JHS - PackRat

JHS - PackRat

In 1978, the most versatile and influential distortion pedal of all time was invented in Kalamazoo, MI: the Proco RAT. Scott Burnham and Steve Kiraly first had the idea after playing, repairing and modifying all the available distortion pedals on the market. They wanted something that didn’t exist in the mainstream product lines like MXR, DOD and BOSS. They wanted a pedal that could go from overdrive to distortion and then all the way to fuzz. By 1979 Scott had perfected the circuit in his RAT-infested basement workshop, and the rest is history.

The PackRat is the ultimate tribute to the 40+ years of rodent evolution and its impact on the guitar’s sound. Artists from every genre have used the iconic tones in this unassuming black box to create their sounds, including Nirvana, John Scofield, Pink Floyd, Metallica, REM, the Eagles, Jeff Beck and Radiohead.

Building on our Multi-Mode pedal series that includes the Muffuletta and Bonsai, the PackRat uses the same unique digital runway system to direct the paths of 261 components through 40 individual switches. This means that when you choose one of the nine legendary or rare modes, you are playing fully analog circuits that perfectly replicate that mode, even down to the aging components (also known as component drift). If you purchased these nine hard-to-find pedals on the used market right now, you would pay around $4,000. When you put it that way, $249 sounds pretty reasonable.

Let’s take a look at the controls.

The operation of the PackRat is about as simple as it gets. The “Volume” control adjusts the overall volume of the pedal. The “Distortion” control lets you raise and lower the amount of gain or distortion that the circuit produces, and the “Filter” control allows you to brighten and darken the sound of the overall effect. This is effectively a simple, low-pass filter. Lastly, we have “Mode” control. This is a stepped pot that clicks into place as you scroll through the nine legendary versions of this circuit. As you change the mode, the analog circuitry is rewired, resulting in brand new values of resistors, capacitors, diodes and op amps.


Although I’ve put several years of research into the history, circuit topology and version history of the RAT, I know that my findings may still ruffle some feathers. I’m okay with that.

I have tracked down over 100 different RAT specimens for study, and I’ve performed almost twenty hours of interviews with former ProCo employees about the circuit design, evolution and production of this pedal series over the decades. And basically? A lot of the widely accepted “facts” about the differences in RAT versions, including some of my own beliefs, were wrong. Most assumptions about how specific RAT models sound different or better than the rest are, at best, misinformed. Generally speaking, they’re flat-out incorrect.

To find the facts and give this circuit the proper understanding it deserves, every RAT model ever made (and quite a few prototypes that never saw the light of day) were obtained and studied in great detail. I wanted to understand the exact production differences over the years, so we disassembled the units, analyzed them using state-of-the-art Audio Precision equipment, measured individual components, built comparison charts, traced each circuit and closely examined the branding, logos and other identifiers of change. As far as I know, no one has ever gotten close to the level of research that we performed between 2018 and 2021.

Reliable sites like Reverb.com had inaccurate timelines with incorrect pictures of the respective models. Even ProCo’s own history timeline was missing tons of details about the RAT variations that have been made over the past 40 years. And Wikipedia?… No. Just no.

There’s a reason for that.

A vintage unit is typically dated by reading the manufacturer codes on the back of the pedal’s potentiometers/knobs. Unfortunately, this is a flawed dating method. ProCo would have ordered thousands of potentiometers, and in doing so, many pedals were made with parts pulled from backstock at least two to three years older than the actual pedal being dated. In short, this means that you’ll see V1s, V2s, V3s with dates that overlap with each other’s true production years. Combine this with decades of people incorrectly “remembering” what RAT model sounds the best, and you have a historically inaccurate hot mess on your hands.

To properly build an accurate timeline and database of changes, I dated the pot codes, dated their components when possible, interviewed respective people involved in the eras of production and referenced over 1,000 online sales photographs, and studied the prototypes and the evolution of the engineers’ design ideas. I did everything possible to build an airtight case for my work and to not rely on any prior dates and timelines


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