It is
a clone of the Steiner-Parker Synthacon filter, a vintage
monophonic analog synthesizer. The core of this filter is
a diode ladder with 3 mode input jacks ( LP,BP,HP) and one
output . Inputs can be used simultaneously producing amazing
filtering effects, close from a sweet phasor. Used separatly
with different sound source this filter act as a combination
of a 3 voice interpolating scanner with different filtered
inputs .The filter self oscillate with the resonance pot
set at approx 2/3.
The
schematic i have used is available at Ken Stone web site,
i have just applied following changes.