this paper is the tremendous amount of
work necessary to just position the poles of a digital filter close to
the poles of a very simple analog VCF.  There is no attempt made to
deal with nonlinearities or other interesting behavior responsible for
the characteristic sound of the filter.

  -- Don




From bzimmer at voicenet.com  Tue Sep 17 19:12:06 1996
From: bzimmer at voicenet.com (Bob Zimmer)
Date: Tue, 17 Sep 1996 13:12:06 -0400 (EDT)
Subject: New Electronotes Order Arrival
Message-ID: <1.5.4.16.19960917131042.309f2d34@voicenet.com>

At 01:24 PM 9/11/96 PDT, you wrote:
>     Hi DIY list,
>     
>     I have received the first portion of my recent order of the complete 
>     set of Electronotes, from Bernie Hutchins. The cover sheet explains 
>     that large orders (such as this one) will be broken up into a couple 
>     different shipments and to expect them a few days apart.
>     
>     The shipment I received appears to be the most recent materials, so 
>     I'll be reading alot in the near future.
>     
>     Just thought I'd drop a note to the list...
>     
>     - Gene
>     gstopp at fibermux.com

I'd also like to say that Bernie has been shipping my order.  I received a
second package from him last night and now have two 3" binders and one 1.5"
binder full of Electronotes Issues.  I'm not sure, but I think that is about
half of what I've ordered.  So far so good! :^)

To any of you that may want your own copies, this may be a good time to
place orders with Bernie.  He is being very prompt with shipments as I think
I received my first package before the check even had a chance to clear!

BTY, what a blast from the past!  I saw my name mentioned as a new
subscriber on the cover of issue 43!  I had subscribed during my college
days, but never had the money to build much and eventually had given away my
old issues.  P.S. - I beat Bob Moog by one issue.  He is listed on issue 44!

Bob Zimmer


  >=== Bob Zimmer -- Philadelphia PA ===<
  >=== bzimmer at voicenet.com          ===<





From niklasl at eritel.se  Tue Sep 17 19:16:08 1996
From: niklasl at eritel.se (Niklas Lindberg)
Date: Tue, 17 Sep 1996 19:16:08 +0200
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609171716.AA02886@nasse>

Howdy DIYers,

On Mon, 16 Sep 1996 15:03:35 -0700 (PDT) Sean Costello wrote:

>I do find it strange that all of this work has been put into making a very
>powerful DSP system emulate a circuit that can be built with about $2 in
>parts. Oh well, I guess they have to use those NeXT cubes for something. :)

I think the reason that so much effort is put into this, is because if
you're seriously considering constructing and manufacturing a modern
commercial synthesizer today, you're bound to go digital. Otherwise
the price tag of the final product would be way to high to appeal to
any but the most enthusiastic synthesists (ie we :-)

If you can find a way to digitally simulate eg the famous Moog VCF
and implement this in a modern synth (a'la NordLead), its almost
certain that you can make money out of it...

Luckily (for us) it will be quite some time before a digital simulation
of a VCF can really compete with the real thing ;)

/ Niklas
-----------------------------
Niklas.Lindberg at ees.enator.se



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep 17 22:25:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Tue, 17 Sep 96 13:25:00 PDT
Subject: PS-3100 Resonator Section Clone
Message-ID: <323F096A@MSMGATE.M30X.NBG.SCN.DE>


Hi!

Over the weekend, I did the first tests with my PS-3100
Resonator Clone. (Thanks to Romeo, who came up with the
idea to clone this thing!)
Many people love the PS-3100 mostly for this Resonator section
that allows very unique phasing-like sweeps. Like on a 6-pole
Phaser, you have 3 peaks in the frequency response, which are
swept by a common CV. And also like on a Phaser, you have
a common Resonance control for all peaks together. The great
difference is that you can manually adjust the initial position
of each individual peak. The reason is the completely different
implementation. (And to be honest, the peaks of a Phaser are
also shaped in a different way ...)
The resonator consists of 3 voltage controlled BP filters that are
connected in a parallel way (i.e. outputs summed up). The Q
factor of each BPF is fixed to approx. 50. You change the shape
and height of the peaks by simply mixing the filtered and the
unfiltered signal.
The voltage control is made with dual-type optoisolators
(a center-tapped LDR and a LED in a black enclosure).
Now a single BPF only consists of 4 (four!) components:
two capacitors, one opamp, and the optoisolator that replaces
the two resistors of a garden variety BPF.
The ideal thing for DIY experiments!
Of course, there is a little bit of something else around this:
exponential current sources for voltage control, a Low-cut
filter in front of the BPF's to avoid killing your speakers
when all 3 resonators go to the subsonic range.
I plan to make a stand-alone unit, so I added some other useful stuff,
that is a MS-20 style LFO with contiously variable waveshape,
external modulation inputs, and a sophisticated Pedal control
routing that can work on LFO amount and/or directly, both
with different amounts. If you don't plug in either an external signal
or a pedal, the respective potentiometer becomes a manual
control for all 3 bands together.
I also included a tri/sine shaper with a switch to choose sharp
or rounded corners on the LFO.
With these additions, an Eurocard is pretty filled.

As I said, I tested the basic functions (filter and LFO), and it
works just as intended. Does sond different than a Phaser
(I don't have a PS-3100 for A/B comparison). Very good
SNR. I will lay it aside until I get a front panel in a few weeks.
Then I will test the full functionality.

JH.
 



From costello at costello.seanet.com  Tue Sep 17 23:16:26 1996
From: costello at costello.seanet.com (Sean Costello)
Date: Tue, 17 Sep 1996 14:16:26 -0700 (PDT)
Subject: Interesting Paper available on Moog VCF
Message-ID: <199609172116.OAA03597@mx.seanet.com>

At 07:16 PM 9/17/96 +0200, you wrote:
>Howdy DIYers,

>If you can find a way to digitally simulate eg the famous Moog VCF
>and implement this in a modern synth (a'la NordLead), its almost
>certain that you can make money out of it...

Judging from the source of the Moog VCF paper (Julius Smith at Stanford),
the digital Moog money would be going to Yamaha.  Yamaha has subsidized work
at Stanford for a long time; first the FM stuff with Chowning, and now the
physical modelling work of Julius Smith and Perry Cook.  My bet is that
there is a "Virtual Moog" in the works at both CCRMA and Yamaha; another one
of Stilson's papers was how to simulate "classic" analog waveforms in the
digital domain. 

>Luckily (for us) it will be quite some time before a digital simulation
>of a VCF can really compete with the real thing ;)

The Moog VCF paper wasn't even concerned with simulating the particular
quirks of the Moog filter; it was simply trying to come up with a digital
simulation of a filter that used four identical one-pole filters that were
cascaded, with feedback going around all four (you know what I mean - I
can't explain it too well due to my lousy technical abilities).  This is as
much a simulation of an ARP 4075, SSM 2040 or CEM 3320 as it is a simulation
of the Moog filter.  

Sean

  






From impose at oden.se  Tue Sep 17 23:20:03 1996
From: impose at oden.se (Mattias Nord)
Date: Tue, 17 Sep 1996 23:20:03 +0200
Subject: Hey!! Here comes a very stupid question..
Message-ID: <199609172120.XAA26980@hugin.oden.se>

ok.. so this list is for the people who build thier own synths.. But anyway..

Does anyone have a 303!? .. =) That they want to sell!? .. To me!? =)

And another question.. (I?m not on technical side that much) ... 

Does anyone have the scematics for the best 303 clones? Or even the 303!?

(Am I going to get flamed for this.. I wonder)

Well well.. Bye for now.. 

/Mattias ..

---------------------------------------------------------------------
                                                        ,,,
There must be a polarbear somewhere...                 /'^'\
                                                      ( o o )
--------------------------------------------------oOOO--(_)--OOOo----
     Mattias Nord
     impose at oden.se                                .oooO
     http://www.oden.se/~impose                    (   )   Oooo.
----------------------------------------------------\ (----(   )-----
                                                     \_)    ) /
                                                           (_/




From thierry.rochebois at ief-paris-sud.fr  Wed Sep 18 11:15:17 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Wed, 18 Sep 1996 11:15:17 +0200
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609180915.AA02389@zeus.ief-paris-sud.fr>

>You seem to be suggesting that this algorithm is used in the Nord
>Lead,

No, I just say that the NordLead is an example of this kind of implementation.
I do not think that the researches from Clavia are published anywhere.
You know, many "industrial" researchers are not famous and never published
anything in any conference... My example is Ralph Deutch, he worked for
Kawai and patented more than 136 devices... And nobody knows him.

>that the Nord Lead has a good simulation of the Moog filter,

I played the Nord Lead in a shop once.
I tried many things to hear some problems related to digital.
For example, I opened the filter and transposed any waveform at its
maximum (including transpose and pitch bend)... and I didn't hear any
aliasing... You can try this experiment with any digital stuff (exepted
Waldorf, PPG and Fairlight... because they use a DAC per voice)

>and that a digital simulation of a filter is a good thing because a DSP
>evaluation board costs $200 (huh?).

This price must be compared to analog development equipment including
scope, iron... $-)
I own an Atari Falcon030, it includes a 56001DSP and it costs less than
$700 (and its price is going down) second hand... vintage computer ;-)

A DSP can emulate more than one module at the same time.
One can imagine to build up a virtual modular system. The number
of modules is only limited by the power of the DSP (about 60,000,000 Multiply
Add per second /44100 = 1360 MA per sample for the 56002, the half for
the 56001 in the Falcon). 

The difficult thing is to implement good oscillators and filters, without
aliasing and with good tracking curves.

>There is no attempt made to deal with nonlinearities or other interesting
>behavior responsible for the characteristic sound of the filter.

Nonlinearities are not very hard to implement in digital form.. Perhaps another
paper will show this kind of implementation.
By the way, it would be interesting to study a real Moog filter to show if they
really exist ;-)

Maybe, the punchy sound of the Moog filter can be explained in other ways :
Phase relationships between each stage, Envelop dynamics and transient 
behaviour of the filter... ?-)


Thierry Rochebois

+-------------------------------------------------------------+
|                                                             |\
|  Thierry Rochebois      Tel:69 41 79 39  Piece 353          | +
|  IEF   AXIS/TSA(ARCEMA)   Bat 220 UPS   91405 ORSAY Cedex   | |
|  thierry at ief-paris-sud.fr               FRANCE              | |
|  http://www.ief.u-psud.fr/~thierry/welcome.html             | |
|                                                             | |
+-------------------------------------------------------------+ |
 \                                                             \|
  +-------------------------------------------------------------+





From robh at epunix.susx.ac.uk  Wed Sep 18 13:34:00 1996
From: robh at epunix.susx.ac.uk (Rob Hukin)
Date: Wed, 18 Sep 96 13:34 WET DST
Subject: dual-concentric pots
Message-ID: <m0v3LqE-0002gfC@epunix.susx.ac.uk>

Anyone know of anywhere in the UK that supplies/manufactures
dual-concentric pots?

rob.





From tim at redragon.demon.co.uk  Wed Sep 18 17:10:43 1996
From: tim at redragon.demon.co.uk (Tim Cockram)
Date: Wed, 18 Sep 96 08:10:43 PDT
Subject: Serge WaveMultiplier
Message-ID: <Chameleon.4.01.2.960918084024.tim@redragon.demon.co.uk>

Hi the Serge Wave multiplier (again) has three sections, a full wave rectifier as described in Serge's patent, a clipper and a sweeped
odd harmonics generator.
On reading Bob Moogs Patent US 4,180,707 the clipper sounds like the 3080 circuit that Bob describes.  In summary the 3080 is a low gain 
device so at low input levels you can cause the input satages to clip producing a "rounded" clipping, if you increase the input signal level is 
increased the output stage clips producing more transistor like clipping.
Does any one have any suggestions as to haow the third section works? "the middle section produces a sweep of odd harmonics
(1,3,5,7,9,11, and 13) when a sine wave is applied to its input and the control voltage is swept".  I guess that it is a simple non linear function 
generator, however I have forgoten more math than I would care to admit to.

Any Ideas?

Tim 





From don at till.com  Wed Sep 18 18:02:37 1996
From: don at till.com (Don Tillman)
Date: Wed, 18 Sep 1996 09:02:37 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <9609180915.AA02389@zeus.ief-paris-sud.fr>
	(thierry.rochebois@ief-paris-sud.fr)
Message-ID: <199609181602.JAA20012@shellx.best.com>

   Date: Wed, 18 Sep 1996 11:15:17 +0200
   From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)

   >You seem to be suggesting that this algorithm is used in the Nord
   >Lead,

   No, I just say that the NordLead is an example of this kind of
   implementation.  I do not think that the researches from Clavia are
   published anywhere. 

What do you mean by "implementation"?  Stilson&Smith's paper never
mentions any hardware; it was probably never built.  The paper is
about analyzing some of the issues of pole location.

   You know, many "industrial" researchers are not famous and never published
   anything in any conference... My example is Ralph Deutch, he worked for
   Kawai and patented more than 136 devices... And nobody knows him.

A patent *is* published, that's the point of it!

   I played the Nord Lead in a shop once.
   I tried many things to hear some problems related to digital.
   For example, I opened the filter and transposed any waveform at its
   maximum (including transpose and pitch bend)... and I didn't hear any
   aliasing... 

Not being able to hear aliasing (which has more to do with waveform
generation anyway) in a music store environment is a far cry from
having the full-tilt "gazorch" and "balls" of the Moog VCF.

   Nonlinearities are not very hard to implement in digital form..
   Perhaps another paper will show this kind of implementation.

Analog nonlinearities are extremely difficult to implement digitally.
When you add a digital nonlinearity you create an infinite number of
harmonics, and these alias around and sound pretty crappy.

  -- Don



From thierry.rochebois at ief-paris-sud.fr  Wed Sep 18 19:08:14 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Wed, 18 Sep 1996 19:08:14 +0200
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609181708.AA02495@zeus.ief-paris-sud.fr>

>What do you mean by "implementation"?

It can be easily implemented on the DSP 56001 as a "normal" digital filter
with less than 10 instructions.

>Not being able to hear aliasing (which has more to do with waveform
>generation anyway) in a music store environment is a far cry from
>having the full-tilt "gazorch" and "balls" of the Moog VCF.

True. But, you will hear this aliasing effect on any other digital
synth even in this environment.
You can also hear the signal/noise ratio of low quality analogue stuff
(not the Moog of course).


>Analog nonlinearities are extremely difficult to implement digitally.
>When you add a digital nonlinearity you create an infinite number of
>harmonics, and these alias around and sound pretty crappy.

It depends on the way you perform it... If you mean look up tables ;-)

>>My example is Ralph Deutch, he worked for
>>   Kawai and patented more than 136 devices... And nobody knows him.

>A patent *is* published, that's the point of it!

That's true. But the CCRMA people and other university people don't
seem to read patents (just look at their bibliography).

By the way, it would be nice to do a patent web page, with comments and
all that... if anyone is interested...

Thierry Rochebois

+-------------------------------------------------------------+
|                                                             |\
|  Thierry Rochebois      Tel:69 41 79 39  Piece 353          | +
|  IEF   AXIS/TSA(ARCEMA)   Bat 220 UPS   91405 ORSAY Cedex   | |
|  thierry at ief-paris-sud.fr               FRANCE              | |
|  http://www.ief.u-psud.fr/~thierry/welcome.html             | |
|                                                             | |
+-------------------------------------------------------------+ |
 \                                                             \|
  +-------------------------------------------------------------+




From eli at ux3.sp.cs.cmu.edu  Wed Sep 18 19:22:19 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Wed, 18 Sep 1996 13:22:19 -0400 (EDT)
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609181602.JAA20012@shellx.best.com> from "Don Tillman" at Sep 18, 96 09:02:37 am
Message-ID: <9609181722.AA70035@horus.sara.nl>

Don Tillman wrote:
> Analog nonlinearities are extremely difficult to implement digitally.
> When you add a digital nonlinearity you create an infinite number of
> harmonics, and these alias around and sound pretty crappy.

Interesting.  My gut feeling is that if the waveshaping function is
"smooth" in some sense, it should produce a band-limited output.  

For example, waveshaping a sinusoid with a Chebychev polynomial will
exactly produce a known band-limited output.  (Of course, it could
still fall over the Nyquist limit.)  But this waveshaping function
isn't band-limited itself.  So what's "smooth"?  It would have to
depend on the specific input function... I have no idea how to deal
with this.

(The list is analog-only?  Maybe this should move to electronica.)

--
   Eli Brandt
   eli+ at cs.cmu.edu



From wbf at aloft.lucent.com  Wed Sep 18 19:51:47 1996
From: wbf at aloft.lucent.com (wbf at aloft.lucent.com)
Date: Wed, 18 Sep 96 13:51:47 EDT
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609181751.AA07395@acropolis>

Eli Brandt said:
> (The list is analog-only?  Maybe this should move to electronica.)

