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

[Michael Boracci]

Thanks for the reply gents. I was thinking about this a bit more today and
was wondering if an inline VCA ( inline with VCF )would default to high
amplitude and be used more as a VC attenuator than a gain stage.

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.

Harry> But if you don't close the filter to sub-audio, and you have high
resonance you will still hear the VCF when the notes are off.

The sub-audio you are speaking of, is that the AM signal? I could see that
creating a problem. Your solution of using the envelope to carry the AM
signal would solve this, correct? The Sub-Audio would go away as the EG's
release phase ended, I suppose.

John M > Without a VCA in front of the VCF, you don't have
voltage control of the filter's input level

Do you think that this is something valuable? I was wondering why it is not
done more often. Why is the oscillator fed into the filter at full volume
and then attenuated after the fact in the classic model that is taught? I am
speaking of the single oscillator voice of course with VCO-VCF-VCA config.
You mentioned a VCO mixer which indicates attenuation before the VCF. If
that is the case then that mixer is serving as the VCA part of
VCO-VCA-VCF-VCA. That is how it appears to me.

Mike



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