Review: Mezzabarba Custom Amplification M Zero Overdrive

The Mezzabarba M Zero Overdrive is a monster amp that’s built to impressively high standards.
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Never mind the bracing espressos, fine food, and fast sports cars. Italy also has a long tradition of making major contributions to legendary guitar tone, and doing so in style—from EKO-made Vox Phantom “teardrop” guitars and prized Fasel inductors inside Italian Vox Wah-Wahs to work-of-art Wandre guitars. That legacy looks to be mightily expanded with the arrival of Mezzabarba Custom Amplification. Designed and hand-crafted by Pierangelo Mezzabarba (who also owns Masotti Guitar Devices), the M Zero Overdrive is a no-holds-barred take on high-end contemporary rock tone, and simply one mighty 100-watt hunk of rumble and wail by any standards.

The M Zero Overdrive is a footswitchable, two-channel amp with a rhythm channel that boasts Drive and Volume 1 (master) controls, plus a preset Boost function, and a lead channel governed by Overdrive and Volume 2 knobs. The 3-band tone stack—Depth, Feedback, and Presence controls—are shared by both channels. Around back, there’s a full bevy of speaker-cab connectivity, plus a Slave Out with Level control, and send and return jacks for a tube-buffered FX loop. All of which provides a straightforward interface to the five-12AX7 preamp and four-EL34 fired engine—but the special sauce is found inside, in a circuit that Mezzabarba refers to as his masterpiece.


Remove the protective metal grille from the back of the amp and pull the chassis, and there’s nothing inside to dispel the maker’s claim. High-end parts like whopping custom-made Onori transformers reside atop the white-enameled steel box, which contains a totally hand-assembled circuit constructed on three hand-wired boards for signal, bias, and filtering stages. Components include Mallory orange-drop coupling caps and electrolytics, Allen Bradley NOS 1-watt carbon-comp resistors, and military-grade potentiometers, all strung together by impressively tidy wiring.

Tested with a Koll Super Glide Almighty with Lollar Imperial humbuckers and a Fender 1960 Stratocaster reissue, through a 2x12 Port City cab with Eminence CV-75 speakers (both with and without attenuation from a Universal Audio OX Amp Top Box) the M Zero Overdrive quickly proved worthy of its Italian maker’s lofty claims. In short, this thing freaking roars, yet it does so with a combination of clarity and harmonic saturation that’s speaks of some serious design chops.


The amp has Overdrive in its name, and what an overdrive it is: juicy, mean, and incendiary, with searing levels of gain right from about 8 o’clock on the dial, and gobs more heat and saturation as you wind it up. It is most definitely predisposed to 21st century shred ’n’ burn, and eschews dynamic, touch-sensitive characteristics that have already brought it to the attention of Joe Satriani, Doug Rappoport, George Lynch, Steve Vai, and several others of their ilk. If you’re looking for more vintage-tinged overdrive, it ain’t here… but you will find it over on the Drive channel, particularly with the Boost function engaged, which delivers a well-judged leap into crunchier, plexi-at-one-o’clock territory. Players needing to attain consistent levels of crunch and wail in a wide range of rooms will also appreciate the very effective independent master volumes on each channel, which I thought functioned extremely well. The M Zero Overdrive will get loud, and then very loud, but it retains an extremely satisfying texture and response even when dialed down to coffeehouse volumes—a trick few 100-watters can muster.

The 3-knob EQ does much as you’d expect, and does it well, but further down the panel there’s surprising and wonderful voice-sculpting potential lurking via the interplay of the Depth and Feedback knobs. From raw and loose, to thumping and tight, and all points in between, these controls boost the amp’s versatility exponentially. Dial them in right, give the Overdrive some sizzle, and the M Zero eats up dropped-D riffage too. All in all, this is a monster amp that’s built to impressively high standards and deserves a look from any serious contemporary rocker.


MODEL M Zero Overdrive
PRICE $3,999 list
CONTROLS Drive, Overdrive, Bass, Middle, Treble, Volume 1, Volume 2, Depth, Feedback, Presence; switches on Bright and Boost for Ch1
POWER 100 watts
TUBES Five 12AX7s and four EL34s
EXTRAS Two-button footswitch for channel select and boost; dual speaker outs each for 4Ω and 8Ω, single out for 16Ω; slave out with Level control; tube-buffered FX loop
WEIGHT 44 lbs
KUDOS An extremely well-built amp with boatloads of power, outstanding clarity and harmonic content from both its high-gain and rhythm channels.
CONCERNS It’s pricey, but quality costs.