Hmmm... good question.  I thought that the diy in synth-diy stood for do
it yourself.  Unless there's a charter that specifically limits our
topics of interest to analog, I see nothing in the list name to indicate
that digital do it yourself projects are out of bounds.  (Bernie would
approve of us including digital topics!)  Comments/opinions?

Bill Fox	wbf at aloft.lucent.com
------------------------------------------------------------------------
PLEASE NOTE MY NEW ADDRESS!!!!!  (att is now lucent in my address.)
	wbf at aloft.att.com ===> wbf at aloft.lucent.com

P.S.  What's an ASM-1?



From sscprick at horus.sara.nl  Wed Sep 18 20:24:25 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Wed, 18 Sep 1996 20:24:25 +0200
Subject: bulk resistance compensation revisited 
In-Reply-To: Your message of Tue, 17 Sep 1996 14:36:09 MET DST.
             <199609171236.OAA02539@dist.dist.unige.it>
Message-ID: <9609181824.AA85492@horus.sara.nl>


In message <199609171236.OAA02539 at dist.dist.unige.it> you write:
> Hello!
> This is my first posting to this mailing list.
> A few days ago I downloaded Rick Jansen's sawtooth VCO. It uses a LM3046
> transistor array for the lin/exp conversion and for the thermal stabilizati
> on.

'lo Paolo and list,

It's been a while since I made that schematic and was familiar with the
calculations and formulas. Note that the schematic is not an actual
working and/or tested circuit, but still "just" a theoretical exercise!
I haven't put much effort in the circuit after getting the Moog filter
to work (which uses a simpler exp generator) due to other involvements,
like buying a house and increased emphasis (Q?) on work. I'll get back
to your calculations as soon as I can. I still have to put out a new
Xsnow this year too, for those using that windowing system and the 
Macintosh version... Priorities, priorities, priorities!

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From sscprick at horus.sara.nl  Wed Sep 18 21:09:48 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Wed, 18 Sep 1996 21:09:48 +0200
Subject: Synth-diy (was: Interesting Paper available on Moog VCF)
In-Reply-To: Your message of Wed, 18 Sep 1996 13:51:47 MET DST.
             <9609181751.AA07395@acropolis>
Message-ID: <9609181909.AA69028@horus.sara.nl>


> > (The list is analog-only?  Maybe this should move to electronica.)
> 
> Hmmm... good question.  I thought that the diy in synth-diy stood for do
> it yourself.  Unless there's a charter that specifically limits our
> topics of interest to analog, I see nothing in the list name to indicate
> that digital do it yourself projects are out of bounds.  (Bernie would
> approve of us including digital topics!)  Comments/opinions?


Synth-diy is open to all discussions on synthesizer/music electronics.
Unfortunately digital synthesizer electronics tend to go beyond 
diy-electronics, but there is no problem in discussing digital here. It
may even attract Mr. Hutchins to synth-diy :)

The name synth-diy was made up in just a few minutes without giving it
much thought really, 'analogue' was already taken, and would exclude
digital, 'modular' did not cover what I intended, 'diy' seemed proper
at the time.

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From don at till.com  Wed Sep 18 22:53:04 1996
From: don at till.com (Don Tillman)
Date: Wed, 18 Sep 1996 13:53:04 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609172116.OAA03597@mx.seanet.com> (message from Sean Costello
	on Tue, 17 Sep 1996 14:16:26 -0700 (PDT))
Message-ID: <199609182053.NAA10801@shellx.best.com>

   Date: Tue, 17 Sep 1996 14:16:26 -0700 (PDT)
   From: Sean Costello <costello at costello.seanet.com>

   Judging from the source of the Moog VCF paper (Julius Smith at Stanford),
   the digital Moog money would be going to Yamaha.  Yamaha has subsidized work
   at Stanford for a long time; first the FM stuff with Chowning, and now the
   physical modelling work of Julius Smith and Perry Cook.  My bet is that
   there is a "Virtual Moog" in the works at both CCRMA and Yamaha; another one
   of Stilson's papers was how to simulate "classic" analog waveforms in the
   digital domain. 

I don't think that's the case.  My understanding is that this is just
regular research at CCRMA and they got moles of royalties from Yamaha
from the licensing of the DX-7 patent from before.

But Julius plays in my band so I can ask him at the next rehearsal.

(This won't surpise you; his main axe is the Yamaha VL-1.)

   The Moog VCF paper wasn't even concerned with simulating the particular
   quirks of the Moog filter; it was simply trying to come up with a digital
   simulation of a filter that used four identical one-pole filters that were
   cascaded, with feedback going around all four (you know what I mean - I
   can't explain it too well due to my lousy technical abilities).  This is as
   much a simulation of an ARP 4075, SSM 2040 or CEM 3320 as it is a simulation
   of the Moog filter.  

Yes indeed.  I find it completely amazing how complex the effects of
four little dirt-simple integrators in a row can be in the digital
domain.  

  -- Don



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 19 00:20:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Wed, 18 Sep 96 15:20:00 PDT
Subject: Joachim?
Message-ID: <324075B5@MSMGATE.M30X.NBG.SCN.DE>


(Sorry DIY list)

Joachim, are you still there?
My mail to you is bouncing since last weekend ..

JH.



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 19 02:05:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Wed, 18 Sep 96 17:05:00 PDT
Subject: AW: bulk resistance compensation revisited
Message-ID: <32408E67@MSMGATE.M30X.NBG.SCN.DE>



> This is my first posting to this mailing list.

Impressive debut, for sure!

Now, before I start digging your equations (... for some reason, I always
found it harder to read complicated equations than writing some
down, myself (;->) ... ), I have two questions:

(1) Though it would be an elegant solution no doubt, is there
       a different reason to save this single transistor (or the transistor
       in the usual HFT circuit, as in Obie SEM etc. ), than just saving
       it? I mean, will it be easier to calculate, less adjustment, or
       even superior performance ?

(2) Is this just math, or have you tried if it works? You make a few 
assumptions
      about how to model a real vs. ideal transistor, but are you sure you
      are close enough ?

As you might have seen, these questions of mine are just cheap
excuses, not to examine your scaring equations closer (;->).

Anyway, welcome to the club!

JH.



From don at till.com  Thu Sep 19 07:48:57 1996
From: don at till.com (Don Tillman)
Date: Wed, 18 Sep 1996 22:48:57 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <9609181722.AA70035@horus.sara.nl> (message from Eli Brandt on
	Wed, 18 Sep 1996 13:22:19 -0400 (EDT))
Message-ID: <199609190548.WAB17906@shellx.best.com>

   Date: Wed, 18 Sep 1996 13:22:19 -0400 (EDT)
   From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>

   Don Tillman wrote:
   > Analog nonlinearities are extremely difficult to implement digitally.
   > When you add a digital nonlinearity you create an infinite number of
   > harmonics, and these alias around and sound pretty crappy.

   Interesting.  My gut feeling is that if the waveshaping function is
   "smooth" in some sense, it should produce a band-limited output.  

Only for a few special case curves.  Square-law f'rinstance.

But try an exponential curve.  That's pretty smooth, right?  Put a
single sinewave through an exponential transfer function and you've
got a waveform that contains *all* harmonics (the amount diminishes as
the harmonics get higher of course).  That makes for a lot of
aliasing.  But don't take my word for it, prove it yourself; work out
the Fourier series of expt(sin(wt)).

  -- Don



From thierry.rochebois at ief-paris-sud.fr  Thu Sep 19 10:35:54 1996
From: thierry.rochebois at ief-paris-sud.fr (Thierry Rochebois)
Date: Thu, 19 Sep 1996 10:35:54 +0200
Subject: Interesting Paper available on Moog VCF
Message-ID: <9609190835.AA02636@zeus.ief-paris-sud.fr>

For more information about Timothy Stilson's project and goal, read:

http://ccrma-www.stanford.edu/CCRMA/Overview/node52.html



Thierry Rochebois

+-------------------------------------------------------------+
|                                                             |\
|  Thierry Rochebois      Tel:69 41 79 39  Piece 353          | +
|  IEF   AXIS/TSA(ARCEMA)   Bat 220 UPS   91405 ORSAY Cedex   | |
|  thierry at ief-paris-sud.fr               FRANCE              | |
|  http://www.ief.u-psud.fr/~thierry/welcome.html             | |
|                                                             | |
+-------------------------------------------------------------+ |
 \                                                             \|
  +-------------------------------------------------------------+



From E.G.P.Schuijers at stud.tue.nl  Thu Sep 19 11:03:25 1996
From: E.G.P.Schuijers at stud.tue.nl (Erik Schuijers)
Date: Thu, 19 Sep 1996 10:03:25 +0100 (CET)
Subject: A couple of (DIY) questions
Message-ID: <36207.s413692@popserver.tue.nl>

First of all, about Rick Jansen's Moog VCF. Can someone confirm whether it
uses positive feedback (so Q gets bigger as the pot get smaller?)!

I haven't heard a thing from the ASM-1 frontplates (I haven't got the time
to read all my mail). Are these being made or not?

Has anyone got schematics for a MIDI-2-trig converter???

Thanks all,

Erik (The ViKing)



From ftom at netcom.com  Thu Sep 19 19:02:40 1996
From: ftom at netcom.com (Tom May)
Date: 19 Sep 1996 10:02:40 -0700
Subject: digital contents
In-Reply-To: Haible_Juergen#Tel2743's message of Thu, 19 Sep 96 11:00:00 PDT
References: <32418A92@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <199609191702.KAA00097@redshirt.tholian.web>

Haible_Juergen#Tel2743 <HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de> writes:

> Hmm, this is not AH, and you *can* build digital filters yourself,
> nowadays, so I would have no problems with this.
> Though I cannot contribute much to this DSP stuff myself,
> I find it very interesting to see you talk about it. I'd appreciate
> it if you go on with this nonlinearities/aliasing stuff.

Ok, take the square law thing Don mentioned, say out = in + in^2.  For
a sine input, the output will contain the original frequency, the
second harmonic, and a DC component.  With more than one frequency in
the input signal, the output will also contain all the f1+/-f2 cross
terms (actually the DC and second harmonic is just a special case for
f1=f2).  So like Don said, it is bandlimited because the highest
output frequency will be no greater than twice the highest input
frequency.  But, if that frequency exceeds half the sampling rate, it
will be aliased and you will hear nastiness.

Here's an example: take a 120Hz sine sampled at 400Hz.  The second
harmonic would be 240Hz, but that exceeds half the sample rate (200Hz)
by 40Hz, so it will be aliased to 200Hz - 40Hz = 160Hz and that is
what you will hear: 120Hz and 160Hz.  The result will not be at all
like the analog case where harmonics that exceed the bandwidth are
merely attenuated; in the digital case they are aliased into the
audible range and you hear them loud and clear.

Here's another example: suppose you implement a distortion by gently
squashing the top and bottom of the wave.  This mostly amounts to
adding in some third harmonic.  No problem in the analog case, you can
draw some nice smooth waves, squash their tops, and you will get a
periodic 100Hz output of some shape or other.  But in the digital
case, it could be that the third harmonic exceeds half the sampling
frequency.  In my example, the 360Hz third harmonic would be aliased
to 40Hz.  That means that although you can get the squashed effect by
adding 360Hz third harmonic, you can get exactly the same effect by
adding a 40Hz signal, and that is exactly what it will sound like.
Your output wave is no longer periodic at 100Hz.

It helps to draw some smooth analog waves, then figure out where the
sample points are and how this all looks digitally.  Sampled waves
don't look like connect-the-dots analog waves at all once they reach a
certain frequency, and that is why analog-based gut feelings don't
count for much.

Tom.



From ftom at netcom.com  Thu Sep 19 19:11:43 1996
From: ftom at netcom.com (Tom May)
Date: 19 Sep 1996 10:11:43 -0700
Subject: Re Doepfer in keys on filters
In-Reply-To: Tim Cockram's message of Thu, 19 Sep 96 15:07:34 PDT
References: <Chameleon.4.01.2.960919153018.tim@redragon.demon.co.uk>
Message-ID: <199609191711.KAA00103@redshirt.tholian.web>

Tim Cockram <tim at redragon.demon.co.uk> writes:

> Well, Mr Doepfer is sort of right. Bob Moogs filter uses the transistors as "transdiodes" which are for all intents and purposes 
> well behaved diodes.  Roland in the 303 and I belive EMS in the VCS3 etc used the plain old diode to get arround the Moog
> Patent which specificaly mentions the use of transistors ( Shame for Moog that his patent attorneys didn't just say Semiconductor
> Junction).
> 
> Despite being sort of right in his analysis  Mr Doepfer should also  have said that for some inadequately explained reason the filters don't
> sound the same (don't take my word for it try it and hear).  To me the EMS filter sounds  er "mushy" whilst the 303 filter is just 
> not very refined or meaty(so much for quantative analysis).

As was pointed out to me recently on this list (thanks folks, and
hopefully I'll get this right this time), the transistors in the Moog
filter serve a dual purpose: 1) they provide a varying incremental
resistance by varying the bias current, just like the diode filter;
2) they are current buffers providing isolation between each of the
four stages (pretty damn clever!).  The isolation gives four poles all
in the same place for the Moog filter.  The poles of the diode filter
are quite different, and you can find a nice analysis of them by Don
Tillman in the archives.

Tom.



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 19 20:00:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Thu, 19 Sep 96 11:00:00 PDT
Subject: digital contents
Message-ID: <32418A92@MSMGATE.M30X.NBG.SCN.DE>


>
>> (The list is analog-only?  Maybe this should move to electronica.)
>
> Hmmm... good question.

Hmm, this is not AH, and you *can* build digital filters yourself,
nowadays, so I would have no problems with this.
Though I cannot contribute much to this DSP stuff myself,
I find it very interesting to see you talk about it. I'd appreciate
it if you go on with this nonlinearities/aliasing stuff.

JH.



From don at till.com  Thu Sep 19 20:10:04 1996
From: don at till.com (Don Tillman)
Date: Thu, 19 Sep 1996 11:10:04 -0700
Subject: A couple of (DIY) questions
In-Reply-To: <36207.s413692@popserver.tue.nl> (E.G.P.Schuijers@stud.tue.nl)
Message-ID: <199609191810.LAA20984@shellx.best.com>

   Date: Thu, 19 Sep 1996 10:03:25 +0100 (CET)
   From: "Erik Schuijers" <E.G.P.Schuijers at stud.tue.nl>

   First of all, about Rick Jansen's Moog VCF. Can someone confirm whether it
   uses positive feedback (so Q gets bigger as the pot get smaller?)!

Negative feedback, BUT the main filtering section shifts the phase of
the signal over frequency, so it's 0 degrees at DC, easing to -90
degrees as you approach the tuned frequency, through -180 degrees at
the tuned frequency (-12 dB down), through -270 degrees above the
tuned frequency, and hitting -360 degrees at really high frequencies.

So the feedback at low and high frequencies is negative (lowering the
gain) and the feedback near the tuned frequency is positive (making
the resonance).

  -- Don



From mj20279 at janus.swipnet.se  Thu Sep 19 20:51:44 1996
From: mj20279 at janus.swipnet.se (Ricard Wolf)
Date: Thu, 19 Sep 1996 20:51:44 +0200 (MET DST)
Subject: Doepfer in KEYs on filters
In-Reply-To: <32419859@MSMGATE.M30X.NBG.SCN.DE>
Message-ID: <Pine.LNX.3.91.960919203609.111E-100000@lupus.pollux.se>

On Thu, 19 Sep 1996, Haible_Juergen#Tel2743 wrote:

> There is a statement by Mr. Doepfer printed, where he claims
> that there is no real difference between a Minimoog filter and
> a TB-303 filter, at least no more than component tolerances!
> 
> To "proove" this, they show details of both, the Minimoog
> and the TB-303 schematics - closeups of the filter circuits.
> ...

(Hi Juergen!)

I don't know if this has been discussed to death before, but I think
the _major_ reason for the "Moog" sound is the actual ladder design with
"diode-junction-based" controlled impedance element. I'm not saying that
the 'Mini and the '303 sound the same (and I don't really know exactly
what KEYs have messed up - I'm just using this as a starting point for 
discussion...maybe they were misquoting Doepfer, or he was really 
comparing a VCS-3 and '303 ???).

My guess is something along the line of that the nonlinearity of the
diode junction creates a slight bit of distorsion to create the 
"organic, airy" Moog sound. I love it personally - I borrowed a '303
a while ago and really loved the sound. Not worth what their asking these
days but I liked the sound, it gave me similar feel to other Moog (or
rather Moogish) designs.

