VCA

Analog Voltage Controlled Amplifier with dual cv in

This module is a Voltage Controlled Amplifier, two of them side by side. It’s DC-Coupled so you can use it for control voltage or audio. There should be no difference in the left and right channels, other than the fact it’s all analog and you could have subtle differences. Driven by one LM13700, this circuit is similar to the Music From Outer Space Dual Log-Lin VCA.

The switch chooses an exponential response or a linear response, and the knob adds to the CV to set the zeropoint (loudness). Dual input CV sockets may look confusing, but you’ll enjoy summing envelopes and LFOs here.

Measuring 6HP, and skiff friendly, one PCB deep. The trimmer is for offset zeroing because the analog LM13700 output buffer will have some amount of nonzero resting point, and you’ll want to have

https://karltron.com/vca/