The MXR CSP101CL Script Phase 90 LED is an analog phaser from MXR, part of the company's Custom Shop line. It recreates the original "script" version of the Phase 90, the pedal RockBoard's PedalPedia says "practically defined the classic phase shift" sound, and adds two practical modern touches: an LED to show when the effect is on and an AC power jack for pedalboard power1.
What it does
As a phaser, the pedal sweeps notches through a guitar's signal to produce the shifting, swirling tone the effect is known for. The Script version is voiced after the earliest Phase 90 circuits rather than the later block-logo ones. RockBoard's PedalPedia describes it as bringing "back the headroom and clarity of the original, along with its ultra warm and smooth phasing and reduced midrange swell"1. In practice, that means a cleaner, less colored phase effect than the more aggressive block-logo voicing, with less of the midrange bump that the standard Phase 90 is known for.
The CSP101CL comes dressed in the original smooth orange paint job and script logo, with the LED and AC power jack added "direct from" the Custom Shop1.
Power and specifications
The 5mA current draw is light enough for any standard power supply, and the built-in AC power jack means the pedal can be run from a pedalboard supply. MXR's manual for the pedal is available from Dunlop1.
Where it sits in the Phase 90 family
MXR has built a wide range of pedals on the Phase 90 circuit. The Script Phase 90 is the Custom Shop's take on the earliest voicing, while other versions cover different eras and features:
- MXR Phase 90: the standard block-logo reissue
- MXR Script Phase 90: the standard-run script voicing
- MXR '74 Phase 90 and MXR CSP-026 '74 Vintage Phase 90: vintage-era recreations
- MXR Phase 95: a mini pedal combining Phase 45 and Phase 90 circuits with Script and Block voicings
- MXR EVH Phase 90: an updated Phase 90 with a Script switch for vintage and modern phaser tones
- MXR 50th Anniversary Phase 90: a gold limited edition released in 2025
For a broader look at the effect type, see the site's guide to Phaser Pedals.
Questions
What is the difference between the Script Phase 90 and the standard Phase 90?
The Script Phase 90 recreates the original script-logo version of the Phase 90, which MXR offered from the company's inception to the late '70s. MXR says it brings back the headroom and clarity of that original, along with its ultra warm and smooth phasing and reduced midrange swell, and the CSP101CL adds an LED and AC power jack to the vintage-style package.
How is the MXR CSP101CL Script Phase 90 LED powered?
It runs on 9V DC, center negative, and draws 5mA. The pedal includes an AC power jack, so it can be connected to a standard pedalboard power supply rather than relying on a battery.
Sources (1)
- CSP101CL Script Phase 90 LED by MXR, RockBoard PedalPedia, 2026
