MXR M300 Reverb

The MXR M300 Reverb is a compact reverb pedal from MXR, built by Dunlop Manufacturing, that packs six reverb types into the classic small MXR box: Plate, Spring, Room, Mod, Epic and Pad¹². It runs at a 96 kHz sample rate while keeping your dry signal path 100% analog, so your original guitar tone passes through untouched and only the reverb itself is digital³⁴.

The appeal for most players is the combination of size and range. Gearnews called the form factor "a huge bonus for those players that like to either have a small board or cram lots of pedals onto a larger board," and the pedal still manages stereo output, an expression pedal input, trails bypass and a 100% wet mode⁴¹.

The controls: Decay, Tone and Mix

The M300 keeps everything on three knobs, which Pedal of the Day summed up as "Decay, Tone and Mix are all you need to worry about"⁴. Gearnews praised the "simple three-control layout, making it easy to tweak on the fly"¹.

The reverb types are accessed by pressing the Tone knob rather than by a dedicated switch, and each mode is alternately illuminated by either a red or green LED so you can see which one is active²⁴. MusicRadar flagged one practical drawback: the push-knob type selection "could cause problems with a misplaced foot on a dark stage"².

The six reverb types

Four of the voices are the familiar ones, and two are less common²:

• Plate: classic studio plate emulation
• Spring: spring reverb emulation
• Room: room ambience
• Mod: a modulated studio plate reverb, indicated by a red LED³
• Epic: MusicRadar describes it as sounding "like a multi-tap delay with added reverb"²
• Pad: adds an octave up and a sub-octave below the original signal¹

The Pad mode is the unusual one. Gearnews explains that it "adds an octave up and a sub-octave below the original signal," and MusicRadar compares it to "octave-up shimmer on other pedals"¹². In this mode the Tone knob stops being an EQ control and becomes the octave blend instead³.

Stereo, trails and hidden modes

Several of the M300's features live beneath the surface rather than on the knobs. The pedal includes a 100% wet mode, stereo I/O, and both a true relay bypass mode and a trails bypass mode⁸. The trails mode lets the effect ring out after the pedal is switched off, and the 100% wet mode sends only the wet signal from the pedal to your amp⁴.

To reach these settings you put the pedal in startup mode: disconnect the power supply, set the decay and mix controls to noon, then push and hold the Tone knob while reconnecting the power source⁷.

Stereo works, but reviewers found it clumsy. Output is a single TRS stereo jack, and the mono/stereo switch is a tiny switch accessible only on the PCB inside the pedal². Pedal of the Day notes you can run it in stereo via a TRS splitter cable⁴. MusicRadar listed the "awkward stereo setup" among its criticisms².

The expression input is more straightforward. Connect a Dunlop DVP series volume/expression pedal and you can toggle and blend between two different knob setting configurations, manipulating the effect in real time⁸¹. MusicRadar called it "a nice feature, allowing you to blend between reverb settings"².

History: from Winter NAMM to release

The M300 Reverb first caught attention at Winter NAMM in January 2016, where Guitar.com's sister publication G&B highlighted it as one of the show's standouts⁵. Gearnews reported the full announcement that March: six reverb types at an RRP of $199.99¹. By July 2016 Guitar.com had published a video demo of the new pedal, and its full review followed in Guitarist Vol 28 No 01⁵⁷. At launch it was priced at £187 in the UK⁷, and MusicRadar's later buying guide lists the launch price as $199⁶.

What reviewers said

MusicRadar's review was positive on the core question of sound: "the M300 sounds great and delivers a lot of tones from a small footprint," with sound quality that "puts it firmly among the top shelf of reverb pedals," thanks in part to what the reviewer called a studio-grade 96 kHz sample rate². The settings themselves were praised as "very usable" and offering "authentic replications of their designated sizes"².

Guitar.com's verdict, from editor Chris Vinnicombe, was more measured on value but equally positive on tone⁵:

Guitar.com's reviewer found that "the M300 sounds great and delivers a lot of tones from a small footprint," and that "the sound quality puts it firmly among the top shelf of reverb pedals," with "all the settings are very usable and offer authentic replications of their designated sizes"⁵². The same review flagged practical drawbacks: an "awkward stereo setup," and the tone knob's use for reverb type selection, "a feature that could cause problems with a misplaced foot on a dark stage"².

The pedal placed in Guitar.com's 2016 effects coverage, where the writers noted it was "a good £300 cheaper than some of those high-spec digital reverb machines"⁵. Pedal of the Day highlighted the analog dry path, kept "analog and pure, too, thanks to the patented Constant Headroom Technology"⁴.

The criticisms were consistent across reviews: the awkward stereo setup, and the push-knob type selection being easy to hit by accident on a dark stage².

Specifications

Videos

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