Numerical has released MIDIRack, a MIDI toolkit for iPad. MIDIRack takes every keyboard from the KB-1 Expressive Keyboard Suite, adds a suite of step sequencers, and lets users arrange them on a custom touch control surface — with an optional visual MIDI processing graph underneath. It runs standalone or as an AUv3 plugin.
The base app is a performance surface builder. Users place keyboards, sequencers, knobs, faders, XY pads and buttons on a snapping grid, bind controls to MIDI CC, and send MIDI to any synth, app or hardware over CoreMIDI and an always-on virtual port (“MIDIRack Out”). A built-in polyphonic synth and drum kit mean it also plays out of the box.
Keyboards
All six KB-1 keyboards return as building blocks: a velocity-sensitive piano, diatonic chord pads, a scale-locked keyboard, an MPE Seaboard-style ribbon, an MPE Strings grid in 4ths, and a 4×4 GM drum-pad grid. Each keyboard is its own routable node with latch and octave shift.
Sequencers
Tap-to-edit drum, melody, chord, analog and CC step lanes plus a Matrix note grid, with per-step velocity, probability, tie, trigger conditions and microtiming. Patterns chain into arrangements (4 banks per lane) and a 4-pad scene launcher switches every lane’s pattern at once, each lane crossing over on its own downbeat. The Analog Seq is a knob-per-step machine that re-roots live from played notes, SH-101 style.
With a desktop DAW
MIDIRack connects to Logic, Live, Bitwig, Cubase or any DAW over a single USB cable (IDAM) or Bluetooth MIDI, with no driver or helper app. The two MPE surfaces send per-note pitch bend, slide and pressure, and the surface can be rearranged and saved per project — MPE ribbon for a lead pass, drum pads and step lanes clocked to the DAW for a beat.
Graph Editor (in-app unlock)
An optional one-time purchase adds a visual MIDI graph: wire MIDI In → processors → MIDI Out on a canvas with 60+ node kinds, including arpeggiators, quantizers, euclidean rhythms, LFOs and CC tools, generative nodes (Game of Life, Turing machine, Wolfram rules, Markov, Lorenz attractor) and instrument nodes (Synth, Drums, Sampler and a loop Slicer). Every keyboard on the surface is a node in the graph, and surface knobs bind to graph parameters — an LFO modulating a patch moves the knob on the surface in real time. Non-buyers can open and run the factory graph patches; editing and saving require the unlock.
MIDIRack ships with factory presets and patches — control surfaces, generators, keyboards and utilities, including self-playing patches such as the Amen Engine breakbeat machine — plus built-in hands-on tutorials.
Pricing & Availability
MIDIRack is available now on the App Store for iPad (iPadOS 18 or later), standalone + AUv3. Introductory pricing through August 31, 2026: $7.99 for the base app and $7.99 for the Graph Editor unlock (regularly $14.99 each). One-time purchases, no subscription. iPhone and Mac (Apple silicon) versions are in development.
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