Other instruments that have similar designs are:

* Korg Polysix and Mono-Poly, using the SSM 2044 chip, which internally
  uses a Moog ladder. Early Prophets used SSM chips, though I don't know
  if it was the 2044 or 2040.
* EMS VCS-3 - uses diodes instead of transistors connected as diodes.
* Practical Electronics' Minisonic.
* others...?

A question of detail is what the difference is between transistors and 
diodes...I won't try to go into that...

/Ricard
--
Ricard Wolf (mj20279 at janus.swipnet.se)

Analog synth, railroad and Citroen fanatic




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Thu Sep 19 21:00:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Thu, 19 Sep 96 12:00:00 PDT
Subject: Doepfer  in KEYs on filters
Message-ID: <32419859@MSMGATE.M30X.NBG.SCN.DE>


I didn't believe my eyes, when I received the latest
KEYs issue. Now, this happens every now and then, but this
time they just hit the jackpot.

There is a statement by Mr. Doepfer printed, where he claims
that there is no real difference between a Minimoog filter and
a TB-303 filter, at least no more than component tolerances!

To "proove" this, they show details of both, the Minimoog
and the TB-303 schematics - closeups of the filter circuits.
The funny thing is: The difference is clearly visible, the
transistors connected as diodes in the 303 filter. It's just
the text beneath  the pictures that says: Look, exactly
the same thing.

I am ready to doubt that this is really Dieter Doepfer's
statement - I am quite sure he knows better ! God knows
what KEYs have mixed up this time ... and how stupid
do they think their readers are !?

See, I don't have problems with a bit of misinformation
now and then - nobody is perfect. But  they make
a large feature on filters, as opposed to the various
"myths"(how they call it)  around, and then they write
this bloody nonsense.

I called Mr. Doepfer, but I didn't get him on the phone
yet. As soon as I hear from him, I'll inform you again.

Now, let me make a wild guess what KEYs will present
us in the next issue: A closeup picture of a Pitch Bend
Wheel, and a Roland style Lever, and look, we found
an expert who prooves there is no difference at all (;->)

JH.



From eli at ux3.sp.cs.cmu.edu  Thu Sep 19 21:01:27 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Thu, 19 Sep 1996 15:01:27 -0400 (EDT)
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609190548.WAB17906@shellx.best.com> from "Don Tillman" at Sep 18, 96 10:48:57 pm
Message-ID: <9609191901.AA17396@horus.sara.nl>

Don Tillman wrote:
>    Interesting.  My gut feeling is that if the waveshaping function is
>    "smooth" in some sense, it should produce a band-limited output.  
> 
> Only for a few special case curves.  Square-law f'rinstance.

Okay, maybe this "smooth" would be more constraining than I thought. :->
My hope is that "smooth" might correspond to something like finite
support over the set of Chebychev polynomials, but I don't have an
intuitive handle on non-linear waveshaping -- let's see how the math
comes out.

If we're stuck with infinite harmonics coming out of our waveshaping,
the conceptually simplest solution would be to supersample, waveshape,
lowpass, and subsample.  The crud probably falls off at least
inverse-linearly with frequency, so moderate oversampling shuold
substantially reduce the amount of energy that gets sprayed into your
spectrum: n-times gives a reduction of 2n-1.

   |
   |   |                        hits 22kHz here --------v
   |   |   |   |   |   |   
   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
   +----------+--------------------+--------------------+
             22k                 n*22k            (2n-1)*22k

This chain of operations might simplify, but probably not.  I've
considered just doing all digital work at a multiple of audio rate,
and lowpassing whenever spurious harmonics are generated.  This costs
you a constant factor everywhere, but avoids the expense of resampling
up and down all over the place.

-- 
. Eli Brandt                                            usual disclaimers .
. eli+ at cs.cmu.edu                                      PGP key on request .
. "Certain deliberate disturbances of the beat are extremely beautiful."  .
.       -- C.P.E. Bach                                                    .



From mugen at spacelab.net  Thu Sep 19 22:09:45 1996
From: mugen at spacelab.net (J P M)
Date: Thu, 19 Sep 1996 20:09:45 +0000
Subject: Re Doepfer in keys on filters
References: <Chameleon.4.01.2.960919153018.tim@redragon.demon.co.uk>
Message-ID: <3241A889.4884@spacelab.net>

>From what I understand (looking at minimoog schems and of course hearing 
the sound)is that the Minimoog dosen't sound great because of the filter 
,but instead because of the DUAL VCA wired in PARALEL . This way you can 
overdrive the signal into and after the filter WITHOUT having the sound 
leak as you would using a single VCA.That is the secret of the Mini ??!!

As far as sounding like a 303 ,I've achieved the same sound (exactly the 
same sound) on a MiniMoog when using just one oscillator,but without 
that nutty glide it won't sound/act the same (and whats the point 
anyway).


Jason'
Vocod'o'rama
http://www.spacelab.net/~mugen/vocolist.html




From ftom at netcom.com  Thu Sep 19 22:34:30 1996
From: ftom at netcom.com (Tom May)
Date: Thu, 19 Sep 1996 13:34:30 -0700
Subject: Interesting Paper available on Moog VCF
Message-ID: <199609192034.NAA00249@redshirt.tholian.web>

Eli Brandt writes:

>Okay, maybe this "smooth" would be more constraining than I thought. :->
>My hope is that "smooth" might correspond to something like finite
>support over the set of Chebychev polynomials, but I don't have an
>intuitive handle on non-linear waveshaping -- let's see how the math
>comes out.

Any polynomial with a finite number of terms will produce a band
limited output when used as a transfer function.  But the bandwidth of
the output will be N times the bandwidth of the input, where N is the
degree of the polynomial.  That pretty much falls out of the sin^2(x)
= (1 - cos(2x))/2 type of identity when you keep applying it for each
degree of the polynomial.  (Or am I making an analog gut feeling
mistake?)

A year or so ago I experimented with digital distortion and if you
warp your signal too far with, say, some kind of transcendental
function you do get a lot of horrible noise.  At lower frequencies
and/or with less distortion it's not so noisy.  I didn't have time to
think about it at the time or I would have tried using low order
polynomials and oversampling.  Actually, out = sgn(in) gave pretty
good results :-)

Tom.



From tim at redragon.demon.co.uk  Fri Sep 20 00:07:34 1996
From: tim at redragon.demon.co.uk (Tim Cockram)
Date: Thu, 19 Sep 96 15:07:34 PDT
Subject: Re Doepfer in keys on filters
Message-ID: <Chameleon.4.01.2.960919153018.tim@redragon.demon.co.uk>

Well, Mr Doepfer is sort of right. Bob Moogs filter uses the transistors as "transdiodes" which are for all intents and purposes 
well behaved diodes.  Roland in the 303 and I belive EMS in the VCS3 etc used the plain old diode to get arround the Moog
Patent which specificaly mentions the use of transistors ( Shame for Moog that his patent attorneys didn't just say Semiconductor
Junction).

Despite being sort of right in his analysis  Mr Doepfer should also  have said that for some inadequately explained reason the filters don't
sound the same (don't take my word for it try it and hear).  To me the EMS filter sounds  er "mushy" whilst the 303 filter is just 
not very refined or meaty(so much for quantative analysis).


Tim








From ms20 at itchy.serv.net  Fri Sep 20 01:46:23 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Thu, 19 Sep 1996 16:46:23 -0700 (PDT)
Subject: EN CV Mixer Problem
Message-ID: <Pine.BSD.3.91.960919163439.18133A-100000@itchy.serv.net>


For the last three or four days I've been trying to finish up a pair of 
Electronotes CV mixers from the Musical Engineers Handbook (Sec. 5D 
P.7).  Everything works fine, except when I connect the output to an amp, 
I get a very high frequency signal mixed into output (around 600 KHz, 
5VPP).  

I built the circuit exactly like the diagram plus a few additions - caps 
to filter PS noise, a 30 PF cap across the output buffer, a level pot, 
and a second output. I've gone over the circuit with a fine tooth comb 3 
or 4 times and found no mistakes.  Now I'm wondering if it's possible 
that there might be a problem with the design itself.  

Is there anyone on the list that has this circuit diagram that would look 
at it for me, just so I know whether that is the problem or not?  Any 
other advice would be appreciated as well.

ROmeo




From MHELIN at tne01.tele.nokia.fi  Fri Sep 20 09:38:39 1996
From: MHELIN at tne01.tele.nokia.fi (Mikko Helin)
Date: Fri, 20 Sep 1996 10:38:39 +0300 (EET-DST)
Subject: digital contents
Message-ID: <960920103839.25c07132@tnclus.tele.nokia.fi>

>frequency.  But, if that frequency exceeds half the sampling rate, it
>will be aliased and you will hear nastiness.

   I think that this kind of aliasing distortion can be avoided by using 
   oversampling, which means that sampling rate is increased so that
   aliasing occurs at higher frequencies, which are then filtered out
   before D/A conversion or resampling to lower (original) sample rate.
   This of course requires more prosessing power, but this is the method
   used in most of the audio DACs to avoid expensive analog post-DAC
   filters. 

   -Mikko



From E.G.P.Schuijers at stud.tue.nl  Fri Sep 20 13:22:20 1996
From: E.G.P.Schuijers at stud.tue.nl (Erik Schuijers)
Date: Fri, 20 Sep 1996 12:22:20 +0100 (CET)
Subject: About AD-DA
Message-ID: <44544.s413692@popserver.tue.nl>

What technique many companies use these days is called sigma-delta
conversion. It's a certain oversampling technique which doesn't require very
precise components. As a matter of fact in two weeks from now I've got the
study-assignment in which I'll have to design a s-d converter. Anyway, how
more oversampling the less aliasing at lower frequencies.

But don't forget the higher harmonics you'll get from the s&h part.

Erik (The ViKing)



From eli at ux3.sp.cs.cmu.edu  Fri Sep 20 19:15:51 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Fri, 20 Sep 1996 13:15:51 -0400 (EDT)
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609192034.NAA00249@redshirt.tholian.web> from "Tom May" at Sep 19, 96 01:34:30 pm
Message-ID: <9609201715.AA100649@horus.sara.nl>

Tom May wrote:
> Any polynomial with a finite number of terms will produce a band
> limited output when used as a transfer function.  But the bandwidth of
> the output will be N times the bandwidth of the input, where N is the
> degree of the polynomial.

Oh, duh: T_n has degree n, and they're orthogonal.  So let me lay this
out to see if I've got it yet:

Take the case where we've got harmonic partials and they're all in
phase.  So the input signal x(t) is a sum of cos(kt) terms, out to K.
Each term a_k cos(kt) can be expanded, using the Chebychev* T_n, to a
degree-k polynomial in cos(t).  Waveshaping their sum with a degree-D
polynomial gives one of degree-KD.  Then translate each cos^n(t) back
to a sum of cos(kt) terms, k<=n.  So we have a sum of cos(kt) terms,
k<=KD.

If we have harmonic partials but they're not in phase, each can be
split into a sine and cosine term.  After the waveshaping, each term
has a maximum total degree of KD in {sin, cos}.  Any desired
waveshaping curve can be approximated arbitrarily closely by some
polynomial, so waveshaping of harmonic signals can be band-limited.

The tricky case is inharmonic partials.  If they're related by a ratio
of integers, the above stuff generalizes.  If they're irrationally
related, I think you're hosed.

> Actually, out = sgn(in) gave pretty good results :-)

Yeah, I like comparator functions.  You may get harmonics all the way
out to daylight, but it sounds good to me...

 * The n'th Chebychev polynomial is defined as 
        T_n(x) = cos(n arccos x)
This is nice because then T_n(cos t) = cos(n arccos cos t) = cos nt,
so the Chebychevs are very useful for controlled waveshaping.  What's
a little surprising is that they turn out to be polynomials at all --
T_1(x) = x, and you can get a recurrence relation.

--
   Eli Brandt
   eli+ at cs.cmu.edu



From ms20 at itchy.serv.net  Fri Sep 20 20:56:37 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Fri, 20 Sep 1996 11:56:37 -0700 (PDT)
Subject: CV Mixer Prob. Solved
Message-ID: <Pine.BSD.3.91.960920115226.22063A-100000@itchy.serv.net>


First of all, thanks to all for responses to my query.

I tried replacing the 30pF cap across the output buffer with larger 
values, but this did nothing.  

As a last ditch effort, I replaced the buffer IC (LF411) with a 741 and 
the problem went away.  I don't know why and I do find it surprising, but 
the circuit works now.  (Any ideas why?)

ROmeo



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Fri Sep 20 21:55:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Fri, 20 Sep 96 12:55:00 PDT
Subject: talked to Mr. Doepfer ...
Message-ID: <3242F6F0@MSMGATE.M30X.NBG.SCN.DE>


I saw there was some response to my posting
about this KEYs article with technical misinformation,
where they claim to quote Mr. Doepfer.
I had a nice talk to Mr. Doepfer on the phone this morning,
and he seemed to be quite upset to be misquoted
in such way. He told me he had never made these statements
as they are printed in the magazine. They only asked him to
send him the two schematics (minimoog and tb303), and
he admits that he has said something like "its almost the same thing"
in a hurry, but it was never been intended as an article where
he would occur as an "expert" about the 303 filter.
He told me that he had done Spice simulations of the moog filter,
and of course he knows about component selection and
everything that is important to build a moog cascade into its
products, but he never cared much about the 303-cascade
or other diode ladder filters.
He also said, the first time he knew of this article "of his" was
when he received the printed KEYs issue. And the photo of him
that was in the article must be "10 years old at least".

I felt I had to tell you this.
( And I am sorry that my first posting has started the old filter discussion
again: This is really not necessary; it's all in the synth-DIY archives.)

JH.




From wbf at aloft.lucent.com  Fri Sep 20 21:55:04 1996
From: wbf at aloft.lucent.com (wbf at aloft.lucent.com)
Date: Fri, 20 Sep 96 15:55:04 EDT
Subject: CV Mixer Prob. Solved
Message-ID: <9609201955.AA20446@acropolis>

> Date: Fri, 20 Sep 1996 11:56:37 -0700 (PDT)
> Orig-From: "A.S.P." <ms20 at itchy.serv.net>
> To: synth-diy <synth-diy at horus.sara.nl>
> Subject: CV Mixer Prob. Solved
> Sender: owner-synth-diy at horus.sara.nl
>
> First of all, thanks to all for responses to my query.
>
> I tried replacing the 30pF cap across the output buffer with larger
> values, but this did nothing.
>
> As a last ditch effort, I replaced the buffer IC (LF411) with a 741 and
> the problem went away.  I don't know why and I do find it surprising, but
> the circuit works now.  (Any ideas why?)
>
> ROmeo

Sometimes circuits will oscillate as yours did when replacing older op
amps with newer models that have improved slew rate or different
internal compensation.  Try comparing spec sheets on the 741 and LF411;
maybe you can spot such parameter changes.  Then you'll be able to
modify your schematic to use the "better" part.  Or just leave the 741
in there and make music now!  How well is the amp's power supply pins
bypassed?

Bill Fox	wbf at aloft.lucent.com



From costello at costello.seanet.com  Fri Sep 20 23:24:48 1996
From: costello at costello.seanet.com (Sean Costello)
Date: Fri, 20 Sep 1996 14:24:48 -0700 (PDT)
Subject: X-Y Pedals
Message-ID: <199609202124.OAA08820@mx.seanet.com>

Hi everybody,

Does anyone know anything about X-Y pedals?  I'm looking to construct a
control voltage pedal that works along two axes; moving the pedal up and
down (like a wah or volume pedal) would produce one control voltage, while
the second would be produced by the side-to-side motion of the pedal.  Are
there any commercial sources for such a pedal, either just the casing or
perhaps a commercial effect that can be gutted?  

For that matter, does anyone know of a source for wah or volume pedal
casings?  I've managed to buy a few broken wah pedals, but they are very
difficult to find.  I'd like to build a filter box for my guitar with
several inputs for control voltages (to control filter cutoff, LFO speed and
depth, and self-modulation amount); the more pedals I can find, the merrier.
Having an X-Y pedal would allow me to control two parameters at the same
time with one foot, while using the other foot to, say, stand.

Thanks,

Sean


 






From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Fri Sep 20 23:50:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Fri, 20 Sep 96 14:50:00 PDT
Subject: FW: digital contents
Message-ID: <324311D2@MSMGATE.M30X.NBG.SCN.DE>


I forward this to the list (I asked Paolo), because I think it will be
of more general interest. (large signal response!)
My answer to this will follow; then we can
go on with this in DIY, if we like! (JH)
 ----------
From: Paolo Predonzani
To: HJ2743
Subject: Re: digital contents
Date: Thursday, 19. September 1996 15:06

> Hmm, this is not AH, and you *can* build digital filters yourself,
> nowadays, so I would have no problems with this.
> Though I cannot contribute much to this DSP stuff myself,
> I find it very interesting to see you talk about it. I'd appreciate
> it if you go on with this nonlinearities/aliasing stuff.
>
I've been working on a numerical implementation of the Moog filter for
a month. The non-linearities I considered are the differential input
and the 4  current buffers.
The non-linearities are a major problem because they are present in
every term of the (4th order) differential equation the filter obeys to.
This makes the poles move in the s-plane for constant cutoff freq and Q.
The small signal analysis shows 4 coincident poles in -p (open loop).
The large signal analysis shows that the poles move between -p and the
origin of the s-plane. The static open loop gain also varies.
Standard DSP filters rely on the fact that the coefficients of the
FIR/IIR filter are constant but this is not true for the Moog filter.

