PWM based VCA

Ever since I saw the Buchla 257, I was intrigued by using PWM for a VCA. I needed some small mixers/attenuverters for my system anyway, so I decided to design a little (multi functional) module around this idea.

At it’s core is a high speed switch, controlled by PWM. The switch is basically used as a crossfader to fade from signal A to signal B. Signal A has 2 inputs, one can be switched to a constant DC voltage. All inputs have attenuverters.

I use this module as a mixer, VCA or crossfader.