How to Use

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GrainHeads is a granular synthesizer for iPhone and iPad. It takes any audio sample, cuts it into tiny overlapping fragments called "grains," and plays them back in configurable streams to build evolving textures, rhythmic patterns, ambient pads and glitchy soundscapes.

Key Concepts

• Playheads — Independent grain streams (up to 8 in the app, up to 5 in the AUv3 plugin). Each one has its own source, scope, pointer, grain settings, pitch, two filters and output stage
• Grains — Short fragments (10 ms to 2 s, or 5 s with the Pro setting) cut from the sample and shaped by an envelope curve
• Slots A–D — Four sample slots, used as two pairs. A playhead reads the A/B pair or the C/D pair and blends between the two samples with the A/B Mix knob
• Play modes — Every playhead is set to Mute, Latch (a continuous grain stream), Seq (driven by its own step sequencer) or Sampl (finger-triggered zones on the waveform)
• Modulation — 8 LFOs and 2 envelopes. Any knob can take several sources at once, and any knob can also be handed to a sequencer lane

Quick Start

1. Open the app — a factory sample is already loaded into slot A
2. Press Play — the green button in the PLAY section
3. Drag the scope on the waveform — the Start and End edges set the region grains are taken from
4. Turn Length and Rate in the GRAINS section to change the texture from a stutter to a smooth cloud
5. Turn Scan in the POINTER section — the playhead now drifts through the scope on its own
6. Add a playhead — tap + next to the colored circles and give it different settings
7. Open the Effects tab and tap a chain block to switch that effect on
8. Tap the dot to the left of any knob and assign an LFO for movement
9. Set a playhead to Seq and draw a pattern in the SEQ tab
10. Save your patch as a preset

The Main Screen

Everything lives on one screen. The top row holds the global controls, the waveform sits below it, the selected playhead's parameter sections fill the middle, and the bottom panel switches between Effects, Modulation, Macros and the sequencer.

Top Row

• Menu (hamburger) — Settings, this guide, contact, privacy and the purchase screen
• Presets — Opens the preset browser
• Playhead circles — One colored circle per playhead. Tap to select, long press to delete, tap + to add one (up to 8)
• Undo / Redo — Steps back and forward through dice rolls
• Dice — Randomizes everything, across all playheads
• Level meter and CPU — Stereo output level and current DSP load, in the top corner

Waveform

• Two waveforms are drawn together: the A sample on top and the B sample below it (or C and D when the playhead is on the second pair)
• The smpl A / smpl B buttons open the sample browser for that slot. Long press one to clear the slot
• Each playhead draws a colored scope — the region between its Start and End. Drag either edge to resize it, or drag the middle to slide the whole scope
• A moving marker shows where the pointer currently is inside the scope, and grains flash as they fire
• In Sampl mode the waveform switches to zones — see below

Bottom Panel

• Play — The performance view: both pairs of waveforms, sample switches, the noise bed, the send pad, macros and stutter
• Effects — The chain, Noise, Delay, Reverb, Lo-Fi and the Limiter
• Modulation — The 8 LFOs and 2 envelopes
• SEQ — Appears as soon as a playhead is in Seq mode, and shows that playhead's sequencer

On iPhone the playhead parameters are a tab of their own, so the bottom bar reads Play, Heads, Effects and Modulation.

The Play Section

Opened from the Play tab, this is the performance view: a full-screen backdrop carrying the controls you reach for while a patch is running, and none of the ones you don't. Not to be confused with the PLAY controls on a playhead below.

• Waveforms — The A/B pair on the left, C/D on the right, drawn in white with a line for every grain as it fires, so you can watch each playhead work. A line sits over the sample actually being read, following A/B Mix
• Sample switches — Arrows and the file name beside each wave step through the library without opening the browser. Only samples you own are included
• Noise — The noise bed gets its own waveform, with a cursor showing where in the loop it is and the same arrows to change it
• Send pad — X is the reverb send, Y the delay send. The pad and the two knobs in Effects follow each other in both directions
• Transport — Play and stop, top left
• Macros and Stutter — Across the bottom; both are described below

Reach for the send pad, or the noise arrows, while that effect is switched off in the chain and it is switched on for you — the chain lives on another tab, so the section says what it changed.