The algorithm I use could have been written in the 70's and can be found
in many books on discrete-time control theory of that period.
Unfortunately it is very slow and has a poor conditioning (= noise).
The typical computation time is 40sec for 10sec of music at 22050Hz on
a 80486DX266.

For the aliasing problem I use superresolution. Adaptive oversampling
is used (much like in ray tracing). The oversampling values are x1, x2, x3.
The rules of thumb to choose the oversampling level are:
 - oversampling is proportional to the cutoff frequency.
 - oversampling is set to x3 when there is a step-transition of any
  oscillator (saw, pulse).

Adaptive oversampling is not adequate for a real-time implementation.
Please note that SPICE (circuit simulation program) uses adaptive
oversamplig too.

My concern was to ensure the convergence of the poor conditioned algorithm
but the solution (oversampling) turned out to be an effective anti-aliasing
tecnique.

 --
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Fri Sep 20 23:51:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Fri, 20 Sep 96 14:51:00 PDT
Subject: FW: AW: Re: digital contents
Message-ID: <324311D7@MSMGATE.M30X.NBG.SCN.DE>



 ----------
From: Haible_Juergen#Tel2743
To: Paolo Predonzani
Subject: AW: Re: digital contents
Date: Thursday, 19. September 1996 15:48


Wow, this is interesting stuff!

BTW, my mailer show that this mail goes only to me (no cc),
but I am sure that the DIY list in general and people like
Don  or Joachim would be very interested in this as well!

>The non-linearities are a major problem because they are present in
>every term of the (4th order) differential equation the filter obeys to.
>This makes the poles move in the s-plane for constant cutoff freq and Q.
>The small signal analysis shows 4 coincident poles in -p (open loop).
>The large signal analysis shows that the poles move between -p and the
>origin of the s-plane. The static open loop gain also varies.

This really caught my attention! So far I have only looked at the
nonlinearities as a cause of harmonics/distortion, and not shifting
poles as well! This would mean that the cuttof frequency changes
with signal input strength ...
Now, this makes me question: (1) How are "poles" defined for
large signal analysis? I only know this concept for linear circuits.
How are they defined for nonlinear circuits? Time domain
response for a certain input signal, and then inverse fourier
transform? If so, for which input signal ??
(2) How *far* would these poles move? Usually, the signal amplitude
thru the ladder is small in comparison with the bias current. (?)


> The typical computation time is 40sec for 10sec of music at 22050Hz on
> a 80486DX266.
> For the aliasing problem I use superresolution. Adaptive oversampling
> is used (much like in ray tracing).

I think people who say, that nonlinearities in Digital are much of a 
problem,
have real time processing in mind, where oversampling is more critical;
but you might  check this with Don Tillman - he is for sure the most
knoledgeable person I have found on the net. Digital implementation
is way over my head to say anything serious - but keep me on track
about these discussions as well!

Now for me, my main quest is to *understand* what exactly happens
in the original analogue circuits, so this stuff about large signal
analysis is very interesting to me - can't hear enough of it!
(Equations welcome (;->) )

Regards,

JH.

(I did not forward your letter to DIY because it was a private mail;
but if you want, I highly sugest that you forward both your mail and
my answer to DIY ! We need such discussion here!)



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Fri Sep 20 23:55:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Fri, 20 Sep 96 14:55:00 PDT
Subject: FW: AW: Re: digital contents
Message-ID: <324312F5@MSMGATE.M30X.NBG.SCN.DE>



 ----------
From: Paolo Predonzani
To: HJ2743
Subject: Re: AW: Re: digital contents
Date: Friday, 20. September 1996 14:04

>
>
>
> Wow, this is interesting stuff!
>
> BTW, my mailer show that this mail goes only to me (no cc),
> but I am sure that the DIY list in general and people like
> Don  or Joachim would be very interested in this as well!

I'm sorry for that. Probably I pressed the wrong key on elm. I' ll
check it twice the next time.
Please forward my message to synth-diy because I didn't save it on
local HD. Include your reply/questions as they are interesting too.

 --
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From wizrad at ix.netcom.com  Sat Sep 21 00:38:58 1996
From: wizrad at ix.netcom.com (Tomy Hudson)
Date: Fri, 20 Sep 1996 18:38:58 -0400
Subject: X-Y Pedals
References: <199609202124.OAA08820@mx.seanet.com>
Message-ID: <32431D02.5826E9D6@ix.netcom.com>

Sean Costello wrote:
> 
> Hi everybody,
> 
> Does anyone know anything about X-Y pedals?  I'm looking to construct a
> control voltage pedal that works along two axes;

Fender use to make such a pedal. I think theirs was used for volume 
and tone. You might try pawn shops for these. I've never been able to
come across any, just seen 'em in old catalogs. Nice concept though,
a joystick for the foot.

For standard one axis foot controllers, buy the cheapest volume pedal
you can find. Typically most have a slide-on plastic gear that will
fit on a standard toothed-shaft pot, allowing you to change values
for specific applications.

Sometimes you need to change the jack. For example, making a 
controller for the Lexicon Vortex required a connection for all 
three terminals, a stereo jack and cables.

Roland makes a pedal used in their guitar synth line called the EV-5.
These have a built-in cable terminated w/ 1/4 inch phone jack and are
probably less flexible (and more expensive) than the average volume
pedal. 


--



From lists at heading.demon.co.uk  Sat Sep 21 01:03:55 1996
From: lists at heading.demon.co.uk (Brendan Heading)
Date: 20 Sep 96 23:03:55 +0000
Subject: Posting in the US
Message-ID: <843.6837T1383T2777@heading.demon.co.uk>

This is a teeny bit off topic, if that's a problem please reply in private...

A good friend of mine is thinking of shipping a Poly800 synth out of the US
(West coast) over here to the UK. Do any of you US people know a decent
shipping company ? The UPS are doing for around $70, and that's way too steep.

Thanks in advance.

--
|-------------------------------------------------------------------|
|***** Brendan Heading : email brendan at heading.demon.co.uk    ******|
|***** A1200 28Mhz 020 545MB HD 6MB RAM <= (I'm not that sad) ******|
|***** Analogue Synth freak || JarreVangelisKraftwerkTangerineDream*|
|***** Northern Ireland vibe spreader||CarlosNumanErasureTomita ****|
|-------------------------------------------------------------------|

"Eek, Eek, Wibble Hatstand, my old man's a monkey"
                -- Blackadder Goes Forth




From eli at ux3.sp.cs.cmu.edu  Sat Sep 21 05:03:33 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Fri, 20 Sep 1996 23:03:33 -0400 (EDT)
Subject: FW: AW: Re: digital contents
In-Reply-To: <324311D7@MSMGATE.M30X.NBG.SCN.DE> from "Haible_Juergen#Tel2743" at Sep 20, 96 02:51:00 pm
Message-ID: <9609212307.AA44495@horus.sara.nl>

Juergen Haible wrote:
> Now for me, my main quest is to *understand* what exactly happens
> in the original analogue circuits, so this stuff about large signal
> analysis is very interesting to me - can't hear enough of it!

Seconded!  I'm very interested in the techniques you used to introduce
the non-linearity into the analysis.  Probably I don't have the
background to understand it, though -- is there a text or review
article that could get me up to speed?  I'd like to see any code or
analysis that you feel is in a releasable state.  (For that matter,
this sounds like publishable work.)

If 22k runs at 4:1 on a 486/66, the model at 44k should run in real
time on a p5/133 with about a 50 percent margin.  That should be
enough margin to do three oscillators and an envelope: a MiniMoog on
your average new PC.  So, how does this thing sound?

--
   Eli Brandt
   eli+ at cs.cmu.edu



From don at till.com  Sat Sep 21 09:01:55 1996
From: don at till.com (Don Tillman)
Date: Sat, 21 Sep 1996 00:01:55 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609192034.NAA00249@redshirt.tholian.web> (message from Tom
	May on Thu, 19 Sep 1996 13:34:30 -0700)
Message-ID: <199609210701.AAA22236@shellx.best.com>

   Date: Thu, 19 Sep 1996 13:34:30 -0700
   From: Tom May <ftom at netcom.com>

   Any polynomial with a finite number of terms will produce a band
   limited output when used as a transfer function.  But the bandwidth of
   the output will be N times the bandwidth of the input, where N is the
   degree of the polynomial.  That pretty much falls out of the sin^2(x)
   = (1 - cos(2x))/2 type of identity when you keep applying it for each
   degree of the polynomial.  (Or am I making an analog gut feeling
   mistake?)

Woah...  I hadn't thought about this before, but yeah, this is
absolutely right.  The exponential transfer function I proposed that
rendered an infinite number of harmonics was an example of an
*arbitrary* distortion curve.  But if the curve is limited to an Nth
order polynomial, then yes, the aliasing will be limited to N times
the original signal's maximum frequency.

   Date: Fri, 20 Sep 1996 10:38:39 +0300 (EET-DST)
   From: Mikko Helin <MHELIN at tne01.tele.nokia.fi>

   I think that this kind of aliasing distortion can be avoided by using 
   oversampling, which means that sampling rate is increased so that
   aliasing occurs at higher frequencies, which are then filtered out
   before D/A conversion or resampling to lower (original) sample rate.

Yes, this is standard way to implement it.

   Date: Thu, 19 Sep 1996 15:01:27 -0400 (EDT)
   From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>

   If we're stuck with infinite harmonics coming out of our waveshaping,
   the conceptually simplest solution would be to supersample, waveshape,
   lowpass, and subsample.  

Just as above, yes.  And yeah, it'll reduce the aliasing, but with
infinite harmonics you still have a good chance of the aliasing effect
being annoying.

   This chain of operations might simplify, but probably not.  I've
   considered just doing all digital work at a multiple of audio rate,
   and lowpassing whenever spurious harmonics are generated.  This costs
   you a constant factor everywhere, but avoids the expense of resampling
   up and down all over the place.

Not really an issue; the resampling isn't especially costly.

   Date: Fri, 20 Sep 1996 12:22:20 +0100 (CET)
   From: "Erik Schuijers" <E.G.P.Schuijers at stud.tue.nl>

   What technique many companies use these days is called sigma-delta
   conversion. 

I can't see how sigma-delta conversion would help here.

   Date: Fri, 20 Sep 1996 13:15:51 -0400 (EDT)
   From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>

   Take the case where we've got harmonic partials and they're all in
   phase.  So the input signal x(t) is a sum of cos(kt) terms, out to K.
   Each term a_k cos(kt) can be expanded, using the Chebychev* T_n, to a
   degree-k polynomial in cos(t).  Waveshaping their sum with a degree-D
   polynomial gives one of degree-KD.  Then translate each cos^n(t) back
   to a sum of cos(kt) terms, k<=n.  So we have a sum of cos(kt) terms,
   k<=KD.

Wow, I have no idea what you're talking about!

  -- Don



From don at till.com  Sat Sep 21 09:25:43 1996
From: don at till.com (Don Tillman)
Date: Sat, 21 Sep 1996 00:25:43 -0700
Subject: FW: digital contents
In-Reply-To: <324311D2@MSMGATE.M30X.NBG.SCN.DE> (message from
	Haible_Juergen#Tel2743 on Fri, 20 Sep 96 14:50:00 PDT)
Message-ID: <199609210725.AAA06688@shellx.best.com>

   From: Haible_Juergen / Paolo Predonzani
   Date: Thursday, 19. September 1996 15:06

   I've been working on a numerical implementation of the Moog filter for
   a month. The non-linearities I considered are the differential input
   and the 4  current buffers.

Yes.

   The non-linearities are a major problem because they are present in
   every term of the (4th order) differential equation the filter obeys to.
   This makes the poles move in the s-plane for constant cutoff freq and Q.
   The small signal analysis shows 4 coincident poles in -p (open loop).
   The large signal analysis shows that the poles move between -p and the
   origin of the s-plane. The static open loop gain also varies.
   Standard DSP filters rely on the fact that the coefficients of the
   FIR/IIR filter are constant but this is not true for the Moog filter.

Yes indeed!  How much this dynamic tuning effect contributes to the
sound of the filter is unknown.  (Also whether the effect is
aesthetically pleasing or not.)

   The algorithm I use could have been written in the 70's and can be
found
   in many books on discrete-time control theory of that period.
   Unfortunately it is very slow and has a poor conditioning (= noise).

Yeah, but this is about the only way there is to simulate
nonlinearities that dynamically affect tuning.

   From: Haible_Juergen
   Date: Fri, 20 Sep 96 14:51:00 PDT

   This really caught my attention! So far I have only looked at the
   nonlinearities as a cause of harmonics/distortion, and not shifting
   poles as well! This would mean that the cuttof frequency changes
   with signal input strength ...

True, but it also means that the distortion is much more bizarre than
a simple nonlinear curve.  You've got gain and phase-shift (!!!)
changing over the course of a single cycle.  And than adding feedback
on top of that.  Yow!

   Now, this makes me question: (1) How are "poles" defined for
   large signal analysis? I only know this concept for linear circuits.
   How are they defined for nonlinear circuits? Time domain
   response for a certain input signal, and then inverse fourier
   transform? If so, for which input signal ??

Poles are really only defined for small-signal analysis -- they don't
begin to describe what happens when these sort of nonlinearities kick
in.

   (2) How *far* would these poles move? Usually, the signal amplitude
   thru the ladder is small in comparison with the bias current. (?)

Maybe not that small.  Overdriving the Moog filter is standard
operating procedure.  (That's a good way to get a more sinusoid wave
from a triangle.)

  -- Don



From Per.Mattsson at mkv.mh.se  Sat Sep 21 09:50:05 1996
From: Per.Mattsson at mkv.mh.se (Per Mattsson)
Date: Sat, 21 Sep 96 08:50:05 +0100
Subject: Re(2): X-Y Pedals
Message-ID: <1667408.ensmtp@mkv.mh.se>

costello at costello.seanet.com,Internet writes:
>>Does anyone know anything about X-Y pedals?

>Fender use to make such a pedal

I believe Morley had one to. Morley used LDRs on many pedals so they might be
more difficult to "implement" in an existing synthmodule than if you simply
had to replace the existing pots with the values you need.

/per


--

__________________________________________________________________________
Per Mattsson                               Per.Mattsson at mkv.mh.se
Lecturer and Computersystems manager       http://www.mkv.mh.se/staff/per/
Department of Media and Communication      Phone: +46-60-188825
Mid Sweden University, Sundsvall, Sweden   Fax:   +46-10-188934



From Per.Mattsson at mkv.mh.se  Sat Sep 21 09:55:03 1996
From: Per.Mattsson at mkv.mh.se (Per Mattsson)
Date: Sat, 21 Sep 96 08:55:03 +0100
Subject: More on X and Y
Message-ID: <1667411.ensmtp@mkv.mh.se>

Does anybody know if there's exists a device similar to a touchscreen that
sends out either analog (resistance) or digital signals that responds to X and
Y position? It wouldn't be a bad thing if it could sense pressure aswell.


/per


--

__________________________________________________________________________
Per Mattsson                               Per.Mattsson at mkv.mh.se
Lecturer and Computersystems manager       http://www.mkv.mh.se/staff/per/
Department of Media and Communication      Phone: +46-60-188825
Mid Sweden University, Sundsvall, Sweden   Fax:   +46-10-188934



From sscprick at horus.sara.nl  Sat Sep 21 13:55:01 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Sat, 21 Sep 1996 13:55:01 +0200
Subject: More on X and Y 
In-Reply-To: Your message of Sat, 21 Sep 1996 08:55:03 MET DST.
             <1667411.ensmtp@mkv.mh.se>
Message-ID: <9609211155.AA58324@horus.sara.nl>


In message <1667411.ensmtp at mkv.mh.se> you write:
> Does anybody know if there's exists a device similar to a touchscreen that
> sends out either analog (resistance) or digital signals that responds to X 
> and
> Y position? It wouldn't be a bad thing if it could sense pressure aswell.


Wacom makes small drawing tablets for Macintosh an PC that are
touch sensitive too. They're not expensive either, and very nice.

