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Quadrature Oscillator

2004-06-07 by paradigmshiftbeats

A few questions about this module:

1) I have read comments about the NTO/PCO not having "pure" sine
waves due to the waveshapers used in these modules. Does the QUO
utilize the same circuits or does it in fact produce true sines?

2) Does the 1v/oct tracking function accurately enough to use as an
audio sine wave oscillator, i.e as sub-osc enhancement or ring mod
source?

3) Anyone care to share their experiences using the "hold" or "VCA
gain" inputs?

Re: Quadrature Oscillator

2004-06-07 by john duval

I use my QUOs for Xfading, paning and anywhere else
that requires a smooth transistion... fast or slow.
The VC gain and hold functions are just the thing to
stop the swirling in "mid air" so to speak and the
gain control is great for controling the voltage swing
by making it as subtle as you want. This doesn't help
you a bit i'll bet. Read the wizardry section on the
EGRES page. When i read it long ago it didn't make a
lick of sense until i started experimenting with
them.Now i can't live without them... hence i have at
least 10 in my system. Overkill??... not at all.
kind regards
john duval

Show quoted textHide quoted text

--- paradigmshiftbeats <c.d.sawyer@...> wrote:

> A few questions about this module:
>
> 1) I have read comments about the NTO/PCO not having
> "pure" sine
> waves due to the waveshapers used in these modules.
> Does the QUO
> utilize the same circuits or does it in fact produce
> true sines?
>
> 2) Does the 1v/oct tracking function accurately
> enough to use as an
> audio sine wave oscillator, i.e as sub-osc
> enhancement or ring mod
> source?
>
> 3) Anyone care to share their experiences using the
> "hold" or "VCA
> gain" inputs?
>
>
>
>

__________________________________
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Re: Quadrature Oscillator

2004-06-07 by John P

I don't have one but I believe that it's the same circuit that's used in
the frequency shifter.
The sine wave has to be very pure for that. I would think that the
v/oct would be accurate/useful for most audio & musical applications as
well as control.

Anybody else?

paradigmshiftbeats wrote:

Show quoted textHide quoted text

>A few questions about this module:
>
>1) I have read comments about the NTO/PCO not having "pure" sine
>waves due to the waveshapers used in these modules. Does the QUO
>utilize the same circuits or does it in fact produce true sines?
>
>2) Does the 1v/oct tracking function accurately enough to use as an
>audio sine wave oscillator, i.e as sub-osc enhancement or ring mod
>source?
>
>3) Anyone care to share their experiences using the "hold" or "VCA
>gain" inputs?
>
>
>
>
>
>
>Keep on Patchin'!
>
>Yahoo! Groups Links
>
>
>
>
>
>
>

--
m/n/m/l
surreal electronic music, sound, noise
http://mnml.soulcatcher.net

Re: Quadrature Oscillator

2004-06-07 by metafoetus2002

"hence I have at least 10 [QUOs]"now that's a recommendation :-)

Now are the 2 sine wave outputs bipolar, or unipolar? So if I'd use these f=
or vibrato,
would my received pitch stay centered (increasing modulation amount just ma=
kes the
vibrato more intense, but does not shift the perceived center pitch)?

Curious regards,
Jan-Hinnerk

--- In SergeModular@yahoogroups.com, john duval <darkstr717@y...>
wrote:

Show quoted textHide quoted text

> I use my QUOs for Xfading, paning and anywhere else
> that requires a smooth transistion... fast or slow.
> The VC gain and hold functions are just the thing to
> stop the swirling in "mid air" so to speak and the
> gain control is great for controling the voltage swing
> by making it as subtle as you want. This doesn't help
> you a bit i'll bet. Read the wizardry section on the
> EGRES page. When i read it long ago it didn't make a
> lick of sense until i started experimenting with
> them.Now i can't live without them... hence i have at
> least 10 in my system. Overkill??... not at all.
> kind regards
> john duval
>
>
> --- paradigmshiftbeats <c.d.sawyer@t...> wrote:
> > A few questions about this module:
> >
> > 1) I have read comments about the NTO/PCO not having
> > "pure" sine
> > waves due to the waveshapers used in these modules.
> > Does the QUO
> > utilize the same circuits or does it in fact produce
> > true sines?
> >
> > 2) Does the 1v/oct tracking function accurately
> > enough to use as an
> > audio sine wave oscillator, i.e as sub-osc
> > enhancement or ring mod
> > source?
> >
> > 3) Anyone care to share their experiences using the
> > "hold" or "VCA
> > gain" inputs?
> >
> >
> >
> >
>
>
>
>
>
> __________________________________
> Do you Yahoo!?
> Friends. Fun. Try the all-new Yahoo! Messenger.
> http://messenger.yahoo.com/

