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33KΩ

sw

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Fuzz Face

Probably the most famous fuzz of all time, the Dallas Fuzz Face has been

around since the dawn of stompbox effects and has spawned a huge

number of clones and variants. It is simple to build and is very tweakable,

which makes it a great DIY project. Presented here is the silicon version of

the fuzz face, along with a bunch of interesting mods.

beavis board project

A100K

Volume

in

out

Mods!The first thing to read is The Technology of the Fuzz Face, R.G. Keen’s seminal

paper on the Dallas Fuzz Face: http://www.geofex.com/Article_Folders/fuzzface/

fffram.htm

Try different NPN transistors to see how more or less gain affects the sound. You

can even try different values in Q1 and Q2. Be sure to check the pinouts!

Replace the R4 fixed resistor with a 10K linear pot (B10K). This allows you to

tweak the bias of the second transistor for some great splatty/starved sounds.

Use the voltage sag knob on the i/o breakout box: you can sag the voltage to the

entire circuit for some great sounds.

Super compressed bass mod: put a film capacitor between the base and collector

of Q2. Try values from 10nf to 100nf.

You can subtly change the output by using a 100K log pot (A100K) instead of the

standard A500K volume pot.

Experiment with different values for R1. Try values from 1K up to 470K.

Q1

BC109

E

C

B

R2

33KΩ

R3

330Ω

R1

100KΩ

Q2

BC109

E

C

B

VR1

B1KΩ

(Fuzz)

C2

.01uf

C3

22uf

VR2

A500KΩ

(Vol)

C1

2.2uf

9 volts +

InputOutput

R4

8.2KΩ

2.2uf

+100KΩ

10nf330Ω

8.2

KΩ

22uf

+

B1K

Fuzz

BC109

E

B

C

BC109

E

B

C

revision: 1.1 13 november 2008 © 2008 beavis audio research