The M3 emthree Mini Synthy is a 1970s Italian effects unit made by Meazzi Musica Milano. TONEHOME describes it as "basically a double octave splitter and wave shaper": it takes the incoming guitar signal, splits it into octaves, and reshapes the waveform to produce distorted low octave content alongside the played note. It belongs to the family of octave and pitch effects, and players interested in that territory can compare it with modern octave and pitch pedals and synth pedals.1
The controls
The Mini Synthy carries three controls and a two-position switch, each shaping a different part of the split signal1:
| Control | What it does |
|---|---|
| Left knob | Gradually increasing square wave, described as distortion without frequency variation1 |
| Middle knob | Frequency splitting of the incoming signal, adding a lower octave with distortion1 |
| Right knob | Adds an extra low octave1 |
| Soft/hard switch | Enables either the distorted octaves or just the distorted incoming signal1 |
The middle knob is the heart of the octave-splitting function, and the right knob stacks a further low octave beneath it, so the player can build up the effect in stages. The left knob works differently: rather than changing pitch, it drives the signal into a square wave shape, which TONEHOME characterizes as distortion without frequency variation. The soft/hard switch then decides whether the octave voices or only the distorted dry signal reach the output.1
Origins and documentation
The unit was developed by T. Danko, whose name is mentioned on the steel case, and it was built in Italy by Meazzi Musica Milano in the late 1970s.1 An owner's manual for the Mini Synthy survives as a PDF on TONEHOME, so the original documentation is still available to owners.1
The Subdecay M3
A separate, unrelated pedal shares the M3 name: the Subdecay M3 Guitar Synthesizer. Subdecay's product page lists a voltage controlled amplifier among its features and a Resonance knob that "controls the resonance of the filter."2 RockBoard's PedalPedia entry identifies it as "M3 by Subdecay" and links to an English-language manual on the maker's site.3 It is a modern design with no connection to the Italian Meazzi unit beyond the name.
Videos
Vintage Stompboxes
Questions
What does the soft/hard switch do on the M3 emthree Mini Synthy?
The soft/hard switch selects between two voicings. In one position the pedal produces the distorted octaves, and in the other it passes just the distorted incoming signal without the added octave content. It is the main character control on the unit, letting the player choose between the full split-octave effect and a straight distorted tone.
Who designed the Meazzi M3 emthree Mini Synthy?
TONEHOME credits the Mini Synthy to a designer named T. Danko. His name appears on the pedal's steel case, which is where the attribution comes from.
Where is the Meazzi M3 made?
The M3 emthree Mini Synthy was made in Italy by Meazzi Musica Milano in the 1970s.
Is there a manual for the M3 emthree Mini Synthy?
Yes. TONEHOME hosts an owner's manual for the M3 emthree Mini Synthy as a PDF download, so original documentation for the unit is still available.
Does the Mini Synthy add octaves up or down?
Down. The middle knob provides frequency splitting of the incoming signal and adds a lower octave with distortion, and the right control adds an extra low octave on top of that. The pedal works downward from the played note rather than upward.
Sources (3)
- TONEHOME, TONEHOME
- M3 3 oscillator monophonic guitar synthesizer, Subdecay, 2025-12-26
- M3 by Subdecay, RockBoard PedalPedia, 2026