MIDI effects and the arpeggiator

A MIDI effect changes the notes before the instrument hears them: it can transpose them, turn one key into a chord, repeat each note, or play a held chord as an arpeggio. MIDI effects sit on an instrument track's channel strip, in the MIDI FX slots above the instrument.

Adding a MIDI effect

  1. Select an instrument track.
  2. In its channel strip, click ＋ MIDI FX and choose an effect. Your installed Audio Unit MIDI effects are listed after Nebula's own.
  3. Click the effect's name in its slot to open its window.

The notes go through the slots from top to bottom, then to the instrument. Hover over a slot and click its power button to bypass the effect; its settings are kept. Each window has Reset, which puts every control back where it starts.

Nebula's MIDI effects

  • Transposer: moves every note by Semitones and Octaves, holds notes to a Scale on a Root (Song Key follows the song), and moves them along the scale with Scale Steps, so a melody stays in key.
  • Velocity Processor: changes how hard notes play. Mode is Scale, Fixed, Compress or Expand, with Minimum, Maximum and Offset.
  • Modifier: turns one controller into another: Input CC (1 is the mod wheel) becomes Output CC (11 is expression), with Scale, Offset and Thru to keep the original too.
  • Randomizer: humanises a part with Velocity ±, Pitch ±, Pitch Chance, Timing, Note Chance and Length +. It plays the same on every playback and in a bounce; Variation picks another set.
  • Chord Trigger: one key plays a whole chord of the scale. Choose the Scale, Root, Chord (Triad up to Thirteenth, Sus, Power and more) and Voicing. Your Note is the root or the melody on top; Bass adds the root below; Evolve changes a held chord by itself every beat, bar or two bars.
  • Note Repeater: plays each note again. Mode is Echo (a set number of Repeats) or Roll (repeats while you hold the key). Set Rate, Feel, Climb (each repeat higher or lower), Velocity (fades or grows), Gate and Speed Up. Pattern can be Euclidean, with Hits, Steps and Rotate.
  • MIDI Modulator: a wave that moves a controller, pitch bend, aftertouch or a knob of your instrument. Choose its Shape, Rate (or free, in Hertz), Depth and what it Moves, plus an envelope each note fires. Choose Steps to draw your own wave. It is not one of the channel's modulators: those move its fader, pan, sends and plug-ins (see Modulators).
  • Scripter: describe what you want in plain words ("octave up, echo 3 times climbing in key, humanize") and press Build; it is built from the effects above. RECIPES has ready ones. Unpack into the Chain turns what it built into ordinary slots you can edit one by one.
  • Arpeggiator: see below.

The arpeggiator

The Arpeggiator plays the notes you hold one after another, in time with the song. To use it:

  1. Add Arpeggiator from ＋ MIDI FX on an instrument track, and click its slot to open it.
  2. Hold a chord on your keyboard. The arp plays it.
  3. On the Play tab, choose the Order (Up, Down, Up/Down, Converge, Pinky Up, As Played, Random, Chord, Strum and more) and the Rate (1/1 to 1/64), with Feel for straight, dotted or triplet.
  4. Set Octaves (1 to 4) and which way they go (Octaves Go), Gate (how long each note lasts; over 100 % notes overlap) and Swing.
  5. Choose Latch: Off stops when you let go; Latch keeps playing; Add puts each new key in; Transpose moves the pattern with one key.
  6. Turn the big Energy knob, from only the downbeats to a storm of octaves and rolls. Automate it to build into a drop.

Faster ways to a pattern:

  • The menu at the top lists the factory patterns by style; the arrows step through them. Save Pattern As… keeps your own under Yours.
  • Surprise Me makes a fresh pattern. Undo takes it back.
  • Type in the Describe field ("darker, busier, with rolls in the chorus") and press Shape It.
  • A/B keeps two versions to compare; Copy to B copies what plays now.

Restart on Key starts the pattern from step one on every new key. Low Key and High Key leave keys outside the range to play normally, for a bass or melody beside the arp. Source can be Keys, Idle: Chords (the chord track when you are not playing) or Chord Track, so the arp plays the song's chords with no keys held.

The arpeggiator's other tabs

  • Steps: up to 32 steps in lanes (Rhythm, Velocity, Gate, Octave, Chord Tone, Roll, Chance, Condition, Nudge, Slide, Stroke, Motif, Mod A, Mod B). Each lane has its own LENGTH, direction and speed (Every Step to Every 4th). The lock keeps a lane when you press Surprise Me.
  • Harmony: Chords from Scale turns each key you hold into a chord of the scale for the arp to play. Happy End lands the pattern home every few bars, at each section's end, or at the loop's or song's end.
  • Motif: teach the arp a melody shape with Learn — Play It, Step Record or From Selected Region. It then plays it on every chord, in key.
  • Patterns: eight slots, A to H. Slots Follow By Hand, Song Sections (each section plays its slot) or Keyswitches (keys from Keyswitch From up pick a slot at the next bar). Fills & Evolve adds fills every few bars.
  • Sound: Glide, Second Voice, a Bass line (on the same channel, another channel or another track), Groove (including one taken from a drum track), Keep Above/Keep Below and a Pedal note.

MIDI Learn in the header lets a knob on your controller turn any of the arp's controls.

Recording and baking

When you record on a track with MIDI effects, the region keeps the notes you played, not what the effects made of them. On playback they go through the effects again, so you can change the arp's pattern after recording.

To edit the arp's notes themselves, click Bake in the Arpeggiator's header. What it plays becomes a new MIDI region; the regions it played from are muted and the arp is bypassed. Undo puts it all back.

Keyswitches and articulations

An articulation's keyswitch in a region goes straight to the instrument, past the MIDI effects. An arpeggiator or a Transposer never plays or moves it, so the right articulation is chosen however the notes are changed.

Automating MIDI effects

Every control of Nebula's MIDI effects (except the Scripter, which you unpack first) can be automated: open the track's automation (A) and choose the effect's submenu in the lane's parameter menu. See the Automation chapter.

What Claude can do

Claude can do this for you: ask it to add an arpeggiator to a track, load a pattern, set its rate, or "make the arp busier in the chorus". It can list and change a track's MIDI effects, build a Scripter from words, bake an arp into a region, and remove an effect.