2Q12 VCF

12dB state variable VCF with voltage controlled resonance

Compact 6HP VCF for Eurorack Modular synthesizers

DIY - PCB AND PANEL ONLY

This is a state variable filter with a nice fat sounding low pass output. The two pole filter has simultaneous -12dB per octave roll-off for high pass and low pass and a -12 db wide (-6dB either side) bandpass output. It has voltage control of cutoff frequency (F) and voltage control of resonance (Q). F and Q are adjustable with panel controls and from external sources using three F CV inputs and two Q CV inputs.

The frequency response is exponential at 1Volt/Octave. The Q response is also exponential.

Some great videos courtesy of Randy Piscione
A demo of the filter
Fun demo with two Q inputs
2 pole to 4 pole Comparison

The design uses a positive feedback resonance circuit that maintains the input signal at a high level as resonance is increased. This enables low noise output regardless of the resonance. The input level control can be used to provide a smooth or clipped high pass output during resonance, further increasing the opportunities for sound experimentation.

-Two pole 12dB filter
-Simultaneous high pass, low pass and band pass outputs
-Exponential 1V/octave response
-Exponential voltage control of resonance
-Self-resonance adjustable
-Three frequency CV inputs
-Two Q CV inputs. This frees up one Q input to be used to track the frequency input allowing constant bandwidth on the BP output
-Input level control for smooth or overdriven sounds-6HP Eurorack with our panel

https://www.tindie.com/stores/pmfoundations/