1976 Electro-Harmonix Octave Multiplexer

Model Description:

During the latter half of the 1970s, effect pedals were becoming quite varied and manufacturers were looking for something innovative to give their products an edge over their competitors. New‑York‑based Electro‑Harmonix always had a quirky, whacky approach to effects to make them stand out. On the surface, the Octave Multiplexer (the OM to its friends) is just another octave generator. However, the filter controls gave the OM added flexibility, not only for guitar but also helping it to adapt to bass, keyboards or vocals, albeit with mixed results. The OM is strictly analogue and monophonic and, like many attempts to synthesise and pitch shift, the Octave Multiplexer has difficulty tracking certain notes. For a while in the 1970s, the Octave Multiplexer was also produced in ‘Deluxe’ form in an even larger box. This venerable basic stomp box has been re‑issued by Electro‑Harmonix for the 21st century.

Pedal Description:

I have a soft spot for Electro‑Harmonix pedals, including the Octave Multiplexer. It appears quite staid in its presentation just black and white graphics over the trademark chromed pressed steel box. In terms of identifying features to help date it, it doesn’t have a DC input, the screws are slotted rather than the later Phillips screws, and there is no battery compartment on the base, so I reckon this is an earlier version. The printed circuit board is dated 1975, so it is later than that. Best estimate is probably 1976. Overall it’s in very all‑original condition for its age, albeit without a box or instructions. Cool. Sound‑wise, it provides all the oomph and unpredictable tones that you’d expect from such a device – very evocative of its time. The tracking is very dependent on playing style, guitar and settings and extreme settings can lead to typical EHX weirdness. While not particularly rare, vintage values are rapidly increasing, fuelling demand and pushing prices up higher.


  • Made in New York City, U.S.A. in 1976
  • The ‘High Filter’ knob controls the tone of the sub-octave’s higher order harmonics
  • The ‘Blend’ knob controls the level of the sub-octave that is mixed with the original signal
  • The ‘Bass Filter’ knob controls the tone of the sub-octave’s lower order harmonics and only operates when the pedal’s ‘Bass’ switch is on
  • The ‘Bass’ switch switches the Bass Filter control in and out
  • Standard footswitch turns the effect on and off
  • Standard ¼” input and output mono jack sockets
  • 9V battery only
  • No LED status indicator
  • No battery compartment in the base of the unit
  • Slotted screws on the top of the pedal
  • No box or instructions

Detail Gallery:

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