The Dallas-Arbiter Fuzz Face has been around since 1966, and shows no signs of dying any time soon. Through the designs past you'll find all kinds of different variations in the basic original circuit, from PNP Germanium to NPN Silicon, and a countless number of fuzz pedals that are based on it.
The Fuzz Face has been played by almost every famous guitar player that has ever lived, and will most likely continue for years to come.
Here's a schematic of the original Germanium transistor version of the Dallas-Arbiter Fuzz Face:
What's Inside - The Silicon Years
As time went on, the old germanium transistors were slowly being replaced in favor of the more stable and consistent Silicon versions. As a result, Dallas-Arbiter began equipping the Fuzz Face pedals with these new transistors with different sound results. They are different from the original Germanium versions, usually with a more harsh and aggressive clipping as opposed to the soft clipping characteristics of Germanium. There was only one part that was changed in the circuit other than the transistors.
The 470-ohm resistor was replaced with a 330-ohm. The position of the 33K and the 330 resistors are opposite of what they are in the Germanium version. The 470 was in the center in the previous version, but now it's moved to the outside next to the 20?F capacitor. The transistors that were used in these versions included: BC108C, BC183L, BC109, BC109C, and BC209C. Most, if not all, of these transistors are still being produced and are readily available. The circuit has BC183L transistors, which have the B-C-E pinout. All the other transistors that were used have the more standard C-B-E pinout, so if you run across a Fuzz Face with something other than the BC183L, the base and collector leads will be twisted around to work properly.
The New Fuzz Faces...Arbiter Reissues
In recent years there has been a huge resurgence of interest in the original Arbiter Fuzz Faces, probably fueled by the very mediocre sounding Dunlop Fuzz Faces. A couple of years back, the Arbiter company made a limited run of reissue Fuzz Faces, complete with AC128 transistors. If you take a look at the schematic below, you'll see that it's not exactly a reissue, but an improved version of the original.
The 470-ohm resistor that's in series with the 0.01?F output cap has been replaced with a 1K resistor, which boosts the output of the circuit quite a bit. The collector resistor on Q2 has been decreased from 8K2 to 6K8. This will increase the voltage being supplied to the transistor and probably fattens up the sound a bit. The output capacitor was also changed from 0.01?F in the original issue pedals to 0.047?F in the reissue pedals. This change will increase the bass reponse of the pedal. The last change is the Volume pot. The 500KA original value has been replaced with a 100KA, which allows more highs to get through. These modifications are some great improvements to the original circuit, and are some of the mods being performed by DIYers and custom effects builders.
It's impossible to draw a conclusion as to which version is "better" than the other, because some people like the Silicon versions, and some people don't. It is safe to say, however, that the Silicon versions will obviously be free of one major problem that plagued the Germanium Fuzz Faces...temperature instability. It's been noted many times over that if they get too hot...they'll stop working.
It was also much easier to produce more consistent sounds from unit to unit with the Silicon versions (whether those "sounds" were good or not was left for the purchaser of pedal to decide). A problem with Silicon transistors that doesn't seem to exist with Germanium is that they can have too much gain. Too much gain will cause a Fuzz Face to sound horrid. With Silicon it becomes very difficult to stick with the Q1 hfe of 70 and Q2 hfe of 120, because most Silicon transistors are way over 120 to begin with. Someone in Aron's Stompbox Forum said that placing a 100pF capacitor across the Collector-Base junction of the transistors in a Silicon Fuzz Face clone would help control the gain and oscillation, so if you decide to build this version, keep that in mind.
Photo of a vintage late 60s early 70s model
Photo of Dunlops version of the JD-F2 Dallas-Arbiter Fuzzface.