The circuit is a special suboctave generator which output signal is quite similar to the input signal. The module is very simple and straightforward and makes some interesting results when the input signal contails lots of harmonics.Tthe circuit freaks out, though when fed with inharmonic sounds, that's why the stability control was added. Another potentiometer controls the dry/wet mix.
input and output
3U Eurorack module, 6HP wide, 3cm deep