Re: Quadrature Oscillator

2004-06-07 by Carbon111

> Now are the 2 sine wave outputs bipolar, or unipolar? So if I'd use these f=
>
> or vibrato,
> would my received pitch stay centered (increasing modulation amount just ma=
>
> kes the
> vibrato more intense, but does not shift the perceived center pitch)?

Black outputs = AC = Bipolar
Blue outputs = DC = Unipolar
Red outputs = Gate

The QUO is an *excellent* choice for vibrato as it does not shift the center pitch.
FWIW - For folks (like me) who do not have a QUO, you can make one out of a VCFQ by making a feedback loop from the band output into the regular (non-AGC)input - you'll get perfect sines 90 degrees out of phase from each other...yummy!
Best Regards, James
--
http://www.carbon111.com

Re: Quadrature Oscillator

2004-06-07 by John P

Since the linear FM inputs are ac coupled, that's all that matters. Any
oscillator patched into them will have the offset removed.

metafoetus2002 wrote:

Show quoted textHide quoted text

>"…hence I have at least 10 [QUOs]…"…now that's a recommendation :-)
>
>Now are the 2 sine wave outputs bipolar, or unipolar? So if I'd use these f=
>
>or vibrato,
>would my received pitch stay centered (increasing modulation amount just ma=
>
>kes the
>vibrato more intense, but does not shift the perceived center pitch)?
>
>Curious regards,
>Jan-Hinnerk
>
>--- In SergeModular@yahoogroups.com, john duval <darkstr717@y...>
>wrote:
>
>
>>I use my QUOs for Xfading, paning and anywhere else
>>that requires a smooth transistion... fast or slow.
>>The VC gain and hold functions are just the thing to
>>stop the swirling in "mid air" so to speak and the
>>gain control is great for controling the voltage swing
>>by making it as subtle as you want. This doesn't help
>>you a bit i'll bet. Read the wizardry section on the
>>EGRES page. When i read it long ago it didn't make a
>>lick of sense until i started experimenting with
>>them.Now i can't live without them... hence i have at
>>least 10 in my system. Overkill??... not at all.
>>kind regards
>>john duval
>>
>>
>>--- paradigmshiftbeats <c.d.sawyer@t...> wrote:
>>
>>
>>>A few questions about this module:
>>>
>>>1) I have read comments about the NTO/PCO not having
>>>"pure" sine
>>>waves due to the waveshapers used in these modules.
>>>Does the QUO
>>>utilize the same circuits or does it in fact produce
>>>true sines?
>>>
>>>2) Does the 1v/oct tracking function accurately
>>>enough to use as an
>>>audio sine wave oscillator, i.e as sub-osc
>>>enhancement or ring mod
>>>source?
>>>
>>>3) Anyone care to share their experiences using the
>>>"hold" or "VCA
>>>gain" inputs?
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>__________________________________
>>Do you Yahoo!?
>>Friends. Fun. Try the all-new Yahoo! Messenger.
>>http://messenger.yahoo.com/
>>
>>
>
>
>
>
>Keep on Patchin'!
>
>Yahoo! Groups Links
>
>
>
>
>
>
>

--
m/n/m/l
surreal electronic music, sound, noise
http://mnml.soulcatcher.net

Re: Quadrature Oscillator

2004-06-07 by john duval

you have it... it just makes it more intense. that's
the beauty of it. You can VC the intensity(depth) and
you can VC the speed. Now when you combine that
feature with the ability to stop the vibrato and the
panning at the same time, if things are spinning
rather fast, it's a dramatic effect. Add a little
panned delay/chorus at the desk and you have a nice
little effect
--- metafoetus2002 <jan-hinnerk.helms@...>
wrote:

