The MXR Phase 99 is a phaser pedal from the MXR Custom Shop that combines two Phase 90 circuits in a single Phase 90-sized housing1. Where the standard Phase 90 gives you one rate knob and one sweep, the Phase 99 doubles the circuit and adds switches for routing, voicing and rate sync, opening up phasing sounds a single Phase 90 cannot make. Premier Guitar called it "a more versatile phase unit" with "stereo outputs that make the Phase 99 an impressively varied and colorful phaser"2.
The Phase 99 is a legacy product and no longer in production, per Dunlop's product page1. It was released in late 2013 as a limited edition3, so it is a used-market pedal today.
Two Phase 90 circuits in one housing
At its core, the Phase 99 is two Phase 90s in a single enclosure, as Premier Guitar put it in their review2. The Phase 90 itself is based on 4 phase shifting units creating 2 notches in the frequency spectrum4, so the Phase 99 carries two of those sweeps in one box. MusicRadar described the range this opens up: "The Phase 99 creates a multitude of sounds from a subtle, long cycle to a fast, watery warble... and 100s of sparkling vibrations in between"3.
The controls: two Rate knobs and the P/S, Vintage and Sync switches
The Phase 99 keeps the Phase 90's one-knob simplicity only in pairs. Premier Guitar's reviewer noted that "the 99's speed 1 and speed 2 knobs are rate controls, each dedicated to a Phase 90 circuit"2. Above the speed and output knobs sits a trio of small white push switches, labeled P/S, Vintage and Sync, which MusicRadar said "offer a wealth of output options"3.
| Control | What it does |
|---|---|
| Speed 1 knob | Rate control for the first Phase 90 circuit2 |
| Speed 2 knob | Rate control for the second Phase 90 circuit2 |
| P/S switch | Toggles signal flow between the circuits from series to parallel1 |
| Vintage switch | Toggles between modern and vintage style phasing1 |
| Sync switch | Synchronizes the rate of each phase circuit1 |
The Vintage switch mirrors the script-versus-block voicing choice MXR offers across the Phase 90 family, such as the '74 Vintage Phase 90, which Dunlop builds with hand-matched FETs and a hand-wired circuit board for the vintage voice5.
Series, parallel and stereo
With the P/S switch in series, the two phase circuits stack in the signal path; in parallel, they run side by side. Premier Guitar's reviewer found the parallel mode especially rewarding with two amps: "You get even more interesting variations on these sounds when you use the Phase 99 in parallel mode with two amps," including a faux Leslie setup2. The pedal's stereo outputs are part of what makes that possible2.
Sync and unsynced rates
The Sync switch locks both circuits to the same sweep rate1. With Sync off, Dunlop says the "separate rate controls for each circuit allow you to create intense complex phasing"1, since the two sweeps drift against each other rather than moving together.
Where it sits in the MXR phaser line
The Phase 99 is a Custom Shop offshoot of the Phase 90 (model M101)61, which remains MXR's core phaser. Players comparing options today will find the family spread across the Phase 95, which packs Phase 45 and Phase 90 circuits with Script and Block voicings into a mini enclosure, and the Deep Phase, a compact two-knob phaser with Speed and Feedback controls and 4- and 8-stage modes. The Phase 99 stands apart from all of them by being the only one with two independent phase circuits and the routing switches to combine them.
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Questions
Is the MXR Phase 99 discontinued?
Yes. Dunlop lists the Phase 99 as a legacy product that is no longer in production. It was released in late 2013 as a limited edition MXR Custom Shop pedal, so finding one now means searching the used market.
Can the Phase 99 run on a battery?
Yes. Dunlop says the pedal can be powered by a 9-volt battery or a Dunlop ECB003 9-volt adapter. It is also compatible with Dunlop's DC Brick, Iso-Brick and Mini Iso-Brick power supplies, which are sold separately.
What does the P/S switch do on the Phase 99?
The P/S switch toggles the signal flow between the two phase circuits from series to parallel. In series the circuits stack; in parallel they run side by side, which Premier Guitar's reviewer found especially interesting with two amps, such as a faux Leslie setup.
Can you sync both rates on the MXR Phase 99?
Yes. The Sync switch synchronizes the rate of each phase circuit, so both Phase 90 circuits sweep together. With Sync off, the separate rate controls let the two circuits run at different speeds for more complex phasing.
Sources (6)
- 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
- MXR® '74 VINTAGE PHASE 90, Dunlop (jimdunlop.com)
- MXR® PHASE 90, Dunlop (jimdunlop.com)
