CRAIG ANDERTON

ELECTRONIC GUITARThe Legendary Fuzz Face

Resistors (1/4 W except as noted)RI 470 ohms. 1/2 Watt (330 ohms for NPN

version)R2 Ik linear-taper potR3 8.2kR4 33kR5 lOOkR6 500k log-taper pot

CapacitorsCl 0.1 uF disc ceramic (see text)C2 2.2 uF electrolyticC3 20 uF electrolytic

Other partsBl 9V batteryJl. J2 Stereo 1/4"'jacks with insulated ground

(see text)QI AC128 or NKT275 PNP transistors (seeQ2 text; BCI08C for NPN version)SI DPDT footswitchMisc. Case. solder. etc.

''''HY IS THE FUZZ FACE legendary? A"'few words by Don Menn from Guitar Play-

er's September '75 Jimi Hendrix issue shouldsuffice: "When Jimi walked onstage to begin aconcert during the years of his greatest popularity.he coulci count on finding a Univibe, a Fuzz Face,and a Vox wah-wah plugged together into hisMarshall amps ... the Fuzz Face. Jimi felt, wasthe most distorted sounding of such units."

In the September '83 column, I asked whetherany of you could help a reader whose Fuzz Facewas stolen and who needed a schematic. As usual,you came through: Not just one, but several read-ers sent along schematics and comments.

The Fuzz Face, manufactured in England, islong gone, but the schematic remains. I would loveto credit the designer, but all attempts to find outwho was behind the Fuzz Face have proved fruit-less. So once more, I'm turning to the readers forhelp. If you know anything about the Fuzz Face'sorigins, please write in so that in a future column Ican give credit where credit is due.

Apparently, there were two very similar ver-sions of the early Fuzz Face. In one, the transistorswere PNP germanium types. while in the otherthey were NPN. The schematic shown is for thePNP version. Taking an educated guess based onthe information provided by readers, I think thatthis version is probably the "original" Fuzz Face,and as the PNP germanium transistors becamemore difficult to obtain, the manufacturerswitched over to NPN types. If you build the NPNversion, change R I to 330 ohms and reverse thepolarities of the battery and electrolytic capacitors(important!). Incidentally, readers with the NPNversion seemed equally satisfied with the sound asthose with the PNP model. I would be interested inany comments from those who build circuits usingboth kinds of transistors as to which they prefer.

The Fuzz Face used stereo input and outputwhose ground connections were insulatedthe chassis. Ground was made thrQugh the

+ II11Bl9V

RSlOOk

CI0.1 uF

Q2AC 128PNP

VolumeIn

•• SIB Tip

:: ~I-L Ring

Note: Plugging into the input jack closes the switch connection, completing the circuit (rom the battery's"+" to ground. Also note that the input and output jack grounds are insulated from the chassis.

stereo jack's ring connection, which contacted theinput and output plug ground sleeves when thesewere inserted into their respective jacks. The ringconnections. as well as all other ground connec-tions, were then brought to a single groundingpoint on the metal case. If you can't find equivalentjacks (I wouldn't be surprised). you can use stand-ard stereo jacks if you mount them on some kindof insulating material (such as plastic) and thenbring the ring connections to a single ground pointthat connects to all other ground points. Note thatyou must use a mono plug when plugging intothese jacks. The original jacks also included aswitching function to turn the battery on and off.This could be replaced by an SPST switch in serieswith one of the battery leads.

Some minor component differences exist be-tween units, probably because the factory ran outof one part during production and substituted asimilar part. For example, C I was listed as 0.1 uFon some schematics, 0.047 uF on others, and 0.03uF on one. Providing that you are feeding a high-impedance amplifier, using any of these valuesshould produce essentially the same sound.

Now for some reader comments. Regardingthe NPN version. Brian Rost, from Westborough,Massachusetts, says: "The transistors are the heartof the unit's sound, but the BCI08C is rare. It'squite old, but is still listed in the National Semi-conductor 1982 Data Book. This is a low-powerNPN type with an unusually high hfe (gain factor)of 600, which is why it provides such good clip-ping. The input jack power switching and theOPOT in/ out switch are quite sophisticated forsuch an old design; no wonder these pedals are solegendary. AU the resistors can be I /4-watt. exceptfor the 330-0hm. which should be 1/2-watt. Theamplifier is basically a current-shunt type usingnegative feedback. with the feedback varied by theJk pot. 1be 20 uF cap is used, I think, to fJ.lterout

high-frequency oscillation at high gain settings."Dave De Leersnyder, from Kansas City, Mis-

souri, also comments on the rarity of BC 108Ctransistors, suggesting that these can be replacedby the RCA SK3444 or Sylvania ECG 123A.(Incidentally, my Radio Shack Transistor Substi-tution Guide lists the Radio Shack RS-2009 as a.suitable replacement.) Also regarding parts substi-tutions, a reader identified only as Bill, fromChico, California, says: "A truly unusual design,but typically British. Substitutions will work (aslong as they are within IS%) to achieve that super-bright Fuzz Face sound." Another reader, whosesignature could not be deciphered, noted on hisschematic that the 20 uF capacitor was replaced bya 32 uF on some models.

Regarding the PNP version, Francis Fima,from Paris, recommends using the NewmarketNK T germanium transistor (my Radio Shacksubstitution guide lists the RS-2005 as an equiva-lent PNP type). A.J. Corscadden, from Leeds.England, offered a wealth of information. Accord-ing to A.J .• "Arbiter Electronics became DallasArbiter sometime in the late '60s. I've built manyFuzz Faces for friends of mine, although findingthe NKT 275 is difficult. The AC128, a Europeanequivalent, can still be bought in England, but I'vefound that almost any PNP germanium transistorswork. I've also used PNP silicon types, but theyclip too severely and give a harsh sound." A.J. alsomentions that he has repaired a number of FuzzFaces, and that they all used the PNP transistorcircuit.

Researching and writing this column has beena lot of fun. and 1 hope you've enjoyed taking alook at this claSsic circuit. In an upcoming issue,Guitar Player and I have a surprise in store foryou-alII can say is make sure that your turntableis in good working condition. See you next month.!

. fJ