Key data

Liquid filter

Parameter Value
Width 8HP
Depth 25mm
+12V current 35mA
-12V current 35mA
Lifetime 08/13 to 04/20
Modulargrid Link

Original printed manual

PDF download


A multimode filter

  • 2-pole band-pass.
  • 2-pole low-pass.
  • 4-pole low-pass.
  • 4-pole low-pass processed by an internal VCA - the perfect "end of subtractive chain" output!

All the CV inputs you need

  • Un-attenuated frequency CV, calibrated for 1V/Oct tracking of the self-oscillation tone over 4 octaves.
  • Frequency CV with attenuverter.
  • Resonance CV. Self oscillation starts at 4V. Control voltages above 5V are non-linearly compressed, for fine control of resonance overdrive.
  • VCA level for the LP4>VCA output.


  • Cutoff knob range: 18Hz to 18kHz.
  • Fully analog, based on the V2164 low noise/distortion quad VCA chip, and LM13700 OTA for that extra bit of non-linearity.
  • Frequency CV inputs impedance: 100k.
  • Audio input impedance: 75k.
  • Resonance and VCA CV input impedance: 30k.
  • All CV inputs handle audio-rate modulations.

Revisions and variants


Hardware revision labelled "v4" with the following differences:

  • Thonkiconn jacks.
  • FM attenuverter has no center detent.
  • Calibration trimmer soldered on the same side as the jacks, accessible from the side.