Show quoted textHide quoted text

> "�hence I have at least 10 [QUOs]�"�now that's a
> recommendation :-)
>
> Now are the 2 sine wave outputs bipolar, or
> unipolar? So if I'd use these f=
> or vibrato,
> would my received pitch stay centered (increasing
> modulation amount just ma=
> kes the
> vibrato more intense, but does not shift the
> perceived center pitch)?
>
> Curious regards,
> Jan-Hinnerk
>
> --- In SergeModular@yahoogroups.com, john duval
> <darkstr717@y...>
> wrote:
> > I use my QUOs for Xfading, paning and anywhere
> else
> > that requires a smooth transistion... fast or
> slow.
> > The VC gain and hold functions are just the thing
> to
> > stop the swirling in "mid air" so to speak and the
> > gain control is great for controling the voltage
> swing
> > by making it as subtle as you want. This doesn't
> help
> > you a bit i'll bet. Read the wizardry section on
> the
> > EGRES page. When i read it long ago it didn't make
> a
> > lick of sense until i started experimenting with
> > them.Now i can't live without them... hence i have
> at
> > least 10 in my system. Overkill??... not at all.
> > kind regards
> > john duval
> >
> >
> > --- paradigmshiftbeats <c.d.sawyer@t...> wrote:
> > > A few questions about this module:
> > >
> > > 1) I have read comments about the NTO/PCO not
> having
> > > "pure" sine
> > > waves due to the waveshapers used in these
> modules.
> > > Does the QUO
> > > utilize the same circuits or does it in fact
> produce
> > > true sines?
> > >
> > > 2) Does the 1v/oct tracking function accurately
> > > enough to use as an
> > > audio sine wave oscillator, i.e as sub-osc
> > > enhancement or ring mod
> > > source?
> > >
> > > 3) Anyone care to share their experiences using
> the
> > > "hold" or "VCA
> > > gain" inputs?
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> >
> > __________________________________
> > Do you Yahoo!?
> > Friends. Fun. Try the all-new Yahoo! Messenger.
> > http://messenger.yahoo.com/
>
>

__________________________________
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Re: Quadrature Oscillator

2004-06-07 by john duval

Oh yea... been so long since i used that approach, i
forgot. Adds its own little dimension doesn't it.
You'd think they would be the same but somehow it's
just a little different. Kinda like,what flavor is
chocolate.
kind regards
john duval

Show quoted textHide quoted text

--- Carbon111 <carbon111@...> wrote:

>
> > Now are the 2 sine wave outputs bipolar, or
> unipolar? So if I'd use these f=
> >
> > or vibrato,
> > would my received pitch stay centered (increasing
> modulation amount just ma=
> >
> > kes the
> > vibrato more intense, but does not shift the
> perceived center pitch)?
>
> Black outputs = AC = Bipolar
> Blue outputs = DC = Unipolar
> Red outputs = Gate
>
> The QUO is an *excellent* choice for vibrato as it
> does not shift the center pitch.
> FWIW - For folks (like me) who do not have a QUO,
> you can make one out of a VCFQ by making a feedback
> loop from the band output into the regular
> (non-AGC)input - you'll get perfect sines 90 degrees
> out of phase from each other...yummy!
> Best Regards, James
> --
> http://www.carbon111.com
>
>

__________________________________
Do you Yahoo!?
Friends. Fun. Try the all-new Yahoo! Messenger.
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Re: Quadrature Oscillator

2004-06-07 by John P

Another side note: for those without the QUO but who have an SSG - the
'Smooth' section can be patched as an oscillator, and 'hold' will stop
the waveform in its tracks, just like the QUO... but with the Smooth
section you're getting a triangle, not a sinewave.

