ProCo gear on the Anagram

Pro Co Sound is a cable and audio company from Kalamazoo, Michigan. Its one famous pedal is the RAT, a distortion first built in the late 1970s. The basic circuit uses an op-amp for gain and a pair of diodes to clip the signal hard, and it has barely changed in decades.

Nembrini Audio says Black is modelled on the RAT 2, and Mercuriall Audio calls RODENT Distortion its take on the RAT circuit. Both are confirmed by the developers and both are free.

Clack Digital says Bassement Plague Distortion morphs between two famous versions of the same distortion pedal. It never prints the name, but its page art is full of RATs, so the badge reads likely. Darkglass's built-in Chinchilla is also likely a RAT, inferred from the rodent name and the controls.

The RAT's sound runs from a light grit to something close to fuzz. It has a strong mid snarl that cuts through a mix. Its Filter knob works backwards to most tone controls, so turning it up rolls off treble. Guitarists use it as a dirty channel or a solo boost. Bassists like it because it stays defined on the low strings, especially when blended with the clean signal.

On bass, put the RAT before a clean amp block and keep the Filter around noon, or run it in a parallel path so the low end stays clean. On guitar it works in front of a clean amp or as a boost into a driven one.

Start with Black. It is free and it gives you the RAT 2 with no extras to set up.