The MXR Distortion+ is one of the classic stompbox designs that helped define the sound of hard rock and heavy guitar from the late ’70s into the ’80s. Its simple two-control layout delivers everything from warm, amp-like overdrive to aggressive, fuzzy distortion.

The Distortion+ is especially well suited to classic rock, hard rock, ’70s rock, ’80s metal, blues-rock, and lead guitar. It is strongly associated with the classic Randy Rhoads/Ozzy-era approach to guitar tone, making it an excellent choice for players chasing that cranked Marshall-style, singing lead and crunchy rhythm sound. MXR itself describes the M104 as capable of everything from blues overdrive to huge ’80s hard-rock distortion. 

Circuit / Electronics

• Analog distortion circuit
• Single-op-amp gain stage topology
• Germanium-diode clipping in the M104 design documentation
• Variable gain/distortion stage
• Simple, direct signal path with no tone-control circuit
• Two controls: DISTORTION and OUTPUT
• Distortion gain: approximately 10–45 dB @ 1 kHz according to the M104 specification sheet
• Hardwire bypass
• Input impedance: 1 MΩ
• Output impedance: 25 kΩ
• Nominal input level: -22 dBV
• Maximum output level: -14 dBV
• Noise floor: -74 dBV
• Current draw: approximately 2.5 mA
• Power: 9V DC / 9V battery 

Controls

OUTPUT — Controls the overall volume/output level of the effect.

DISTORTION — Controls the amount of gain and clipping, ranging from relatively mild overdrive to much more saturated, fuzzy distortion. 

Hardware

• Heavy-duty metal stompbox enclosure
• 1/4” instrument input and output connections
• Mechanical footswitch
• Red status LED on the M104 version
• Two large knurled control knobs
• 9V battery operation and 9V DC adapter capability
• Compact pedalboard-friendly enclosure
• Approx. 59 × 111 × 48 mm for the current M104 specification 

One of the great tricks with the Distortion+ is to turn the DISTORTION down and OUTPUT up, using it to push a naturally overdriven tube amp harder. Turn the DISTORTION control up and it becomes considerably more saturated and fuzzy.

Condition: This pedal is being sold AS-IS, exactly as pictured. Please examine all photos carefully for cosmetic condition, wear, markings, and overall condition. No cosmetic restoration or touch-ups have been performed.