Guyatone MO3 Micro Octaver

Guyatone MO3 Micro Octaver

The MO3 was something of a surprise to me. I have used other analogue octave-down effects - such as the Korg OCT-1 - and had always presumed the Guyatone octavers were the same kind of thing. I was wrong.

"The MO-3 Micro Octaver is a 100% analogue octave divider based on a vintage 1970’s Guyatone circuit. The MO-3’s operation will vary greatly depending on input signal and playing dynamics. Featuring One Octave Down, Two Octaves Down, and Dry Blend, the MO-3 can create a wide variety of effects, from standard “doubling effects” to more bizarre synth-like tones reminiscent of such desirable vintage pedals as the MXR Blue Box and Mutron Octave Divider. If you are an experimental musician looking for a unique effect with tons of personality and a highly unpredictable nature, then the MO-3 is the pedal for you!"

- Guyatone description

Whereas something like the Korg OCT-1 can be used to simulate bass tones using an electric guitar (admittedly with limited success), you can forget about that with the MO3. Unless, of course, your idea of a bass is a distorted, glitchy mess.

It doesn't sound too promising, does it?

Well, here's the thing, while it can sometimes - initially at least - be a little unpredictable (as promised by Guyatone), and it glitches, wobbles and generally destroys your carefully crafted tone, it is a lot of fun to use and very usable. For subtle thickening of riffs and lead lines, the MO3 works a treat. But where the fun really starts is when you push the controls to the point where your guitar sounds like a broken synth.

It takes a little getting used to but pretty quickly, the once 'unpredictable' nature will actually be accepted as part of the effect; you'll work out that where and how you play your notes influences the overall effect, and even the glitches will become somewhat controllable.


There are three level controls to set the volume of each octave respectively (normal/dry, -1 and -2). In addition there is a mini gain trim control which, as you'd expect, sets the signal level going through the effect circuitry. A lower input will result in less distortion but significantly improved tracking of notes, whereas a stronger input will result in more distortion but less accurate tracking. There is also a 3-way 'Filter' switch which also affects the overall amount of distortion and quality of tracking; with the filter switch turned off, the maximum amount of distortion is available. The remaining two filter options tame the distortion (and improve the tracking) to varying degrees.

Playing technique is also very important in getting different sounds out of this pedal; your control of dynamics can be seriously tested.

For simpler doubling effects, it is best to just use one of the lower octaves in combination with the direct sound. This will produce the cleanest, smoothest sound with the best tracking of notes. It isn't really going to sound as accurate or natural as you'd get with one of Electro-Harmonix's pitch shifters (either the HOG, or one of the POG series), but that's not really the point.

It is worth pointing out at this moment (better late than never!) that the MO3 is monophonic, so it is unfair of me to even mention the EHX HOG/POGs as they are very different things. Playing power chords through the MO3 can sound OK, but playing chords will usually result in the octaves jumping around.

I notice that the MO3 lacks sustain (running a compressor before the Micro Octaver doesn't even seem to help). It seems as though once the signal level falls below a certain threshold, the octave signal sputters out in a fashion reminiscent of how a gated fuzz strangles the life out of your notes.

It is when you start to blend the two lower octaves that some of the more interesting effects occur. The two octaves - one and two octaves down - will at times fight with each other for dominance. This can result in 'evolving' synth-type sounds which, when combined with other effects (e.g. filters, phasers, chorus, distortion etc.) can produce some very un-guitar-like textures.

The Guyatone MO3 Micro Octaver is certainly a niche product, but one I'm sure most guitarists would get a kick out of using. Just as I do. Whether you can work it into the music you play is another matter entirely, though.

Gear used:
  • Guitar - Epiphone Casino
  • Amp - 1980s Roland Cube 20
  • Recording set-up - amplifier direct output via Palmer PDI-09 Speaker Sim/DI, to Adobe Audition on PC (via MOTU audio interface) with no additional processing.