Steggo Finally Builds a Fuzz Face!

Introduced in 1966 by Arbitrer Electronics, the Fuzz Face is one of the earliest guitar effect pedals. It gained a great deal of popularity because Jimi Hendrix made extensive use of the pedal. The circuit itself is fairly simple, only consisting of 2 transistors, 4 resistors, 3 capacitors, and 2 potentiometers. The catch is the gain and leakage of those two transistors is vitally important to the overall final tone of the effect. In modern clones, variable resistors are used to help individually bias the transistors to ensure good tone for both the silicon and germanium versions of the circuit. I'd always wanted to put together a fuzz face, but which one?

Fortunately and PedalPCB has a great board called the Twin Face which combines both the silicon and germanium versions into one pedal!

As you can see from the PCBs above, there are very few components in the build itself - even given that there are two independent circuits on the PCB. I'm using carbon film resistors for this build (as it's a vintage pedal). The only semi-exotic components are the germanium transistors which I picked up from Smallbear. I did make one minor modification to the circuit. Most modern Fuzz Face boards include an input pull-down resistor (usually around 1MΩ), but the Twin Face board did not. I went ahead and added one at the input on the main PCB.

One problem with germanium fuzz face pedals is they generally required a positive ground - making using one with other effects on your pedal board more difficult. The Twin Face PCB gets around this by incorporating an on-board voltage inverter which permits the use of normal 9V center negative power supplies. The board also includes trimmer resistors so you can set the bias on both the germanium and silicon transistors independently. 

I decided to relocate the LED to the bottom of the enclosure, so I used one of my 3PDT daughter boards which lets you put it on either side of the stomp switch. The main PCB and daughter board are connected with 2.54mm ribbon cable. The jacks are connected to the boards with aviation grade wire from Tube Depot and the connections are insulated with heat shrink tubing. The only challenge here was the fact that the germanium transistors are a bit tall and had to be pushed over gently to fit.

Our mascot for this pedal isn't technically a dinosaur, it's a synapsid. According to Wikipedia:

"Lycaenops ("wolf-face") is a genus of carnivorous therapsids. It lived during the Middle Permian to the early Late Permian, about 260 mya, in what is now South Africa. Like the modern-day wolves from which it takes its name, Lycaenops had a long and slender skull, with a set of dog-like fangs set into both its upper and lower jaws.[2] These pointed canine teeth were ideal for the use of stabbing and/or tearing at the flesh of any large prey that it came upon. Lycaenops most likely hunted small vertebrates such as reptiles and dicynodonts.

"Lycaenops walked and ran with its long legs held close to its body. This is a feature found in mammals, but not in more primitive amniotes, early reptiles, and synapsids such as pelycosaurs, whose legs are positioned to the sides of their bodies. The ability to move like a mammal would have given Lycaenops an advantage over other land vertebrates, since it would have been able to outrun them."

I'd found a collection of some mostly good licensable art which included the Lycaenops. It took me a little while to figure out whether it was a smilodon or something else. I eventually decided it most looked like the Lycaenops.

In terms of the sound - it's a fuzz face through and through. You do get a bit of a pop sound if you toggle between the two, but otherwise it sounds amazing. It has all of the raw early character of the original!