VCA/overdrive

'Persephone' is a VCA (Voltage Controlled Amplifier) using a discrete JFET as the gain element. The JFET can be tastefully (or violently) overdriven for saturation/distortion effects.

Persephone also includes a zero-crossing detector, which can be used to restrict gain changes to zeros in the audio waveform, preventing clicks and pops that can occur with very fast envelopes, especially on lower pitched sounds. In fact, with the zero-crossing circuit engaged, you can use a simple gate as the CV input without clicks.

The module's signal and CV paths are 100% analogue (there is a little discrete logic involved in the zero-cross circuitry).

https://expert-sleepers.co.uk/persephone.html