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From E.G.P.Schuijers at stud.tue.nl  Sat Sep 21 14:24:13 1996
From: E.G.P.Schuijers at stud.tue.nl (Erik The ViKing)
Date: Sat, 21 Sep 1996 13:24:13 +0100 (MET)
Subject: Interesting Paper available on Moog VCF
Message-ID: <48255.s413692@popserver.tue.nl>

>
> Date: Fri, 20 Sep 1996 12:22:20 +0100 (CET)
> From: "Erik Schuijers" <E.G.P.Schuijers at stud.tue.nl>
>
> What technique many companies use these days is called sigma-delta
> conversion.
>
> I can't see how sigma-delta conversion would help here.
>

I didn't say it would help.... It's just a sneaky way of getting a high-res
AD-conversion.
The anti-aliasing filter could be very simple thanks to the high
sampling-frequency.

Note: in the decoding part of a sigma-delta conversion there's a sum of
quantisation errors.


> Date: Fri, 20 Sep 1996 13:15:51 -0400 (EDT)
> From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>
>
> Take the case where we've got harmonic partials and they're all in
> phase.  So the input signal x(t) is a sum of cos(kt) terms, out to K.
> Each term a_k cos(kt) can be expanded, using the Chebychev* T_n, to a
> degree-k polynomial in cos(t).  Waveshaping their sum with a degree-D
> polynomial gives one of degree-KD.  Then translate each cos^n(t) back
> to a sum of cos(kt) terms, k<=n.  So we have a sum of cos(kt) terms,
> k<=KD.
>

Hmmm, this is a nice method for making samples. But I don't think this would
work in real-time. (Unless you'd want to give up on your P6-200!!!)

Erik



From eli at ux3.sp.cs.cmu.edu  Sat Sep 21 22:18:22 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Sat, 21 Sep 1996 16:18:22 -0400 (EDT)
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609210701.AAA22236@shellx.best.com> from "Don Tillman" at Sep 21, 96 00:01:55 am
Message-ID: <9609212307.AA54484@horus.sara.nl>

> Wow, I have no idea what you're talking about!

I had Chebychev polynomials on the brain, so it was way too
complicated and not correct either.  Replace with the following:

Write your input signal as the real part of a degree-k polynomial in e^it.
Run that through a degree-d poly to get a degree-kd poly in e^it.
Take the real part of this.  

So waveshaping with a degree-d polynomial increases bandwidth by a
factor of d.  (This may be obvious, but not to me.)  And the argument
generalizes readily to inharmonic partials and arbitrary phase.

--
   Eli Brandt
   eli+ at cs.cmu.edu



From bthrail at comp.uark.edu  Sun Sep 22 01:43:51 1996
From: bthrail at comp.uark.edu (Berry R. Thrailkill)
Date: Sat, 21 Sep 1996 18:43:51 -0500 (CDT)
Subject: Toy keyboard hacking?
Message-ID: <Pine.SOL.3.94.960921183449.14674A-100000@comp.uark.edu>


   I'm trying to come up with a low-budget keyboard interface for a small
project I'm working on. Basically, I need a simple switch-closing
interface (no frills necessary, though if I could close two circuits
at once with one key I'd be happy).  I was thinking of using an old 'toy'
keyboard since it can also serve as a housing and make the whole thing
nice and neat.

   Has anyone out there successfully adapted a cheap keyboard for use like
this?

<*>-------- - - - - - - - -  -  -  -  -  -  -  -  -   -   -   -   -   -   -
The trouble with being a god is that you've got no one to pray to.
                                            --Terry Pratchett, "Small Gods"




From roytate at ionet.net  Sun Sep 22 23:43:30 1996
From: roytate at ionet.net (Roy Tate)
Date: Sun, 22 Sep 1996 16:43:30 -0500
Subject: Electronotes - Full collection received.
Message-ID: <01BBA8A5.4D14CE60@bart-sip-08.ionet.net>

A short note to let everyone know that I received the full Electronotes collection from Mr. Bernie Hutchins.  I sent a short note with my order, and received a note in reply.  This collection covers alot of territory, from the mathematics behind filter design to the practical side - building circuits.

Cheers,

Roy Tate
roytate at ionet.net



From ftom at netcom.com  Mon Sep 23 03:51:47 1996
From: ftom at netcom.com (Tom May)
Date: 22 Sep 1996 18:51:47 -0700
Subject: Interesting Paper available on Moog VCF
In-Reply-To: Don Tillman's message of Sat, 21 Sep 1996 00:01:55 -0700
References: <199609210701.AAA22236@shellx.best.com>
Message-ID: <199609230151.SAA08371@redshirt.tholian.web>

Don Tillman <don at till.com> writes:

>    Date: Fri, 20 Sep 1996 13:15:51 -0400 (EDT)
>    From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>
> 
>    Take the case where we've got harmonic partials and they're all in
>    phase.  So the input signal x(t) is a sum of cos(kt) terms, out to K.
>    Each term a_k cos(kt) can be expanded, using the Chebychev* T_n, to a
>    degree-k polynomial in cos(t).  Waveshaping their sum with a degree-D
>    polynomial gives one of degree-KD.  Then translate each cos^n(t) back
>    to a sum of cos(kt) terms, k<=n.  So we have a sum of cos(kt) terms,
>    k<=KD.
> 
> Wow, I have no idea what you're talking about!

Neither did I.  The interesting thing about Chebyshev polynomials is
this: using a Chebyshev polynomial as a transfer function has the
property that if you put cos(x) through the Nth order Chebyshev
polynomial, you get cos(Nx) out.  It works for sin, too; the phase
doesn't matter.  So you can "dial in" the harmonic content that your
waveshaping function gives by using a linear combination of the
C. polynomials, where the weight for each polynomial is just the
amount of that harmonic you want.  Note, however, that you only get
the desired harmonic mix when the amplitude of the input is one.

For the record, the zeroth and first order Chebyshev polynomials are
trivial to find: C_0(x) = 1 and C_1(x) = x.  And for some strange
reason, the rest of them can be computed from the relation C_n(x) =
2x*C_{n-1}(x) - C_{n-2}(x).

Tom.



From kimmo at clara.hut.fi  Mon Sep 23 10:49:32 1996
From: kimmo at clara.hut.fi (Kimmo Koli)
Date: Mon, 23 Sep 1996 11:49:32 +0300 (EETDST)
Subject: digital contents
In-Reply-To: <199609191702.KAA00097@redshirt.tholian.web>
Message-ID: <Pine.HPP.3.91.960923112126.2177C@clara.hut.fi>

The difficult thing to make a nonlinear VCF in DSP in the resonance 
feedback even with one nonlinear term in one integrator:

On 19 Sep 1996, Tom May wrote:

> Haible_Juergen#Tel2743 <HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de> writes:
> 
> > Hmm, this is not AH, and you *can* build digital filters yourself,
> > nowadays, so I would have no problems with this.
> > Though I cannot contribute much to this DSP stuff myself,
> > I find it very interesting to see you talk about it. I'd appreciate
> > it if you go on with this nonlinearities/aliasing stuff.
> 
> Ok, take the square law thing Don mentioned, say out = in + in^2.  For
> a sine input, the output will contain the original frequency, the
> second harmonic, and a DC component.  With more than one frequency in
> the input signal, the output will also contain all the f1+/-f2 cross
> terms (actually the DC and second harmonic is just a special case for
> f1=f2).  So like Don said, it is bandlimited because the highest
> output frequency will be no greater than twice the highest input
> frequency.  But, if that frequency exceeds half the sampling rate, it
> will be aliased and you will hear nastiness.
> 

Resonance feedback brings back the doubled frequency and doubles it and 
feeds it back and doubles it and ...

SO: 
With feedback even the simplest nonlinearity produces an infinite 
number of other frequencies!

AND:
Antialiasing this with an additional filter affects the pole locations
of the DSP VCF. These anti-alias filter poles should be at ten times higher 
frequency at least in order not to move the VCF-poles. And this means quite
an increase in sampling frequency !

ALTERNATIVE:
Spice-transient analysis: numerical solutions of differential equations 
of the nonlinear filter time step by time step. This means unknown number of
Newton iterations and numerical integration. This is not DSP, this is raw 
floating-point calculation on a workstation. But with a well written 
algorithm for this special case it may even work at slow realtime with a few
Alpha-chips in parallel...

It seems to me that REAL digital replacements of analog synths are not 
here for a long time,
--------------------------------------------------------------------------------
  Kimmo Koli      			     Email: kimmo at clara.hut.fi 
  Helsinki University of Technology          URL:   http://clara.hut.fi/~kimmo
  Electronic Circuit Design Laboratory
  Otakaari 5 A 
  FIN-02150 Espoo     			     Tel:  +358 0 451 2273
  Finland      				     Fax:  +358 0 451 2269
--------------------------------------------------------------------------------




From E.G.P.Schuijers at stud.tue.nl  Mon Sep 23 14:00:42 1996
From: E.G.P.Schuijers at stud.tue.nl (Erik of zo)
Date: Mon, 23 Sep 1996 13:00:42 +0100 (CET)
Subject: Interesting Paper available on Moog VCF
Message-ID: <46843.s413692@popserver.tue.nl>

About the cap: sigma-delta conversion is based on very small changes in the
signal. Not the actual signal but the difference between two signals is
'sampled'. So only small voltages can be sampled. The cap is probably just
needed for decoupling of the input-signal. I don't really know whether it
must be in for the sampling. It should work both ways. It'll just kick the
offset away.

Don't know about that other question (don't even know the question anymore).

Erik



From predo at dist.dist.unige.it  Mon Sep 23 16:36:26 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Mon, 23 Sep 1996 16:36:26 +0200 (MET DST)
Subject: FW: AW: Re: digital contents
In-Reply-To: <324311D7@MSMGATE.M30X.NBG.SCN.DE> from "Haible_Juergen#Tel2743" at Sep 20, 96 02:51:00 pm
Message-ID: <199609231436.QAA25010@dist.dist.unige.it>

> >The non-linearities are a major problem because they are present in
> >every term of the (4th order) differential equation the filter obeys to.
> >This makes the poles move in the s-plane for constant cutoff freq and Q.
> >The small signal analysis shows 4 coincident poles in -p (open loop).
> >The large signal analysis shows that the poles move between -p and the
> >origin of the s-plane. The static open loop gain also varies.
> 
> This really caught my attention! So far I have only looked at the
> nonlinearities as a cause of harmonics/distortion, and not shifting
> poles as well! This would mean that the cuttof frequency changes
> with signal input strength ...

The nonlinearities can be seen in both ways so long as reactive components
(capacitors) are present in the circuit.

> Now, this makes me question: (1) How are "poles" defined for
> large signal analysis? I only know this concept for linear circuits.
> How are they defined for nonlinear circuits? Time domain
> response for a certain input signal, and then inverse fourier
> transform? If so, for which input signal ??

Poles are defined for the small signal approximation. For large signals
the operating point moves and so does the (instantaneous) small signal
approximation.
I'll make an example. Consider an envelope tracking automatic wha-wha.
It can be described as a time-varying n-pole band-pass filter. But if
x and y are signals (loose notation) and the function the whawha performs
is f() then f(x+y) != f(x) + f(y). So the system is not linear. This is
so because the transfer function is correlated to the input signal.

> (2) How *far* would these poles move? Usually, the signal amplitude
> thru the ladder is small in comparison with the bias current. (?)

It's not so small. The open loop poles almost touch (0,0) in the s-plane.
As to the closed-loop poles I never examined them in detail because I
would have to find the roots of a 4-th order polinomial. Currently I don't
have an algorithm for that. Nevertheless I tried to find a graphical
solution by means of roots-loci. The result is (I think): if the cutoff
frequency is close to the fundamental freq of the oscillator (not more
than 1 octave above it) then the closed-loop poles perform a kind of
elliptical trajectory.

> (Equations welcome (;->) )

The current (handwritten) documentation is 11 pages long and I'm studying
new integration algorithms. I'd like to make a paper out of it.

Paolo 

-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From predo at dist.dist.unige.it  Mon Sep 23 17:03:12 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Mon, 23 Sep 1996 17:03:12 +0200 (MET DST)
Subject: FW: digital contents
In-Reply-To: <199609210725.AAA06688@shellx.best.com> from "Don Tillman" at Sep 21, 96 00:25:43 am
Message-ID: <199609231503.RAA25322@dist.dist.unige.it>


> Yes indeed!  How much this dynamic tuning effect contributes to the
> sound of the filter is unknown.  (Also whether the effect is
> aesthetically pleasing or not.)

It is very important. My simulation is probably inaccurate but it
definitely sounds different from linear digital filters. The detuning
can be heard setting the Q to infinity (self-oscillation) and feeding
the filter with white noise at different levels (poles move).
Moreover the self-oscillation frequency (null input)is slightly lower
then the theorical value that can be calculated with small signal
frequency response.
> 
>    (2) How *far* would these poles move? Usually, the signal amplitude
>    thru the ladder is small in comparison with the bias current. (?)
> 
> Maybe not that small.  Overdriving the Moog filter is standard
> operating procedure.  (That's a good way to get a more sinusoid wave
> from a triangle.)

For 0.1V p-p input the filter is almost linear. For 1V p-p it's definetly
overdriven. Low Qs overdrive the filter more than high Qs. 
> 
>   -- Don
> 


-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From predo at dist.dist.unige.it  Mon Sep 23 17:10:43 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Mon, 23 Sep 1996 17:10:43 +0200 (MET DST)
Subject: moog poles plots
Message-ID: <199609231510.RAA25419@dist.dist.unige.it>

I added some code to the simulator to produce a postscript file
of part of the analysis.
The pole position and the output waveform are shown.
uudecode this message, gunzip the result and print/view the postscript.


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M*U5^V_RZ$9O1H??= W3V_N.YP3'8?(''?17(K,E9T@/ M]2ZY.J.:V?HA2%_
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MP;WK2?#]*KB+)Q7>J<; N^/ ^2:B<WL R%.A&/< X 0<CUX0\CN9"](@+OSE
M?=D7Y+NF?-U;LIU_=W3U *R9+2TG;P\P5S/5ULXJBT5S*<_[7:#&UK04\G<M
MH\RFUW[< T#^I"P?<H;$J72]T^_ZLD_ at D<@B[VRD7$6,N0=@XTK_!,\] +-Q
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A=;RSKA>9/(^@78M]VP?@'QR_/O[P]-U_ 7"P'S"*/@  
 
end
-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From eli at ux3.sp.cs.cmu.edu  Mon Sep 23 23:58:59 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Mon, 23 Sep 1996 17:58:59 -0400 (EDT)
Subject: FW: AW: Re: digital contents
In-Reply-To: <199609231436.QAA25010@dist.dist.unige.it> from "Paolo Predonzani" at Sep 23, 96 04:36:26 pm
Message-ID: <9609232159.AA123785@horus.sara.nl>

Paolo Predonzani wrote:
> Poles are defined for the small signal approximation. For large signals
> the operating point moves and so does the (instantaneous) small signal
> approximation.

Once you have an instantaneous small-signal model, how do you apply it
to an arbitrary input signal?  I could deal with the steady-state 
behavior of each instantaneous model, but that won't do here.

--
   Eli Brandt
   eli+ at cs.cmu.edu



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Tue Sep 24 03:05:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 23 Sep 96 18:05:00 PDT
Subject: Poles and large signals ...
Message-ID: <3247340F@MSMGATE.M30X.NBG.SCN.DE>


> Poles are defined for the small signal approximation. For large signals
> the operating point moves and so does the (instantaneous) small signal
> approximation.

Ok, this sounds reasonable to me. Just to be sure I've got it, you're
not speaking of some (averaged) effect over one or even several periodes,
but you divide the input signal in such small steps, that even a single 
period
is divided into many steps, and then you define poles for a linearized
circuit in that very operating point.
But wouldn't this concept also imply that you don't calculate the 
interaction
of a periodic (sine shaped, for example) signal with these poles anymore,
but rather the response of more or less linear input *segments* with this
momentary pole configuration ?? (The reality of course being an infinite
amount of very small segments ...) I am ready to believe that these 
momentary
defined poles can do rather strange things (see below), but what would be 
the
(average) effect on a whole period?

But let's think about these momentary steps, first.
I'll try to separate momentary bias points and momentary small signal 
behaviour,
and I will look at one single stage of the moog cascade now to simplify 
things.
I center my view to one capacitor in the middle, and I see two collectors
below, which will be two current sources (sinks, actually), providing 
Ibias+Isignal
in the left branch and Ibias-Isignal in the right branch. Above me, I see 
two
BE junctions that are tied to a bias voltage, and which form two current 
controlled
resistors. (And I know that the voltage across these resistors will be 
passed
on to the next stage as current, again with some nonlinearity, but this
process being not that much frequency dependend, I'll omit it here.)
I see that a large signal current will make one of these BE impedances lower
than it would be just from the bias current, and making the other one 
higher.
Now let's go to the extremes, say we have much input overdrive, and we have
almost the double current in the left branch, and almost zero current in the
right branch. So my small signal approximation for this case would be like
this: a differential (floating) AC current source, a capacitor across this 
current
source, and two very different resistors from either side of the current 
source
to GND. My filtered output signal would be the voltage across the current
source (actually, with factor gm of the next stage). Now  the resulting "R" 
of this
 "RC" combination is the *sum* of both resistors ... and with one of these
becoming very large (Ibias-Isignal near zero ...), the sum would be 
dominated
by this large resistor, forcing the pole of this stage down. Is this the 
idea?

