How Fuzz (audio effect) works?

Question

I am relatively new to the world of guitar pedals, and I have recently (after a few failed attempts) built a successful Bazz Fuss.

Although I've successfully built it, I'm not sure how exactly it works. I would like to learn what each part in it does.

Here's the circuit:

My main questions are:

1. What are capacitors doing in the circuit?

2. What is diode's purpose and why is it connected this way? I've thought it would be connected straight from the capacitor to the transistor base.

3. And of course, how fuzz works (in general).

Answer 1

And of course, how fuzz works (in general).

In words, adding fuzz is adding harmonics to the original signal. Harmonics are frequencies that are higher than the original signal but are tonally related.

More technically, this circuit essentially converts a sine wave

to something resembling a square wave

A sine wave is a pure tone which sounds dull

but a square wave contains the pure tone as well as odd order harmonics

which sounds more interesting.

Answer 2

Oh, I built the same thing a while back!

1. The capacitors filter out DC voltage, which could damage your pickups and mess with some things further down the signal chain. They also control the frequency response, in this case how much low end goes through.
2. The diode is used to bias the transistor. I'm not sure what you mean in regards to its connection- it is electrically connected to both capacitors and the transistor's base.
3. Fuzz is basically using an excessive amount of gain to push an amplifier (in this case, your transistor) beyond its limits. This changes the signal of your instrument from something like a sine wave to more of a square wave.