Voltage controlled filter that I built for my techno rack. It’s based on “Korg late MS20 filter” by René Schmitz.

René explains in the description how to add the high pass input. I didn’t manage to make it a switch, so there are two separate inputs for high pass and low pass 🤷‍♂️

Then I accidentally found out that if I remove one of the diodes in the original design, the resonance gets a crunchy color (which I find particularly nice for bass voices). So I implemented this function with a switch: Soft and hard resonance.


  • Width: 6 HP
  • Depth: 46 mm (with power jack plugged in)
  • Current Draw: 16 mA @ +12 V; 16 mA @ -12 V


Right view on the module:

Panel and main board from top:

Control board and main board from bottom:

You can find a detailed step-by-step assembly on Imgur.


Revision 2 (breadboard prototype)

Revision 3 (two piece PCB)

Revision 4

What’s new? Optimized footprints, updated panel design and information on the PCB. It’s the commercialized version available as a DIY kit at Exploding Shed.

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