Now, how many other synthmakers offer 2 different modules that can do that?

john duval wrote:

Show quoted textHide quoted text

>Oh yea... been so long since i used that approach, i
>forgot. Adds its own little dimension doesn't it.
>You'd think they would be the same but somehow it's
>just a little different. Kinda like,what flavor is
>chocolate.
>kind regards
>john duval
>--- Carbon111 <carbon111@...> wrote:
>
>
>>>Now are the 2 sine wave outputs bipolar, or
>>>
>>>
>>unipolar? So if I'd use these f=
>>
>>
>>>or vibrato,
>>>would my received pitch stay centered (increasing
>>>
>>>
>>modulation amount just ma=
>>
>>
>>>kes the
>>>vibrato more intense, but does not shift the
>>>
>>>
>>perceived center pitch)?
>>
>>Black outputs = AC = Bipolar
>>Blue outputs = DC = Unipolar
>>Red outputs = Gate
>>
>>The QUO is an *excellent* choice for vibrato as it
>>does not shift the center pitch.
>>FWIW - For folks (like me) who do not have a QUO,
>>you can make one out of a VCFQ by making a feedback
>>loop from the band output into the regular
>>(non-AGC)input - you'll get perfect sines 90 degrees
>>out of phase from each other...yummy!
>>Best Regards, James
>>--
>>http://www.carbon111.com
>>
>>
>>
>>
>
>
>
>
>
>__________________________________
>Do you Yahoo!?
>Friends. Fun. Try the all-new Yahoo! Messenger.
>http://messenger.yahoo.com/
>
>
>
>Keep on Patchin'!
>
>Yahoo! Groups Links
>
>
>
>
>
>
>

--
m/n/m/l
surreal electronic music, sound, noise
http://mnml.soulcatcher.net

Re: Quadrature Oscillator

2004-06-08 by John Loffink

True, but ideally you want vibrato at the exponential FM input so the pitch
range is balanced on both high and low cycles, though I suppose for mild
vibratos it may not matter.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: John P [mailto:johnp299792@...]
>
> Since the linear FM inputs are ac coupled, that's all that matters. Any
> oscillator patched into them will have the offset removed.
>

Re: Quadrature Oscillator

2004-06-08 by John Loffink

I have the QUO. I don't know if it is the same circuit as the Frequency
Shifter. The one on the Serge FS that I played with 4 years ago seemed to
have a wider range.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: John P [mailto:johnp299792@...]
>
> I don't have one but I believe that it's the same circuit that's used in
> the frequency shifter.
> The sine wave has to be very pure for that. I would think that the
> v/oct would be accurate/useful for most audio & musical applications as
> well as control.
>

Re: Quadrature Oscillator

2004-06-08 by John Loffink

The QUO is especially nice for panning since the Serge panning VCs lack
attenuators, while the QUO essentially has them built in. This allows
moderate panning effects rather than full left to right panning.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: john duval [mailto:darkstr717@...]
> Sent: Sunday, June 06, 2004 10:35 PM
> To: SergeModular@yahoogroups.com
> Subject: Re: [SergeModular] Quadrature Oscillator
>
> I use my QUOs for Xfading, paning and anywhere else
> that requires a smooth transistion... fast or slow.
> The VC gain and hold functions are just the thing to
> stop the swirling in "mid air" so to speak and the
> gain control is great for controling the voltage swing
> by making it as subtle as you want. This doesn't help
> you a bit i'll bet. Read the wizardry section on the
> EGRES page. When i read it long ago it didn't make a
> lick of sense until i started experimenting with
> them.Now i can't live without them... hence i have at
> least 10 in my system. Overkill??... not at all.
> kind regards
> john duval
>
>

Re: Quadrature Oscillator

2004-06-08 by John Loffink

That is a good approach if you don't have the QUO. However, I believe the
QUO is probably quadrature phase triangle wave based with sine wave shapers
on the outputs. When I used the hold function, I noticed the sine wave
always resumes where it left off in the cycle, not where it would have been
had the wave been free running as in a filter oscillator type circuit.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: Carbon111 [mailto:carbon111@...]
> FWIW - For folks (like me) who do not have a QUO, you can make one out of
> a VCFQ by making a feedback loop from the band output into the regular
> (non-AGC)input - you'll get perfect sines 90 degrees out of phase from
> each other...yummy!
> Best Regards, James
> --

Re: Quadrature Oscillator

2004-06-08 by sasami@hotkey.net.au

> From: "paradigmshiftbeats" <c.d.sawyer@...>

>A few questions about this module:
>
>1) I have read comments about the NTO/PCO not having "pure" sine
>waves due to the waveshapers used in these modules. Does the QUO
>utilize the same circuits or does it in fact produce true sines?

