PedalBuilder
Well-known member
At the beginning of the year I had ten Big Muff PCBs fabricated. I used two of them to build these V7A/V7B Big Muffs. I pulled the values from Kit Rae's website. As Kit explained, there isn't much difference between the two circuits:
One note on the diodes—I breadboarded both of these before building them and tried KD521V, 1N914, 1N4150, and 1N4001. The 1N4150 and 1N4001 sounded almost identical to the KD521V. The 1N914, by contrast, sounded subtly, but noticeably different from the other the others—less compressed and slightly less bass heavy.
UV printing and drilling was done by Tayda. The KD521V diodes came from Sovcom on eBay.
I flipped that around here. I used parallel 390pF and 53pF silver mica capacitors (~440pF) in the Green Russian version, and parallel 470pF and 27pF C0G ceramic capacitors (~500pF) in the Civil War version. The Green Russian used BC549C and 2N5088 transistors with hFE between 550 and 580; the Civil War used BC549C and 2N5088 with hFE between 480 and 510. I picked the transistor hFE ranges based on measurements that others had taken of the KT3102 transistors used in the originals. Both builds used NOS Soviet KD521V diodes, which were used in the original Civil War and (some) Green Russians. I also used different polarity protection for each. The Civil War used a MOSFET circuit for polarity protection, and the Green Russian used a 1N5817, so VCC is ~0.25v lower on the Green Russian. Soundwise, they're very similar, with the Civil War having a more smooth and mid-focused sound, and the Green Russian having a boomier low end and raspier treble. Is the difference due to the different filter capacitor values? The slightly higher hFE on the Green Russian build? Component tolerance (the Green Russian tone pot was 102k, compared to 94k for the Civil War; the Civil War had a 108k distortion pot, compared to 95k on the Green Russian)? No idea, but both of them sound great to me.
One note on the diodes—I breadboarded both of these before building them and tried KD521V, 1N914, 1N4150, and 1N4001. The 1N4150 and 1N4001 sounded almost identical to the KD521V. The 1N914, by contrast, sounded subtly, but noticeably different from the other the others—less compressed and slightly less bass heavy.
UV printing and drilling was done by Tayda. The KD521V diodes came from Sovcom on eBay.
