Infinite Fuzz
This is my own version of the Fuzz Face pedal. This pedal is hand-wired on turrets and the transistors are in sockets, so you can easily change them out to try different transistor sounds. I've included both a Germanium set and a Silicon set, so right out of the box you've got the Jimi at Monterey Germanium thing and the Band of Gypsies Silicon thing goin' on. There's a front panel Bias control so you can adjust the pedal to the transistors you're currently using. The Silicon pair are 2N3799 transistors. Q1 is 159 hFE and Q2 is 227 hFE. Q1 is identified with a black dot on top of its metal encapsulation. The Germanium transistors are a recent-production AC128 in Q1 and a vintage 2N527 in Q2. The AC128 is 72 hFE and the 2N527 is 126 hFE. To switch from germanium to silicon you have to back the bias control almost all the way down, but it's still in-range. Sounds great both ways and both ways have a nice range on the, "Fuzz" control and clean up when you back off the guitar's volume.
The Fuzz Face circuit is a classic, but it's always had a few minor issues. First off, it doesn't normally work well with guitars that have humbuckers. Most Fuzz Faces are great with a Strat, but anything with a humbucker loses some tone and the ability to control it with the guitar's Volume knob. In this version I've added some series resistance to the Input to change the pedal's input impedance. Works like a charm. It doesn't negatively change the pedal's response for single-coils, but it makes the pedal much more manageable for humbuckers.
I've also always hated the Volume control on a Fuzz Face. It interacts with the Input Capacitor and forms a High-Pass Filter. With the standard .01 uF cap and the normal 500K pot the corner frequency on the Fuzz Face Volume control is 31.8309886184Hz. Of course, as you turn it down that nastiness audibly influences the range of frequencies up to 10 times the corner frequency, so you're way up into the range of the high E string. I've opted to use a 1 meg pot. With my 1 meg pot layout the corner frequency (naturally) drops to half that, or 15.9154943092Hz. Much better. The very top of its nastiness can reach into the range of the D string, but overall it seems pretty transparent to me. Such a little shift in components, but it seems to have addressed the ugly sound I was starting to feel like you couldn't avoid with a Fuzz Face Volume control.
Those sockets have spring-loaded retainers that grab the legs nice and tight so they won't go anywhere once they're in the socket. I color-code the legs, so Emitter, Base and Collector are, "Emerald," "Blue" and, "Scarlet," respectively. It makes it easier to remember, but triangle-to-triangle works fine.
This case is very similar to the old Big Muff case. Electro-Harmonix just used to let the circuit board, "float" and hang from the wires to the pots and footswitch, but I really don't like that at all. I could have mounted the circuit board on the base, but then every time you opened up the case you'd have to be careful not to tug any of the wires going to the pots and footswitch loose. Instead I drilled mounting holes and mounted both the circuit board and battery clip to the back of the control panel. The circuit board is attached with standoffs and screws, but the battery clip gets a lot of manhandling, so I riveted that in place. This way everything lifts out as one unit when you open it up to replace the battery or change transistors. The service life should be MUCH longer this way.
The components are all good stuff. Full-sized 24mm Alpha pots instead of the little 16mm mini-pots that almost everyone uses now. Metal oxide resistors; they don't carry the nostalgia of carbon comps, but they're less prone to noise and that's important in these transistor circuits. A Roederstein, 'Golden Bullet' bypass capacitor, Philips MKC "Chicklet" output capacitor. The board should be as nice a Fuzz Face circuit board as you're likely to find...but even cooler, since it's on a turret board instead of a PCB. That means it's easy to mod if you ever decide to try something new. And of course transistor sockets so you can change out the transistors for whatever you happen across in the future. If someone happens across a pair of Newmarket NKT-275 transistors from Brian Jones' footlocker or whatever, you can plug 'em in and go.
I've been obsessing over this circuit for a while. This is the variation I've been the happiest with. I hope you'll love it as much as I do.
