Coolest Versions of the Pro Co RAT

Pro Co Sound is an idiosyncratic company in the world of guitar effects. Founded in Kalamazoo, Michigan in 1974 by Charlie Wicks, Pro Co's bread and butter has always been audio connectors and interface devices like cables and snakes, DI boxes, mic splitters, and the like. In fact, they quite modestly refer to themselves as the "plumbers" of the audio industry. Despite this, the one product they are most widely known for around the world is a guitar stompbox; the RAT distortion, a singular black box of filthy sonic magic created in 1978 by the company's "Hippie in Charge of Technology," Scott Burnham, while sequestered in the dungeon-like (and truly rat-infested) basement of Pro Co's Kalamazoo factory. Burnham had been mulling over the idea of designing a distortion pedal that would simulate the punch and grind of a large tube amp being pushed to the limits of safe operation, and after some tinkering and a fortuitous happy accident or two, the RAT was born.

Consisting of a simple circuit with controls for gain, passive tone filtering, and volume control, the RAT's unique sound encompassed elements of amp-like overdrive, edgy distortion, and thick, spitty fuzz, depending on the setting. At the heart of the pedal was the now famous Motorola LM308 op-amp, a chip known for its sluggish slew rate (which relates to how fast it can respond to and follow the input signal), a characteristic that might sound unfavorable at first, but which ultimately has a very pleasant effect on the tone of a distorted guitar, imparting it with a bit of the warmth and molten chewiness of good power tube saturation.

ProCo RAT2 Distortion (Original) | Reverb Demo Video

The RAT started off as a custom order product, with only twelve of the original, handbuilt "Bud Box" version being produced in total, including the prototype. By 1979, however, orders had taken off to the point that Pro Co designed a custom box and logo for the RAT and began manufacturing it in quantity. By the mid-eighties the RAT was a bona fide classic, with Jeff Beck, David Gilmour, Andy Summers, Joe Perry, Joe Walsh, and lots of other hit-making guitar hero types making use of its resplendent palette of dirty tones. Since those early days, the RAT has undergone numerous, mostly small, changes and has been produced in quite a few different versions and reissues. Some of these versions sound better than others, and a few are relatively rare and valuable on the used market, but all retain the essential scuzzy glory of the original. Let's take a look at a handful of the most interesting variations of Pro Co's most infamous and inspiring product.

The "Bud Box" RAT

The "Bud Box" RAT

This is the original grandaddy RAT that started the infestation. Birthed in the dank, dark confines of the Pro Co factory basement by Scott Burnham, it was originally a custom order item that was never intended for mass production. Constructed entirely by hand from off-the-shelf parts stuffed into a hand-drilled, generic project box, only twelve of these were ever made, a number which includes the original prototype. They were finished in black crinkle and silk-screened with a bright orange minimalist logo featuring the outline of the pedal's namesake rodent and the words "The RAT" overlaying it in a fetching design that I, for one, wish had survived into the mass production phase. Obviously, since only twelve were ever made, you're just not going to find a Bud Box RAT for sale, and if you did you should take it directly to the Smithsonian.

The RAT v2

The original 1979 production model RAT, which had established the familiar black wrap-around enclosure and white silk-screened logo, was updated in 1981. The updates were mostly minor and cosmetic, with new knobs and some small changes to the logo lettering, but the most significant change heralded by the v2 RAT was the new Filter control, a feature which would remain a signature element of the pedal's design to this day. The first production models had a tone knob with a linear taper pot that added high frequency content as it was turned clockwise—a familiar arrangement for most modern players who have played a dirt pedal or two. The new Filter control on the 1981 v2 RAT reversed this function, however, with a logarithmic taper pot that cut treble content as the knob was turned clockwise.


In the eighties everybody in the MI biz had to get into the rack game to stay alive, and Pro Co was no different. Unlike a lot of the antiquated remnants of the rack boom, though, Pro Co's R2DU (did you say R2D2?) rack unit was, and still is, a really great and useful piece of guitar gear. Far from being some flashy technological marvel, the R2DU is just two classic LM308 RAT circuits in a single rack box, with a simple two-button remote footswitch for switching between them. They could also be cascaded together for a ferocious, dual-rodent onslaught. The R2DU was only produced for four years, from 1984-1988, but there must have been a fair number of them made, as they come up on the secondhand market with some regularity, often for very fair prices.


In 1988 Pro Co began producing the new incarnation of the RAT, the RAT 2, and this pedal is still in production today, being the most popular and longest running RAT in the Pro Co product line. Updates included a big, bold new glow-in-the-dark logo, a red status LED, and some time later, a sloped small box-style enclosure, slope edged knobs, and true bypass switching. Originally the RAT 2 still used the LM308 chip, but current production versions use a Texas Instruments OP07DP. Despite this move away from the original op-amp, the RAT 2 maintains the aggressive, furry gain and warm sustain of the original. Dave Grohl and Jeff Beck are two notable users of this venerable version of the pedal.

Deucetone Rat

The excellently-named Deucetone RAT might be the one RAT to rule them all. It was launched in 2002 as both an evolution of the 2-in-1 RAT concept that started with the R2DU rack unit, and as competition for the burgeoning boutique pedal builders that were beginning to horn in on Pro Co's business. This all-analog firebreather is two OP07DP-based RAT circuits in one double-wide stompbox enclosure, with separate true bypass footswitches for each channel. Like the R2DU, these channels have separate, independent input and output jacks so the channels can be used by themselves, in stereo, or cascaded together. That right there is already well worth the price of admission, but Pro Co also gave each channel three different selectable RAT modes, accessible via mini switches on the back panel. Channel A can be set for Vintage RAT (with silicon clipping diodes), Turbo RAT (LED clipping diodes), or You Dirty RAT (germanium clipping diodes), while Channel B can be set for Vintage RAT, Turbo RAT, or Clean RAT, a clean boost setting with no clipping diodes that's only available on the Deucetone. For insatiable RAT fanatics, the Deucetone is a must-have pedal.

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