Celestine Granular FX: A Live-Buffer Granular AUv3 for iPad and iPhone
Most granular apps ask you to load a sample before anything happens. Celestine Granular FX from ijo audio (developer Ian Johnston) works more like a pedal: put it on a track, play, and it starts turning your audio into grains straight away. It began life as a Max for Live device, and ijo audio says the iPadOS version runs virtually the same engine, exported from the original and rebuilt with a touch interface. The App Store listing now covers both iPad and iPhone, and in October the developer posted a new video walkthrough of the AUv3.
This is an Audio Unit effect only, so you'll need a host such as AUM, Cubasis, Logic Pro for iPad, GarageBand, or Loopy Pro.
How the live buffer works
Celestine keeps a rolling one-bar buffer of whatever comes in. While Live is on, that buffer keeps refreshing. Turn Live off and the captured bar freezes, so you can repeat, smear, or tear it apart while the rest of the song moves on. When you switch Live back on, recording resumes at the next bar, so the buffer rejoins the session in time.
A playhead decides which part of that bar becomes grains. You can drag it by hand, map it to a controller, or let Move scrub through the buffer automatically, from slow four-bar sweeps down to faster note values. Reverse flips the direction of travel.
The visualizer doubles as a small XY pad: horizontal movement sets the playhead position and vertical movement sets pitch. With Pitch Mode II, those gestures favour fifths and octaves, which keeps wide swipes musical instead of landing on every semitone.
The eight granular modes
All eight modes share one engine, but the controls behave differently in each:
- Grain: classic granular clouds and scattered slices.
- Mosaic: pitched tiles, broken chords, and shimmering collages.
- Glide: each grain bends in pitch, for tape-style swoops.
- Reverie: grains play backwards for soft reverse washes.
- Bloom: a secondary halo of ghost echoes around the grains.
- Tide: the grain field rises and falls like a slow pulse.
- Stars: grains sit at fixed points in the buffer for sparkly, sequenced patterns.
- Orbit: grains circle the write head for moving stereo width.
Turn on Sync and grain triggering locks to the host tempo. The Grid control sets the division; ijo audio singles out 1/8 and 1/16 as the most useful settings for rhythmic beds and glitches that stay locked to the track. Up to 30 grain voices can run at once.
Shaping the sound
The Grain panel covers density, size, spray, pitch, jitter, spread, reverse probability, stereo placement, and smoothing. After the grains, three sections colour the output:
- Magic: a one-knob multi-effect with seven modes, including chorus-style thickening, widening, drift, shimmer, diffusion, echo, and swell.
- Verb: reverb with Decay, Tone, and Mix.
- Dirt: wavefolding and bitcrushing with a blend control.
Presets, undo and redo, preset import and export, and a constrained randomizer round it out. The developer's own support notes warn that many knobs react differently depending on where the others are set, so expect to explore rather than dial in by numbers.
Insert or send?
The developer suggests two setups, and they suit different jobs:
- Insert on one track. Load Celestine directly on a vocal, guitar, keys, or synth channel and blend with the dry/wet control. The grains stay tied to that part, which works well for adding a halo or shimmer under a lead.
- Fully wet on a send. Put Celestine on an aux bus at 100% wet and send small amounts from several tracks. Fragments of the whole arrangement end up in the same cloud, which is a quick way to build an ambient bed that follows the song.
On drums, Sync with a 1/16 Grid and the Stars or Grain modes is a sensible starting point for rhythmic glitching; on pads and piano, try Reverie or Bloom with Move set to a long sweep.
Price and requirements
Celestine is listed at US$9.99 on the App Store and needs iOS or iPadOS 17 or later plus an AUv3 host. There's no standalone app. The ijo audio product page has more detail, and the Max for Live version is sold separately for Ableton Live users. The developer has said VST3 and AU desktop versions are planned.
Where it fits
If you picked up SL DREAD for dark atmospheres, Celestine is the brighter, more playable counterpart: it rebuilds your own material in real time rather than layering in prepared scenes. It also pairs well with the synths in our October 2026 roundup — feed it a simple arpeggio and let it do the rest.
Browse more effects and Audio Units on iOS Musician.
App Store prices and system requirements change often — check the listing before you buy.