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Pricing and availability
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Average Price: $94
Standard/Professional
$60
$181+
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Based on price data from 4 merchants for "MXR M103 Blue Box". Prices shown reflect NEW condition. Tracking began Apr 2, 2026.
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Description
Unleash the beast in your guitar performance with the MXR M103 Blue Box. This pedal isn't your average distortion box; it's a monstrosity that combines aggressive fuzz with an unpredictable two-octave-down tone generator, creating a chaotic yet captivating sonic experience. The Blue Box takes your guitar signal, fuzzes it up, then duplicates it two octaves down. You have complete control over the output and the mix between the dry signal and the effect.
The charm of this pedal lies in its simplicity. With the Output knob, you can dial in the amount of fuzz you desire and use the Blend knob to adjust how much double-octave sound you want. More conservative settings yield familiar sounds, but crank the Blend knob up to 100% and the MXR Blue Box starts spitting out 8-bit-style glitches and quirks, reminiscent of an Atari console having a tantrum.
This pedal is not just an effect; it's an adventure. It's a favourite among the musically adventurous and has been used by greats such as John 5 - Rob Zombie, Jimmy Page, and Mick Thompson - Slipknot. If you're looking to add a unique twist to your sound, the MXR M103 Blue Box is the pedal for you.
Key Features:
- Aggressive fuzz tones
- Unpredictable 2-octave-down tones
- Output and Blend controls for complete customization
- Robust metal casing for longevity
- Slip resistant rubber pad for stability
- Powered by a single 9V battery or optional power supply
- Adds a two-octave lower signal to the original signal for a unique sound
Owner's manual
MXR M103 Blue Box User ManualProduct specs
| Pedal Type | 2 Octave Down Fuzz |
| Inputs | 1 x 1/4" |
| Outputs | 1 x 1/4" |
| Power Source | 9V DC power supply required (sold separately) |
| Batteries | 1 x 9V |
| Height | 1.25" |
| Width | 2.37" |
| Depth | 4.37" |
FAQs
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What kind of sound can I expect from the MXR M103 Blue Box?
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The MXR M103 Blue Box delivers a unique octave fuzz effect, combining a fuzz tone with a signal two octaves lower. This creates a deep, bass-heavy sound that is ideal for experimental and psychedelic music styles.
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How does the Blend knob on the MXR Blue Box work?
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The Blend knob on the MXR Blue Box allows you to mix the fuzz effect with the two-octaves-down signal, giving you control over the intensity and texture of the effect.
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Can the MXR M103 Blue Box be powered by a standard 9V adapter?
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Yes, the MXR M103 Blue Box can be powered using a standard 9V DC power supply, such as the Dunlop ECB003, or a 9V battery.
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Is the MXR M103 Blue Box suitable for bass guitar?
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While primarily designed for electric guitar, the MXR M103 Blue Box can also be used with a bass guitar to create unique, heavy octave fuzz sounds.
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Does the MXR M103 Blue Box have true bypass?
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Yes, the MXR M103 Blue Box features true bypass switching, ensuring your signal remains unaffected when the pedal is not in use.
