MIDI Generator Rack

First, the thing that trips everyone up in Live 12: the new MIDI Tools (Generators — Seed, Rhythm, Shape, Stacks, Euclidean Sequencer; Transformations — Arpeggiate, Connect, Ornament, Quantize, Recombine, Strum, Time Warp, Velocity Shaper, Glissando, LFO, Expressive Chords) live in the clip editor, not in the device chain. They write or rewrite notes inside a clip when you press Apply; they are not real-time devices and they cannot go inside a MIDI Effect Rack. What can go in a rack are the real-time MIDI effects: Arpeggiator, Chord, Scale, Random, Velocity, Note Length, Pitch, Note Echo (plus Expression Control, Envelope/LFO M4L devices and the Random/Scale pair). This rack uses those eight devices on chains that a macro switches between, so one held note becomes a line, a chord cascade, a random melody or a pulse — and the clip tools and Follow Actions supply the long-term variation a rack cannot. Genres: techno, IDM, ambient, electro, anything generative.

Layout

How it's built

1. On a MIDI track with your instrument (an Operator pluck, Drift bass, or External Instrument to the TD-3), insert a MIDI Effect Rack before the instrument. Name it "Pattern Engine". Create four chains: Arp, Random melody, Echo cascade, Pulse. In the chain list, set chain-select zones 0–31, 32–63, 64–95, 96–127 — one chain active at a time. Set the chain selector to 0.
2. Arp chain: Scale (base C, scale Minor, Fold on so out-of-scale notes snap down rather than up) → Chord (Shift 1 +7 st at 100%, Shift 2 +12 st at 80% velocity) → Arpeggiator (Style Up, Rate 1/16 synced, Gate 50%, Steps 2 with Distance 12 st so the pattern spans two octaves, Retrigger Off, Hold off, Repeats inf) → Velocity (Random 20, Out Hi 110, Out Lo 60, Drive 0, Compand 0) → Note Length (Mode Trigger, Length 50%, synced to 1/16). Scale sits first so the Chord adds in-key intervals; a second Scale after the Chord would be stricter but doubles notes.
3. Random melody chain: Random (Chance 60%, Choices 8, Scale 1 st, Mode Rnd — each incoming note may be replaced by one of 8 semitone steps up) → Scale (C minor, Fold on — this is what turns semitone randomness into melody) → Arpeggiator (Style Random, Rate 1/8, Gate 60%, Repeats 1 so each held note yields one random pass per retrigger) → Velocity (Random 40, Out Hi 120).
4. Echo cascade chain: Note Echo (Delay 1/8 dotted synced, Feedback 60%, Transpose +12 st per echo, Velocity Decay 70%) → Pitch (0 st; the Octave macro moves it) → Scale (C minor, Fold on, so the stacked transpositions stay in key when Octave moves by non-octave amounts) → Note Length (Trigger, 25%). Note Echo generates notes after the fact, so with a 1-bar loop and 60% feedback the tail crosses the loop point — set the track's instrument release to taste.
5. Pulse chain: Arpeggiator (Up, 1/16, Gate 30%, Retrigger Note so every new note restarts the pattern on the grid) → Random (Chance 25%, Choices 2, Scale 12 st, Mode Alt — alternates octave jumps, 25% of the time) → Velocity (Random 60, Out Lo 40, Out Hi 127; wide velocity for accents) → Note Length (Trigger, 10% = very short, for a Drift or Operator pluck it becomes a sequencer-like ticking).
6. Enter Map mode. Density → every Arpeggiator's Rate, min 1/4 max 1/32 (the macro steps through the synced values; map all three arps to it), plus Note Echo Feedback 0 → 80%. One knob: sparse to machine-gun in every mode.
7. Range → Arpeggiator Steps 1 → 4 (Arp and Pulse chains) and Random Choices 2 → 24 (Random melody chain). Range = how far from the played note the pattern reaches.
8. Chance → every Random device's Chance 0 → 100% and every Velocity device's Random 0 → 100. At 0 the rack is deterministic; at 127 it is a different pattern each bar.
9. Gate → every Note Length's Length 5 → 100% (percentage of the synced note) and every Arpeggiator's Gate 10 → 100%. Short = plucks, long = legato lines that overlap and trigger the instrument's glide.
10. Scale → the scale-type selector of all four Scale devices (Live 12's Scale device has a scale-name chooser alongside the grid). The macro walks the device's list in its fixed order, so pick a min/max range in the mapping browser that spans the scales you want adjacent — Minor → Dorian → Phrygian is contiguous enough for a mood knob; Whole Tone sits further down, so widen the max if you want it. Keep Fold on everywhere, and if you need a root change map the Base note on a spare macro rather than on this one.
11. Octave → Pitch (Echo cascade) −24 → +24 st, macro centre = 0, and Arpeggiator (Arp) Distance 0 → 24 st (changes the interval between arp octaves: 12 = octaves, 7 = fifths stacking).
12. Mode → the rack's Chain Selector 0 → 127. Exit Map mode. Show all 8 macros.
13. Randomization: exclude Mode and Scale (random key changes are not "generative", they are wrong) and keep everything else. Save Macro Variations: "Pluck line" (Mode 10, Density 50, Gate 30, Chance 10), "Drift melody" (Mode 45, Chance 70, Range 60), "Cascade" (Mode 80, Density 60, Octave 90), "Machine" (Mode 110, Density 100, Gate 10, Chance 40).
14. Combine with clip generators: on the clip, open MIDI Tools → Generate → Seed (Density 40%, Pitch range one octave in C minor, Length 1/16 to 1/4) and press Apply to get a starting phrase. Or Rhythm with a 1/16 grid and 60% density for a pulse, or the Euclidean Sequencer generator (Steps 16, Pulses 5 on one pitch) for a kick-style ostinato. Then the rack transforms it live.
15. Follow Actions for the long game: make four clips, each generated differently, each with a Follow Action: Chance A "Next" 60% / Chance B "Any" 40% after 4 bars, with the last clip looping back to "First". The rack gives bar-level variation; Follow Actions give section-level variation. Add a Shape generator pass on one clip for a contour that rises over 8 bars.
16. To capture the result, record a second MIDI track whose input is this track, Post FX; then Quantize or Recombine the recorded clip offline.

Macro map

Signal flow notes

Why Scale after Random and after Chord: Random and Chord generate pitches without musical knowledge; Scale with Fold on maps every pitch to the nearest in-scale note below. Put Scale before them and the random intervals land outside the key again. The only exception is the Arp chain, where Scale first lets the Chord device build correct intervals from a corrected root.

Why Note Length last: Arpeggiator and Note Echo both emit note-offs on their own schedule; Note Length in Trigger mode re-times every note-off relative to its note-on, so switching chains with the Mode macro never leaves a long stuck note.

Variations

TD-3 driver

Put an External Instrument after the rack sending MIDI to the TD-3 (set the TD-3 to MIDI mode, channel 1). Pulse chain with Gate macro around 70 gives overlapping notes, and the TD-3 responds to overlapping notes with slide (legato) — the rack becomes a 303 sequencer with random slides. Add Velocity Out Hi 127 and a Random Chance of 30% for accents (the TD-3 accents above velocity 100). See acid 303.

Chord engine

Replace the Arp chain's Arpeggiator with a second Chord device (+3, +7, +10, +14 st) and a Velocity device with Compand for soft voicings; map Range to the number of active Chord shifts via each shift's velocity 0 → 100%. Combine with the Expressive Chords (12.2) clip tool to generate voicings offline and this rack to re-voice them live. See chords & stabs.

Ambient generative

Echo cascade chain only, Density 20, Note Echo Delay 3/8, Feedback 85%, Transpose +7 st, feeding the granular rack. One note every 4 bars from a Follow-Action clip chain with 1-bar clips and "Any" at 100%; see generative sounds.

Performance notes

• Push: macros 1–8 on the encoders; Mode on encoder 7 or 8 steps through chains. In Note mode on Push, play with the track's Scale set to match the macro; use Push's own In Key layout so the input is already diatonic and the Scale devices only tidy the generated notes.
• Live tweaks: Density and Gate are the performance knobs; Chance is the "surprise me" knob. Change Mode on the bar — chain switching is immediate and unquantised, and the arps restart on their next synced step.
• Automation vs macro: automate Mode and Scale in Arrangement (they are structural), ride Density/Chance/Gate live. Macro Variations work as sections but do not glide between values.
• CPU: negligible — MIDI effects cost nothing. The instrument after the rack decides. Note Echo with high feedback can generate dozens of simultaneous notes; cap the instrument's polyphony at 8.

Related

• MIDI tools
• Generative sounds
• Plucks & arps
• Acid 303
• Tuning, scales & MPE
• Racks & macros
• Automation & modulation
• Acid rack
• Electro