Pro Co Rat

The Pro Co Rat, introduced in 1979, is one of the most iconic distortion pedals in guitar history. Designed by Scott Burnham and Steve Kiraly in Pro Co's Kalamazoo, Michigan basement, the Rat was developed to provide a unique, aggressive distortion that could emulate the sound of a cranked amplifier. Its distinctive tone and versatility have made it a staple for guitarists across genres for decades.

History and Design

• Origins: The Rat's circuit originated from a happy accident when Burnham used an incorrect resistor value, causing the op-amp to clip heavily. This "op-amp distortion" became the foundation of the pedal's sound. The first batch of Rats, known as "Bud Box" Rat, was hand-built in 1978, with mass production beginning in 1979.
• Circuitry: The Rat features a simple three-knob layout—Distortion (gain), Filter (tone), and Volume. Its signature tone comes from a hard-clipping circuit using an LM308 op-amp, which provides smooth distortion with excellent dynamic response. Later versions, such as the Turbo Rat and You Dirty Rat, introduced different clipping diodes for tonal variation.
• Evolution: Over time, Pro Co released numerous versions of the Rat, including the Rat 2 (still in production), Turbo Rat (LED clipping for higher headroom), and You Dirty Rat (germanium diodes for softer clipping). Despite minor changes in components over the years, the core circuit has remained largely unchanged.

Popular Settings

• Classic Distortion: Distortion at noon, Filter at 1 o'clock, Volume slightly above unity. Delivers balanced distortion with cutting highs.
• Fuzzy Saturation: Distortion maxed out, Filter at 3 o'clock or higher to tame highs, Volume adjusted for output. Produces thick, fuzz-like tones.
• Boosted Crunch: Distortion at 9 o'clock or lower, Filter at noon or slightly below, Volume boosted. Ideal for pushing an amp into natural breakup.

Notable Players

The Rat has been used by countless legendary guitarists across genres:

• David Gilmour (Pink Floyd): Used it during his Pulse era for soaring lead tones.
• Kurt Cobain (Nirvana): Incorporated it into his rig to achieve raw, grunge-inspired distortion.
• Jeff Beck: Known to use it for its dynamic response and versatility.
• John Scofield: Relied on it for its warm yet articulate tones in jazz-fusion settings.
• Bands like Metallica and Radiohead have also used variations of the Rat to craft their iconic sounds.

Legacy

The Pro Co Rat remains one of the most influential distortion pedals ever made. Its ability to deliver everything from subtle overdrive to saturated fuzz-like tones has made it a favorite among guitarists spanning rock, metal, punk, and jazz. With its enduring popularity and numerous iterations, the Rat continues to be celebrated as a timeless classic in the world of guitar effects.