Electro Harmonix have always been a company that pushes a guitarists’ creativity further with innovative effect pedal designs. Founded in the 60′s, it pushed analog audio circuitry to new standards, morphing a standard guitar tone into sounds that immediately jump off the record with a huge question “What the f@#k was that!?” One such example is the Micro Synthesizer – an all analog, octave-divided, filter following fuzz that was inspired by the analog synths of the 1970′s (see Moog, Arp et al.)

There are two sections to the Micro Synth; the Voice Mix and the Filter Sweep. The Voice Mix consist of three octaves (SUB OCTAVE, GUITAR and OCTAVE) that can be blended in parallel and distorted using the SQUARE WAVE control. This mix can also have an ATTACK DELAY added to it, a great feature that removes the attack of your playing and swells in those big octave chords. The second section, the Filter Sweep, has four controls, RESONANCE, START FREQ, STOP FREQ and RATE. The Start and Stop Frequency sliders control the “vowel-like” sounds of the envelope with the resonance boosting the selected frequency. The RATE control allows a range of fuzzed envelopes from slow, long filter sweeps to fast, ray-gun sounds. This filter section is clearly inspired by the synthesizers of the 70′s and within those ten sliders are a multitude of sounds that can then be radically altered with additional effects.

cubisteffects offers a few modifications to the Electro Harmonix Microsynthesizer to maintain your guitar tone and to make experimentation easier.


In this mod the Microsynth has a 3PDT switch added and is true bypassed, preserving your original guitar tone when the effect is off. This pedal is known to be a “tone-sucker” or introduce noise into your chain even though the pedal is off.
Part of the original design is the presence of a POWER ON/OFF switch. When the power was ON, an indicating LED would remain on at all times, regardless if the effect was on or off. This is also changed with a superbright, waterclear blue LED added to the pedal and turning on and off when the effect is engaged/disengaged.
Note: the POWER switch remains, only the LED is changed.


Using this modification, an expression pedal jack is added to the pedal to control the STOP FREQ slider. The expression pedal can be used to control the full sweep of the slider, allowing wah-like control at your feet. This mod gives you more sounds at your control – wide, filter sweeps to short, quacky vowel lines. This mod does not include the expression pedal.


Several components are interchanged and placed on a switch so you can change your Guitar Microsynth to Bass Microsynth or vice versa. The bass version allows smoother tracking on the bass notes and holds bottom string power chords more tighter. The difference in versions also suits brighter/darker amps. The mod provides another flexibility to the pedal.


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  1. cody says:

    Hey there christian , cody here im the fellow who bought your old green big muff , and you bought my WH4 whammy , anyway i have one of the old Bass micro-synths id like to get modded by you with all the above mods so if you could give me a quote on that thatd be super :) , i also have a couple of repairs on a couple of stomp boxes that need to be done before i get into the studio , the muff has developed a sort of motorboating if that makes any sense ,and certainly has gotten alot noiser but ill discuss the repairs as i talk to you.
    thanks and best regards

  2. cubisteffects says:

    Hey Cody,
    No problems mate.
    I’ll be in touch.

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