The backdrop can be changed in Settings, including your own image.

Playhead Sections

These sections always apply to the selected playhead. Every section has a small i for an in-app explanation, and every knob has a dot on its left that opens the modulation popup.

PLAY

• Play, REC, Link and BPM — Global transport. Press and drag BPM for the tempo slider
• Mute — The playhead produces nothing
• Latch — A continuous grain stream, the default
• Seq — The playhead is driven by its own step sequencer, and any parameter can be routed to a lane of that sequencer
• Sampl — The waveform becomes a set of zones you trigger with your fingers
• The small dice next to the section title randomizes this playhead only

SOURCE

Choose the slot pair — A/B or C/D — and blend between the two samples in it with A/B Mix. The mix is a normal parameter, so an LFO or a sequencer lane can morph between two completely different sources while everything else stays put.

POINTER

Controls where inside the scope grains are taken from, and how that spot moves.

• Point — The pointer's position inside the scope
• Scan — Direction and speed of drift. Center is still, left drifts backwards, right drifts forwards
• Scatter — How unstable the pointer is; higher values throw each grain further from the pointer
• Ricochet — The pointer bounces off the scope edges and keeps drifting the other way instead of wrapping around

GRAINS

• Start and End — The scope, the region of the sample grains come from. These are the same handles you drag on the waveform
• Length — Duration of each grain, 10 ms to 2 s (5 s with the Pro setting)
• Rate — How many grains fire per second, 1–40 Hz
• Chance — Probability that each grain actually plays, 0–100%
• Reverse — Plays grains backwards

PITCH

Pitch shifts grains by −24 to +24 semitones. The Scale button below the knob quantizes it: Free (no quantization, the default), Chromatic, Major, Minor, Harmonic Minor, Melodic Minor, Pentatonic Maj/Min, Blues, Dorian, Phrygian, Lydian, Mixolydian, Whole-Half and Whole Tone. Once a scale is set, even modulated or randomized pitch snaps to the nearest note in it.

GRAIN ENVELOPE

The loudness curve applied to every individual grain. Drag the control points and bezier handles to sculpt it — sharp transient attacks, slow fades, plateaus or asymmetric shapes. Each playhead keeps its own curve, and it is saved with the preset.

FILTER 1 and FILTER 2

Every playhead has two full filters with a live response graph.

• Type — LP, BP, HP, Notch, Low Shelf or High Shelf
• Freq — Cutoff, 20 Hz to 20 kHz on a logarithmic knob
• Res — Resonance
• Drive — Saturation inside the filter. In either shelf mode it becomes Gain, ±12 dB
• 12 / 24 — Filter slope in dB per octave
• Parallel / Serial — Sums the two filters, or runs filter 1 into filter 2
• Free / Link / Mirror — How filter 2's cutoff follows filter 1. Free is independent, Link keeps the gap between them, and Mirror moves them in opposite directions around their midpoint

AMP

• Pan — Stereo position
• Spread — The higher the value, the further from center individual grains land
• Amp — Level of this playhead
• FX Send — How much of this playhead is sent into the effects chain. At 0% it stays dry, so you can layer dry percussive playheads with wet ambient ones

Parameter Ranges

Samples and Slots

GrainHeads has four sample slots, A to D. Tap smpl A or smpl B on the waveform to load into that slot; a playhead reads either the A/B pair or the C/D pair, chosen in its SOURCE section.

• Categories — The sidebar lists All, Factory Samples, Online Samples, any sample collections, your own groups and Unsorted
• Long press the waveform thumbnail to preview a sample before loading it
• Swipe left on a row to delete a sample
• Groups — Imported samples can be filed into groups you name yourself
• Import (Pro) — Add audio files from your device (WAV, MP3, AIFF, M4A, CAF)
• Record (Pro) — Record a new sample from the microphone

Five factory samples are included: Beat Meat, Grand Hammers, Grotesk, Morning Glory and Ocean Strum.

