This module is how we control volume in our modular system. There are two complete voltage controlled amplifiers here, and an output that can mix (sum) them together. The jacks at the bottom of the module are the audio inputs, the jacks at the top are the audio outputs, and the topmost knobs act like you would expect a volume knob to (clockwise turns the volume up, counterclockwise turns it down).
What makes a voltage controlled amplifier special is what’s going on in the middle of the module. This is where we input control signals that can turn the volume up and down in ways that our fingers couldn’t do. The switches change how the module responds to a control voltage, and the knob above those inputs changes how much of an effect the control has.
Inspired by the MFOS dual VCA, built around an LM13700 OTA and featuring cv input attenuverter and output sum. Can be used as two separate VCAs or a voltage controlled mixer with switch between exponential and linear cv response.
Low Frequency Oscillator with sine, saw, ramp, triangle, and square wave outputs. Switch between three frequency ranges and adjust with freq knob. LED flashes to indicate rate of square wave high and low. Frequency ranges from low audio to cycles lasting more than a minute. [For more information about how this module is used and fits into a modular system, check out the pages about amplitude and frequency].