Halo / EHX Big Muff Pi DIY PCB

Halo - Electro-Harmonix Big Muff Pi Guitar Pedal PCB



New version 1.5 with ENIG gold plating! The layout has been adjusted slightly to make the drill template consistent with other projects. Version 1 documentation can be downloaded here.

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Project overview

There’s no shortage of PCB offerings for a Big Muff, but I’ve tried to make a board that could be used to build any variation or clone out there as well as incorporating a number of mod options. Here are a few of the features:

  • Optional “Presence” or midrange control (more info at AMZ). If you choose not to use this control, the Tone pot has two possible orientations so you can still have a symmetrical control layout.
  • Extra pads for clipping diodes, allowing you to easily use LEDs or just about anything else
  • Choice between two different gain recovery/output stages: “classic” or JFET (like in the BJFE Fire Red Fuzz)
  • Space for large 1uf film caps where appropriate, allowing you to build any historical variant of the BMP