Bitters Out Now!

Pro Co Rat

Pro Co Rat

Well hello, I didn’t see you standing there. Thanks for checking out the first Cabinet piece of 2021; and this one is one of my all-time favorites. There aren’t many pedals that have been continuously made for almost 50 years. And of that choice few, one stands alone at the top of the pile: the Pro Co Rat.

In the time that’s elapsed since the first Pro Co Rat rolled off the “assembly line,” now-legendary companies apexed and faded, several were established and pushed to the present day, but none of those have lineage this deep. And few produced were as well-loved as the Rat; so much so Pro Co produced nearly only Rats and variations of it since 1978.

Just four years prior, one Charlie Wicks sat down after punching his first clock at Pro Co, assembling cables and other live accessories—still the bulk of Pro Co’s business. In the late ‘70s, Pro Co engineer Scott Burnham stuffed the first handful of Rat guts into an off-the-shelf project enclosure made by BUD Industries, known for providing the enclosures to MXR in its nascence. After custom-making 12 pieces (including the prototype), the “big-box” Rat was born with plenty of siblings. It was an out-and-out infestation across the country, with Rats popping up in every music shop in America.

This new enclosure was built to last a nuclear explosion, made of rolled steel and adorned with plenty of sturdy fittings. While Rat enclosures were likely just as sturdy as the cast zinc enclosures MXR was using, the Rat had the looks and the durability, with the tone to match the brawn.

Eventually the enclosure shrunk, underwent several graphical revisions and ended up settling on the Rat 2 in 1988. An aesthetically revamped addition to the family, the Rat 2 featured a hidden LED and a sleeker look. Although the exterior was tweaked, the early days of the Rat 2 featured the very same innards as days past, including the heart of the unit, the LM308 op-amp.

Along with NKT275s, MN3005s and OC44s, the LM308 is considered to be one of those essential parts by which a pedal is defined. While many, many op-amps were available to anyone able to walk into a Radio Shack, the LM308 had one crucial statistic in its datasheet: the slew rate.

Unlike several off-the-shelf op-amps, the LM308 had what’s called “external compensation,” which lets the designer limit the slew rate by installing a small capacitor between two of its pins. This limits the output swing speed of the op-amp which allows it to only process guitar harmonics within a certain frequency range.

The flipside of this operation is the gain-bandwidth product, which when parameterized with other design choices, causes the op-amp to perform out-of-spec and distort heavily across selective frequency bands. Crushing.

Throughout Pro Co’s production career, nearly everything was rodent-adjacent. On top of the five distinct “Rat” named variants, Pro Co also produced the Turbo Rat, whose chief circuit change was a pair of LEDs in place of the 1N4148 clipping diodes. Another variety was the You Dirty Rat, which made a similar diode swap, this time to germanium parts. Over the years, Pro Co released a rackmount Rat, a dual version, a fat version, an ‘80s neon-covered version and a low-budget version. The bread and butter of the line has always been the original, and there was even a little mini scavenger hunt included in the older units.

Some units contained a printed sticker across the back of the potentiometer featuring the “stage name” of the technician that assembled it. Even though all the Rats were built to the same specs, it became a piece of internet folklore that the best Rats were built by a man whose label read “THE WOODCUTTER.”

Pro Co Rat

There were many other names found on the inside of Rats, but Woodcutter got all the fame. Two different effects manufacturers released Rat-based pedals called “Woodcutter,” and now that name is a footnote. But for a brief period, everyone in the world was cracking open their Rats. Mine is a Woodcutter.

Above all the vintage hype and varietals, the LM308-equipped old school Rat is the one that keeps players coming back. Sometime within the lifespan of the pedal, Pro Co switched the chip over to the OP07DP, another externally compensated op-amp. To me, the differences are slight, but to others, the difference is night and day. In the interest of keeping the cabinet classy, only the original chip will do. Your mileage may vary.