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Friday, April 1, 2016

Keeley Fuzz Head

Over a decade ago Robert Keeley was kind enough to share this design with the DIY community. It's a fairly unique fuzz, with a germanium treble booster at the beginning, a differential amplifier in the middle, and a basic buffer at the output (this is so it will play nice with other effects). Robert's full explanation of the circuit can be found here, however note that the schematic in that document isn't what I used. I used this later one with a tone control, and ended up laying it out with all controls externally. The PreGain control originally was a trimmer because it has a tendency to crackle when turned, but for ultimate tweak-ability I moved it externally.



The switch is a SPST on/off, by the way.

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8 comments:

  1. BerkicauApril 1, 2016 at 9:45 PM

    more keeley pedals please? :D

    ReplyDelete
  2. wainer.said@gmail.comApril 2, 2016 at 4:44 PM

    hello I have this scheme to a flanger using two PT2399 , would be able to do the layout for the great man , the this scheme the link is also my email if you need more informations , thank you. link below with the scheme

    http://www.4shared.com/office/iaobaoTcce/flanger2399.html?

    ReplyDelete
  3. alexmanJune 12, 2016 at 5:06 AM

    Hello pedal sounds really good, but the sound is a little quieter effetkta net that can be changed to fix it. Thank you.

    ReplyDelete
  4. UnknownSeptember 23, 2016 at 10:18 PM

    I built this. My first etched pcb, wow, not simple at all. Quite a bit of work. But this thing fired up right away! Fuzzy and awesome. Really happy with its tone. You can mark this as verified. However, the volume and the pre-gain go in the opposite direction than what I would expect, i.e. I need to turn them counter clockwise to increase them. Not a big deal just have to mark the enclosure the direction they need to go. The tone control also doesn't do all that much, you basically need to be at either end to really notice it.

    ReplyDelete
  5. ZZOYDOctober 29, 2018 at 11:14 AM

    I made it, & i wanted break it, becouse i had a lot of fuzzes. But now it's my favorite fuzz, using it with a little bit flanger. It's the lowest noise fuzz, which i have built!

    ReplyDelete
  6. EETFUKDecember 26, 2020 at 9:34 PM

    Can i use silicon tr instead of ac187?? Which one do you recommend??

    ReplyDelete
    Replies
    1. Effects LayoutsDecember 28, 2020 at 11:41 AM

      I suppose you could. It will change the sound a good bit though from germanium. I would start with a low hFE transistor, like 2N2369, 2N2222, etc.

      Delete
  7. ZZOYDJanuary 29, 2021 at 4:37 PM

    rebuild today this one. Used npn mp38a, so i removed 220 ohm from emiter Q1, & changed 56kom to 180 kom on base Q1. I have got realy good gain & sustaine. Q2,Q3 - any with hfe more 500
    There are pregain & volume pots inverted.

    ReplyDelete