The MB-40 Distortion Booster for Guitar by Maxon

The Maxon MB-40 Distortion Booster is a vintage distortion/booster pedal made in Japan in the late 1970s / early ’80s by Maxon (the same company behind many classic Ibanez effects).
It’s part of Maxon’s early MB series, offering a compact plug-in style distortion booster that produces silicon-diode clipped distortion with a compressed, gritty character that enhances amp drive and adds sustain.
Designed for guitarists who want classic analog distortion texture and boost in a simple format, the MB-40 is a rare collector’s item today and prized for its unique tonal flavor and vintage build quality.
The MB-40 is rare and considered a vintage collectible, often appearing on the used market with original boxes and tags.
It was sold under Maxon and sometimes under Ibanez model numbers in the same series context.

Specs:

• Type: Vintage distortion booster / guitar effect (analog)
• Era: Late 1970s / early 1980s Japan production
• Effect: Distortion with added boost / compression via silicon-diode clipping
• Operation: Plug-in (guitar output plugs directly into unit) with output jack to amp (typical MB series format)
• Circuit: Simple discrete transistor circuit with diode clipping for distortion
• Sound: Compressed grit and drive, distinct vintage character more than a clean booster but not as high-gain as later distortion pedals
• Power: Battery-powered (often internal 9 V) or used with passive plug format
• Made in: Japan collectible for vintage pedal enthusiasts
• Controls: Single control style (simple gain/boost focus rather than multiple knobs) classic minimalist design

Product specs