Then, if I try to make some kind of averaging over a whole periode, there 
would
be times where you have the initial pole locations (s = -1, at the zero 
crossing
of the input signal), and every lower poles when you cycle thru a half 
period,
reaching its minimum at the input signal peak, and reaching a maximum of -1
at the next zero crossing.
So all in all, pole frequencies only go lower, eventually near zero,
so the "average" must be in between -1 and 0.
This would sound reasonable to me; but where exactly would be such an
"average" pole location be? As I said, the *momentary* pole locations would
be of academic use only, because they "don't have time" to interact with
a ore-or-less periodic input signal).

Now this whole approach should bring the same results for specific cases
that we know or we can measure. We could set a filter to f=100Hz,
and measure how far an input signal of 200Hz would be attenuated,
dependend on input level. Of course we would measure the strengh of the
fundamental only, at the output, to make sure that we just examine the
effect of pole shift on the fundamental.
I'd expect the fundamental being more attenuated in the case when the
input is overdriven. *But* what is the reason for this:
(1)The momentary pole migration, as described above?
(2) The well-known *compression* effect of an overloaded differential pair 
??
Or would both effects add to each other ???
Or: Would (1) and (2) be just different descriptions of one and the same 
thing
????


Thanks for listening - hope this is readable
Any comments / correction welcome!

JH.



From djmaytag at terracom.net  Tue Sep 24 07:20:48 1996
From: djmaytag at terracom.net (DJMaytag)
Date: Tue, 24 Sep 1996 00:20:48 -0500 (CDT)
Subject: ms-20 modifications
Message-ID: <199609240520.AAA11648@mendota.terracom.net>

i've finally gotten around to opening up my ms-20 and i've been thinking
about adding some extra patch points and a few other things to it, more so
now that i see how much space is available inside the beast (you could fit a
body in there the thing is so big). i'm not exactly sure how to do
everything i want to do, so i've got a few questions.

first big question: there's a big metal (aluminun?) bar across the top of
the circuit board. is this a heat sink of some sort? and does it HAVE to be
there? sorry, i guess that was two questions.

anyway, these are the things i want to add:

        VCO1 audio output
        VCO2 audio output
        ENV2 CV output
        VCO1 PWM by LFO (a la ms-50) input (is this even possible?)
        LP VCF audio input (input between the HPF and LPF)
        and an extra input (w/ amount knob) for the filters and VCO's

        i'd also like to mod the speed range on the LFO, if possible.

anyway, i'm ordering the schematics tomorrow, but even with the schems, i'm
not exactly sure how to add/mod these things. i'm sure the VCO audio outs
would be no problem, just do 'em like the 606 indy outs, right? it seems
like the outs wouldn't bee too much of a problem, but the ins are what i'm
not exactly sure about. if anyone has any advice or experience they'd like
to share, i'd greatly appreiciate it.

thanx,
mitch

djmaytag at terracom.net
http://www.terracom.net/~djmaytag/index.html

three things to remember about me:
1) i'm not a dj, (but i play one on TV)
2) i have no intentions of becoming a dj, (or an actor)
3) i'm not a washer and dryer repairman either

how's my posting? see http:\www.byte.me.com





From don at till.com  Tue Sep 24 09:54:06 1996
From: don at till.com (Don Tillman)
Date: Tue, 24 Sep 1996 00:54:06 -0700
Subject: FW: AW: Re: digital contents
In-Reply-To: <199609231436.QAA25010@dist.dist.unige.it> (message from Paolo
	Predonzani on Mon, 23 Sep 1996 16:36:26 +0200 (MET DST))
Message-ID: <199609240754.AAA28518@shellx.best.com>

   From: Paolo Predonzani <predo at dist.dist.unige.it>
   Date: Mon, 23 Sep 1996 16:36:26 +0200 (MET DST)

   > How *far* would these poles move? Usually, the signal amplitude
   > thru the ladder is small in comparison with the bias current. (?)

   It's not so small. The open loop poles almost touch (0,0) in the s-plane.
   As to the closed-loop poles I never examined them in detail because I
   would have to find the roots of a 4-th order polinomial. Currently I don't
   have an algorithm for that. 

I'm not sure that I understand you here.  If you mean the positions of
the (linear) poles with feedback, I can tell you that the poles start
at -w (real, negative), and, as feedback is applied, they split off in
an X pattern at 45/135/-45/-135 degrees.  Eventually the two rightmost
poles hit the axis and it oscillates.

I've had a lot of success using an iterative method to solve n-th
order polynomials, up to about 12-th order or so.  Newton's method,
while fine for real numbers, fails completely for complex numbers
because the second dimension makes it just too easy to overshoot.  So
instead you have to make a 2-dimensional parabolic approximation to
the curve at the point in question, and that's easily solvable
generating a fine point for the next iteration.

I have some software to do this; it was part of a speaker design
program I wrote once -- I wanted to derrive pole positions for
arbitrary filters whose characteristics were defined by their
polynomials (ie., Bessel).  

Code fragment available to synth-diy'ers on request, but be warned,
it's written in Lisp.

Or you can use Mathematica.

  -- Don



From don at till.com  Tue Sep 24 09:57:20 1996
From: don at till.com (Don Tillman)
Date: Tue, 24 Sep 1996 00:57:20 -0700
Subject: moog poles plots
In-Reply-To: <199609231510.RAA25419@dist.dist.unige.it> (message from Paolo
	Predonzani on Mon, 23 Sep 1996 17:10:43 +0200 (MET DST))
Message-ID: <199609240757.AAA29840@shellx.best.com>

   From: Paolo Predonzani <predo at dist.dist.unige.it>
   Date: Mon, 23 Sep 1996 17:10:43 +0200 (MET DST)

   I added some code to the simulator to produce a postscript file
   of part of the analysis.
   The pole position and the output waveform are shown.
   uudecode this message, gunzip the result and print/view the postscript.

Wow, looks great!  Reality check: see, when the signal goes high or
low, the pole frequencies dip.

  -- Don



From c908369 at student.dtu.dk  Tue Sep 24 10:07:20 1996
From: c908369 at student.dtu.dk (Isac Georg Jensen)
Date: Tue, 24 Sep 1996 10:07:20 +0200
Subject: Midi-CV converter finished
Message-ID: <324796B8.6046@student.dtu.dk>

This is just to inform you all, that my Midi-CV project is (nearly)
finished. If anyone's interested I'll be happy to copy the relevant
schematics, code, etc. and send it by mail. 

Here's the details:

Single channel Midi-CV converter.
Motorola 68HC705C8 converter (approx. $20) with internal 8k memory.
8 configurable CV out's (each with optional Gate signal).
2x16 character LCD display.
Up-to 16 push buttons.


Its doing very well functioning as a controller for my small modular
synth, consisting of about 20 modules (3 VCO's, 3 LFO's, 3 EG, VCF's,
etc.). At the moment I'm trying to implement various things like user
setups, midi filtering, echo (?!) and more. 

This project, altough I've used much more time than expected, has turned
out to be a great learning experience. I can recommend this to anyone
who wants to learn the details of midi.

A final note: It's only possible to reproduce the (my :) Midi-CV
converter if you have access to a Motorola 68HC705 (or eqaul)
development kit, consisting of a PC, and an evaluation module. So before
you ask for the schematics and code, you should REALLY consider the
(new?) kit from Paia, of which I only have had nice things about.

Thank you all for positive feedback.

ISac



From Paul.Maddox at bew.co.uk  Tue Sep 24 12:15:09 1996
From: Paul.Maddox at bew.co.uk (Paul.Maddox at bew.co.uk)
Date: Tue, 24 Sep 96 10:15:09 +0000
Subject: Midi->Cv Converter
Message-ID: <"00042FFA000008C3*."@MHS>

Dear ISac,

	I would love to get teh scematics and
code for your midi to CV convertor But you didnt
include your e-mail address. Could you e-mail
as I have a question about it.
	
	Yours

	Paul Maddox


---------------------------------------------------------------------------
Paul.Maddox at bew.co.uk
"T T F N" - Tigger
"Watch that E-Mail address!" - Me
---------------------------------------------------------------------------







From predo at dist.dist.unige.it  Tue Sep 24 15:01:52 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Tue, 24 Sep 1996 15:01:52 +0200 (MET DST)
Subject: FW: AW: Re: digital contents
In-Reply-To: <199609240754.AAA28518@shellx.best.com> from "Don Tillman" at Sep 24, 96 00:54:06 am
Message-ID: <199609241301.PAA07865@dist.dist.unige.it>

> 
>    It's not so small. The open loop poles almost touch (0,0) in the s-plane.
>    As to the closed-loop poles I never examined them in detail because I
>    would have to find the roots of a 4-th order polinomial. Currently I don't
>    have an algorithm for that. 
> 
> I'm not sure that I understand you here.  If you mean the positions of
> the (linear) poles with feedback, I can tell you that the poles start
> at -w (real, negative), and, as feedback is applied, they split off in
> an X pattern at 45/135/-45/-135 degrees.  Eventually the two rightmost
> poles hit the axis and it oscillates.

Ok, this is the root locus for constant fcutoff and increasing open-loop
gain but I was considering the case when the poles start 
moving as the large input signal makes them move.
The X pattern locus is correct when there are 4 coincident poles in open 
loop. As you can see in the plot I posted, the open-loop poles don't
move together. Their trajectories are similar but not identical. In
addition they are slightly shifted in time. So the X shaped root locus
is only an asimptotical approximation (The center of the X being the 
average of the open loop pole positions).
So my problem is: let's consider one closed-loop pole (say the one on
the imaginary axis in the self-oscillating case); if the input is null
the pole is exactly on the axis but if the input is large enough the
closed-loop poles move too. How do they move?


-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From predo at dist.dist.unige.it  Tue Sep 24 15:58:19 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Tue, 24 Sep 1996 15:58:19 +0200 (MET DST)
Subject: Poles and large signals ...
In-Reply-To: <3247340F@MSMGATE.M30X.NBG.SCN.DE> from "Haible_Juergen#Tel2743" at Sep 23, 96 06:05:00 pm
Message-ID: <199609241358.PAA08604@dist.dist.unige.it>

> source
> to GND. My filtered output signal would be the voltage across the current
> source (actually, with factor gm of the next stage). Now  the resulting "R" 
> of this
>  "RC" combination is the *sum* of both resistors ... and with one of these
> becoming very large (Ibias-Isignal near zero ...), the sum would be 
> dominated
> by this large resistor, forcing the pole of this stage down. Is this the 
> idea?

Yes. Keep in mind that the poles are re-calculated at EVERY simulation step.
This can be once, twice or 3 times per period, depending on the oversampling
factor.

> Now this whole approach should bring the same results for specific cases
> that we know or we can measure. We could set a filter to f=100Hz,
> and measure how far an input signal of 200Hz would be attenuated,
> dependend on input level. Of course we would measure the strengh of the
> fundamental only, at the output, to make sure that we just examine the
> effect of pole shift on the fundamental.
> I'd expect the fundamental being more attenuated in the case when the
> input is overdriven. *But* what is the reason for this:
> (1)The momentary pole migration, as described above?
> (2) The well-known *compression* effect of an overloaded differential pair 
> ??
> Or would both effects add to each other ???

Both effects are present.
Did you look at the pole plot? The test conditions are:
input: 262Hz 0.5V peak-peak
fcutoff: 4KHz
full resonance.
Now: the filter self-oscillates. Count the oscillations in one (output) period.
They are 11. What? They should be 4000/262 = 15 !!
I tested the circuit varying the input amplitude:
0.1V p-p  ->  14 oscillations
0.025V p-p  ->  15 oscillations
Of course the shape of the input wave is important too (a square wave 
overdrives the filter more than a sawtooth) but the results are similar.


> 
> 
> Thanks for listening - hope this is readable
> Any comments / correction welcome!
> 
> JH.
> 


-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From 932674 at student.iae.dtu.dk  Tue Sep 24 14:50:51 1996
From: 932674 at student.iae.dtu.dk (Stefan Nielsen)
Date: Tue, 24 Sep 1996 14:50:51 MET 
Subject: Electronotes. What? Where? How? Why? When? Who?
Message-ID: <2D24A1F1A65@student.iae.dtu.dk>

Howdy all!

Now that the dust is settled after that really wild mail-war, I 
submit this question, hoping i won't trigger (gate?) a new batch of 
mud-slinging. (Please!).

1) What exactly *is* Electronotes? Is it correct that it is a 
   collection of preferred schematics?

2) How can I buy it, and how much does it cost? Postal/email-adr's?

3) Who is Bernie Hutchins? Is he the editor or something?

Yes, I *do* know that it has possibly been explained a couple of 
times by now, but most of the discussion only got as far as my DELETE 
button.

If I dont reply at once, it's because my mail-computer is in another 
city, and I have to drive 45 mins every time I have to check my 
mailbox.

Have a nice day!

Stefan
-------- URL: http://www.iae.dtu.dk/u/932674/home.htm --------
------------- E-mail: 932674 at student.iae.dtu.dk --------------



From paulmb at pi.net  Tue Sep 24 20:33:28 1996
From: paulmb at pi.net (Paul Boelen)
Date: Tue, 24 Sep 1996 20:33:28 +0200
Subject: Midi-CV converter
Message-ID: <32482978.7091@pi.net>

Recently I bought a Philip Reese Little-MCV Midi to CV converter.
I have found that there is a delay in the gate signal when you play
legato. This makes it very difficult to use. You can never play more
than one key at a time.

Does anybody have any experience with this converter?

======================================================================
Paul Boelen
E-Mail: paulmb at pi.net
Phone : (31) 23 5252339
======================================================================



From ms20 at itchy.serv.net  Tue Sep 24 20:58:00 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Tue, 24 Sep 1996 11:58:00 -0700 (PDT)
Subject: EMS VCF Failure/Happy Accident
Message-ID: <Pine.BSD.3.91.960924114527.2415A-100000@itchy.serv.net>


Last night I finished an EMS VCF clone, built it pretty much identical to 
the design in the book (Sorry, don't know the title off hand), except 
that I added a non inverting buffer/summer at the audio input.  I pump in 
a 2Khz squarewave, turn on power and look at the output on my scope - out 
of control!!!  I don't know how to describe what's happening, other than 
the sound is closer to two VCOs crossmodulating than a VCF.  Adjusting 
the cutoff and resonance changes the sound from buzzy to raspy to 
earsplitting buzzsaw, not the soft mellow filtering effect I'd expect.  I 
guess I've accidentally created a timbre modulator of sorts.  
  
At this point I'm tempted to leave it as is and build another one that 
does what it's supposed to.

Romeo



From Christopher_List at Sonymusic.Com  Tue Sep 24 21:50:57 1996
From: Christopher_List at Sonymusic.Com (Christopher_List at Sonymusic.Com)
Date: Tue, 24 Sep 1996 15:50:57 -0400
Subject: EMS VCF Failure/Happy Accident
Message-ID: <852563AF:006C5DB9.00@mailgw1.sonymusic.com>





  > expect.  I guess I've accidentally created a timbre modulator of sorts.
  >
  > At this point I'm tempted to leave it as is and build another one that
  > does what it's supposed to.

  ...or figure out what's wrong and let us know so we can all build it :).

  - sounds cool - good job!

  Reminds me of when I first built a Moog VCF based on a transistor-only
  schem I got from Gene. I screwed something up and couldn't get it to
  work. In an attempt at getting *some* kind of filter I graphed the Ric
  Miller Moog VCF's op-amp based input and output section to the transistor
  ladder "heart" I had already built. The result was a heavy distortion VCF
  with a strange sound. I never made it into a full module, but a I have
  the protoboard sitting in my dresser / workbench (sad but true) waiting
  for a rainy day....

  - CList





From impose at oden.se  Tue Sep 24 23:42:03 1996
From: impose at oden.se (Mattias Nord)
Date: Tue, 24 Sep 1996 23:42:03 +0200
Subject: Stupid query again (maby) .. =)
Message-ID: <199609242142.XAA27341@hugin.oden.se>

Is there anyone of you diy-enthusiasts that is in to Csound and know how to
make it sork in realtime on a PC (if that is possible) .. !?!? .. 

