The MXR Custom Shop Phase 99 is a limited edition phaser pedal from MXR's Custom Shop that puts two Phase 90 circuits into a single Phase 90-sized housing1. Where the standard Phase 90 gives you one four-stage phase sweep with a single speed knob, the Phase 99 gives each circuit its own speed control and adds switches for voicing, routing and synchronization, opening up far more modulation territory than the original ever covered on its own1.
The MXR Custom Shop Phase 99 is a limited edition phaser built around two Phase 90 circuits, each with its own speed knob, so a player can dial in two rates at once21. Premier Guitar's reviewer summed it up as offering "lots of very useful modulation colors in a compact package"2.
Two Phase 90 circuits in one pedal
The Phase 90 itself dates to 1974, a phaser designed by Keith Barr that went on to become, in Aion FX's words, "unquestionably the most popular phaser pedal of all time"45. MXR has kept it in the lineup in several forms over the years, from the standard M101 Phase 90 to the hand-wired '74 Vintage Phase 90 reissue and the Custom Shop Script Phase 90 LED, which adds an LED and AC jack to the vintage script circuit.
The Phase 99 takes a different approach to expanding the formula. As Premier Guitar put it, "the Phase 99 is, at its core, two Phase 90s in a single enclosure"2. Each of the two speed knobs is a rate control dedicated to one of the two Phase 90 circuits, so you can set the two sweeps independently2. MXR's own description of the pedal says it "opens up the sonic palette of the iconic Phase 90" by combining the two circuits in one box1.
Modes, LEDs and stereo outputs
The Phase 99's extra controls sit as a trio of small white push switches, labeled P/S, Vintage and Sync, positioned above the speed and output knobs3. Each switch changes something fundamental about how the two circuits behave:
| Switch | What it does |
|---|---|
| P/S | Toggles signal flow between the circuits from series to parallel1 |
| Vintage | Toggles between modern and vintage style phasing1 |
| Sync | Synchronizes the rate of each phase circuit1 |
The Vintage switch mirrors the script-versus-block voicing choice MXR offers across its Phase 90 family, letting you pick between the smoother vintage-style sweep and the more pronounced modern one1. The Sync switch locks the two circuits' rates together, so the two sweeps track each other rather than drifting apart1.
The P/S switch is where the Phase 99 most departs from simply owning two Phase 90s. Premier Guitar's reviewer explained the difference plainly12:
"In series mode, you hear both phasers together, running in a line, just as if you had two phasers on a pedal board."2
Running the circuits in parallel instead puts the two sweeps side by side in the signal path, which produces a different set of phase interactions than chaining them1.
The pedal also carries stereo outputs, which Premier Guitar credited with making "the Phase 99 an impressively varied and colorful phaser"2. Each of the speed, vintage and P/S controls has a dedicated LED: the two speed LEDs flash to indicate the rate of each phase circuit, while the vintage and P/S LEDs illuminate when those functions are engaged2.
What reviewers said
Premier Guitar's 2021 review was positive on the pedal's core appeal, listing among its pros "lots of very useful modulation colors in a compact package"2. The reviewer also noted the family resemblance in the finish, describing the pedal as "subtly sparkling in orange metallic" and "unmistakably the offspring of the Phase 90"2.
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Questions
What is the MXR Custom Shop Phase 99?
It is a limited edition phaser from MXR's Custom Shop that combines two Phase 90 circuits in a single Phase 90-sized housing. Each circuit has its own speed knob, and small push switches select vintage or modern voicing, series or parallel routing, and whether the two circuits run in sync.
Is the Phase 99 stereo?
Yes. Premier Guitar's review notes the Phase 99 has stereo outputs, which the reviewer credited with making it an impressively varied and colorful phaser. The stereo outputs are part of what sets it apart from the single-output Phase 90 it is based on.
What does series mode do on the Phase 99?
The P/S switch toggles signal flow between the two phase circuits from parallel to series. In series mode you hear both phasers together, running in a line, just as if you had two phasers on a pedalboard. In parallel the two circuits run side by side instead.
Is the Phase 99 a limited edition?
Yes. When MXR announced it in November 2013, MusicRadar described it as a tweaked, limited edition version of the Phase 90, available immediately from MXR Custom Shop dealers. As a Custom Shop limited run it is not part of MXR's standard catalog.
How much does the Phase 99 cost?
Premier Guitar listed the street price as $169 in its August 2021 review. Because the pedal is a limited edition, prices on the used market can differ from that original street figure.
What color is the Phase 99?
The Phase 99 comes in an orange metallic finish. Premier Guitar's reviewer described it as subtly sparkling in orange metallic and unmistakably the offspring of the Phase 90, whose orange paint job is one of its trademarks.
Sources (5)
- MXR® PHASE 99, Dunlop (jimdunlop.com)
- MXR Custom Shop Phase 99 Review, Premier Guitar, 2014-02-27
- MXR announces Phase 99 pedal, MusicRadar, 2013-11-19
- MXR Phase 90 Analysis, GuitarPCB, 1974
- Zenith Vintage Phaser / MXR® Phase 90, Aion FX, 2024-04-19
