Distortion+

MXR began near Rochester, New York, with Keith Barr and Terry Sherwood, who had met at Rush-Henrietta Senior High School. They started the company in 1972 or 1973, depending on who’s counting, and the idea was a practical one. Other makers’ pedals broke. Effects came in big boxes. MXR’s would be small and reliable.

The first ones had a cursive logo, silk-screened in the founders’ basement. Barr was the company’s chief designer, and he went on, years later, to found Alesis.

Their phase shifter, the Phase 90, did well. In 1974 they followed it with a trio of pedals, and one of the three was the Distortion+.

Inside, there’s barely anything. One op-amp turns your signal up. After it, two germanium diodes run to ground, one for each side of the wave, and they chop off whatever goes past their limit. That chopping is the distortion. Turn the Distortion knob up and you get more of it, and more treble at the same time.

The range is wider than it looks. At the bottom of the knob it adds about 3.5 dB of gain, barely a nudge. At the top it adds about 46.5 dB. The other knob, Output, sets the volume. There’s no tone control at all.

What it doesn’t do is paint over your amp. Plug it into two different amps and you still hear two different amps, mostly. It suits anybody who already likes their amp and wants more of it.

Around 1976 the cursive logo went and block letters came in. The circuit didn’t change. Until 1981 there was no LED and no power jack, either: you found out it was on by listening.

1980. Ozzy Osbourne has a new guitarist, Randy Rhoads, and they’re making Blizzard of Ozz. The producer, Max Norman, remembered where the amps went:

Randy’s amps were set up in a stone room underneath the control room; they were facing into the stone steps that led down to the stone room.

The amp was a 100-watt Marshall Plexi with two 4×12 cabinets. The guitars included a 1974 Les Paul Custom and a polka-dot V. And the pedalboard had a Cry Baby, the Distortion+, an MXR 10-band EQ, an MXR Stereo Chorus, an MXR Flanger, and a Roland volume pedal.

Rhoads used the Distortion+ to slam that amp with harmonics, and it’s in the riffs for “Crazy Train” and “Mr. Crowley.” He said it himself, plainly: “The MXR Distortion Plus is the only gadget I use a lot.”

So put on “Crazy Train” and listen to the riff. The pedal’s in there. So are the Marshall and that stone room. It’s part of the sound, not the whole of it.

He wasn’t the only one. In the late ’70s Jerry Garcia used a Distortion+ for all his distortion with the Grateful Dead.

MXR closed in 1984. Dunlop bought the name in 1987 and put the Distortion+ back into production, and it has stayed there, a yellow box on the shelf next to far fancier ones.

Dave Murray of Iron Maiden, overdubbing on The Book of Souls in 2015, described his method like this: “I plug straight in, put on a Uni-Vibe or a Distortion +, maybe a flanger, and then I just feel it out.” Bob Mould had one on his board in 2013 for an Austin City Limits taping, playing a 1987 Stratocaster.

In 2024 MXR put out a Randy Rhoads Distortion+, polka dots and all. Dunlop’s engineers built it to match Randy’s own pedal, the one from the Chip Pan, with Kathy Rhoads working with them directly.

It’s a tribute, not the pedal on the record. That one is still Randy’s.

Two knobs, one chip, two diodes. Every Distortion+ comes out of the same simple circuit. The one Dunlop copied was special for a single reason: Randy had stood on it.