[sdiy] Basic Synth Patch? VCO-VCF-VCA

[harrybissell]

Yes of course, you are correct...
the summing idea is simplistic. You really need
to multiply. Summing would give most of the
effect.

I'm presuming that you don't HAVE two
VCA in this case (or a multiplier...)

H^) harry

Ingo Debus wrote:

> Am Sonntag, 30.11.03 um 05:24 Uhr schrieb Michael Boracci:
>
> > Harry> You could also sum the "AM" signal with the envelope and get
> > the AM
> > mod you wanted from a single VCA.
> >
> > This is a really great solution Harry. I did not consider that, but it
> > makes
> > a lot of sense and would probably be the way to go in order to
> > integrate
> > several functions in to one circuit.
> >
>
> Summing the envelope cv and the AM cv might not give the expected
> result here. If the envelope is completely finished (at zero) and an AM
> cv (say, a LF sine) is applied you would still hear something. If the
> VCA is adjusted in such a way that zero cv from the envelope is a lower
> voltage than required to shut the VCA completely off, then the envelope
> gets "distorted": parts of the attack and release phase are cut off.
>
> I think what we really want  here is multiplying both CVs. But to do
> this we'd need another VCA...
>
> The (old) Formant VCA module had two VCAs in series: one for the
> envelope and one for AM.
>
> Ingo