Pro Co’s The RAT: The First “Modern” Guitar Distortion Pedal?

Well noted as the first one to extensively use IC op-amps in its construction, can the Pro Co Rat be considered the first “modern” guitar distortion pedal due to its reliability and tonal consistency?

By: Ringo Bones 

The raison d’être of guitar distortion pedals is to replicate the pleasing tone of accidentally damaged electric guitar combo amps – i.e. ripped and torn speaker cone and / or a dislodged vacuum tube, etc. – and thus the birth of iconic and pioneering guitar distortion pedals of the 1960s like the Dallas Arbiter Fuzz Face and the Big Muff Pi which primarily uses early germanium transistors. Despite of their wicked sustain and tone, germanium transistor based guitar distortion pedals from the 1960s are not well known for their tonal consistency – especially in live performance / touring situations – because early germanium transistors were notorious for their wild parameter drift with ambient temperature changes and thus tonal consistency from start to finish of a live performance – never mind from the next concert venue to the next – eludes these great sounding but notoriously unreliable guitar distortion pedals. Legend has it that the late great Jimi Hendrix once bought 10 individual Dallas Arbiter Fuzz Face pedals and switch between ones that maintained the most tonal consistency when played live. 

The stated problems of early guitar distortion pedals probably what inspired Pro Co engineers Scott Burnham and Steve Kiraly to hot-rod existing distortion pedals during the mid 1970s – such as the Dallas Arbiter Fuzz Face - as suggested by their clients in order to make these units sound better. But eventually, the two Pro Co engineers discovered the “weaknesses” of these early guitar distortion pedals and thus paved the way to a better new and improved guitar distortion pedal. 

The original Pro Co Rat was developed in the basement of pro Co’s Kalamazoo, Michigan facility in 1978. It was notable for its extensive use of IC op-amps – or integrated circuit operational amplifiers – such as the 8-pin dual in-line monolithic Motorola LM308 op-amp. The Pro Co “The RAT” in a nutshell is a distortion pedal with a quite simple circuit that can be broken down into four simpler blocks – the distortion stage, tone control stage, output stage and power supply. Given that the basic circuit was based on a public domain Popular Electronics published design based on an IC op-amp that was published around 1966 but was, at first, dismissed by serious guitar players because it’s sustain wasn’t as good as that of germanium transistor based guitar distortion pedals. But Burnham and Kiraly noticed the tonal consistency and immunity from temperature drift of the op-amp based distortion circuit and thus worked on it until they managed to design one with a tone and sustain that is more on less equal to that of germanium transistor based units. 

The IC op-amp based circuitry of “The RAT” inspired a host of copycat models during the 1980s – especially during the heyday of Hair Metal bands. And some of them use other op-amps such as the ubiquitous during the 1980s Motorola LM741. The original Dallas Arbiter Fuzz Face and Big Muff Pi with their original germanium transistor based circuits may be fetching sky-high second hand prices on eBay these days, but these units can be a pig to maintain tonal consistency in live concert tour situations, never mid if you’re a bar-based working musician. Thus, the Pro Co’s “The RAT” and its op-amp based variants now reign supreme in the loud guitar playing world.