That would be expected. The sine generator is the exact same generator as
used in the tripple wave shaper and the original VCOs. In my experience, it
leaves a glitch or at best, some distortion.

Ken
_______________________________________________________________________
Ken Stone sasami@... or sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: Quadrature Oscillator

2004-06-08 by John Loffink

I see a barely noticeable peak/spike at the top of my 2002 era NTO sine wave
outputs. This doesn't seem like it would add much harmonics. The overall
shape is a little more rounded than a sine wave, but this is typical of sine
waves shaped from triangle waves.

If I get a chance I'll run this through Wavelab's FFT and see what the
harmonic content is.

My 1995 era QUO sine output does not have the spike, and the shape looks
pure sine to me. Maybe Serge did use a high Q filter circuit for this
despite the hold function. Now I'm getting curious.

My QUO frequency tops out at 577 Hz, even with maximum VC input, so this has
limited use as an audio oscillator.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: sasami@... [mailto:sasami@...]
> >
> >1) I have read comments about the NTO/PCO not having "pure" sine
> >waves due to the waveshapers used in these modules. Does the QUO
> >utilize the same circuits or does it in fact produce true sines?
>
> That would be expected. The sine generator is the exact same generator as
> used in the tripple wave shaper and the original VCOs. In my experience,
> it
> leaves a glitch or at best, some distortion.
>

Re: Quadrature Oscillator

2004-06-08 by Peter Grenader

John Loffink wrote:

> I see a barely noticeable peak/spike at the top of my 2002 era NTO sine wave
> outputs. This doesn't seem like it would add much harmonics. The overall
> shape is a little more rounded than a sine wave, but this is typical of sine
> waves shaped from triangle waves.

I believe the NTO is saw core, not tri core. This means Serge first had to
shape a triangle, then from that triangle he shaped the sine. Is the saw
and sine out of the PCO/NTOs in the same phase relation? I bet not.

I believe this is where the bump is coming from in the NTO's sine - the
triangle. I say this because the sine shaper he used (close derivative of
the Thomas Henry's circuit) is considered the best of all of them. Grant
Richter pointed out recently what a glorious result this shaper has when
coming off a triangle core VCO, such as the Wiard and Aries, among others.
One of those others was made by Jurgen Bergfors and in that his sine shaper
is driven by a current mirror I believe he used the Henry design as well and
his sines are picture perfect . To see just how perfect, go here for a
pciture:

http://hem.bredband.net/bersyn/vco.htm

Another Henry user was Nyle Steiner and the Steiner-Parker sines are by far
the cleanest I've ever heard. I'm not at a Steiner Schematic right now to
verify if his circuit was saw or triangle core however.

If I remember correctly Serge's sines look a lot like the Analogue Systems
variety, a sort of a rounded square wave. Analogue System used a completely
different method for sine shaping, the differential amplifier shaper found
in Electronotes Vol. 1 which among hard-core synth DIY'ers is considered the
less pure of all of them.

This leaves one other that I know of - the diode method used by Buchla
which if done right (as he did) will also yield an extremely clean sinewave.
This was not Buchla's design. Electronotes credits this as first appearing
in Electronics Magazine in 1965. Two diodes forced into non-linearilty,
then to an FET. I've played around with this circuit and if I were to
produce a VCO, this is the one I'd use. Less parts and impressive fidelity
across the entire frequency spectrum.

Off soap box.

- Peter

Re: Quadrature Oscillator

2004-06-08 by Mattias Rickardsson

From: "John Loffink" <jloffink@...>

>
>> Since the linear FM inputs are ac coupled, that's all that matters.
>> Any oscillator patched into them will have the offset removed.
>
> True, but ideally you want vibrato at the exponential FM input
> so the pitch range is balanced on both high and low cycles,
> though I suppose for mild vibratos it may not matter.

If I remember correctly from a discussion on SAS (Analogue Heaven's
Swedish sister) some years ago, the implementation of linear FM in a VCO
core can be done in more than one way, one of which resulting in a "scaled
linear FM" where the scale factor of the linear FM depends of the
frequency set by the exponential CV inputs.

