MIDIRack vs SetClass
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
MIDIRack
Design custom MIDI control surfaces with a variety of instruments and sequencers. Unlock advanced features like a visual MIDI processing graph for complex routing and generative music creation. Use it standalone, as an AUv3 plugin, or to control desktop DAWs.
- Customizable touch surface design
- KB-1 keyboard suite with MPE support
- Advanced step and matrix sequencers
- Visual MIDI processing graph
- Built-in instruments and samplers
- Connects to desktop DAWs via USB or Bluetooth
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MIDIRack is a MIDI toolkit for iPad. Build a custom touch surface from the KB-1 keyboard suite, an all-new sequencer suite, knobs, faders, buttons and more — then unlock a visual MIDI processing graph (one time in-app purchase) and wire it into anything, from a simple custom controller to a full-on groovebox or a self-playing generative composer. Play it on its own and send MIDI anywhere, as an AUv3 plugin in your favourite host or a standalone instrument. THE BASE APP — PERFORMANCE SURFACE Design a custom control surface on a snapping grid: • The KB-1 keyboard suite — piano, diatonic chord pads, scale-locked keyboard, MPE Seaboard ribbon, MPE Strings grid (4ths), and a 4×4 GM drum-pad grid. Each is its own routable node with latch and octave shift. Successor to the KB-1 Expressive Keyboard Suite. • A suite of sequencers — drum, melody, chord, analog and CC step grids and a Matrix note grid, with a moving playhead, swing and microtiming. Per-step velocity, probability, tie and trigger conditions; pattern chaining and 4-pad scene switching for full arrangements; a knob-per-step analog machine that re-roots live as you play. • Knobs, faders, XY pads, buttons and live visualizers — bind to raw MIDI CC or graph parameters. On its own: a rich custom control surface builder — send MIDI and CC to any synth, app or hardware, no graph required. WITH YOUR DESKTOP DAW Expressive MPE hardware costs hundreds. MIDIRack turns the iPad you already own into a controller for Logic, Live, Bitwig, Cubase or any desktop DAW: • Two MPE surfaces — the Seaboard ribbon and the Strings grid send per-note pitch bend, slide and pressure to any MPE-capable instrument on your desk. • A controller that changes per track — MPE ribbon for the lead, drum pads for the beat, chord pads for the progression, faders mapped to CC for a mix move. Rearrange in seconds; save a surface per project. • Sequence it too — clock the step lanes to your DAW and drive its tracks. • Easy to connect — one USB cable to a Mac via IDAM (Inter-Device Audio and MIDI), or wirelessly over Bluetooth MIDI. No driver, no helper app. UNLOCK — MIDI GRAPH (in-app purchase) Wire MIDI In → processors → MIDI Out on a visual canvas: • 60+ node kinds — arpeggiators, scale/key quantizers, transposers, chords, echoes, swing, humanize, euclidean rhythms, random/generative melodies, LFOs, CC tools, an analog knob-per-step sequencer, a Matrix sequencer and a Counter. • Built-in instruments — Synth, Drums, a Sampler and a loop Slicer make sound right in the graph; no external synth required. • Emergence generators — Conway's Game of Life, Turing machine, Wolfram rules, Markov, bouncing balls, Lorenz attractor — for evolving, living patterns. • Presets — factory patches grouped by category (control surfaces, generators, keyboards, utilities): Amen Engine, Starfield, Conway Choir, Turing Bass, Cellular Drums… Save your own. ROUTING & MPE • MIDI Out exposes all 16 channels plus an MPE connector — multitimbral, multi-instrument setups. The built-in synth responds to MPE. • Every keyboard is its own node — process and route each one independently. PLAYS OUT OF THE BOX • Built-in polyphonic synth, drum kit, sampler & slicer or send MIDI to your gear via CoreMIDI and an always-on virtual port.
SetClass
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SetClass is an interactive tool for exploring Pitch Class Set Theory — the analytical framework behind atonal and post-tonal music, from Schoenberg and Webern to contemporary composers. BUILD & HEAR Tap notes on the chromatic wheel to construct any chord, scale, or pitch collection. Hear it instantly with a jazz piano soundfont or built-in synthesizer. EXPLORE THE THEORY • Normal form, prime form, and Forte number for every set • Interval vector analysis • Transpositional and inversional symmetry • Z-relation detection TRANSFORM Apply serial operations: transposition (T0–T11), inversion, retrograde, retrograde inversion, and multiplication (M5, M7, M11). Watch the geometry change in real time. COMPOSE & SEQUENCE • Sequencer: build rhythmic patterns with serial transformations, arpeggios, swing, gate, and glide • Melody Generator: create melodic lines with contour control (free, rising, falling, arch) • Morph: blend smoothly between two sets with optional portamento • Export to MIDI or MusicXML FIND & GENERATE • Set Finder: enter any melody or chord and identify the pitch class set inside • Generator: produce sets by cardinality, symmetry (mirror, symmetric), and density LEARN Built-in theory reference covering pitch classes, normal form, prime form, interval vectors, Forte numbers, transposition, inversion, retrograde, symmetry, Z-relation, set class, morphing, and serial technique — with musical examples from Debussy, Schoenberg, Bartók, Webern, Berg, Stravinsky, and Messiaen. Available in English, Spanish, French, Italian, German, and Chinese.
Screenshots
Verdict
The clearest difference is price: SetClass at $4.99 against MIDIRack's $14.99. SetClass also leads on in-app purchases (none vs 1). MIDIRack's advantage is update cadence (every 4 days vs every 3 months). On ads, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
MIDIRack costs $14.99 and SetClass $4.99 up front. MIDIRack sells 1 one-off in-app purchase. SetClass asks for nothing beyond the download.
MIDIRack ships an update every 4 days, SetClass every 3 months. The most recent releases landed on September 20, 2026 and October 3, 2026 respectively.
| Parameter | MIDIRack | SetClass |
|---|---|---|
| Price | $14.99 | $4.99 — better |
| Rating | 4.8 (8 ratings) — better | — |
| Positive reviews | 66.7% of reviews | — |
| Number of ratings | 8 — better | — |
| Update frequency | Every 4 days — better | Every 3 months |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 — better | 18.0 |
| Further details — not scored | ||
| Size | 28 MB | 88 MB |
| Age rating | 4+ | 4+ |
| Developer | Kai Aras | Martin Adler |
In-app purchases
MIDIRack
- Graph Editor Unlock$7.99
SetClass
No in-app purchases