Videos
ProGuitarShopDemos
MXR Blue Box Fuzz / Octave
MXR Blue Box Fuzz / Octave
ProGuitarShopDemos
MXR Blue Box Octave Fuzz
jimdunlopusa
MXR M103 Blue Box Octave Fuzz | Reverb Demo Video
Reverb
MXR Blue Box - 2 Octave Down Fuzz Chaos! | Gain Appreciation
Science of Loud
MXR M-103 Blue Box Pedal Video Demo
tunnelvisionmusic
MXR M103 Blue Box Octave Fuzz Demo - Harmon Music - HIGH DEFINITION
Harmon Music
MXR M103 Blue Box (Octave Fuzz)
Dandy and The Cosmic Official
Reviews
PROS
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Unique fuzz/octave effects create distinctive sounds
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Durable, "built like a brick" construction
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Inspires creativity with glitchy, bitcrusher sounds for unique lead lines
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Versatile for various genres including rock, metal, and experimental music
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Simple operation with just two knobs (blend and volume)
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Can achieve thick sub-octave fuzz and gritty unstable fall-off
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Affordable for the unique tonal options it provides
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Capable of generating 8-bit, video game-like tones
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Can be modded for improved functionality and sound customization
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Works well when combined with other effects pedals
CONS
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Volume drop when pedal is engaged, requiring mods or additional pedals to correct
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Not suitable for polyphonic playing; best with single notes
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Limited controls with no separate fuzz or tone adjustment
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Not ideal as a primary fuzz pedal due to its specific and quirky sound
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The heavy distortion of the octave effect can muddy sound separation
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Requires experimentation to find the sweet spot for the desired effect
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The blend knob's range from bland fuzz to overpowering octave can be hard to balance
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Some users find the pedal's unique effects too niche or impractical for regular use
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Not conducive to all musical styles, particularly traditional rock or blues
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Can be challenging to fit a 9-volt battery due to internal foam placement
Owner Insights
We analyzed real musician discussions from forums and Reddit to find what players love, question, and tweak about MXR M103 Blue Box.
Setup and maintenance
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Improved tracking can be achieved by using the neck pickup with the tone control rolled back completely.
Source
Comparisons
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Some users find the Blue Box's output too low compared to other fuzz pedals, preferring alternatives like the Meatbox for more pronounced octave-down effects.
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Catalinbread Perseus is suggested as a more refined alternative, offering similar sounds with potentially better build quality.
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The Blue Box is likened to the FX33 Buzz Box when combined with a ring modulator, offering an alternative to this expensive gear.
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Users compare the Blue Box to the Atreides, which shares its quirky nature but is noted to be louder.
Source
Use cases and applications
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Experimentation with running drums through various fuzz pedals is encouraged, with one owner noting success using a Bass Big Muff for distinctive filtered distortion tones.
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The Blue Box is praised for its ability to create "Them Crooked Vultures" and "Queens of the Stone Age" inspired tones, enhancing hard blues and lo-fi drum tracks.
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Works exceptionally well when paired with additional fuzz pedals or a wah pedal for more experimental sounds.
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It can create retro video game sounds, making it appealing for younger guitarists or those seeking nostalgic tones.
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The pedal excels at replicating the "Fool in the Rain" Jimmy Page sound and is also linked to Melvins' early work.
Source
Mods and upgrades
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Owners reinforce the benefits of removing a treble bleed to achieve louder output, enhancing the pedal's usability without altering key frequencies.
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Adding a switch to toggle between one or two octaves down is suggested to enhance usability and versatility.
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A recommended mod involves removing capacitor C11 to mitigate volume drop, reportedly increasing volume noticeably without altering tone significantly.
Source
Build quality
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The bypass on older script reissue models is noted for being less effective, subtly affecting tone at higher volumes.
Source
Features and functionality
4.0 out of 5
Based on 16 Reviews and 94 Ratings
229
Can't find a use for it.
I can't find any other use for it exept a noice-machine. The fuzz lacks the sustain that I'm used to and the monophonic sub-synth is way too glitchy for my taste. I guess a noice-machine can be great for some msicians but not for me. It has the annoying thing all MXR pedals have. That is that even if the output knob is at max level the signal is quieter than if the pedal is in bypass.
Preferred Settings + Usage:
Output MAX and Blend at minimum ;)
387
Fun, but not very useable
When I started building a new pedalboard a few years back, I thought I’d be able to use this as a fuzz, and only kick in the octaves when I wanted something extra glitchy. I quickly found out it doesn’t work that way. To me the fuzz sounds like a pretty basic ‘70s distortion, and while the octaves are fun with their bad tracking, I’ve never found a way to incorporate it into a song.
