A couple of germanium fuzzes

[spi]

I just completed two fuzz builds. I've had a couple of fuzzes in the past, but never germanium ones. I've always wanted to try a Ge fuzz just to see what the buzz is about.

This is the Twin Face. It's my first build using a PedalPCB board. It went smoothly, although I didn't realize how tall the 4pdt switch would be, which raised the PCB higher, leaving just barely enough lead from the pots sticking through to make a connection.

On the PNP side, I used a matched pair of transistors from smallbear and the provided resistors (which differ from the schematic), and bumped the 10K trim to 20K because the resistor in that position was 12K.

On the NPN side, I used a 2n2369/2n2222 combo (I auditioned a few a combinations of silicon transistors before settling on this pair). This side followed the components in the schematic.

The two sides actually sound pretty similar, with the Ge being a touch warmer.

 

[spi]

This is the Phobos from Aion (a Tonebender mkiii). It's also using a matched set of transistors from smallbear. With this one, my drill template wasn't centered, so the knobs are a bit off-center, but is still came out alright.

I was a bit worried about the biasing of this one. The Aion docs recommend setting Q3 to -2V, and the closest I could get was -4V. However, researching docs for other pcbs of this circuit (madbeans, GGG, etc.) I see it's common to bias in the -4:-4.5V range, so I guess this is OK. In retrospect I should've bumped the 10K trim to 20K just to have more range available. I don't like desoldering if I don't have to--too much risk of messing it up, so I can live with it as-is.

 

[Bret608]

These look great and probably sound that way too! On your MkIII, don't sweat the Q3 bias too much. If you're getting in the neighborhood of 4v on the collector, I can tell that's because you used a low-leakage transistor. In this circuit, I've tried leaky ones, non-leaky ones, and even simulated leakage on a non-leaky one by shorting the base and collector with a resistor, pretty much like the trimmer in the Soul Bender does. They all sound great. Vintage units tended to have in that 2v neighborhood because they used leakier transistors for Q3. Higher voltages make it sound just a touch more raw and raspy in my experience, but nowhere near a deal-breaker.