Infinite Fuzz
This is my own version of the Fuzz Face pedal. This pedal is hand-wired on turrets and the transistors are in sockets, so you can easily change them out to try different transistor sounds. I've included both a Germanium set and a Silicon set, so right out of the box you've got the Jimi at Monterey Germanium thing and the Band of Gypsies Silicon thing goin' on. There's a front panel Bias control so you can adjust the pedal to the transistors you're currently using. The Silicon pair are 2N3799 transistors. Q1 is 159 hFE and Q2 is 227 hFE. Q1 is identified with a black dot on top of its metal encapsulation. The Germanium transistors are a recent-production AC128 in Q1 and a vintage 2N527 in Q2. The AC128 is 72 hFE and the 2N527 is 126 hFE. To switch from germanium to silicon you have to back the bias control almost all the way down, but it's still in-range. Sounds great both ways and both ways have a nice range on the, "Fuzz" control and clean up when you back off the guitar's volume.
The Fuzz Face circuit is a classic, but it's always had a few minor issues. First off, it doesn't normally work well with guitars that have humbuckers. Most Fuzz Faces are great with a Strat, but anything with a humbucker loses some tone and the ability to control it with the guitar's Volume knob. In this version I've added some series resistance to the Input to change the pedal's input impedance. Works like a charm. It doesn't negatively change the pedal's response for single-coils, but it makes the pedal much more manageable for humbuckers.
I've also always hated the Volume control on a Fuzz Face. It interacts with the Input Capacitor and forms a High-Pass Filter. With the standard .01 uF cap and the normal 500K pot the corner frequency on the Fuzz Face Volume control is 31.8309886184Hz. Of course, as you turn it down that nastiness audibly influences the range of frequencies up to 10 times the corner frequency, so you're way up into the range of the high E string. I've opted to use a 1 meg pot. With my 1 meg pot layout the corner frequency (naturally) drops to half that, or 15.9154943092Hz. Much better. The very top of its nastiness can reach into the range of the D string, but overall it seems pretty transparent to me. Such a little shift in components, but it seems to have addressed the ugly sound I was starting to feel like you couldn't avoid with a Fuzz Face Volume control.
Those sockets have spring-loaded retainers that grab the legs nice and tight so they won't go anywhere once they're in the socket. I color-code the legs, so Emitter, Base and Collector are, "Emerald," "Blue" and, "Scarlet," respectively. It makes it easier to remember, but triangle-to-triangle works fine.
This case is very similar to the old Big Muff case. Electro-Harmonix just used to let the circuit board, "float" and hang from the wires to the pots and footswitch, but I really don't like that at all. I could have mounted the circuit board on the base, but then every time you opened up the case you'd have to be careful not to tug any of the wires going to the pots and footswitch loose. Instead I drilled mounting holes and mounted both the circuit board and battery clip to the back of the control panel. The circuit board is attached with standoffs and screws, but the battery clip gets a lot of manhandling, so I riveted that in place. This way everything lifts out as one unit when you open it up to replace the battery or change transistors. The service life should be MUCH longer this way.
The components are all good stuff. Full-sized 24mm Alpha pots instead of the little 16mm mini-pots that almost everyone uses now. Metal oxide resistors; they don't carry the nostalgia of carbon comps, but they're less prone to noise and that's important in these transistor circuits. A Roederstein, 'Golden Bullet' bypass capacitor, Philips MKC "Chicklet" output capacitor. The board should be as nice a Fuzz Face circuit board as you're likely to find...but even cooler, since it's on a turret board instead of a PCB. That means it's easy to mod if you ever decide to try something new. And of course transistor sockets so you can change out the transistors for whatever you happen across in the future. If someone happens across a pair of Newmarket NKT-275 transistors from Brian Jones' footlocker or whatever, you can plug 'em in and go.
I've been obsessing over this circuit for a while. This is the variation I've been the happiest with. I hope you'll love it as much as I do.