12dB state variable VCF with voltage controlled resonance

Compact 6HP VCF for Eurorack Modular synthesizers


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


  • ? mA +12V
  • ? mA -12V
  • ? mA 5V
  • 52 mm deep

Module is available as a DIY project only.

This Module is currently available.

$20 Price in €
6 HP Filter
submitted Aug 27th 2017, 18:24 by jnfrench | last Change Dec 10th 2017, 13:22 by jnfrench
Specs are approved by the manufacturer

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