MOTM

Hey MOTM'ers,

I have a 2 osc system with a few filters, e.g.'s and 1 VCA.  So far 
I haven't done much FM with my modular b/c from what I understand, I 
need a VCA for the modulating signal, and another VCA for the 
carrier.  Since I only have 1 VCA, I've been wondering if there are 
other ways around this, such as sampling some waveforms from my 
VCO's and using the envelopes in my sampler to provide the envelope 
for the modulating signal.  Can this work?  

Does anyone have any experience working this way or have any 
suggestions?

Thanks,
-Matt

>>>>
I have a 2 osc system with a few filters, e.g.'s and 1 VCA. So far 
I haven't done much FM with my modular b/c from what I understand, I 
need a VCA for the modulating signal, and another VCA for the 
carrier. Since I only have 1 VCA, 
<<<<

If you have a MOTM-110, you actually have 2 VCAs. The Ring Mod can 
also be used as a VCA in a pinch. 


Moe

Matt writes:
>>I have a 2 osc system with a few filters, e.g.'s and 1 VCA.  So far 
I haven't done much FM with my modular b/c from what I understand, I 
need a VCA for the modulating signal, and another VCA for the 
carrier.<<

As pointed out by someone else, you don't need VCA's. I don't have a DX synth, 
but I don't remember them having VCA's for their carriers and modulators. Some 
of the DX algorithms use a bunch of operators, and that would be a hell of a 
lot of envelopes to adjust if they existed.

You may be new to the list, but I posted an MP3 a while back of the MOTM doing 
hi-hats and a kettle drum type sound (and a JP-8080 doing low piano notes) 
using FM. The pseudo bass/kettle drum sound in the "Lost at Sea" demo is an 
example. There isn't always much memory retention on these lists, but I 
probably explained the general setup and none used VCA's.  The piano sound I 
think used square waves, and the MOTM sounds used sawtooth carriers, sine 
modulators, and noise to modulate the modulators.  So depending on the sound, 
you don't have to stick with sines.

Larry Hendry writes:
>>Another waveshaping technique that is not FM, but is very cool with a VCA
and single VCO was posted to the list about a year ago by Elhardt I think.
Ken, was that you?<<

Yeah, that was me.  But with a few exceptions, most of those waveforms were 
more intesting to look at on an oscilloscope than useful at providing anything 
significantly different than the standard OSC waveforms.

Mike March writes:
>>My understanding is that Yamaha FM synthesis is actually using phase
modulation and not frequency modulation.  Am I correct?<<

No. It's called FM, because it's one sine modulating the frequency of another.  
Now I see how rumors get started.

Ken Tkacs write:
>>I thought that was Casio that used Phase Modulation...?<<

Either Casio or Technics, I can't remember which. The huge Con Brio digital 
synth also did PM.

-Elhardt

I will agree with that somewhat.  But, I am very appreciative that you
posted that.  What I found is that this method does allow one to do PWM type
sounds with the other waves, not just the standard square wave PWM.
Larry

----- Original Message -----
From: <elhardt@...>
Larry Hendry writes:
>>Another waveshaping technique that is not FM, but is very cool with a VCA
and single VCO was posted to the list about a year ago by Elhardt I think.
Ken, was that you?<<

Yeah, that was me.  But with a few exceptions, most of those waveforms were
more intesting to look at on an oscilloscope than useful at providing
anything
significantly different than the standard OSC waveforms.

On Wed, 4 Dec 2002 elhardt@... wrote:

> As pointed out by someone else, you don't need VCA's. I don't have a DX synth,
> but I don't remember them having VCA's for their carriers and modulators.

The Envelope Generators, LFOs, and other mod sources on a DX would require
VCAs to perform the same functions on an analog synth.

While you don't need a VCA to do FM on a modular, you would want several
to do an FM patch with any complexity.  Remember, with FM, as you increase
the modulator's levels, you increase the carrier's frequency content.
It's a different effect than varying the modulator's frequency or harmonic
content, which is pretty much all you could do without a VCA.

JDM

JDM writes:
>>While you don't need a VCA to do FM on a modular, you would want several
to do an FM patch with any complexity.  Remember, with FM, as you increase
the modulator's levels, you increase the carrier's frequency content.
It's a different effect than varying the modulator's frequency or harmonic
content, which is pretty much all you could do without a VCA.<<

Good point. I took the original post about VCA's meaning he wanted to modulate 
the levels of modulator with something like an EG or LFO. If all that is needed 
is attenuation then the motm mixer can give him a couple of channels of that.

-Elhardt