MXR Poly Blue Octave

The MXR Poly Blue Octave (model M306) is a digital octave and pitch pedal from MXR that combines polyphonic pitch shifting with a fuzz circuit and a built-in modulation effect. It gives you four separate octave divisions, each with its own level control: one octave down, two octaves down, one octave up and two octaves up, blended against your dry signal¹. The fuzz is inspired by the classic MXR Blue Box, and the modulation shifts character depending on whether you are in polyphonic or monophonic mode².

MXR describes the pedal as bringing "modern and classic pitch shifting styles together with fuzz and modulation"³. It was announced in January 2022 and released that year⁴.

What it does: polyphonic octaves with Blue Box fuzz and modulation

In its default polyphonic mode, the pedal shifts multiple notes at once, so you can strum a full chord and have every note tracked and shifted. On the JHS Show demo, Josh Scott put it plainly: "when I have this pedal on I can strum multiple notes, I can strum a chord and it will read it really well and move it all"¹¹. Each of the four octave divisions has its own level knob, so you can build anything from a subtle octave-doubling blend to stacked organ-like textures¹.

The fuzz is drawn from the Blue Box lineage. MXR says the fuzz sounds "thick and subterranean" on the sub-octave signals and "searing and synth-like" on the higher pitched signals, and that it applies to all five signals (dry plus four octaves) when engaged². The modulation is dual-mode: in polyphonic mode it simulates a Leslie rotary speaker, and in monophonic mode it produces swirls and swooshes inspired by the MXR Phase 90²³.

The controls

The pedal carries six knobs and two color-changing top push-buttons⁵⁸. The buttons handle fuzz and mono switching⁶.

The two top buttons:

• Fuzz: activates the Blue Box sound⁵. Press and hold it to enter fuzz volume adjustment, set the level with the Dry knob, then push it again to save³.
• Mono: removes the pedal's polyphonic ability and switches to monophonic pitch shifting⁵³.

The EXP jack accepts an expression pedal or an off-board switch. MXR says you can use it to sweep between two different knob and switch configurations, toggle the fuzz and mono modes on and off, or control the rate of modulation²³. Guitar World's editors noted the expression input "adds a further creative tool to your arsenal, allowing you to control the rate of modulation, fade in octaves, or switch the fuzz on and off"¹².

Mono mode and the modulation

The Mono switch takes you back to "the gritty, monophonic tones of analog style pitch shifters," according to MXR's product page². In this mode the pedal focuses on a single note at a time rather than reading chords³. MXR says the sub-octaves in mono mode resemble the MXR Vintage Bass Octave, while the higher octaves resemble the Octavio Fuzz with the fuzz intensity dialed back².

The modulation also changes character with the mode. In the default polyphonic mode, the modulation circuit simulates the Leslie speaker effect; in monophonic mode, it sounds similar to the MXR Phase 90³. Like the fuzz, the modulation applies to all five signals when engaged, and the Mod knob's rate control turns it off entirely when rolled fully counterclockwise².

Power: 9V, 265 mA

The Poly Blue Octave is powered by a 9-volt AC adapter such as the Dunlop ECB003/ECB003EU or an MXR Brick Series power supply²³. It draws 265 mA³.

Other specifications from the manual: input impedance 1MΩ, output impedance 100 Ω, maximum input level +5 dBV, noise floor -97 dBV³.

History: Blue Box roots and the M306

The Poly Blue Octave is a modern descendant of the MXR Blue Box, an octave/fuzz pedal from the mid-1970s and one of the earliest pedals MXR manufactured¹²¹³. The original Blue Box takes the guitar signal, duplicates it two octaves down, and combines it with fuzz for a huge subterranean tone¹⁴. It ran on a single 9-volt battery installed under the bottom plate¹⁵, a contrast with the M306's adapter-only power.

Guitar World called the M306 a pedal in which "MXR has tapped into the DNA of the iconic Blue Box," now with four separate octave divisions, each with its own level control¹. MusicRadar described it as "an expanded version of the iconic Blue Box octave/fuzz pedal" with a switchable fuzz circuit¹⁰. The pedal was announced in January 2022, available for pre-order at $199.99 street / $285.70 MSRP with shipping to begin February 1⁸. JHS Pedals credits the design to Jeorge Tripps, whom their blog calls a "master of DSP"⁵.

What reviewers said

Premier Guitar's reviewer found the pedal tracks well: "The Poly Blue tracks well, so at clean settings, it's easy to evoke baritone and bass sounds"¹⁶. The same review notes the Poly Blue Octave "significantly expands upon the Blue Box"¹⁶.

Gearnews called it "a completely brilliant pedal and execution," comparing it to the Boss OC5: "Comparing to the Boss OC5 it only loses range control. Otherwise it destroys" the Boss. Their one complaint was presets: "Shame you can't set up more presets because there's plenty of great sounds in there"⁶.

On the JHS Show, Josh Scott called it "a true versatile multi-effect thing with the rotary, the phasing, the fuzz, the expression options, the tap tempo" and said that if you like the POG or Micro POG, "this is like that really jazzed up"¹¹.

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JHS Pedals' own write-up frames the comparison directly: "If you like the POG or the Micro POG, you're going to love the Poly Blue Octave, which takes that same concept to the next level"⁵. They also note it pairs especially well with the MXR Reverb on the plate reverb setting in octave-up mode⁵.

Videos

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