That's what I have on the smaller board, great fuzz pedal.BC109 Sunface, by far my favourite.
But which one do you like?It is such a standard design "engine" in so many pedals, that it is hard to decide.
I made a Fuzz Face years back using BC108C transistors and loved it. Very Hendrix. Unfortunately, I got so lucky with that first one that I thought it would be easy to replicate and cannibalized the parts.
The Univox Square Wave and Jack Orman's Mos-Face are both essentially Fuzz Faces with a FET in the second position for the Univox and a MosFet in the same postion for the Mos-Face. My Mos-Face has a trio of 3-position toggles to adjust the "sag" (supply voltage), feedback resistance from Q2 to Q1, and bass content of the input signal. It'll go from very smooth and barely growly to seriously sputtery gated chaos.
The ZVEX Wooly Mammoth is essentially a FF, adapted for bass. The Lovetone Big Cheese is also a FF with some tone tweaks and an input buffer. The JSH/Jen fuzz is a FF with some clipping diodes on the output, as is the EHX Muff Fuzz. I made a couple of these for Budda and his band-mate, with some tonal options.
I recently made myself a variation of the EHX Double Muff, which is normally a pair of fixed-gain Muff Fuzzes in series. So, two silicon Fuzz Faces of modest gain, with a pair of clipping diodes on the output. For mine, I made the gain of the first one variable, and able to dial in a serious sustaining fuzz. I also included a control to dial back the clipping effect of the diodes in the first stage. The stock Double Muff allows you to run the first into the second one and control how much the first pushes the second. Stock, the one-vs-both switching is a slide switch. I made it foot-switchable. I also included a 3-position treble-cut switch on the second stage, since the treble can get a little too serious when you have one fuzz pushing another.
Finally, I put in what I labelled a "choke" switch. Since encountering the "Pinch" control on the Wooly Mammoth, I've become fascinated with the impact of altering the value of the feedback resistance that goes from Q2 back to Q1. Making it a higher value than normal, starts to introduce a certain glitchiness to the tone, that can vary from simply more apparent treble to sputtery gated tones. Right now, the unit simply aims for a more "zippery" tone, using a 2-position toggle. I may aim for 3 different sounds in future. I put the "choke" function on the second stage, so that if you're only running one of the Muff Fuzz sections, it doesn't apply. Step on the Dubbl switch, though, and it comes into effect.
There's a lot of sonic variety in this puppy.