If you're looking for absolute vintage fuzz face tone, the BYOC E.S.V. Fuzz is it. The E.S.V. series Fuzz features extra beefy traces and solder pads for better continuity, easier soldering, and more abuse. BYOC have also added 1/2watt carbon comp resistors, those shiny blue Vishay electrolytic caps, and that big flat yellow film cap for extra vintage mojo.
The BYOC E.S.V. Fuzz comes with a hand selected set of the extremely rare NOS Philips AC127/01. Like the E.S.V. 2-Knob Bender kit, the E.S.V. Fuzz was inspired by BYOC's recent acquisition of a large lot of pristine AC127/01.These are, in their opinion, the holy grail of negative ground vintage fuzz tone. Very thick, very wooly and very dark sounding. But with focus, clarity, sustain, and the ability to clean up into a nice grindy overdrive just like a vintage fuzz face should.
And since these are NPN transistors, as opposed to the PNP NKT275 or AC128 that work best with a positive ground, the AC127/01 works best with negative ground. So they get along with all your other pedals and can run off a normal power supply, but still produce the vintage fuzz tone you expect.
The high price of boutique versions, the inadequate reissues, the pantheons of rock legends who've used it, and the extremely low level of build difficulty has made the fuzz face one of the most popular pedals among DIYers. You can't be serious about copping vintage tones without a good fuzz face...and this is one of the best.