Maybe this mechanism could be used to keep the depth of the vibrato
between notes, but still have the vibrato in a non-offsetting linear FM
fashion? :-)

/mr

Re: Quadrature Oscillator

2004-06-08 by Steve Ridley

> I believe the NTO is saw core, not tri core. This means Serge first had

> shape a triangle, then from that triangle he shaped the sine. Is the saw
> and sine out of the PCO/NTOs in the same phase relation? I bet not.

One of the catalogues on the SMOG site (the 70s one)
shows the phase relationships. Can't remember if the
Sine out and NTO Variable out set to sine have the same
phase.

steve

Re: Quadrature Oscillator

2004-06-08 by Peter Grenader

Steve Ridley wrote:

> Can't remember if the
> Sine out and NTO Variable out set to sine have the same
> phase.

I belivee they would be - as the variable out is a quad panner in reverse
(or so it seems form the unit I had for repair). So it takes the four
waveshapes and pans between them. I was talking about the triangle and sine
being out of phase.

- P

Re: Quadrature Oscillator

2004-06-09 by John Loffink

On my NTO, sine and triangle are 180 degrees out of phase with one another.
This could just be from an extra inverting op amp in the circuit.

The sawtooth edge coincides with the peak of the sine wave, where the slight
discontinuity is seen.

Sine and sawtooth position on the variable wave output look nothing like the
normal sine and sawtooth outputs, or any mix in between.

Sine out and variable out set to sine have different phases, 180 degrees
apart. The variable "sine" peak is much sharper than the valley.

I maintain that the variable out can't be a quad crossfader. For instance,
the square to pulse transition changes the pulse width of the waveform from
about 40% to 90%. It does not create a stairstep in the intermediate
position as you would get by crossfading square and pulse waveforms.

What was the vintage of the NTO you repaired?

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: Peter Grenader [mailto:peter@...]
> Sent: Tuesday, June 08, 2004 6:28 PM
> To: SergeModular@yahoogroups.com
> Subject: Re: [SergeModular] Re: Quadrature Oscillator
>
> Steve Ridley wrote:
>
> > Can't remember if the
> > Sine out and NTO Variable out set to sine have the same
> > phase.
>
>
> I belivee they would be - as the variable out is a quad panner in reverse
> (or so it seems form the unit I had for repair). So it takes the four
> waveshapes and pans between them. I was talking about the triangle and
> sine
> being out of phase.
>
> - P
>

Re: Quadrature Oscillator

2004-06-09 by Peter Grenader

John Loffink wrote:

> It does not create a stairstep in the intermediate
> position as you would get by crossfading square and pulse waveforms.
>
> What was the vintage of the NTO you repaired?

First gen I would assume - it was in the system Darrel made for himself.
Late 70's- early 80's.

<<t does not create a stairstep in the intermediate position as you would
get by crossfading square and pulse waveforms. ..

I can't post the schematic. But from the one I have, it sure looks like a
crossfader to me. Put it this way...the waveshape circuit has four inputs.
Sine, pulse, saw, tri - those come from the non-variable outs of each of the
four. All four are gated through 3080's to a summed output which becomes
the variable out. The four 3080's are controlled (pin 5) by a single source
(pot or VC input) through a series of op amps (this part of my explanation
is simplified). Each of the four op amps have a different ref voltage -
hence, they fade on at different voltage thresholds from a single source.

Now who knows if this schematic is correct. I didn't have to repair this
function of the NTO and did not 'test' this part of the diagram - but I did
use it to repair another section of the VCO and it proved accurate.

In any event, there is no apparent waveshaping going on here. This has
already occurred by the time these four signals go into this crossfader.

If you're not seeing what you expect as far as the morphed waveshapes, keep
in mind the four are not in phase relation to one another. if you take that
shift into account, possibly it will prove this theory?

- Peter

Re: Quadrature Oscillator

2004-06-09 by Steve Ridley

> Now who knows if this schematic is correct. I didn't have to repair this
> function of the NTO and did not 'test' this part of the diagram - but I did
> use it to repair another section of the VCO and it proved accurate.

I've never seen a schematic of the NTO waveshaper, but I've
seen the circuit board of a (later) NTO and there aren't enough
3080s for it to be a crossfader. There is an LM3900 like in the
TWS, so I'd _guess_ it could be based on that. Maybe Serge
changed the design at some stage...

