Saturday, 16 January 2016

Faustone Fuzz Unit

   Faustone was kind enough to post their schematic on their website for DIY use, and they make great products. Support this cool company if you are able :)

Info from Faustone:

   "The Faustone Fuzz Unit is a replica of the rare Barnes and Mullins (B&M) Champion Fuzz Unit. The original pedals were built by Colorsound in London in the late 70s. Rebranded under many names —B&M, CMI, G.B., Pro’Traffic— electronically the circuit was the British cousin of the Electro Harmonix Big Muff, and —allegedly— it was featured on “A Girl Like You”, the Edwyn Collins hit single.
This Faustone version is based on my April 1977 original which was carefully dissected, studied and re-assembled. The circuit on mine is a tad different from the available Internet schematic, and features Zetex brand transistors instead of the ubiquitous BC184Cs.
The circuit is basically a clone of a Big Muff minus the fourth transistor position. In the Fuzz Unit, two ZTX383C transistors —with a gain of around 600— occupy the two first positions (Q1 and Q2). A lower gain transistor is used for Q3 —ZTX382B, gain of 150— which in my opinion is the key to achieving the characteristic musical flute-like sound of the original pedal."












This layout omits the 220K output resistor for increased output








13 comments:

  1. Great! Faustone makes cool pedals. Maybe the most impressive it's the Valve Klipper (Laney Klipp channel).

    Thanks for the schematics Fausto.

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    1. It would be nice to see a vero of this pedal.

      http://faustone.com/pdf/Faustone_Valve_Klipper_schematic.pdf

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  2. Thanks zosotone! The Klipper was my introduction to Faustone, but I didn't realize that he posted the schematic for that one too.

    At any rate, I'm a bit uncomfortable uploading a layout for that on the main site. I have never drawn a layout with tubes or transformers and the lethal voltages found in that circuit are not something to play around with.

    With that said, I really want to build one, and it is a prime candidate for the amp section in the forum

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  3. I'm building this to verify right now and I've noticed two mistakes. The top leg of the 470K at Q3 needs to come down one row so that it goes between Q3 base and collector. Also, I must have accidentally deleted the collector resistor for Q2 during editing.

    Sorry folks, if you hold off on building for an hour or two I should have this edited and verified shortly

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  4. My build is working fine, but since I moved a few things around I'll keep this tagged as unverified for now just to be safe. Should be good to go though

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  5. Thanks for the post. Just built this and it is working, however the tone is reversed, so 1 and 3 need to be swapped and the output is really low. I looked at the schematic and it is noted that the 220k resistor at the output is optional, so I removed it and it is much louder now.

    I used MPSA18's (hfe around 660) for Q1 and Q2, and a 2N2222A (hfe 180) for Q3.

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  6. Thanks servant07, I forgot to flip tone 1 and 3

    I'll update and tag the layout when I get back from work.

    Regarding the 220K output resistor, this cut too much output for me too. I dropped mine to 100K, but I may omit it altogether. I used BC550C for Q1 and Q2 and 2N2222A for Q3

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  7. Layout updated and tagged. I also added a version without the output resistor so you can get some extra output.

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  8. Just build it today. Works but sustain is not famous.

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  9. Hmm. Did you do the one with or without the output resistor?

    Maybe post some good pics of your build in the debugging section on the forum and I'll take a look. Sounds like there's a problem in your build. Mine definitely sounds really sweet with plenty of sustain

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  11. After changing the wrong resistor, it sounds awsome !
    Thanks all

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    1. Glad you got it fixed! Hope you enjoy, I know I'm enjoying my build. This is a badass muff variant.

      One thing I've noticed about these muff variants with only one clipping stage is that they seem to mix in a bit of clean-ish signal into the overall output. My theory is that the 470K feedback resistor on q3 mixes in some clean signal, and since there isn't another clipping stage following that bit of clean signal makes it all the way through. It has a subtle but interesting effect on the overall sound

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