The XinSound Fuzz FD-20 is a Big Muff V2 Ram's Head guitar pedal clone.
i've traced out the board, you can find it as attachment. The schematic is next to the Electro Harmonix Big-Muff Pi 1975-15-10 original circuit.
Then i made a few mod. I've changed the original electrolytics capacitors with Nichicon, all the four XinSound C1815 transistors where changed with classics 2N5088.
And i've add an extreme boost section in front of it.
My modded circuit is attached here also.
You can find the full review as a blog post here:
http://davidegironi.blogspot.it/2015/10 ... ff-v2.html
A demo video here: