Detail 01
Octave-down fuzz
Adds a note one octave below what you play, then fuzzes it. The result is thick and deliberately unstable.
Product detailSKU #1274228082339
MXRM103 Blue Box Effects Pedal
rockpsychedelicblueshard rockgarage rockblues rock
1/4
Independent shopping perspective
The Korena take
MXR's octave fuzz. Blends a snarling fuzz with a note one octave below, giving a broken, synthetic tone. For players chasing chaos, not subtlety.
Strong match
Who this is for
- Psychedelic and garage rock leads that need to sound unhinged
- Adding a sub-octave growl to single-note riffs
- Noise, texture and freak-out sections in a set
Consider the trade-offs
When to look elsewhere
- Players wanting a clean, tracking octave pedal
- Chord work — the octave circuit garbles anything but single notes
- Anyone after a transparent overdrive or everyday drive pedal
What matters in use
The specifications, translated
Catalog numbers tell only part of the story. These are the details most likely to change how this product feels, sounds, or fits into a setup.
Detail 02
Blend control
Sets how much sub-octave sits under the fuzz, from a hint of grit to full synthetic collapse.
Detail 03
Analog octave tracking
It does not track cleanly by design. Notes glitch and stutter, especially low on the neck.
Detail 04
Standard MXR enclosure
Compact box that fits normal pedalboard rows without hogging space.
Detail 05
True bypass-era stompbox layout
One footswitch, simple knobs. No menus, no presets — you set it and stomp.
Final check
Know before you order
- 01Power supply not included — needs 9V battery or standard center-negative adapter
- 02Tracks best on the neck pickup, high on the fretboard, single notes only
- 03This is an effect, not a subtle drive — it will dominate your signal
Product questions
Before you decide
Straight answers to the questions shoppers most often ask about this product.
01What does the MXR Blue Box actually do?
It generates a fuzzy note one octave below what you play and blends it with the fuzzed original signal, producing a thick, glitchy, synthesized tone.
02Does the Blue Box work on chords?
Not well. The octave circuit needs one clear note to follow. Chords come out garbled — some players use that on purpose.
03Does it come with a power supply?
No. Use a 9V battery or a standard 9V center-negative adapter.
04Where should the Blue Box go in my chain?
Early, before other drives and before time-based effects. It needs a clean, strong guitar signal to track at all.
Reference
Full specifications
The complete catalog record, organized around the decisions musicians make when comparing gear.
1 detailsBody & build
- Color
- Blue
