[sdiy] Best VCA circuit for synth module..

[David G Dixon]

> SSM2164 is a more modern component with a bit better 
> performance. It's expo but you can linearize it with one 
> section in the feedback loop ala Mike Irwin's article in EDN.
>
> I think temperature compensation is usually left out of most 
> designs as the drift is not detectable when you are talking 
> about volume. Most transconductance ICs have the 3500ppm drift.

Actually, the temperature coefficient of the 2164 is perfectly compensated
when the Irwin linearization scheme is employed.

Also, take the second VCA away from this scheme, and you've got yourself a
very handy logarithmic amplifier.