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, May 31, 2019

ProAnalog MkIII Fuzz

Here's a variation of the classic Tone Bender Mk II Professional from ProAnalog Devices. It uses PNP transistors, so you'll have to use either a battery or voltage inverter to daisy chain this with other pedals. It seems they've used several different transistors, but they're outlined in the schematic from Scotty himself. Easy fit in a 1590B. And if you want to make it as a negative ground effect, use NPN germanium transistors and flip all polarized components in the layout.


  1. David, can you go to the "Craig Anderton Tremolo"? There is wrong pins with 4049 Ube. Absolut no the same with that schem...1,2,3,4,5 legs go wrong, 1 have to go 9!

  2. I built this layout using NPN Si transistors (2N4401) and all polarized components flipped, but no other modifications. My build works, but sounds harder and has way more gain on tap compared to the one in the video. I do not know if you would call the layout verified, but the right set of Ge transistors should work here.

    My build can get pretty noisy with the fuzz pot high up, so I will try to bring it closer to other Si MkII's by adding series resistance to Q2 and Q3's emitters and maybe lowering the value of the feedback resistor. There should be enough room for the tweaks on this layout. Of course, it would have been easier to start with one of the Si variants on this site.

  3. I ended up rebuilding this one with PNP Ge transistors, so it is for sure verified. Compared to my first version, this one has more warmth, less noise, and a gain level comparable to the demo video. Hfe for my transistors was about 83, 95, and 113 for Q1, Q2, and Q3, respectively.

    Since the circuit does work with Si transistors in any position, I tried Si transistors for Q1 and Q2. I though that an Si transistor sounded better as Q1 than Q2, with the circuit retaining more of the all-Ge configuration's warmth and character.