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Pro Co RAT
Pro Co
The Pro Co RAT is a distortion pedal for electric guitar, first prototyped in 1977 or 1978 and entering full production in 1979. Its distinctive aggressive distortion stems from an accidental 47 ohm resistor substitution that increased op-amp gain, combined with diode-based hard-clipping. It uses an op-amp to amplify and diodes to limit the signal.