From the very beginning, the RAT was destined to define “The Sound of the Underground.” It was, after all, born underground in the cavernous basement of the Pro Co Sound factory in downtown Kalamazoo, Michigan. From these humble origins, the RAT has evolved from a single, hand built prototype into a family of the most versatile and most recorded distortion pedals in the world.

Do you want to see how the RAT has evolved? The RAT Family Timeline details the expansion of the RAT product line throughout the years. Also, since there is no accurate way of dating a RAT pedal by its serial number alone, this timeline can help you determine the general age your pedal.

“Bud Box” RAT

Never intended to be a mass produced product, the original RAT pedals were built completely by hand, enclosed in an off-the-shelf project box. All of the holes were hand drilled and were finished in a black crinkle coating with a bright florescent silk-screened logo. Only twelve of these pedal were built, one prototype and eleven production models.

The Rat

This was the first RAT pedal manufactured in large numbers. To give the RAT a unique look, a custom 20 gauge wrap-around enclosure was designed. The white RAT logo was silk-screened on black, painted metal. The “EQ” on this pedal is labeled Tone. The Tone control increased high frequencies when it was turned clockwise, the opposite of later models.

The Rat (ver. 2)

The main difference between this model and the earlier version is the switch from a Tone to the Filter control. The Filter cuts high frequencies as it is turned clockwise. The RAT logo was also switched from an all caps logo to one that was more stylized, while the “a” and “t” were now lower case.

Small Box RAT

The switch to the “Small Box” RAT was essentially just a cosmetic makeover. While the circuit remained the same, the enclosure evolved into a more compact version, with a 12-gauge U-shaped base. The Pro Co logo sat next to the RAT logo on the pedal top, silk-screened in black inside of a white box. In 1986, the logo was reversed to white on the black, painted metal.


During the rack effects boom of the 1980s, Pro Co introduced the R2DU, which was essentially two RAT circuits in a single rack space box. The two units could be used separately or cascaded together for a more powerful distortion. The R2DU included the RFS-2 dual footswitch for remote control of the unit.


The RAT 2 signaled the next generation of RAT pedals. While the enclosure remained the same, the silk-screened logo gave way to a Lexan/Mylar overlay with glow-in-the-dark graphics. A red on/off LED was also added. In 2003, Pro Co converted the RAT 2 to a sloped enclosure, which had been used on the Turbo RAT since its introduction.

Turbo RAT

Eleven years after the birth of the RAT, the Turbo RAT was the first product to expand upon the tonal base of the RAT design. Essentially the same circuit with different clipping diodes, the Turbo RAT provides a more aggressive tone. The Turbo RAT also introduced the now standard sloped face enclosure.

Vintage RAT

As the vintage instruments market surged, demand grew for a reissue of the “large box” RAT pedal. The Vintage RAT can easily be identified from an original in two ways. First, the Pro Co logo does not contain the “Sound Inc.” text written down its right side. The reissue also features an easy access battery compartment on the pedal’s bottom.


The Brat signaled Pro Co’s entry into the economy priced effects pedal market. Still built in the USA, the BRAT featured a tone similar to its more expensive brothers, but was built with a less indestructible enclosure. The BRAT was adorned in a florescent purple and yellow color scheme. The “EQ” control was labeled Tone instead of Filter.

Deucetone RAT

As boutique pedal builders pushed effects prices higher and higher, Pro Co introduced the Deucetone RAT to compete in this market. The Deucetone RAT is the evolution of the R2DU, with two RAT circuits in one enclosure, but now in a pedal . Each RAT circuit is switchable between three RAT tones. The Deucetone introduced the Dirty RAT and Clean RAT settings to guitarists.

You Dirty RAT

Due to the popularity of the Dirty RAT setting in the Deucetone RAT, the You Dirty RAT brought that tone into a single channel pedal. Like the Turbo RAT, the You Dirty RAT shares much of the same circuitry with the original RAT, but with germanium clipping diodes.