[sdiy] That 2180 with modular cv??

[David G Dixon]

> I got some 2180 samples.
> Hooked it up as per data sheet.
> Hooked up the out of a env gen
> Sounded horrible
> Tried with a square wave cv
> More horrible
> What do I need to do to make these VCAs work with +/-5volt 
> input and 0-10volt gates??
> Thanks for any advice

The datasheet says that the control pins are to be limited to +/-1V.  If you
feed an undivided gate or envelope signal to the control pin, the VCA will
clip hard.  I would sum a CV attenuator pot and a CV bias pot (the latter
injecting voltages from 0 to 5V into the summing node) pots to convert any
control signal (e.g., 0/+5V, 0/+10V, or -5/+5V) to 0/-5V, and then invert
the result at a gain factor of 0.2 to 0/1V and use the circuit in Figure 2.
I'm not sure whether you'd want to use the Ec+ pin or the Ec- pin (I haven't
looked at it that closely -- in either case, the unused one is grounded),
but the main point is that the THAT 2180 is about 5 or 6 times more
sensitive to control voltage than the SSM2164.