rous front 11

The RAT Distortion belongs to that very exclusive pedal circuit “elite” that provides seemingly infinite inspiration to stompbox builders. We know something about it, since we’ve been working for over a year on a comprehensive article about RAT clones, and each and every time we try to finalize it we are overwhelmed by the sheer size of models on the market.

Oregon’s boutique builder Pettyjohn Electronics has built a solid reputation in the dirt box arena, and a RAT-style pedal was missing from their roster: enter the ROUS. The references to the RAT aren’t disguised – ROUS stands for “Rodent of Unusual Size” – but, of course, this is far from a simple recreation.

Here are the main differences from the original:

  • The Pettyjohn ROUS runs at 7-18v, which allows for an extended gain range and, at higher voltage, adds headroom and dynamics
  • It features two EQ knobs (pre-gain Lows and post-gain Highs) instead of one, for more precise tone sculpting.
  • Fire/Swamp toggle switch delivers two different style of distortion: Fire delivers silicon hard clipping that more closely resembles the aggressive tone of the original unit, while the Swamp mode adds a Germanium diode into the equation, delivering softer clipping with vintage overtones, making it perfect for less aggressive genres like country, blues and pop. 

Here are the latest videos of the Pettyjohn Rous Distortion. You can find other similar pedals in our Rat-Style Distortion Pedal coverage.

The ROUS, “Rodent of Unusual Size”, is a highly evolved member of the RAT family. The ROUS features a simple but powerful four knob control set: Level, Gain, Lows and Highs, similar to the other CORE series pedals.

Its gain range moves from low gain overdrive to unusually large sounding distorted tones quickly with the turn of the GAIN knob. One may take matters of fate into their own hands and journey deeper into the un-known with a flick of the Fire Swamp switch.

Explore the feature set in detail below and for those looking to choose their own adventure, you can discover more paths to sonic nirvana with custom mod options only available from the Pettyjohn online shop.

Audio Demos


  • Versatile, overdrive and distortion circuit with deep nostalgic origins.
  • Extended gain range over the original, specifically with better low gain characteristics
  • FIRE-SWAMP switch for two special tone experiences in one pedal.
  • Buffered Level control for no tone suck or loading with other pedals.
  • Re-designed LOWS circuit that sweeps from 30Hz to 1kHz before the GAIN stage, which interacts with the distortion.
  • Active 18db/oct sweepable HIGHS control, comes after the gain stage with a wide sweep from 22kHz down to 1 kHz, it can powerfully shape the harmonics content.
  • High headroom with internal doubling from 7v-18v power input. Draws under 100mA.
  • Quiet bypass relay based true-bypass system for quiet switching.
  • Designed for guitars, bass and keys.
  • Low noise with premium analog parts.
  • Hand made in Oregon, USA.
  • New enclosure by GORVA design.
  • Rear mounted jacks.

Gain Control

The GAIN control moves the internal gain amp from a relatively low gain overdrive into all out distortion fairly quickly, though no doubt, some will enjoy the low gain magic this box has to offer.

Designed to keep the max gain somewhere in the neighborhood of the original design but this is by no means a clone so it has its own thing going on! Much like the original, the gain amp drives an array of diodes in shunt position but we have take several years to fine tune this array to be something a little more unique in the pedal world.

Furthermore, we couldn’t decide on our favorite setting so we included a mini toggle switch for you to choose two options: FIRE or SWAMP.

Fire Swamp

The Fire Swamp switch adjusts the diode clipping array between two settings that make for a remarkable change in tone.

We can not reveal all of our tone secrets but we can say that the FIRE setting is pure silicon hard clipping, and this setting most closely resembles the original rat design, making it great for more aggressive rock tones.

The SWAMP setting adds some mystical Germanium into the equation and increases the headroom and softens the clipping effect in a vintage, musical way that we love. The SWAMP is perfect for less aggressive genres, like country, pop, blues and indie players who would normally find it inconceivable to use rodent style drive.

More Power

The ROUS features our CORE series dual rail doubling power supply, which can scale from +/-7v to +/-18v, effecting the headroom, tone and feel of the pedal.

The internal supply achieves this by mirroring whatever input voltage you apply via the external power supply.


The LEVEL control has been carefully placed in the circuit to control the overall level of the signal and help deal with the huge amount of gain.

It is also fully buffered from the outside world and will not load or tone suck, AND the ROUS loves to be stacked with other drive pedals.


The LOWS control has been designed for the CORE series and offers a huge sweep range from sub 30Hz to beyond 1kHz, rolling off at 18db/octave.

This control is located before the GAIN stage and greatly impacts how the circuit distorts. Keep this in mind as you experiment with the control at the extremes and you’ll find a vast array of overdrive and distortion and tones just by sweeping the LOWS control.


The HIGHS control has been re-designed as well for the CORE series and is now fully buffered against any external loading making it more robust than ever.

The ROUS generates a huge amount of high end harmonics and you can easily tame it or unleash the wrath with this wide range control that sweeps from 22kHz down to 1kHz. 

Quiet Bypass

The ROUS features a big update first introduced in our flagship Foundry MKII line: our quiet bypass switching system. It is a true bypass, relay based system for minimum pop when engaging the effect.

If you happen to use a true bypass looper and want state memory we offer the pedal with Hard Click True Bypass via our custom shop as a post-purchase mod or at time of purchase via our online shop.