The Mistake That Changed Guitar Tone Forever

The ProCo RAT is the most influential distortion pedal in rock history.

There, I said it.

This pedal shaped the sound of punk, grunge, and alternative rock. It gave voice to Kurt Cobain, Dave Grohl, and countless garage bands.

And it’s still one of the best-selling pedals of all time.

Built in a basement (with actual rats)

Do you know how it got its name?

Well, the RAT really was created in a rat-infested basement.

In 1978, ProCo was a small sound company in Kalamazoo, Michigan. Nothing fancy. No venture capital. Just two guys, Scott Burnham and Steve Kiraly, repairing gear in a damp basement.

The happy accident that changed guitar tone

I was surprised to find out that the RAT’s signature sound was a complete accident.

Burnham installed the wrong resistor in his circuit.

If you know anything about resistors, it was a 47-ohm instead of a 470-ohm.

This tiny mistake boosted the gain and compression, creating the RAT’s signature aggressive, harmonically rich distortion. It was the exact thing that set it apart from other pedals at the time.

It was a mistake that would change guitar tone forever.

Why the RAT became the sound of a generation

It didn’t take long for the RAT to become the sound of a generation, and it was for one reason only:

It was simple.

The RAT has just three knobs: Distortion, Filter (tone), and Volume.

No presets.

No digital screens.

No complexity.

Remember, this was a time when punk and grunge musicians rejected excess. They didn’t want overproduction, and they despised polished tones.

The RAT fits that ethos perfectly.

It wasn’t polished. It was raw, unfiltered, and in-your-face, just like the music of the time.

A simple pedal with a deep sound

I like to think of it this way:

The RAT is simple enough for anyone to use but deep enough to reward those who dig in.

This is why I’ve kept a couple of versions of the RAT in my collection for over 15 years now.

I don’t always use a RAT, but when I do put it on my pedalboard for a jam, something happens that no modeling or digital pedal has ever done for me.

It’s immediate. It’s visceral. It’s real.

And what’s best about the RAT is that it’s extremely affordable compared to many other distortion and overdrive pedals on the market.

It can be a thick, amp-pushing overdrive at low gain, a crushing distortion at high gain, or even a fuzz-like sustain… If you crank it.

No matter your style, there’s a way to make it work.

A pedal with no limits

We’ve all read similar stories of legendary pedals throughout music history.

The Fuzz Face gave Hendrix his psychedelic roar.

The Big Muff powered Pink Floyd’s Wall solos.

The Tube Screamer pushed Stevie Ray Vaughan’s amps into Texas blues heaven.

But none have been as versatile as the RAT.

It’s been used by jazz guitarists like Bill Frisell, metal icons like James Hetfield, and art-rock pioneers like Radiohead.

That’s because great pedals don’t limit you. They inspire you to find your voice.

Cheers,