/mattias .. =) 

---------------------------------------------------------------------
                                                        ,,,
There must be a polarbear somewhere...                 /'^'\
                                                      ( o o )
--------------------------------------------------oOOO--(_)--OOOo----
     Mattias Nord
     impose at oden.se                                .oooO
     http://www.oden.se/~impose                    (   )   Oooo.
----------------------------------------------------\ (----(   )-----
                                                     \_)    ) /
                                                           (_/




From eli at ux3.sp.cs.cmu.edu  Wed Sep 25 02:23:01 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Tue, 24 Sep 1996 20:23:01 -0400 (EDT)
Subject: Stupid query again (maby) .. =)
In-Reply-To: <199609242142.XAA27341@hugin.oden.se> from "Mattias Nord" at Sep 24, 96 11:42:03 pm
Message-ID: <9609250023.AA111013@horus.sara.nl>

Mattias Nord wrote:
> Is there anyone of you diy-enthusiasts that is in to Csound and know how to
> make it work in realtime on a PC (if that is possible) .. !?!? .. 

If you mean a PC running DOS/Windows, I think you'd need to write a
MIDI device handler for Csound.  It's got some real-time output
capabilities (never tried it myself -- too slow a machine), but it
only knows how to deal with MIDI files, not an MPU-401.

But if you run Unix, this should be easier.  Write a program that
watches /dev/midiXX and generates appropriate Csound score lines.
Tell Csound to run from stdin, and pipe this into it.  (Don't worry
about the translation latency; you have to get the kernel's DAC
buffers down to a reasonable size first.)

In ICMC '96 there are some papers on the MIT group's "Extended
Csound", which does real-time.  Apparently the plan is for it to be a
commercial product and run on a SHARC DSP board.  (ICMC is
"International Computer Music Conference".)

--
   Eli Brandt
   eli+ at cs.cmu.edu



From eli at ux3.sp.cs.cmu.edu  Wed Sep 25 02:42:22 1996
From: eli at ux3.sp.cs.cmu.edu (Eli Brandt)
Date: Tue, 24 Sep 1996 20:42:22 -0400 (EDT)
Subject: Interesting Paper available on Moog VCF
In-Reply-To: <199609230151.SAA08371@redshirt.tholian.web> from "Tom May" at Sep 22, 96 06:51:47 pm
Message-ID: <9609250042.AA93778@horus.sara.nl>

> And for some strange reason, the rest of them can be computed from
> the relation C_n(x) = 2x*C_{n-1}(x) - C_{n-2}(x).

Oh, this is pretty cute.  Not on-topic, necessarily, but cute:

C_n(x) = cos (n arccos x)
C_n(a) = cos na,    a = arccos x

C_n+1(a) = cos (n+1)a = cos na cos a - sin na sin a
C_n-1(a) = cos (n-1)a = cos na cos a + sin na sin a

C_n+1(a) + C_n-1(a) = 2 cos a cos na = 2 cos(arccos x) C_n(a) = 2x C_n(a)

C_n+1 = 2x C_n - C_n-1

--
   Eli Brandt
   eli+ at cs.cmu.edu




From sscprick at horus.sara.nl  Wed Sep 25 11:28:48 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Wed, 25 Sep 1996 11:28:48 +0200
Subject: Temperature control for transistors/crystals
Message-ID: <9609250928.AA77843@horus.sara.nl>


This month's Elektuur (Dutch Elektor) magazine has a temperature
stabilization circuit for crystals, which we could use very well 
to keep dual transistors in VCO's temperature stable.

It uses a Darlington transistor as both the heater and the sensor.
80% of the time the darlington acts as a heater, 20% of the time
as the temperature sensor. It is switched between these functions
with 4 switches in a 4066 ic. A 555 timer, an opamp, two 8V
regulators and a short-circuit-proof 2x9V 3.3VA transformer are 
main the other components.

The crystal is kept at a temperature of 40-50 degrees (adjustable).
It's locked away together with the darlington in a styrofoam box.
The transistor and crystal are simply joined, no extra heat"sink"
to act as a flywheel are used.

You could use this circuit to temperature-stabilize dual transistors
in exp-generators. By far the best way to do this is substrate
heating, i.e. heat the silicon chip the transistors are on directly.
You need at least two extra transistors on the wafer to do this, 
one transistor as the heater, the other as the sensor. The problem
here is that transistors that really have good log characteristics
are usually duals (MAT-02, MAT-03) and single-sourced components.
The only multi-sourced transistor array I know is the 3046/3086,
which has 5 transistors, but the transistors in there are not the 
best for exp purposes. There is a (single-sourced!) MAT-04, which has 
4 transistors, and is very promising as a substrate temperature
stabilized part. But, it is a single-sourced part. If you base a
design on it you may find yourself in the "uA726 situation". The
uA726 was a dual transistor made by Fairchild, with on-chip 
temperature control. The uA726 was used in various Moog, Roland
and Kobol VCO's and also in the Elektor Formant VCO's. Fairchild 
does not exist any more, uA726 was single-sourced and thus it is 
highly unavailable today.

With the above circuit you could use the best and the best available 
dual transistor of the day in an exp converter.

Source: Elektuur (Dutch Elektor) - oktober 1996

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good




From colinf at eimpc10.ei.csg.mot.com  Wed Sep 25 12:04:48 1996
From: colinf at eimpc10.ei.csg.mot.com (Colin Fraser)
Date: Wed, 25 Sep 1996 11:04:48 +0100
Subject: Temperature control for transistors/crystals
In-Reply-To: Rick Jansen <rick@sara.nl>
        "Temperature control for transistors/crystals" (Sep 25, 11:28am)
References: <9609250928.AA77843@horus.sara.nl>
Message-ID: <960925110451.ZM6815@eipc22>

On Sep 25, 11:28am, Rick Jansen wrote:
> Subject: Temperature control for transistors/crystals
> 
> This month's Elektuur (Dutch Elektor) magazine has a temperature
> stabilization circuit for crystals, which we could use very well 
> to keep dual transistors in VCO's temperature stable.
> 
..snip..

> The only multi-sourced transistor array I know is the 3046/3086,
> which has 5 transistors, but the transistors in there are not the 
> best for exp purposes. 

I can get hold of an Elantec produced 4 transistor array containing closely 
matched 2n3904 type transistors.
Maybe this would be suitable..?


Cf



From hbcsc349 at email.csun.edu  Wed Sep 25 18:15:41 1996
From: hbcsc349 at email.csun.edu (JunoMan)
Date: Wed, 25 Sep 1996 09:15:41 -0700 (PDT)
Subject: ms-20 modifications
In-Reply-To: <199609240520.AAA11648@mendota.terracom.net>
Message-ID: <Pine.HPP.3.95.960925091356.16643B-100000@csun1.csun.edu>


I saw a PWM mod posting on music machines for the MS-20.  It's not that
detailed, but it's a starting point.

Pierre

On Tue, 24 Sep 1996, DJMaytag wrote:

> i've finally gotten around to opening up my ms-20 and i've been thinking
> about adding some extra patch points and a few other things to it, more so
> now that i see how much space is available inside the beast (you could fit a
> body in there the thing is so big). i'm not exactly sure how to do
> everything i want to do, so i've got a few questions.
> 
> first big question: there's a big metal (aluminun?) bar across the top of
> the circuit board. is this a heat sink of some sort? and does it HAVE to be
> there? sorry, i guess that was two questions.
> 
> anyway, these are the things i want to add:
> 
>         VCO1 audio output
>         VCO2 audio output
>         ENV2 CV output
>         VCO1 PWM by LFO (a la ms-50) input (is this even possible?)
>         LP VCF audio input (input between the HPF and LPF)
>         and an extra input (w/ amount knob) for the filters and VCO's
> 
>         i'd also like to mod the speed range on the LFO, if possible.
> 
> anyway, i'm ordering the schematics tomorrow, but even with the schems, i'm
> not exactly sure how to add/mod these things. i'm sure the VCO audio outs
> would be no problem, just do 'em like the 606 indy outs, right? it seems
> like the outs wouldn't bee too much of a problem, but the ins are what i'm
> not exactly sure about. if anyone has any advice or experience they'd like
> to share, i'd greatly appreiciate it.
> 
> thanx,
> mitch
> 
> djmaytag at terracom.net
> http://www.terracom.net/~djmaytag/index.html
> 
> three things to remember about me:
> 1) i'm not a dj, (but i play one on TV)
> 2) i have no intentions of becoming a dj, (or an actor)
> 3) i'm not a washer and dryer repairman either
> 
> how's my posting? see http:\www.byte.me.com
> 
> 
> 

        _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
       _/                                                              _/
      _/    _/_/_/_/   _/_/_/_/   Pierre Zarokian                     _/
     _/    _/    _/        _/   E-mail: pzarokian at email.csun.edu     _/       
    _/    _/_/_/_/       _/         or  pzarokian at ccgate.hac.com    _/
   _/    _/            _/      URL: http://www.csun.edu/~hbcsc349  _/
  _/    _/           _/_/_/_/                                     _/
 _/                                                              _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/




From maf at worldonline.nl  Wed Sep 25 20:22:02 1996
From: maf at worldonline.nl (Marc)
Date: Wed, 25 Sep 1996 20:22:02 +0200 (MET DST)
Subject: Midi to CV interfaces
Message-ID: <1.5.4.16.19960925192232.1cf7823a@worldonline.nl>

I've build several Midi interfaces using Motorola 
microcontrollers. For people who are interested in 
building Midi interfaces, take a look at Motorola's
68HC11 controller. The chip contains a on chip 512 
bytes EEPROM (it's enough for Midi applications) and 
is fully programmable via your PC. 

Soon i will convert my handdraw schematics in 
real schematics. Tools and code are available.

Marc




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Wed Sep 25 21:40:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Wed, 25 Sep 96 12:40:00 PDT
Subject: AW: Temperature control for transistors/
Message-ID: <324992FB@MSMGATE.M30X.NBG.SCN.DE>


> You could use this circuit to temperature-stabilize dual transistors
> in exp-generators. By far the best way to do this is substrate
> heating, i.e. heat the silicon chip the transistors are on directly.
> You need at least two extra transistors on the wafer to do this,
> one transistor as the heater, the other as the sensor.

With a clever design, you only need *one* additional transistor!
I think I have seen it in the Micromoog: They use the extra transistor
as a heater, but they measure the BE voltage of one transistor from the
exponential converter, to read the temperature!
This should work fine as long as the current tru this "sensor" transistor
is constant. So we could use the transistor in the "reference current"
path of the expo converter, as long as we do not modultate the reference
current for linear FM.
The 3046/3086 surely not being ideal devices, I found that the tracking of
its two halves is excellent in my SEM-VCO clone, so building a Dual VCO
with one 3086, where the fifth transistor is a heater could be a good 
solution!
(But I haven't trie it exactly; I used the tempco method for my SEM-VCOs,
and in the Micromogg it's a VCO and a VCF that track together, but with
the VCF being used as 2nd VCO, and high effords to make it track ...)

JH.



From thierry.rochebois at ief.u-psud.fr  Thu Sep 26 16:03:26 1996
From: thierry.rochebois at ief.u-psud.fr (Thierry Rochebois)
Date: Thu, 26 Sep 1996 16:03:26 +0200
Subject: Ribon controler
Message-ID: <9609261403.AA00793@zeus.u-psud.fr>

Is there somebody who hear about the FSR155 linear potentiometer.

It is a pressure sensitive film (like other FSR stuff) that can be also
used as a potentiometer. As far as I understood, the overall resistance depends
on the pressure and the potentiometer ratio depends on the pressure point. I
am not sure about this assumption. So if someone knows more about it...

I found this device in the French edition of Radiospares catalog.
It costs about 185F (~$35), it seems to be interesting for designing
a ribbon controller.
Thierry Rochebois

+-------------------------------------------------------------+
|                                                             |\
|  Thierry Rochebois      Tel:69 41 79 39  Piece 353          | +
|  IEF   AXIS/TSA(ARCEMA)   Bat 220 UPS   91405 ORSAY Cedex   | |
|  thierry at ief-paris-sud.fr               FRANCE              | |
|  http://www.ief.u-psud.fr/~thierry/welcome.html             | |
|                                                             | |
+-------------------------------------------------------------+ |
 \                                                             \|
  +-------------------------------------------------------------+






From sscprick at horus.sara.nl  Thu Sep 26 21:18:31 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Thu, 26 Sep 1996 21:18:31 +0200
Subject: Future of ic's (DIL versus SMD)?
Message-ID: <199609261918.VAA119932@horus.sara.nl>


In message <960926161431.ZM6807 at eipc22> you write:
> 
> The way things are going in industry, in 5 to 10 years time it 
> may be a tough job finding any non-smt components. Maybe we'll 
> all be forced to hang up our soldering irons... 

Interesting point! I have no idea wether DIL chips are an
on-going concern for the semiconductor companies...
Personally I have never tried to build something with SMD's,
though Elektor has published a few (very few) projects with
them.

Anyone with an insight in the future of devices in the regular
DIL packages?

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good



From anders.sponton at tellus.vallentuna.se  Fri Sep 27 08:49:39 1996
From: anders.sponton at tellus.vallentuna.se (Anders Sponton)
Date: Fri, 27 Sep 1996 08:49:39 +0200
Subject: 8 note poly kbd
Message-ID: <324B7903.3DED@tellus.vallentuna.se>

Is there anybody out there having the EPROM-dump for the Digisound
8-note poly kbd?

Anders, Sweden

try:
ftp://ns.tellus.vallentuna.se/incoming/anders/sas



From andrejc at tyr.fe.uni-lj.si  Fri Sep 27 10:07:34 1996
From: andrejc at tyr.fe.uni-lj.si (Andrej Cedilnik)
Date: Fri, 27 Sep 1996 10:07:34 +0200
Subject: Midi to CV interfaces
References: <1.5.4.16.19960925192232.1cf7823a@worldonline.nl>
Message-ID: <324B8B46.6E0E@tyr.fe.uni-lj.si>

Marc wrote:
> 
> I've build several Midi interfaces using Motorola
> microcontrollers. For people who are interested in
> building Midi interfaces, take a look at Motorola's
> 68HC11 controller. The chip contains a on chip 512
> bytes EEPROM (it's enough for Midi applications) and
> is fully programmable via your PC.
> 
> Soon i will convert my handdraw schematics in
> real schematics. Tools and code are available.
> 
> Marc

hey!

What's up with your server?
-- 
                       * / *     andrejc at tyr.fe.uni-lj.si
 /-\ |  | |-\  \  /     \|/       http://www.kud-fp.si/rave/andy
 | | |\ | |  |  \/    \--*--\    
 +-+ | \| |  |  /       /|\      "Gabber is the only drug!"        
 | | |  | |-/  /       * / *                "Let's get drugged!!"




From c908369 at student.dtu.dk  Fri Sep 27 12:11:01 1996
From: c908369 at student.dtu.dk (Isac Georg Jensen)
Date: Fri, 27 Sep 1996 12:11:01 +0200
Subject: CV-Midi package
Message-ID: <324BA835.35A2@student.dtu.dk>

This is a note to the people who have requested the info on my midi-cv
converter:

I've just gone through the notes and I figure it needs some editing, so
I'll delay the packages until monday (sorry, but I think you'll
appreciate being able to read my notes !). Maybe I'll send the code by
E-mail (13 pages of text !). 

Also be warned, the PCB layout is 2-sided (You could always do your own
single sided, from the schematic)

I'm off to a nice (code editing and schem' rearranging !)

-Isac



From jdm at synthcom.com  Fri Sep 27 14:46:27 1996
From: jdm at synthcom.com (J.D. McEachin)
Date: Fri, 27 Sep 1996 12:46:27 +0000 ()
Subject: CV Clock for Ana. Seq. - Linear or Exp.?
In-Reply-To: <Pine.BSD.3.91.960927114308.10278A-100000@itchy.serv.net>
Message-ID: <Pine.BSD.3.91.960927123702.2881C-100000@beacon.synthcom.com>

On Fri, 27 Sep 1996, A.S.P. wrote:

> Just a quick question: Should the CV input for the clock of an analog 
> sequencer have a linear or exponential response?

It depends on whether your sequencer is set up for linear or exponential 
CV outs.  You probably want the clock in to be the same as the CV out so 
that you can use the sequencer to modulate itself.

The setup of the outs is dependent upon what sort of potentiometers you
use.  Linear pots are used for exponential outs (CV terminology is screwy
if you ask me), and I think audio taper (or is it reverse audio taper???)
pots are used for linear outs. 

Of course, if you're doing a lot of drum n'bass music using analog 
sequencers (that would be fun), then you want lots of resolution on the 
upper range of your clock tempo, so you want an exponential clock with 
a linear CV out (if you don't get this joke, don't worry).