None of that is to say this is a bad pedal. The distortion still sound pretty good even though it’s not the traditional messy fuzz sound I was hoping for. And the glitchy note tracking is extremely fun to play with even if it’s Rainbow Machine-like in the specificity of its practical uses. They come cheap so there’s no reason not to grab one if you’re interested, but don’t expect it to be your main fuzz.
41029
nothing else like it
I had a script logo first. That now belongs to someone famous from my hometown. I recently picked up a block logo because Iw as missing that 2 octaves down Velcro fuzz.... these are fun effects. I ehar MXRs slash pedal ahs an improved blue box built in that also does octave up, sort of a blue box meets foxx tone machine? but the blue box is so cheap that I went for just the octave down. this is a real sleeper of an octave effect that more people should try.
1798
Great big dirty pedal
What is there to say that hasn't already been said about the MXR Blue Box? -2 octave fuzz pedal with thick fuzzy tones that comes with bad tracking and volume suck. But if you place a compressor before the Blue Box to balance your dynamics, the volume issue disappears and the tracking somewhat improves. The thing that I will say is that I've learned from using it for the past 10 years, is that the bad tracking is part of it's charm and one must lean into it in order to get the most out of it. For me this pedal has become a center piece of my sound. I use this pedal for sludgy riffs and thick noise rock leads when paired with my HM-2 or Life Pedal. I also use it bass synth and drones as well. Since the octave is analog, playing chords or low notes causes a warm glitch in the tracking that can be used for rhythmic elements, but only if your balancing your dynamics with a compressor (it doesn't have to be expensive). If you're a fan of classic fuz tones that can go into really dirty, heavy and noisey guitar tones then you should give this is the pedal a try.
656
The MXR Blue Box is trippy \m/ (-_-) \m/
You can get some really weird noises out of this little pedal. I like the fuzz I can get out of it. I noticed a long time ago DimeBag Darrell had this on his pedalboard. Kind of know where he got his fuzz from. It could have been a blue Arbiter Fuzz Face too.
398
Versatile fuzz pedal for synth-like guitar tones
I love mixing this pedal's creamy gated fuzz and sub octave (-2 octaves) with either amp distortion, an overdrive pedal, and/or a wah pedal for some thick, angry, and ballsy synth-like guitar tones. On its own it's simple and though it leaves much to be desired, i'd rather have something simple than something pointlessly complex, especially for such a niche effect.
280
Octave down fuzz pedal
I have a DIY (replica) version of this unit. I have modified it so I can choose 1 octave or 2 octaves down with a toggle switch. The fuzz is very close to a Marshall stacks OD. A very unique sounding effect.
41029
I had an original script logo one of these for awhile and was incredibly entertained by it for a good 6 months... I am not sure why you are describing its fuzz as sounding like a cranked marshall though, I was never hearing that and I had a cranked superlead in that band.... I am pretty sure the singer from Haelstorn is still using my bluebox sometimes, their band was shelved by their label at the time and they were just doing odds and sods gigs around town and Lizzy bought my blue box off me when I picked up a tonebender... tis a bummer what happened to that band, I am glad for their success, but the original major label album they were working on sounded way better and was way more unique in rough mixes than what eventually got released although their new stuff is a little closer to their real sound... I think my band played a couple 'girls night' kinda bills with those guys because we also had a cute female singer... incidentally, their lead guitarist uses an almost identical a/b rig to what I used back then.... I had vintage fender and marshall amps and I think he has modern fender and hot rod marshall flavored boutique stuff.... I always wonder if he ripped off my rig
280
They are both creamy, singing and sustains forever. When youlisten to the dry signal only the low and high frequencies are very similar too. Of course a Marshall has its own mid range, and this one is more scooped. And of course with the octave down this is a unique voice :)
41029
my old one was really velcroey with the octave dialed out, very transistory
106
Splatty, octave-y, fuzzy
This pedal is simple but has a wonderfully glitchy and scratchy fuzz tone that can go from wild and unpredicatble to being tame and just a touch of sub on top of normal tone. Minus one star for just a hair of volume loss when in use.
