[sdiy] SSM2164 VCAs

[Aaron Lanterman]

On Jun 8, 2009, at 8:50 PM, David G. Dixon wrote:

> (You probably saw this one coming based on my last post...)
>
> I've been looking at the datasheet for the SSM2164 Low-Cost Quad VCA  
> (which
> I just bought a pile of in the form of CoolAudio V2164D clones), and  
> I'm
> thinking about building a -- (wait for it) -- quad VCA!  Based on the
> datasheet, this looks like a refreshingly straightforward thing to do,
> except for one little thing: the gain of the VCA goes DOWN as the  
> control
> voltage goes UP, and 0V CV represents unity gain.

See here (this is a linearized version using two VCAs, but you'll  
probably learn something you can apply to your quad exponential case):

http://charlielamm.com/synth/duallinearvca.php

And see here for its use as a quad exponential VCA, as you want to do:

http://m.bareille.free.fr/modular1/quadvca/quadvca.htm

- Aaron