Pro Co RAT

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Pro Co RAT2 ProCo Rat 2.jpg
Pro Co RAT2

The Pro Co "The RAT" is a guitar effects pedal produced by Pro Co Sound. The original RAT was developed in the basement of Pro Co's Kalamazoo, Michigan facility in 1978. [1] Numerous variations of the original RAT pedal are still being produced today.


The basic RAT has changed in appearance over the years, but its tone has remained largely the same. Pro Co has also introduced tonal variations of the RAT, including the Turbo RAT and You Dirty RAT, among others.

The Pro Co RAT became very popular in the early 1980s, thanks in part to fame gained by its use by several artists, including Metallica, R.E.M. and Weezer. [2]


The origins of the Pro Co "The RAT" can be traced back to the mid-1970s, when Pro Co engineers Scott Burnham and Steve Kiraly repaired and hot-rodded existing distortion pedals, such as the Dallas Arbiter Fuzz Face. Burnham decided he could build a superior product from the ground up, and designed "The RAT" pedal.

In 1978, "The RAT" was being built as a custom-order product. [3] Only twelve of these pedals (including one prototype), commonly referred to as the "Bud Box" RAT, were produced. Each pedal was built in a standard project box, hand painted, and hand drilled. In 1979, Pro Co began mass-producing them. [3] This iteration was built in a custom designed, rectangular sheet-metal enclosure, with an L shaped removable top/back section giving access to the internals. The top panel was labeled with Pro Co Sound "The RAT" and the three control knobs as Distortion, Tone and Volume.

In 1983, Pro Co switched to a smaller, U-shaped enclosure. Finally, in 1988, the RAT2 was introduced, which included an on/off LED. Various RAT2 circuit board layouts and wiring configurations have surfaced in the last few years, including the noted "RAT3 version A and B" all under the RAT2 moniker. The RAT2 model is still available today, but in 2008 production moved to China and is now manufactured by Neutrik for Pro Co Sound.

Other models of RAT products include: [3]


The Pro Co "The RAT" is a distortion pedal with a quite simple circuit, which can be broken down into four simpler blocks: distortion stage, tone control, output stage and power supply. [3]

The design is based around a single opamp, originally the Motorola LM308 (switched to Texas Instruments OP07DP around 2002-2003). The distortion is produced using a variable gain circuit with diodes shorting the output to ground at a certain voltage level to produce hard clipping of the input waveform. Originally, 1N914 diodes were used, which were later replaced with 1N4148 since RAT2. The 'Turbo RAT' pedal uses red LEDs for this purpose (red LEDs have about a twice as high forward voltage as the original silicon diodes), while the 'You Dirty RAT' pedal uses 1N34A germanium diodes (clipping at a lower forward voltage). [3] [4] The distortion stage is followed by a passive 'reverse' tone filter and volume control.

The general design is very similar to the Boss DS-1 distortion pedal. A major difference is the opamp used (the LM308). Known for its poor slew rate, it largely accounts for the sonic difference between the two pedals.[ citation needed ]

Versions of the RAT

Current product line

Non-RAT moniker pedals currently produced by ProCo

Discontinued products

Special Runs

The RAT is a popular pedal for modifying. Some of the possible modifications include:

Notable users

Related Research Articles

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  1. 1 2 Williams, Stuart (2 August 2010). "Pro Co Reissue '85 Whiteface RAT". MusicRadar . Future Publishing. Retrieved 29 January 2012.
  2. Lynham, Alex (6 June 2019). "The FX files: Pro Co Rat". MusicRadar. Future Publishing. Retrieved 10 December 2019.
  3. 1 2 3 4 5 "Pro Co Rat Analysis". ElectroSmash. Retrieved 6 January 2020.
  4. Tranter, G. (9 July 2015). "Multi-RAT". DIYStompBoxes. Retrieved 18 April 2016.
  5. "The Ruetz Rat". DIY Tube Guitar Amp Page. Retrieved 6 January 2020.
  6. "Mightier Mouse". Beavis Audio. Retrieved 6 January 2020.
  7. "Agata of Melt Banana". GuitarGeek. Archived from the original on 22 July 2012. Retrieved 23 July 2012.
  8. Ross, Michael (1998). Getting Great Guitar Sounds: A Non-Technical Approach to Shaping Your Personal Sound. Hal Leonard Corporation. p. 69. ISBN   978-0-7935-9140-4 . Retrieved 29 January 2012.
  9. Nels Cline. "Tech Talk". Archived from the original on 28 January 2012. Retrieved 29 January 2012.
  10. "Lawrence Chandler – Bowery Electric – 1994". GuitarGeek. Archived from the original on 24 March 2014. Retrieved 6 January 2020.
  11. Berkenstadt, Jim; Cross, Charles R. (2003). Nevermind: Nirvana. Music Sales Group. p. 81. ISBN   978-0-8256-7286-6 . Retrieved 29 January 2012.
  12. Chapman, Charles H. (2001). Mel Bay Presents Interviews with the Jazz Greats-- and More. Mel Bay Publications. p. 24. ISBN   978-0-7866-5946-3 . Retrieved 29 January 2012.
  13. Cleveland, Barry. "Bill Frisell". Guitar Player . Archived from the original on 12 May 2012. Retrieved 29 January 2012.
  14. Riis, Bjørn (18 April 2011). "Tip of the week (11) – Overdrive and distortion" . Retrieved 4 February 2012.
  15. Cornish, Pete. "David Gilmour's Pink Floyd 1994 Rig" . Retrieved 4 February 2012.
  16. Doyle, Tom (June 2011). "FOO FIGHTERS: Recording Wasting Light". Sound on Sound . Retrieved 29 January 2012.
  17. Dale Turner (1999). "Rockin' Grohl Hoochie Foo". Guitar One.
  18. Kitts, Jeff; Tolinski, Brad (2002). Guitar World Presents One Hundred Greatest Guitarists of All Time from the Pages of Guitar World Magazine. Hal Leonard Corporation. p. 95. ISBN   978-0-634-04619-3 . Retrieved 29 January 2012.
  19. Prown, Pete; Sharken, Lisa (2003). Gear Secrets of the Guitar Legends: How to Sound Like Your Favorite Players. Hal Leonard Corporation. p. 55. ISBN   978-0-87930-751-6 . Retrieved 29 January 2012.
  20. Ross, Michael (15 November 2017). "Ben Monder on Texture, Ambience, and Guesting on Bowie's 'Blackstar'". Guitar Player. Future Publishing. Retrieved 6 January 2020.
  21. "Kurt Rosenwinkel". Guitar Player. Archived from the original on 2 June 2012. Retrieved 29 January 2012.
  22. John Scofield. "Equipment". Retrieved 29 January 2012.
  23. Kitts, Jeff; Tolinski, Brad (2002). Guitar World Presents One Hundred Greatest Guitarists of All Time from the Pages of Guitar World Magazine. Hal Leonard Corporation. p. 99. ISBN   978-0-634-04619-3 . Retrieved 29 January 2012.
  24. Gill, Chris (1995). Guitar legends: the definitive guide to the world's greatest guitar players. Harper Perennial. p. 127. Retrieved 4 February 2012.
  25. Hunter, Dave (2011). The Rough Guide to Guitar. Penguin Books. p. 223. ISBN   978-1-4053-8244-1 . Retrieved 29 January 2012.
  26. Hunter, Dave (2011). The Rough Guide to Guitar. Penguin Books. p. 222. ISBN   978-1-4053-8244-1 . Retrieved 29 January 2012.
  27. "Fat Sound" . Retrieved 6 January 2020.
  28. "Boris official Instagram" . Retrieved 15 January 2017.