distortion circuit

[BioniC187]

Hey guys,
I am looking into making my own distortion for my guitar, what is the best route to go?
Anyone has done this, and have positive feedback on the best route please
Thanks

 

[unclejed613]

an op amp feeding a pair of "nose to toe" diodes is usually a good start. make one diode silicon and the other a germanium diode, and that will add some even harmonics. adding tone control circuits after the distortion stage makes it a bit more versatile. you'll have to wait until i get home later today for a schematic....

also, quite a few years ago, i came up with a device called an "un-fuzz" that distorts more with less signal, and gets cleaner as you play louder. it simulates what's called "crossover notch distortion" in an improperly biased amplifier.

 

[BioniC187]

Ok i will look in to that, thanks

 

[BioniC187]

I have a 10W opamp, tda2003, gonna try this. is 10W too powerful?

 

[unclejed613]

for a fuzz box, you only need an op amp, not a power amp. the voltage across the diodes that distort the signal needs to be current limited, and a power amp would just burn the diodes out.
look here: https://fuzzcentral.ssguitar.com/schematics/blueclipper.gif

 

[BioniC187]

Okay, i will do some test with some opamps i have here, thanks

 

[WTP Pepper]

Two back to back 0A81 diodes on the feedback of an op-amp give a superb soft clipping sound. I made one in the 80's.
Dunno if germanium diodes are still available. I do remember that schottky and silicon diodes sounded horrible as the biasing of the op-amp relied on the awful leakage of germainium diodes that modern silicon diodes didn't have. I used an LM741 op-amp at the time as it was all I could afford.

 

[unclejed613]

the "dead zone" circuit.... i remember it well. the way it works is the op amp is open loop until the diodes conduct, then it's closed loop. a bit different sound than the overdriven diodes..... the bias problem can be fixed by limiting the gain with a 100k resistor in parallel with the diode pair.