JDM




From ms20 at itchy.serv.net  Fri Sep 27 20:45:11 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Fri, 27 Sep 1996 11:45:11 -0700 (PDT)
Subject: CV Clock for Ana. Seq. - Linear or Exp.?
Message-ID: <Pine.BSD.3.91.960927114308.10278A-100000@itchy.serv.net>


Just a quick question: Should the CV input for the clock of an analog 
sequencer have a linear or exponential response?

Romeo



From Christopher_List at Sonymusic.Com  Fri Sep 27 21:47:17 1996
From: Christopher_List at Sonymusic.Com (Christopher_List at Sonymusic.Com)
Date: Fri, 27 Sep 1996 15:47:17 -0400
Subject: CV Clock to Seqn
Message-ID: <852563B2:006BE2F8.00@mailgw1.sonymusic.com>





  Romeo et DIY -

  Whoops, deleted the original message...

  The question was;
  "Should the CV input for a sequencer clock be linear or exponential?"

  My answer would be: neither!

  Why build a clock into your sequencer? (I assume we're talking analog
  sequencers here - right?)

  I mean, you're going to want it in sync with your other gear - right? So
  much of the time you'll be clocking it from a drum machine trigger signal
  - or a gate out from a MIDI-CV, or something - don't you think?

  Put your energy into building a separate CV-able LFO module with a pulse
  output (as well as triangle, saw, etc) - rather than building this into
  your sequencer. Then I think you'll find that this LFO will get used a
  lot more on it's own to drive other stuff than it will working as a clock
  for your sequencer. As far as linear or exp. scaling goes, if you want
  the LFO to do audio range stuff, it's exponential...

  - CList





From synades at mainz.netsurf.de  Sat Sep 28 11:55:35 1996
From: synades at mainz.netsurf.de (synades)
Date: Sat, 28 Sep 1996 05:55:35 -0400 (EDT)
Subject: CV Clock to Seqn
In-Reply-To: <852563B2:006BE2F8.00@mailgw1.sonymusic.com>
Message-ID: <Pine.LNX.3.95.960928055508.4402I-100000@kernelpanix.aura.of.mankind>

On Fri, 27 Sep 1996 Christopher_List at Sonymusic.Com wrote:

>   The question was;
>   "Should the CV input for a sequencer clock be linear or exponential?"
> 
>   My answer would be: neither!
> 
>   Why build a clock into your sequencer? (I assume we're talking analog
>   sequencers here - right?)

the analog sequencers i build have a clock. it's real fun to uses them as
LFO with a complex waveform.


synades         _-----_         _-------------------------------------------
______________-~       ~-_____-~     http://people.mainz.netsurf.de/~synades

                                                      keine macht den daten!




From ms20 at itchy.serv.net  Mon Sep 30 02:28:24 1996
From: ms20 at itchy.serv.net (A.S.P.)
Date: Sun, 29 Sep 1996 17:28:24 -0700 (PDT)
Subject: CV Clock Pt.II - PW. CVPWM
Message-ID: <Pine.BSD.3.91.960929171355.17637A-100000@itchy.serv.net>


OK, I think I've decided on a design for the sequencer's clock.  It lacks 
one thing, though and that is a pulse width control, as well as a CV 
input for pulse width.  What I'd like to do is split the clock's output 
into five channels, one for clocking the sequencer, the other four to 
provide a gate output for each row.  I'd like each row to have 
independent note lengths, either controlled by a PW knob (as on the SQ10, 
ARP 1601, etc) or a CV input (as on the ARP).  

I'm looking the National Semiconducors Linear Applications databook 
(Specific IC's) and one of the Apps for the 555 looks like it will do 
just this, "When the timer is connected in the monostable mode and 
triggered with a continuous puse train, the output pulse width can be 
modulated by a signal applied to pin 5."

I'd appreciate any second opinions, as well as any leads to a simpler 
approach, if there is one.

Romeo



From predo at dist.dist.unige.it  Mon Sep 30 14:56:22 1996
From: predo at dist.dist.unige.it (Paolo Predonzani)
Date: Mon, 30 Sep 1996 13:56:22 +0100 (MET)
Subject: FW: AW: Re: digital contents
In-Reply-To: <9609212307.AA44495@horus.sara.nl> from "Eli Brandt" at Sep 20, 96 11:03:33 pm
Message-ID: <199609301256.NAA13393@dist.dist.unige.it>

> 
> Seconded!  I'm very interested in the techniques you used to introduce
> the non-linearity into the analysis.  Probably I don't have the
> background to understand it, though -- is there a text or review
> article that could get me up to speed?  I'd like to see any code or
> analysis that you feel is in a releasable state.  (For that matter,
> this sounds like publishable work.)
> 
Sorry for my late reply.
The interesting books are:

R.W.Hamming,E.A.Feigenbaum,Introduction to applied numerical analysis,
 McGraw-Hill,1971 (numerical solutions for integration, differential
 equations, conditioning (= solution stability))

P.Antognetti,G.Massobrio,Semiconductor device modeling with SPICE,
 McGraw-Hill,1987 (diodes, BJTs, JFETs, IGFETs, how they work and how to
 model them)

Some technical documentation on SPICE's routines may be useful but I could
never find it. Source code is available somewhere.
These books are practical even if source code is not printed.


> --
>    Eli Brandt
>    eli+ at cs.cmu.edu
> 

If you are at the cmu it shouldn't be difficult for you to find them.

-- 
+-------------------+----------------------------------+
| Paolo Predonzani  |  email: predo at dist.dist.unige.it |
+-------------------+----------------------------------+




From vco at mindspring.com  Mon Sep 30 17:15:26 1996
From: vco at mindspring.com (tomg)
Date: Mon, 30 Sep 1996 11:15:26 -0400
Subject: efm - tomg - ect..
Message-ID: <199909280541.BAA07810@stsml01.atl.mediaone.net>

Just to let you know xavax is back online. so the efm pages
are now working again, efm-list too. I finally got moved this weekend.
but everything is in boxes. I'll get the Seq2 boards and tempcos 
out tomorrow....  I'll take orders on the vca5 and maybe the vcf8
hopefully by this Friday. Depending on whether on not I can
impliment Marjan's ms-20 switching scheme by then. Look for 
my email address to change by the 1st. I'm now off dialup and 
on broadband....Wow!

http://www.xavax.com/efm

-tg




From vco at mindspring.com  Mon Sep 30 17:15:35 1996
From: vco at mindspring.com (tomg)
Date: Mon, 30 Sep 1996 11:15:35 -0400
Subject: Oldie Hello and ASM-1 homepage
Message-ID: <199909280541.BAA07813@stsml01.atl.mediaone.net>

Hi Magnus, Welcome Back!
-tg




From gstopp at fibermux.com  Mon Sep 30 18:26:00 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Mon, 30 Sep 96 09:26:00 PDT
Subject: Future of ic's (DIL versus SMD)?
Message-ID: <9608308441.AA844101432@ccrelay.fibermux.com>

     It's a good question so when I got a chance I ran it by one of our 
     distributor representatives (who visits us at work every day or two). 
     He said that the dual-in-line package is here to stay, for several 
     reasons, including third-world country factories and support of 
     existing DIL assembly machinery. However one can expect longer 
     ordering lead-times for some components. We will see...
     
     They do make sockets for SM parts, to fit them into thru-hole 
     patterns. They're not cheap, however.
     
     I've soldered wires directly to SM chips and suspended them in mid-air 
     with the wires. Needless to say this is not a very elegant solution 
     and is prone to damage when breathed upon.
     
     Hand-soldering of SM chips is not too difficult, as long as the PCB 
     has sharp and clearly-defined and well-tinned pads. Unfortunately I 
     don't think you can make your own PCB's to such tolerances at home. 
     Once the SM parts are installed, removal can be a big problem. While 
     it is easy to remove a resistor or capacitor, anything with more than 
     two terminals requires special tools which I have not tried myself.
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Future of ic's (DIL versus SMD)?
Author:  Rick Jansen <rick at sara.nl> at ccrelayout
Date:    9/26/96 12:42 PM


In message <960926161431.ZM6807 at eipc22> you write: 
> 
> The way things are going in industry, in 5 to 10 years time it 
> may be a tough job finding any non-smt components. Maybe we'll 
> all be forced to hang up our soldering irons... 
     
Interesting point! I have no idea wether DIL chips are an 
on-going concern for the semiconductor companies... 
Personally I have never tried to build something with SMD's, 
though Elektor has published a few (very few) projects with 
them.
     
Anyone with an insight in the future of devices in the regular 
DIL packages?




From rbussell at lucent.com  Mon Sep 30 19:44:30 1996
From: rbussell at lucent.com (robin bussell)
Date: Mon, 30 Sep 1996 17:44:30 +0000
Subject: Future of ic's (DIL versus SMD)?
References: <9608308441.AA844101432@ccrelay.fibermux.com>
Message-ID: <324FF8EE.5128@mlsma.mlm.lucent.com>

re: Surface Mount Devices

 
>      it is easy to remove a resistor or capacitor, anything with more than 
>      two terminals requires special tools which I have not tried myself.
>      

You can achieve reasonable success with a bit of fine brass shim, slip
it under the pins as you melt the solder.. it's not easy but it is
cheap!

  Robin.



From rbussell at lucent.com  Mon Sep 30 20:06:10 1996
From: rbussell at lucent.com (robin bussell)
Date: Mon, 30 Sep 1996 18:06:10 +0000
Subject: Hacking stomp boxes..
Message-ID: <324FFE02.3DDE@mlsma.mlm.lucent.com>

Regarding a thread of a while back about hacking into guitar effects
units I thought I'd see if anyone else had tried this:

Here's a very easy mod for any cheap digital delay
pedals you may have ( I used an Arion ). Take a peek inside and see
if it uses a ram chip that you recognise, many have a 41256, if so then
you can look up the pinout and find the write enable pin. A quick
cutting of the pin and wiring a switch in results in an 'infinite hold'
feature.
You may need to put in a pullup resistor as well as some chips don't
respond very well to just having the pin disconnected.
In my case I was also able to double the maximum available delay time by
fiddling with a preset in the clock circuit, without the filter being
changed this results in some very interesting noises :)

I daresay feeding a vco clock into the thing would also be worthwhile..
hmmmmmm!

For anyone who tries this on the arion beware that the metal shielding
bracket that needs to be removed to get at the RAM actually acts as part
of the ground circuit and stops things working until you put it back..
had me going for a while :-)

 Cheers,
      Robin.



From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Mon Sep 30 20:15:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 30 Sep 96 11:15:00 PDT
Subject: AW: Re: CV Clock to Seqn
Message-ID: <32500E3B@MSMGATE.M30X.NBG.SCN.DE>


>  Why build a clock into your sequencer? (I assume we're talking analog
>  sequencers here - right?)
>
>  I mean, you're going to want it in sync with your other gear - right? So
>  much of the time you'll be clocking it from a drum machine trigger signal
>  - or a gate out from a MIDI-CV, or something - don't you think?
>
>  Put your energy into building a separate CV-able LFO module with a pulse
>  output (as well as triangle, saw, etc) - rather than building this into
>  your sequencer. Then I think you'll find that this LFO will get used a
>  lot more on it's own to drive other stuff than it will working as a clock
>  for your sequencer. As far as linear or exp. scaling goes, if you want
>  the LFO to do audio range stuff, it's exponential...
>
>  - CList

Good points, but sometimes you find an internal clock very handy,
especially when you want to use one row for note duration. You
can build in a single switch for this, instead of routing a CV to an
external clock VCO and back.
You need expo control for note duration stuff as well, cause you want
your eighths and quarters stay eighths and quarters when you change
the tempo ... ok, this can work with a linear clock as well, but then you 
need
an extra multiplier ...
In my own system, I use CList's method (external clock) so far, but only
because my current sequencer module is a very small one.
But if I will ever come to build the big one which I have planned, it will
have an internal clock with all extras you can think of. The idea is
to make this clock the master of all - you won't find other clock sources
where you can program a "swing" feelig just with one row of analogue
CV's that easy!
Another idea is making it syncable to an external clock, but setting
the pulse width (= gate time) independently: Sync an internal SAW
 VCO to external pulses, but add an internal loop to keep the SAW
amplitude constant. Then derive the Gate Time from this SAW.

JH.





From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Mon Sep 30 20:20:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 30 Sep 96 11:20:00 PDT
Subject: AW: CV Clock Pt.II - PW. CVPWM
Message-ID: <32500F73@MSMGATE.M30X.NBG.SCN.DE>


>OK, I think I've decided on a design for the sequencer's clock.  It lacks
>one thing, though and that is a pulse width control, as well as a CV
>input for pulse width.  What I'd like to do is split the clock's output
>into five channels, one for clocking the sequencer, the other four to
>provide a gate output for each row.  I'd like each row to have
>independent note lengths, either controlled by a PW knob (as on the SQ10,
>ARP 1601, etc) or a CV input (as on the ARP).
>
>I'd appreciate any second opinions, as well as any leads to a simpler
>approach, if there is one.

Sorry for the second mail on this topic, but I sent my other one out before 
I read
this.
I suggest doing the PW stuff exactly the same way as you would in an audio 
range VCO: Use a SAW VCO and a Comparator. You can even use the
Hard Sync input of this VCO to sync it to an external clock source.

JH.



From sscprick at horus.sara.nl  Mon Sep 30 21:08:25 1996
From: sscprick at horus.sara.nl (Rick Jansen)
Date: Mon, 30 Sep 1996 21:08:25 +0200
Subject: Future of ic's (DIL versus SMD)? 
In-Reply-To: Your message of Mon, 30 Sep 1996 09:26:00 MET DST.
             <9608308441.AA844101432@ccrelay.fibermux.com>
Message-ID: <199609301908.VAA134419@horus.sara.nl>


In message <9608308441.AA844101432 at ccrelay.fibermux.com> you write:

>      He said that the dual-in-line package is here to stay

Well, that sounds sort of ok...

>      They do make sockets for SM parts, to fit them into thru-hole 
>      patterns. They're not cheap, however.

When something is made in big enough quantities prices will
come down. I hadn't thought of this solution yet. Maybe 
a small tool could be marketed which will solder thin wires
to SMD's, so they can be used for diy or breadboarding
purposes. Should I copyright this? :)

Thanks for the info!

Rick Jansen
__
rick at sara.nl   http://www.sara.nl/Rick.Jansen
_____________________________________________
S&H's a module and s&h's looking good




From HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de  Mon Sep 30 21:55:00 1996
From: HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de (Haible_Juergen#Tel2743)
Date: Mon, 30 Sep 96 12:55:00 PDT
Subject: pictures of my homebuilt stuff
Message-ID: <325025FC@MSMGATE.M30X.NBG.SCN.DE>


Hi!

I have made several photos of my little "studio", including some closeups
of my own homebuilt stuff (Panels of JH-4 modules etc.).
Sometimes people ask me if they can look at this, and so I wonder if
there is a way to put them somewhere on some Web page.
One friendly person already offered me a free Web page all for my own,
but the problem is: I have no private net access, and I would not (ab)use
my employer's for this. So what I am really looking for is someone I can
send the photos to, who would be willing to scan them and put them
into some archive (Music Machines or something similar).
If this works well, I would also be willing to give away schematic diagrams
and PCB layouts of some of my homebuilt stuff to be published there.
All I need is someone I could send the printed stuff to, who would be
willing to make high quality scans of it and put it to the web space.
Would anybody liketo do this (I know it would mean some
amount of work ...) ??

JH.



From gstopp at fibermux.com  Mon Sep 30 22:29:20 1996
From: gstopp at fibermux.com (gstopp at fibermux.com)
Date: Mon, 30 Sep 96 13:29:20 PDT
Subject: Future of ic's (DIL versus SMD)? 
Message-ID: <9608308441.AA844116010@ccrelay.fibermux.com>

     Yes please invent something! Doing it by hand makes me cross-eyed.
     
     The sockets I've used come in two pieces - first, you lay the SM 
     device in a little "bed", then you clamp a little frame over it that 
     presses the pins into contacts. I've seen others that use two little 
     doors that open up, allowing you to place the SM device inside, and 
     then you close the doors to trap the device.
     
     The type with the doors is actually a SM part itself, so it doesn't 
     make too much sense for breadboarders, but it does allow you to swap 
     out the part easily (for example, when used with FLASH).
     
     - Gene


______________________________ Reply Separator _________________________________
Subject: Re: Future of ic's (DIL versus SMD)? 
Author:  Rick Jansen <rick at sara.nl> at ccrelayout
Date:    9/30/96 12:28 PM
     
When something is made in big enough quantities prices will 
come down. I hadn't thought of this solution yet. Maybe 
a small tool could be marketed which will solder thin wires 
to SMD's, so they can be used for diy or breadboarding 
purposes. Should I copyright this? :)




