Keyboard players had to buy new hardware to play expressively. Guitarists already own the instrument — bending one string while three others ring is the most ordinary thing in the world on a guitar. The problem was never the playing. It was that standard MIDI threw almost all of it away.
Why classic guitar-to-MIDI sounded wrong
In conventional MIDI, pitch bend is a channel-wide message. Send a bend and every note sounding on that channel moves together. On a keyboard that is merely limiting. On a guitar it is fatal: bend the B string during a chord and your synth smears the whole voicing upward. The characteristic gesture of the instrument simply cannot be represented.
This is exactly the problem MPE (MIDI Polyphonic Expression) was designed to solve. MPE spreads notes across a zone of MIDI channels, one note per channel, so each note carries its own pitch bend, its own pressure and its own timbre (CC74). Map one string to one channel and the translation becomes obvious: a guitar is already a six-channel MPE controller waiting for a protocol.
The hardware route: hexaphonic pickups
To get per-string data you need per-string audio. That means a hexaphonic (divided) pickup, where each string gets its own sensor and its own pitch-tracking path.
The best-known option remains the Fishman TriplePlay, which mounts to a standard guitar and transmits wirelessly. Worth knowing before you buy: TriplePlay's default "Poly" mode sends all six strings down a single MIDI channel, which reintroduces exactly the problem described above — independent bending is impossible when two or more notes sound together. You have to switch the system into Mono mode, which assigns one channel per string, to get per-string pitch bend working as intended.
That per-channel-per-string arrangement is the ancestor of MPE, and it is why guitar synth systems from the 1980s onward already used "mono mode" language decades before the MPE specification was formally adopted by the MIDI Association.
The software route: audio-to-MIDI with MPE output
The alternative is to skip the special pickup and track the audio signal directly. Jam Origin's MIDI Guitar 3 is the most prominent effort here, and it is explicitly built around expression rather than note detection alone: it can generate MPE or standard MIDI, with guitar-to-MPE giving every note four dimensions — strike, pressure, brightness and pitch.
Two caveats. First, MIDI Guitar 3 has been in extended beta rather than a formal full release, so expect the usual beta trade-offs. Second, monophonic audio tracking of a polyphonic source is genuinely hard; the developers describe training and evaluating tracking models across hundreds of iterations. Results are strong on clean, well-intonated playing and degrade with heavy distortion or muddy low-string voicings.
There is also the dedicated-instrument route, where the controller is the guitar: the Jamstik range builds sensing into the instrument itself rather than bolting it on.
Setting up your receiving end
Whichever source you use, three settings decide whether it feels right:
- Bend range must match. Set the same semitone range on the controller and the receiving synth. A mismatch is the single most common cause of "my bends go to the wrong note." ±48 semitones is the MPE default, but guitar systems often use ±12 or ±24.
- Choose your zone size. Six strings need at least six member channels. Allocating the full 15-channel lower zone is safest and costs nothing.
- Turn off note quantisation if you want the guitar to sound like a guitar. Some systems snap pitch to the nearest semitone. That is useful for notation and terrible for slides.
On the DAW side, Bitwig Studio and Ableton Live both record per-note expression natively, as do Logic Pro and Cubase. Point a per-string MPE stream at a physical modelling instrument and the results are unlike anything a keyboard produces — string-to-string microtiming and independent vibrato survive intact.
What to play
The temptation is to trigger a pad and marvel that it works. More interesting results come from instruments that reward the gestures guitarists already have: bowed strings that respond to pressure, plucked physical models where your bend actually retunes the string, or brass and reed models where a slide becomes a portamento rather than a step.
The point of MPE for guitar is not to make the guitar sound like a synth. It is to stop the synth from flattening the guitar.