This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Friday, November 14, 2014

Monolith Oracle Fuzz

This is a pretty cool fuzz box. It's a cross (sonically anyway) between an early Vox Tone Bender and a Big Muff. It uses PNP germanium transistors, but still uses a negative ground power supply. Originals have OC76 transistors with hfe of around 100 for Q1 and 300 for Q2. 300 is high for most PNP germ. devices and might be hard to source, but I've read of people using trannies with typical Fuzz Face gains (70, 100) with good results. The switch on the original is a push/pull on the 250k pot, but a DPDT switch can also be used.


  1. works well. Heavy great sounding fuzz between bender/blackrumuff territoty, with a GT115V - 167 hfe as Q1 and GT115D - 323 Hfe as a Q2. Color2 to Output3, Output2 to fx output. thnx u storyboardist!

  2. I think the transistors are backwards/upside on this. The emitter is supposed to hook up to the 820/100k resistors according to the schematic:

    Of course, I might be totally wrong--it wouldn't be the first time.

    1. Hmm, I was thinking so as well, will try it right away

    2. I've tried the schematic you've provided and that one works perfectly (this pedal is a beast!)
      But turning the transistors around seems to work as well o.0
      This could be due an improvisation I had to do, for I had no 1M pot laying around.
      Since this effect is ground negative, I would stick to the schematic you've found.
      Hope it'll help you out.

    3. I had success flipping the transistors around based on that schematic. After not having success with the layout above (the rest of the layout is great!)

      (I just realized that I was the original commenter on this--I must have given up for a number of months, then having gone back to it during quarantine, had success.)

  3. What’s the bias voltage on Q1 and Q2?