The ProCo RAT is one of those unique distortion pedals that has its “own sound”. Going quickly from overdrive to flat-out fuzz, the RAT has been the distortion flavour of many guitarists from Jonny Greenwood and Thom Yorke of Radiohead, Thurston Moore and Kim Gordon of Sonic Youth and some classic rock guitarists like Joe Walsh and Jeff Beck.

A big part of the RATs sound is the LM308 – the IC used to provide the distortion tone unique to the RAT; and its pronounced frequency response provided by two R-C networks and the FILTER control. This wide sweeping tone stack allows the RAT to slot into any guitarist’s setup – regardless of the use of a bright or dark amp. Sweep one way and the high frequencies are rolled off, or if you want to cut through the mix, sweep it the other way for more treble. It is definitely an “in-your-face” distortion flavour, that is really closer to a fuzz sound at maximum gain. There are also a number of RAT variants now – the classic “big-box” RAT, small box RAT, the Whiteface RAT, RAT2 etc, all of which contain part of the RAT heritage but with varying levels of tone that make some more sought-after than others.

This variance in the RAT pedal pedigree is what disappoints many guitarists. The RAT has a reputation of inconsistency between individual pedals. I have played some RATs that sound terrific and I wouldn’t want to change at all, but I have also played some RATs that I would never plug in again. This inconsistency is mostly due to cheap parts as is common in a lot of mass-manufactured products. The cubisteffects Four Headed RAT mod uses the best hi-fi components to provide the ultimate in RAT tone for any RAT2 or vintage “big box” reissue. With these changes, the RAT becomes an articulate, harmonically-rich distortion pedal, but also a great overdrive/boost pedal as the new components provide a cleaner, more defined tone than stock.

The cubisteffects Four Headed RAT mod provides four unique gain voicings – two overdrive settings and two distortion settings – to provide the most flexible RAT pedal out there. Each of these settings has something unique to offer and covers the spectrum of low gain blues to super-fuzz stoner rock.

Not only does the RAT stand on its own… four feet, but the two overdrive settings make it a brilliant “stacking” pedal to provide another tonal flavour to your other overdrive pedals. The cubisteffects modded RAT combines with other drive pedals to provide complex and louder crunchy tones. A lot of the clean signal can be heard when the DISTORTION knob is rolled off and this is ideal when boosting another overdrive or fuzz pedal. Your tone will retain its responsiveness to your playing even though multiple pedals may be stacked.

I offer two stages of modifications of the cubisteffects Four Headed RAT mod: the STANDARD mod and the NOISE mod.


The Standard Mod changes involves four changes:

1. CAPACITOR CHANGE – All capacitors are replaced with hi-fi WIMA capacitors, used in the best audio devices around the world. Every capacitor is changed in the Four Headed RAT mod providing a clarity and more complex sound unique to this mod. Also, certain values are tweaked to capture the tone of the early 80′s RATs.
2. IC CHANGE – The backbone of the original RAT tone was in the LM308 IC chip. Newer RATs have the OP07DP chip which although sounds similar at high gain settings, really differs in the lower gain territory. The LM308 has a different dynamic range that allows it to clean up and be more responsive to your playing. It also sounds more smoother and has less high-end fizziness that the newer OP07DP RATs have. The Four Headed RAT involves replacing the OP07DP with an LM308 chip.
3. DC JACK – the small DC jack that comes stock with the RAT is changed for a “BOSS-style” jack, making it easier for daisy-chained pedal boards.
4. THE FOUR-HEADED KNOB – This four-way switch selects between four different gain voicings. The red chicken-head knob transforms the RAT to a tame low-gain drive to a wild, fuzzy monster.

Each of the four gain voicings are described below:

MODE 1 – Vintage Overdrive – This overdrive setting sees a blend of your clean guitar signal and a slightly fuzzy overdrive signal. The use of germanium diodes provides a spongy overdrive great for blues.
MODE 2 – Overdrive and Boost – This setting has a slightly higher volume than Mode 1 but still has a good balance of clean and overdrive signal. This mode is great for rolling back your guitar’s volume for a crystal clear clean tone and rolling it forward for big harmonic drive.
MODE 3 – Rock – This mode is closest to the stock mode of the old-school RATs. The new components, plus the standard silicon diodes, provide the classic RAT tone but with a richer, more complex sound. This is how a RAT should sound with a more balanced bottom end and less high-end fizz to give a well-rounded rhythm tone or an overtone-rich lead.
MODE 4 – Fuzz -  The fuzz mode takes the gain to another level with a really sagging, compressed sound. Roll up the FILTER control and you’ll have Kyuss riffs for days! Turn the DISTORTION all the way up and the fuzz starts to really dip with the guitar’s attack left dead. A really over-the-top and unique fuzz sound that will have people wondering “What the hell was that?!”


In addition to the Standard mods, the Noise mods see the addition of two features that take the RAT into noisy, feedback territory. All of these mods can be used in conjunction with the Standard mods so you can have your polite, low-gain boost or you can have an oscillating, filtered wild rodent all in one!

1. frEQ POTS – Two pots control the response of the FILTER control, and affects the gain at the same time. Roll each all the way down for a crisp, tight drive sound or push it tom maximum to get squeals, oscillation and Sonic Youth feedback all in the stomp of the RAT.
2. OSCILLATION SWITCH – A two-way switch selects between Standard Mode or Noise Mode. Noise Mode introduces a howling pitch of feedback that can be tuned with the DISTORTION knob or your guitar’s volume/tone knobs. The feedback can be blended to the back of your high gain signal or even be heard over your clean signal.

Below is a video demo made by Jon at Guitar Noize. He has an awesome guitar blog with up-to-date news items and gear demos like the one below. Jon goes through the four modes of the 4HRAT with some nice playing to boot.

Below are some demos of the cubisteffects modded Four Headed RAT mods.
Clip Details: Fender Stratocaster> cubisteffects Four Headed RAT> Marshall JCM600
Recording: SM57 > Mbox2 > Logic Pro
This clip shows how well Mode 1 and 2 clean up by rolling back the volume knob on the guitar. The low gain sounds of the RATs aren’t very popular as they do not clean up well and a high end fizziness is always present. With my mods, the fizziness is gone. This clip starts with the RAT on (D: 2 o’clock, T: 9 o’clock, V: 3 o’clock) with guitar on bridge pickup. All gain is brought in and out by the guitar’s volume pot.

Four Headed RAT Mod – Clean Riff by cubisteffects

This clip goes through each of the four modes of the RAT at half distortion. All pedal settings (D: 12 o’clock, T: 12 o’clock, V: 3 o’clock) are the same and only the red knob is turned. Notice the increasing amount of gain and harmonics as it goes from overdrive to fuzz.

Four Headed RAT Mod – Half Distortion by cubisteffects

This clip again goes through each of the four modes of the RAT, but this time near full distortion. All pedal settings (D: 4 o’clock, T: 12 o’clock, V: 3 o’clock) are the same and only the red knob is turned. Notice the loose spongy sound of the overdrive mode compared to the tighter mode 3. Also, the fuzz really starts to kick in and splutters its way through to the end.

Four Headed RAT Mod – Full Distortion by cubisteffects

Related Posts with Thumbnails

Leave a Reply