904A low pass 904B high pass and Fitzgreyve 904C filter coupler for band reject and bandpass modes.

video upload by Vykaar Tones

"Just finished making this module from Fitzgreyve Synthesis and thought others might like to hear what it does. I am modulating it from a 921 vco and feeding it two sawtooth waves from two other 921 vcos. At the end I input filtered pink noise from a 923 module."