Tuesday, October 13, 2015

XinSound Fuzz FD-20 mod - Big Muff V2 Ram's Head clone

The XinSound Fuzz FD-20 is a Big Muff V2 Ram's Head guitar pedal clone.

It's schematic is next to the Electro Harmonix Big-Muff Pi 1975-15-10 original circuit.
As usually, I would like to experment on this pedal, doing some mods.

On the first and second gain stage of the original circuit, XinSound puts two soldered bridge to select which feedback loop diode and capacitors to use, a simple mod can be just split those bridge so try different sounds, it's the JP6 and JP7 bridge, you can see on the original board below.

The original electrolytics capacitors installed by XinSound where changed with Nichicon brand.
XinSound uses electrolytics capacitors on the clipping stage, but i prefer ceramic ones.
Also, all the four XinSound C1815 transistors where changed with classics 2N5088.
Below my modded board.

A Boost section it is added. The boost section produce an extremly clipped sound on bass.
One again many thanks to my friend Matteo for cutting me vinyl sticks for this pedal.
Found below the XinSound original schematic, as i've traced out, hope it does not contains errors.

And the modded one:

  • read risk disclaimer
  • excuse my bad english


  1. Hello, Davide,

    I was looking for a bargain muff clone and I found your blog. Very useful and well explained mods with good photos. I think I'm going to buy this. They had another fuzz that I think is more on the Fuzz Face side(the orange box one; there is a Chile´s brand called Fuse Electronics that sell them as Muzz Fuzz, you can find a few demos on youtube).

    Thank you very much. Best regards from Madrid, Spain.


    1. Hello! Thank you for your feedback! If you get the orange version one, let me know which pedal is the clone of that version.

    2. Hello,
      I'm going for this muff clone first, I like the way it sounds better than the orange one (more standard to my ears), and with your boost mod it is just terrific, you've make a real beast! The stock pedal sounds fantastic as it is but you've taken it to the next level with so many posibilities in sound. Maybe I'll try your mod myself. Anyway, if i get some information of the other fuzz I'll tell you.
      Good job, Davide. Thank u.

    3. Thank you. As a side note: I've replaced the original C1815 with 2N5088 just to fit other muff clone, but I've to admit that C1815 doesn't sound so different to my ear, and sounds good.

    4. Hello, Davide, just to tell you that I was wrong, I have written to Xinsound through Aliexpress mail and they have told me that FZ-30 Fuzz pedal is based on Boss Fuzz, I guess Boss FZ-3.

    5. Do you think Xinsound meant Bosstone and not Boss (Roland)? It sounds more 60's zippery / buzzy than something Roland would do.

    6. Hello, i do not know the Bosstone, anyway, one friend of mine has a Electro Harmonix Big Muff V2 Ram's Head, he tells me this pedal really sound likes the original one.