A Classic Ladder Lowpass Filter with voltage controlled resonance

The circuit uses a classic 4th order transistor ladder filter core which gives a steep 24dB/octave cut slope. With enough resonance amount the filter will resonate by itself.
The use of a VCA in the circuits feedback path adds voltage controllable resonance, which gives more possibilities in modulating the sounds.
The amount of the FREQ CV and Q CV inputs can be attenuated onboard.

Tunable parameters:
FREQUENCY
FREQ CV AMT
Q
Q CV AMT

Inputs:
FREQ CV IN
Q CV IN
SIGNAL IN

Outputs:
SIGNAL OUT

http://seismic.industries/vcf-lowpass/