This excerpt was taken from Stompbox: A History of Guitar Fuzzes, Flangers, Phasers, Echoes, and Wahs. This book and many other great books can be found at Amazon.com.
Rat designer Steve Kiraly on the birth of "The Rat":
"I was dabbling in modifying Systems and Technology pedals, trying to come up with something of my own because I didn't really like anything that was out there. I liked bits and pieces of different things. The idea for the Rat was to have an input buffer first, then an op-amp to crank it way up. The signal would then be rammed across a couple of parallel diodes that clipped the hell out of it, then sent it through a FET to smooth things out.
I had the basic circuit roughed together and I'd found an op-amp I liked, the LM 308N, which was an instrumentation amp used for seismic and medical sensors. I was experimenting with an EQ boost for this op-amp in order to pre-boost the treble so I could use just a passive tone control to cut back the highs. I was bypassing the voltage divider that sets the gain when I picked up a resistor, looked at it and thought to myself, 'Yellow, violet, brown- that's 470ohm.' I plugged it in, expecting to get about 50db of gain, but when I picked up my Strat and hit a string, it went wooooo. I thought, 'Holy Sh**, this is cool. What did I do?'
I looked real closely and realized that I'd plugged in a 47ohm resistor instead of a 470ohm resistor. That meant it had somewhere around 70db of gain, which, according to its spec sheet, was impossible from that op-amp. Trying to set the gain on this thing, I had stumbled across a combination of resistors that produced this really weird high-frequency shelving boost that the op-amp couldn't possibly sustain. It didn't have enough slew rate to produce that much gain at those frequencies, so it drove the op-amp into incredible slewing distortion. This is usually very bad, but in this case it's what gave the Rat its weird sort of yeowl. I've never heard any other stomp box make that sound.
Just to make sure it wasn't a fluke, I stripped the circuit off the proto board and rebuilt it completely using different parts with the same values. After it happened again, I realized that this was actually going to work. The whole thing was caused by plugging the wrong resistor into the protoboard. If I'd read the resistor color bands correctly the first time, the Rat probably never would have happened."
Well, I guess this proves there is hope for us guys who don't have a clue what we're doing. :-)
Reproduced in accordance with this copyright. (C) 1997 by Art Thompson All rights reserved