Steve

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Re: Quadrature Oscillator

2004-06-09 by Ken Stone

--- In SergeModular@yahoogroups.com, Peter Grenader <peter@b...>

Show quoted textHide quoted text

> I can't post the schematic. But from the one I have, it sure

looks like a

> crossfader to me. Put it this way...the waveshape circuit has four

inputs.

> Sine, pulse, saw, tri - those come from the non-variable outs of

each of the

> four. All four are gated through 3080's to a summed output which

becomes

> the variable out. The four 3080's are controlled (pin 5) by a

single source

> (pot or VC input) through a series of op amps (this part of my

explanation

> is simplified). Each of the four op amps have a different ref

voltage -

> hence, they fade on at different voltage thresholds from a single

source.

That sounds like the circuit I reverse engineered from my DRISCOLL
NTO - it isn't the same thing as the Serge one. Driscoll VCOs are
very similar as far as offerend functionality is concerned, but white
different when you get down to the nitty gritty of it all.

(note - I said sounds like - I haven't seen a Serge schematic for an
NTO, though from fuzzy little photo of the sucker, there didn't
appear to be an array of 3080s.)

Ken

Re: Quadrature Oscillator

2004-06-09 by John Loffink

Think about it. How could you create a variable pulse from 40 to 90% just
by crossfading two waveforms no matter what their phase relationship was?

From your description, it does sound like the NTO variable waveshape circuit
has changed.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

Show quoted textHide quoted text

> -----Original Message-----
> From: Peter Grenader [mailto:peter@...]
> If you're not seeing what you expect as far as the morphed waveshapes,
> keep
> in mind the four are not in phase relation to one another. if you take
> that
> shift into account, possibly it will prove this theory?
>
> - Peter

Re: Quadrature Oscillator

2004-06-09 by Peter Grenader

Probably not. The schematic I had has been mentioned here - so possibly it
ain't the real deal. I've got a four panel coming over in a couple of
weeks. It's got three NTOs and it's old (paper faceplates). I'll have a
look

.Steve Ridley wrote:

Show quoted textHide quoted text

>
>> Now who knows if this schematic is correct. I didn't have to repair this
>> function of the NTO and did not 'test' this part of the diagram - but I did
>> use it to repair another section of the VCO and it proved accurate.
>
> I've never seen a schematic of the NTO waveshaper, but I've
> seen the circuit board of a (later) NTO and there aren't enough
> 3080s for it to be a crossfader. There is an LM3900 like in the
> TWS, so I'd _guess_ it could be based on that. Maybe Serge
> changed the design at some stage...
>
>
>
> Steve
>

Re: Quadrature Oscillator

2004-06-09 by Scott E.

I have never heard of the "Driscoll" modules. Were these functional
copies or licensed clones? Please elaborate.

Thanks, Scott E.
===================================================
Ken Stone wrote:

Show quoted textHide quoted text

> That sounds like the circuit I reverse engineered from my DRISCOLL
> NTO - it isn't the same thing as the Serge one. Driscoll VCOs are
> very similar as far as offerend functionality is concerned, but white
> different when you get down to the nitty gritty of it all.
>
> (note - I said sounds like - I haven't seen a Serge schematic for an
> NTO, though from fuzzy little photo of the sucker, there didn't
> appear to be an array of 3080s.)
>
> Ken

Re: Quadrature Oscillator

2004-06-10 by Ken Stone

--- In SergeModular@yahoogroups.com, "Scott E." <yahudinyhwh@s...>
wrote:

Show quoted textHide quoted text

> I have never heard of the "Driscoll" modules. Were these functional
> copies or licensed clones? Please elaborate.
>
> Thanks, Scott E.

Functional copies, and in a number of cases direct rip-offs of Serge.
They were allegedly made by a Julian Driscoll in Melbourne Australia
around '79 and '80. The use PCB material painted black as the face
plates, and all text on them has been silk screened on at the PCB
house that made them. They are un-branded. The most identification
there is is "JCD79" in the bottom corner of the NTO panel.
The NTO for example, while being quite different from the Serge NTO,
uses a little "clone" VCA module to VC the FM or something like that,
where as the original serge did NOT use one of these little modules.
VCFQ is more or less a direct copy, Envelope generators are either
CEM based or directly out of Electronotes etc.

Ken