ALM Busy Circuits

MCFx2 Dual State Variable Filter


The MCFx2 is our state variable ‘MCF’ filter made double. It features 2 identical classic analog 3 pole filter cores each with Low, High and Band Pass (or Notch) outputs. Direct and voltage control is provided for both filter cut offs and resonance.

Two switches allow the filters to function as one, with the ‘Feed’ switch internally routing audio from one filter to the other in series and the ‘Link’ switch linking the cut off controls for both filter cores.

MCFx2 expands on the great sounding MCF filter (previously available only as part of the System Coupe) to offer both serial and parallel functionality for stereo operation, dual peak, tighter slopes and other complex filtering set ups.


  • 3 pole 18 db/oct filter
  • Lowpass, Highpass, and bandpass/notch filter outputs
  • Bandpass or notch mode selectable for each channel via jumpers on the rear of the module
  • Link button - Links the left cut off to parallel control both filters. The right controls will now set the max range of the right core
  • Feed button - Routes the output of the left filter core to the input of the right (unless patched), with the desired output filter type selected via jumper at the rear of the module
  • CV inputs and attenuators for cutoff and resonance with attenuversion on the cutoff inputs
  • Separate 1v/oct tracking inputs


  • Width: 14HP
  • Max Depth: 32mm
  • Power: 85mA @+12V , 85mA @-12V , 0mA @+5V