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MXR Custom Shop Phase 99 Review

MXR Custom Shop Phase 99 Review

Two classic Phase 90s combined with impressive tone-shaping controls in a single compact enclosure.

Phasers aren’t every player’s cup of tea. But a lot of guitarists, this author included, can’t imagine living without one. With a single stomp, a phaser can send a jam on a new trajectory by massaging—or torturing—even the simplest, most boneheaded lead or set of chords into something alien and uncommon.

One of the straightest lines to subtly swirling and dizzyingly mangled phase tones is the venerable, elegant one-knob MXR Phase 90. It’s hard to fathom tinkering with the utilitarian perfection of the Phase 90—a pedal so simple a half-wit bloodhound could conjure psychedelic magic with it. So when MXR’s custom shop was tasked with designing a more versatile phase unit, the 90—the Model T of modulation—remained the foundation. But while the new Phase 99 is, at its core, two Phase 90s in a single enclosure, the circuit is enhanced with vintage and modern voices, parallel and series signal routing, and stereo outputs that make the Phase 99 an impressively varied and colorful phaser brimming with surprising tones and utility.

L’Orange Deux
Subtly sparkling in orange metallic, the Phase 99 is unmistakably the offspring of the Phase 90. You don’t have to look long, however, to see that this is an ambitious evolution of the form. The guts of the pedal are on an immaculately ordered printed circuit board, though the PCB is populated densely enough to look like an aerial view of Lower Manhattan. All that extra circuitry is the key to the Phase 99’s multitudinous shades of phase.

The 99’s speed 1 and speed 2 knobs are rate controls—each dedicated to a Phase 90 circuit—while the three pushbuttons above them alter each circuit’s voice and control how the two phasers work together. The vintage button alters the intensity of the phase, effectively simulating the differences between an old “script-logo” Phase 90 and the newer, more intense “block-logo” version.

One of the real bonuses of the Phase 99 … is how great it sounds when you dial in more dissonant wave rates. It’s exceptionally forgiving in these settings….

The sync button synchronizes the two circuits and routes output exclusively via the speed 1 control. It also functions almost like a panic switch if two disparate phase sounds get unruly in the heat of a performance. The p/s (parallel/series) button shapes the voice of the Phase 99—often drastically—by altering the flow of the phase signals. The speed, vintage, and p/s controls have dedicated LEDs. The two speed LEDs flash to indicate rate of phase, while the vintage and p/s LEDs illuminate when the associated functions are engaged.

Wave Collider
Anyone who’s ever toyed with two modulation pedals in an effects line knows the unexpected payoffs of colliding, clashing, and interwoven waves. And one of the real joys of the Phase 99 is how easy it is to explore those textures in a musically rewarding way. The twin-phaser circuit assures that you begin with complementary voices, which makes it easy to weave waves together in harmonious or slightly dissonant but complementary ways. The simplest way to accomplish this is to select the series mode.

In series mode, you hear both phasers together, running in a line, just as if you had two phasers on a pedal board. And it’s here that you experience the brotherly harmony of the two Phase 90 voices. There’s a clarity that makes it easy to dial in accurate and harmonious wave divisions—say, a fast modulation pulse from the first circuit, and phasing exactly half that speed from the second circuit. These even subdivisions create deep, rich phase tones that create aural illusions of depth—sometimes even a second guitar. They also sound fantastic with fuzz and distortion, and are great for keeping the dynamics and detail of a lead run intact when you want fuzz and phase raging simultaneously.

One of the real bonuses of the Phase 99, though, is how great it sounds when you dial in more dissonant wave rates. It’s exceptionally forgiving in these settings: Irregular settings that would turn lesser two-phaser set ups to mud deliver the deep, funky, rubbery texture of a wah or envelope filter—even during fast leads and funk chord comping.


Lots of very useful modulation colors in a compact package.

Slightly cramped control layout.


Playability/Ease of Use:




MXR Custom Shop Phase 99

You get even more interesting variations on these sounds when you use the Phase 99 in parallel mode with two amps. One of the most obvious applications is a faux Leslie setup where you dedicate one output to simulating the rotating treble horn and a second to simulating the deeper output of a Leslie’s rotating drum. You can fine-tune a setup like this using amp EQ and contrasting amp voicings (in my case, a blackface Tremolux and a Vibroverb reissue) to achieve a pretty convincing Leslie imitation. But the real fun with these stereo setups comes when you use radical amp EQ settings and odd Phase 99 wave rates to create textures that range from stratospherically huge to strange and disorienting—all without sacrificing musical nuance, dynamics, or sensitivity.

The Verdict
If your phase tastes are simple or you use the effect sparingly, the Phase 99 might be a handful. But if your hunger for more complex and versatile phase modulation is insatiable, the 99 is a feast waiting to happen.

A two-output stereo effect always begs the question of how many players will use two-amp setups. But even if that’s impractical for most gigging players, the Phase 99 has incredible potential in the studio—where you can tinker with phase rates and amp types and then mix the two signals into many shades of swirl. Wise guys will assert that you can accomplish the same effects with two $80 Phase 90s, but the 99 actually offers way more voicing options—and in a much more compact and convenient package. If phase is an integral part of your sound, it’s hard not to be intrigued by the possibilities and value here.