MXR · Phase 100 · Late 1970s–1984 (MXR); reissued by Dunlop as the M107
MXR Phase 100
The Phase 100 is the Phase 90's big brother. MXR released it in the late 1970s with an altogether different circuit. Next to the Speed knob sits a four-position Intensity switch that picks between four preset sweep patterns, from subtle to deep, so one pedal covers more ground than the one-knob 90. Dunlop credits it with Keith Richards' trippy tone on Shattered, and Premier Guitar notes that David Gilmour used one. MXR made it in Rochester until the company closed in 1984. Dunlop later reissued it as the M107, keeping the Speed knob and four-position switch and adding an LED and a power jack. If you want the sound on a working board, the M107 is the simple buy. If you want a Rochester original, the Intensity switch is the part to test, so ask for a clip that steps through all four settings before you commit.
Dunlop MXR M107 Phase 100 (LED and power jack)
Spec at a glance
- Brand
- MXR
- Model
- Phase 100
- Family
- MXR phaser
- Effect
- Phaser
- Circuit
- A different circuit from the Phase 90, with a four-position Intensity switch that selects preset sweep waveforms
- Made in
- USA (Rochester, NY) for MXR-era units
- Power
- 9V battery; MXR units from 1981 on and the Dunlop M107 also take a 9V adapter
- Era
- 1970s
- Years made
- Late 1970s–1984 (MXR); reissued by Dunlop as the M107
What to check before you buy
Scratchy Speed pots, worn footswitches and a tired Intensity switch are the usual wear on old units. Battery snaps on MXR-era pedals often break or corrode.
- 01Intensity switch: Ask for a short clip stepping through all four Intensity settings. Each one should give a clearly different sweep.
- 02Speed knob: Ask the seller to turn the Speed knob slowly in the same clip. The rate should change smoothly with no crackle.
- 03LED and jack: Check the case in the photos for an LED and a power jack. An MXR unit without them was made before 1981 and runs on a battery.
- 04Footswitch: Ask whether the footswitch turns the effect on and off every time. A switch that needs several stomps is worn out.
- 05Battery snap: Ask for a photo with the bottom plate off. The battery snap and its wires should be intact with no green corrosion.
Find one on eBay
We haven’t been through this pedal’s listings yet. Search eBay for the exact model and run every listing through the checklist above. Ask for a photo of the bottom plate and a short video of the pedal on and off through an amp, and pass on any listing that won’t show them.
Search “MXR Phase 100” on eBay ↗eBay searchPower and cables
Plenty of used pedals turn up without a power supply. Check the power line in the specs above, then match the voltage and plug before you buy one. This searches Amazon for the usual kit.
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Specs and what to check →
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