Electro-Harmonix Octave Multiplexer Analog Sub-Octave Generator
 
Large-box EHX analog octave pedal for deep sub-octave bass tones, synth-like textures, and vintage single-note tracking
The Electro-Harmonix Octave Multiplexer is a classic analog sub-octave pedal built to generate a note one octave below the note you play. Unlike modern polyphonic octave pedals, this is a monophonic, old-school analog octave circuit with its own character, best suited for single-note lines, bass riffs, fuzz stacking, synth-style tones, and experimental textures.
This large-box NYC version gives players more tone-shaping control than a basic octave-down pedal. The High Filter shapes the upper harmonic bite of the octave voice, the Bass Filter shapes the deeper low-end content, and the Blend control balances dry signal with the generated sub-octave. The Sub switch activates the deeper Bass Filter section for thicker, bassier octave sounds.
It also includes separate Dry Out and Effect Out jacks, which is useful for wet/dry routing, sending the dry signal to one amp and the octave effect to another, or separating the original instrument from the sub-octave signal in a studio or live setup.
 
Condition:
Good used/player-grade cosmetic condition with visible wear throughout. The enclosure shows surface patina/oxidation, scratches, scuffs, finish wear, label wear, small marks around the edges, and normal signs of previous pedalboard use.
The bottom has a large Velcro-style pad attached with visible adhesive residue/marks around it. The pedal presents as a well-used working player’s pedal rather than a collector-clean example.
Pedal only. No box, power supply, 9V battery, manual, cables, or additional accessories included.
 
Includes:
Electro-Harmonix Octave Multiplexer pedal
Not Included: Original box, power supply, 9V battery, instrument cables, manual, paperwork, or additional accessories
 
Key Details:
Brand: Electro-Harmonix
Model: Octave Multiplexer
Effect Type: Analog sub-octave / octave-down generator
Version: Large-box NYC-style version
Made In: NYC, USA
Controls: High Filter, Blend, Bass Filter
Switch: Sub On/Off
Bypass: True bypass
Audio: Mono
Jacks: Input, Dry Out, Effect Out
Power: 9V battery or 9VDC center-negative adapter
Current Draw: 12mA
 
Key Features:
Analog Sub-Octave Generator: Creates a note one octave below the played note for deep, heavy, synth-like tones.
Old-School Monophonic Tracking: Best used with clean single-note lines, muted unused strings, and controlled playing technique.
High Filter Control: Shapes the brighter harmonic content of the generated octave, allowing anything from smoother lows to gnarlier, fuzzier octave textures.
Bass Filter Control: Adds deeper low-frequency shaping when the Sub switch is engaged.
Blend Control: Mixes the original dry signal with the sub-octave effect.
Sub Switch: Engages the deeper Bass Filter section for thicker, bassier octave sounds.
Separate Dry and Effect Outputs: Useful for wet/dry rigs, dual-amp setups, studio routing, or blending the octave signal externally.
Large-Box EHX Format: Desirable older-style Electro-Harmonix enclosure with classic NYC pedal character.
 
Frequently Asked Questions:
Q: Is this the smaller XO version?
No. This is the larger big-box style Electro-Harmonix Octave Multiplexer.
Q: Is it polyphonic?
No. It is a monophonic analog octave pedal designed for single-note playing.
Q: Does it include a power supply?
No. This listing is for the pedal only.
Q: What condition is it in?
Good used/player-grade condition with visible patina, scratches, scuffs, finish wear, and Velcro/adhesive residue underneath.
Q: What is it best used for?
Bass-style octave lines, synthy single-note riffs, fuzz stacking, experimental tones, octave-down guitar parts, and wet/dry routing.