Dunlop MXR Phase 90 - User Manual

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Summary

MXR Phase 90 Custom 74 Vintage Phase Operation Manual

Product Description and Power

Details the hand-wired circuit, Switchcraft jacks, FETs, analog circuitry, and 9-volt battery power source.

Controls and Operation

Explains the SPEED knob for effect rate and the footswitch for effect on/bypass, with connection and adjustment guidance.

Sample Settings and Specifications

Provides example settings for 'CLASSIC '80s ROCK' and 'PSEUDO LESLIE', along with technical specifications.

The MXR Phase 90 Custom '74 Vintage Phase (model CSP026) is an all-analog guitar effects pedal designed to produce deep and rich phasing effects. This pedal is a faithful recreation of the original 1975 Phase 90, featuring a hand-wired circuit board built with original-spec 1975 components. It incorporates high-quality Switchcraft Input/Output jacks and a Carling bypass switch, ensuring durability and reliable performance. The unit utilizes hand-selected FETs (Field-Effect Transistors) that are matched to achieve its characteristic phasing sound.

Function Description:

The primary function of the MXR Phase 90 is to create a phase-shifting effect, which adds a swirling, sweeping, or undulating quality to the guitar's sound. This is achieved by splitting the input signal, phase-shifting one part, and then recombining it with the original signal. The "Custom '74 Vintage Phase" designation highlights its adherence to the specifications and sound of the early 1970s models, which are highly regarded for their warm and organic phasing.

Important Technical Specifications:

Input Impedance: 470 kΩ
Output Impedance: 10 kΩ
Max Input Level: -5 dBV
Signal to Noise Ratio*: > 95 dB (All controls at mid position, A-weighted, VREF = 1VRMS)
Current Draw: 2.2 mA
Power Supply: 9-volt battery

These specifications indicate that the pedal is designed to integrate well with standard guitar setups, offering a high signal-to-noise ratio for clean operation and a low current draw, which is beneficial for battery life.

Usage Features:

The MXR Phase 90 is remarkably simple to operate, featuring only two primary controls:

SPEED Knob: This knob regulates the overall rate of the phasing effect. Turning it clockwise increases the speed of the phase sweep, resulting in a faster, more intense effect. Turning it counter-clockwise slows down the effect, producing a more subtle and elongated phase.
FOOTSWITCH: This switch toggles the effect on or bypasses it. When the effect is on, the LED indicator (not explicitly mentioned but standard for such pedals) typically illuminates.

Directions for Use:

Connect your guitar to the Vintage Phase 90's INPUT jack using a standard instrument cable.
Connect the Vintage Phase 90's OUTPUT jack to your amplifier's input using another instrument cable.
Set the SPEED control knob to the 12 o'clock position as a starting point. This position often provides a balanced, moderate phase rate.
Depress the footswitch to turn the effect on.
Rotate the SPEED knob to adjust the phasing rate to your desired sound. Clockwise for faster, counter-clockwise for slower.

Sample Settings:

The manual provides two illustrative sample settings:

CLASSIC '80s ROCK: Set the SPEED knob to 9:00. This suggests a slower, more atmospheric phase often associated with rock music from that era.
PSEUDO LESLIE: Set the SPEED knob to 12:00. This setting aims to emulate the rotating speaker effect of a Leslie cabinet, known for its distinctive modulation.

Maintenance Features:

The pedal is powered by a single 9-volt battery. Accessing the battery for replacement is straightforward:

Remove the bottom plate of the pedal. This typically involves unscrewing a few screws.
Once the bottom plate is removed, the battery compartment is accessible for easy replacement.

The robust construction with original-spec components and high-quality jacks suggests a durable device requiring minimal maintenance beyond battery changes. The all-analog circuitry also implies a certain warmth and responsiveness that digital emulations often strive to replicate. The pedal's compact size and simple interface make it a practical addition to any guitarist's pedalboard, whether for live performance or studio recording.