Keith Barr and Terry Sherwood ran an audio repair shop in Rochester, New York, and they were unimpressed by the guitar effects their customers brought in. So they built their own. Their first pedal was the Phase 90, a small orange box with one knob, designed by Barr. Sources disagree on whether it came out in 1972 or 1974, but Dunlop's own history says the first few dozen were built in a basement and sold out of a car at gigs. The Distortion+, the Dyna Comp and the Blue Box followed, and MXR was off.
Who played one
Eddie Van Halen is the name everyone attaches to the Phase 90. MXR's own history says it's on virtually every song on Van Halen I, and Guitar World lists "Eruption", "Atomic Punk" and "Ain't Talkin' 'Bout Love" among them. Van Halen said he liked how subtle it was next to other phasers. David Gilmour used one on "Shine On You Crazy Diamond", Mick Jones of the Clash put it on "Lost in the Supermarket", and Jimmy Page used one too. Muse's Matt Bellamy has a Phase 90 built into his custom guitars.
How the Phase 90 works
The Phase 90 is a four-stage phaser. The signal's phase is shifted at four stages, which creates two moving notches in the sound, and the one knob sets how fast they sweep. The original pedals weren't true bypass, so the signal ran through the pedal even when it was off.
Script logo and block logo
The first Phase 90s carried MXR's cursive script logo. Around the middle of the 1970s the company switched to a block-letter logo in a black box, and the sources put that change anywhere from 1975 to 1977. Wikipedia notes that the very first script pedals, made in the founders' basement, have a slightly larger MXR logo.
The logo change came with a circuit change. As MXR moved to the block logo, its engineers added a feedback resistor to the circuit. Dunlop describes the original script circuit as having a subtle, subdued swoosh, and the block circuit as dirtier and more pronounced. That difference is why collectors chase the script Phase 90. MusicRadar notes that tone hunters swear the early ones sound better.
The catch is the changeover. Dunlop says a small number of early block-logo boxes contain the original script circuit, and Wikipedia adds that some script boxes have the later circuit as well. So the logo is a strong hint and not proof. If the circuit matters to you, ask for a photo of the board and compare it with a known script example.
The block-logo years and Dunlop
The block-logo Phase 90 ran in two stages. From the logo change until 1981 it looked like the script pedal apart from the logo, with no LED and no power jack. In early 1981 MXR added an LED and a 1/8-inch power jack, and Wikipedia says the circuit board stayed the same. MXR went bankrupt in 1984 and production stopped.
Jim Dunlop bought the MXR brand in 1987. Dunlop's first releases were the Phase 90, the Distortion+, the Dyna Comp and the Blue Box, all in block form with an LED and a power jack. Dunlop-era pedals take a modern 9V adapter, such as Dunlop's ECB003, and they're the Phase 90s you'll see most on eBay.
The reissues to recognize
Dunlop has made several script-style Phase 90s, and one of them is easy to mistake for a 1970s pedal.
- '74 Vintage Phase 90. A Custom Shop recreation of a 1974 script pedal owned by Dunlop engineer Bob Cedro. It has a hand-wired board with hand-matched FETs, the script logo, no LED and battery power only. That's exactly how an original looks from the outside, so check the bottom and the board before you treat one as vintage.
- Script Phase 90. The same script look with an LED and a power jack added. An LED on a script box means one of these or a modified original.
- EVH 90. Van Halen's signature pedal from 2004, in red, white and black Frankenstein stripes. A Script switch flips between the vintage script sound and the block sound.
- Phase 95. A mini pedal with both the four-stage Phase 90 and the two-stage Phase 45, each with a Script switch.
The Phase 100 is a different pedal. It came out in the 1970s with its own circuit and a four-position intensity switch, and Keith Richards used it on "Shattered". The Phase 45 is the Phase 90's mellower sibling, a two-stage phaser that followed a couple of years after it and blends into a band mix more easily. If a listing just says "MXR phaser", check the name on the box before you compare it with anything here.
Which one to buy
If you collect, buy an original script pedal with no LED and no jack, and confirm the board matches the early circuit. Expect to wait for a clean one. If you want the script sound to play, the Dunlop Script Phase 90 or the '74 Vintage gets you there without the risk. The EVH 90 is the pick if you want both voices in one box. And if you just want a great phaser, a Dunlop block Phase 90 is the same orange workhorse, and there are always plenty for sale.
What to check in a listing
- Logo, LED and jack. Look at the top and sides in the photos. A script logo with no LED and no jack fits the 1970s, and a block logo with an LED and a 1/8-inch jack fits 1981 to 1984.
- Board. Ask for a photo of the circuit board. On a claimed original it should look like a 1970s board, not a Dunlop Custom Shop one.
- Battery and power. Ask the seller whether it runs on both battery and adapter. A non-original jack on a script pedal means it's been modified.
- Speed knob. Ask for a short video of the sweep at slow and fast settings. It should move smoothly all the way through.
- Box and paperwork. Check for Dunlop branding on the box or bottom. That marks a pedal made in 1987 or later.
For the wider list of things that go wrong with old pedals, read our vintage pedal red flags guide. You can also see every MXR pedal and the rest of the Dunlop line we track.
