[sdiy] SSM2018 VCA

[Tom Wiltshire]

Hi All,

Has anyone used the SSM2018?

I've got a basic VCA circuit set up on my breadboard. I'm using it  
for a voltage-controlled Effect Level.
The control law is -30mV/dB, so 4V gives you -100dB, and -1.3V gives  
you 40dB gain.

I used an op-amp inverting mixer stage to scale and invert my input  
0-5V CV to a 0 to -4V range, and added in a 4V offset so the op-amp  
output was 4V to 0V for the VCA CV. The thing is, I can't hear  
anything until the CV comes up to about 1V. Even at 1.5V, there's  
nothing coming through. This is about -50dB. I expected to be able  
hear something at this level.

Any clues what's going on, or should I just rescale the CV to the  
part of the range that really seems to do something?

Thanks,
Tom