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can someone help me explain the circuit flow of a distortion pedal?

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xo0x

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hi guys!i am trying to build a distortion pedal but im having problem on explaining the circuit flow and what does each part does.
i only know that distortion is caused by clipping nothing more.
can someone help me explain the circuit?
your help will be greatly appreciated. the circuit i used is not mine,its from tonepad.com. follow the link below for the shcematic diagram

http://tonepad.com/getFile.asp?id=117
 

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hi guys!i am trying to build a distortion pedal but im having problem on explaining the circuit flow and what does each part does.
i only know that distortion is caused by clipping noothing more.
can someone help me explain the circuit?
your help will be greatly appreciated. the circuit i used is fro tonepad. it is attached on this message.

OK...the signal from the guitar pickup comes in on transistor Q1. Q1 and Q2 are configured as a darlington pair, which has very high current gain. The 220pF between the base and collector of Q1 provides negative feedback at higher frequencies to suppress high frequency oscillation.

The output signal on the collector of Q2 hits the Fuzz knob, which controls how much of Q2's output signal gets to pass to the input at the base of Q3. Then Q3's output is fed to the tone and volume knobs. The volume knob controls how much of Q3's final output signal gets to pass to the output jack

Diode 1N270 acts as a clamp diode that clips the signal asymmetrically (the positive swing will get clipped more than the negative will).

That circuit is more of a fuzz pedal than it is an overdrive/distortion pedal. But basically the darlington pair formed by Q1 and Q2 acts as one transistor that has super high current gain to overdrive transistor Q3, which causes it to distort the signal.
 
The distortion pedal does NOT distort music. It adds timbre, harmonics, sustain etc to ONE instrument in the music. It greatly increases the sensitivity of the guitar, increasing nuance from the slightest touch of the strings. It is a very important part OF THE INSTRUMENT of a rock guitar player.

Audioguru: I would have liked to hear your analysis of the OP's distorion pedal including discussion of the asymmetrical distortion, the germainum soft curves etc, that would have been something of value to people.
 
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Hi Xoox, in addition to what Jon Wilder said I'll take a stab at it too. The clipping will be asymmetrical which is excellent for guitar as you get 2 distinct clipping stages so depending on the amplitude (how hard to hit the strings) you can work both those stages at will, for more expressiveness. Hendrix was a master of that (he used a asymmetrical germanium fuzz unit), even between note to note he could hit some notes harder than others and be almost like he was playing two instruments at the same time.

On your schematic the clipping will be very soft, I agree with Jon that definitely looks more like a "fuzz" effect than a hard clipped "distortion" effect. It is soft because the clipping is produced by germanium transistors and a germanium diode, which have soft operating curves compared to silicon parts. Also, the diode clipper is fed through a high impedance, (100k pot) so at "low fuzz" pot setting the effect should be a very gentle clipping and not harsh at all.

It's a real shame the people who were masters of making a couple of germanium parts sound wonderful with a guitar are not around or not easy to find. And most of the people who are really skilled at electronics are used to more modern components now and not skilled at tuning the specific *faults* of germanium parts to the specific requirements of guitar players to make the WHOLE instrument sound wonderful... It's becoming a lost art I think. :(

Experimenting with parts values, and having good ears for what you want to accomplish will go a long way. Have fun! :)
 
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