112
For Deep Experiments
Good for stacking with distortions if you are brave, and produces a range of very usable synthy & unpredictable tones. It's affordable, handsome, and plays a unique role in distortion alchemy.
140
Blue box
I recommend installing the mod available for this. Other than "fool in the rain" solo it hasn't made a permanent home in my pedal board. ????
Artist usage
Add artist
In the fifth photo at the bottom labled: "Fennesz's worktop". You can see the MXR Blue Box on top of what looks like a EHX bucket brigade pedal and his custom master distortion box. It's a very fitting unit for Fennesz due to the fact it can give you a synthy bass/lead tone if played in the upper register to glitching, clanging walls of fuzz if played in the lower register on a guitar. It makes since that he'd uses this to run into his chain of pedals and plug-ins.
"I have an old MXR Blue Box that I love and I’ve used that quite a bit. I didn’t use it that much on this record though, but I used it on my last few records," Gilby Clarke says, in this article.
Mentioned in the January 1988 Guitar Player interview "Richard Lloyd: The 6 String Alchemy of Richard Lloyd" by Mark Dery.
Despite his lean attitude toward gizmos, he does have a soft spot for two old gadgets – the long-vanished MXR Blue Box octave divider and Vox' renowned Tone Bender (used by Jeff Beck with the Yardbirds). "The Vox Tone Bender, which I used on the studio version of 'Field Of Fire', is really hard to find. That particular one was in the studio in Stockholm. It's a very unusual device. It's like a distortion pedal, although it doesn't so much distort as squeeze the bandwidth, giving you a real silky, sustainy, bright tone. My Blue Box is one of the original octave dividers. It's really great, but you can't use it live. It makes the top of your fretboard sound like a bass!
"In the future, I want to get away from effects. I've found that when you record with effects, they fill up every available space in the record and then you have no air. And so many people are looking for something that's as magical as the classic rock records, without recognizing that it doesn't come from technology per se. You have to develop a sense of balance."
In > Boss RE-20 Space Echo (A/Mono In > B Out) > Boss TU-3 Chromatic Tuner > Moog MF Boost > MXR Distortion + > Fulltone OCD > Maxon OD808 ReIssue > MXR Blue Box Octave Fuzz > Flux Liquid Ambience > Morley ABC IN > Morley A and B out > Boss DD-20 Giga Delay > Red Custom Box Signal Kill Switch > Stereo Out to Amps
"Typically, I play straight with a touch of delay, but I sometimes use an MXR Flanger, Blue Box" says Scott Kelly
According to this article about gear seen being used by Lockett Pundt, he has used a MXR M-103 Blue Box. It was seen on his board before the Line 6 M9 Multi-Effect took it's place.
It sounds like there are guitar loops, feedback loops, and such. Is that just the way you tracked it?
Feedback loops? Nothing is looped. But Austin and I used [MXR] Blue Box [octave fuzz] pedals, so that gives it a uniformity. It might give the impression that it's one piece from which we're pulling, because it reduces it to this robotic sound. But there were no overdubs; it was all live. There wasn't any editing outside the mixing phase.
In a Facebook post, Matt Sorum shares his passion for collecting music gear, including the MXR M103 Blue Box fuzz pedal, highlighting his extensive collection of guitars, amps, and pedals.
In this diagram, it is revealed that Robertson used MXR Blue Box.
During the mid/late 2000's Everett is using a MXR Blue Box
"I always carry a Dunlop wah, Phase 90 (Re-issue), whammy pedal, vintage 808, Blue Box and a box full of delays, compressors and choruses"
Album Usage
The MXR M103 Blue Box has been featured on the following albums:
Genre Usage
Based on how artists on Equipboard use this gear, it is most commonly found in the following genres.
Used With
Based on how musicians on Equipboard use MXR M103 Blue Box, it is most commonly used with the following gear.
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