Geert Bevin has spent much of his career building instruments that reject the piano-keyboard assumption baked into most MIDI controllers — the Eigenlabs Eigenharp, contributions to the Roger Linn LinnStrument, Moog’s multitouch iOS apps, and the original draft specification that became MIDI Polyphonic Expression (MPE). His newest instrument, Glinster, pushes that line of work one step further: there’s no fixed layout at all. The interface adapts to your hand.
No keys, no grid — just your hand
“On Apple Vision Pro, you play it in the air with your bare hands,” Bevin explains. “On iPhone and iPad, you place your hand anywhere on the glass and the notes appear under your fingers.” Glinster measures the shape and reach of the player’s hand on contact and builds the note layout around it — a spatial hand-tracking surface on Vision Pro, a touchscreen playing field on iPhone and iPad, with note positions set by the player’s actual finger spacing rather than a fixed scale-length grid.
What’s inside
Glinster ships with five sound presets (Aether, Ember, Fathom, Rime, Pillar) and controls for Room, Shimmer, Glide, Response, Cutoff and Resonance. It includes sixteen scales — from the seven standard modes through blues, whole tone, and double harmonic — across twelve roots, with a selectable reference pitch from 432 to 446 Hz, plus an octave control that shifts the whole instrument two octaves in either direction so notes outside a hand’s natural span stay reachable.
As an MPE controller, Glinster assigns a new MIDI channel to every note so release tails don’t get cut off mid-decay, with a configurable number of member channels or a single-channel fallback, and a “Send MCM” button to re-broadcast the MPE configuration for a receiver that started listening late. It also functions as a standalone AUv3 instrument, so its gestures can drive any compatible synth directly inside a host, not just output raw MPE to an external device.
Connectivity covers a virtual MIDI source, direct output to any app’s MIDI port, bidirectional Bluetooth LE MIDI, and Apple’s network MIDI session — meaning a session configured in Audio MIDI Setup on a Mac can connect straight to the device without extra routing software. Performances record as lossless 32-bit float WAV, with playback inside the app while the instrument stays live, so a recorded take and a live hand can layer on top of each other.
Why this matters beyond one app
Fixed-grid controllers (keyboards, pad grids, even most alternate MIDI controllers) all share one constraint: the layout is decided before your hand ever touches it. Glinster inverts that — the layout is decided by your hand, every time you place it. Coming from the person who helped formalize MPE as a spec in the first place, it’s also a pointed demonstration of what the protocol was built to carry: not just pitch bend and pressure, but an interface that can change shape entirely and still speak a standard musicians’ software already understands.