Sample Collections

Curated sample collections appear as their own categories in the browser. You can browse and preview any collection straight away — the previews stream on demand — and a one-time purchase unlocks that collection's full-quality WAV files, which are then downloaded into the app and behave like any other sample. Collections are separate from the Pro purchase, and there is a bundle that unlocks all of them.

Sampl Mode

Set a playhead to Sampl and the waveform turns into a row of zones. This mode plays the sample directly rather than granulating it, so it works like a finger-played slicer sitting alongside your grain streams.

• Touch a zone to play it, and hold several zones at once with several fingers. The zone under your first touch keeps playing even if the finger slides sideways
• The narrow strip along the top edits the zones: tap an empty spot to add a divider, drag a divider to move it, or tap one without moving to remove it and merge the zones either side
• The POINTER and GRAINS sections are replaced by VERTICAL MACROS: a grid of parameters driven in real time by how high or low the finger holding a zone sits
• Any number of macros can be active at once — A/B Mix, Speed, FX Send, Pan, Amp, the frequency, resonance and drive of both filters, and the global delay send and feedback, reverb send and decay, and Lo-Fi bits

Sequencer

Set a playhead to Seq and a SEQ tab appears for it. Each playhead in Seq mode gets its own independent 16-step sequencer, laid out as two rows of eight.

• Tap a step to switch its gate on or off
• Lanes — Switch the grid between Gate, GateLength, GateProb, Retrig, Pitch, Accum and A/B Mix. Drag a step vertically to set its value in the current lane
• GateProb — The chance a gated step actually fires, 100% down to 0. At 100% (the default) every gated step plays; lower it and the step drops out at random, thinning a pattern without erasing its gates
• Retrig — How many times a step fires inside its own time slot, 1 to 8. A gated step starts at 1 and shows as a solid square; touch it and a slider appears, and the square splits into that many equal columns — two for a double, eight for a roll. Every retrigger plays the same step over a proportionally shorter gate
• Accum — How far a step's pitch drifts each time the sequence passes it, −12 to +12, centred on 0 (off). Set it to +5 and the step first plays as written, then one note higher on the next pass, then two, up to five, before falling back and starting over. The walk follows the selected scale, so five steps up a minor scale is five minor-scale notes, not five semitones
• Step count — Drag the step counter to run anything from 1 to 16 steps
• Grains / One-shot — A step either fires a burst of grains or plays the slice once
• Pitch lane — A dedicated lane below the grid, quantized to the selected scale
• Filter envelope — A per-step envelope for the filters, with its own amount knob
• Custom lanes — Send any knob to this sequencer from its modulation popup and it gets a lane of its own, with per-step values
• Detach lane — A lane can run at its own step count, so pitch, filter and grain size each cycle at a different rate inside the same playhead
• The section dice randomizes the whole pattern

Modulation

The Modulation tab holds 8 LFOs and 2 envelopes, each with a live graph.

• Waveform — Sine, Triangle, Square, Saw up, Saw down or Sample & Hold
• Speed — 0.002 Hz to 20 Hz, from a drift that takes minutes to audio-rate wobble
• Sync — Locks an LFO to the tempo and switches its speed control to musical divisions
• Envelopes — Two freely drawn envelopes, 0.01 s to 30 s, which can also be synced
• LFO speed can itself be modulated by another LFO

Assigning Modulation

1. Tap the small dot to the left of a knob
2. Pick one or more sources and set an amount for each — a parameter can take several sources at once
3. The same popup can route the parameter to the sequencer of any Seq-mode playhead, which gives it a step lane instead

Once assigned, the dot is replaced by the names of the sources, and the knob shows the modulation moving in real time.

Macros

Three XY pads — A, B and C — across the bottom of the Play section. Each pad has two axes, and every axis is a modulation source in its own right, sitting alongside the LFOs and envelopes in the modulation popup as aX, aY, bX, bY, cX and cY. Assign one to any parameter, with its own amount and direction, and move a finger to take the whole patch with you.

• A pad rests in the centre and contributes nothing until you move it, so assigning an axis never changes how a patch sounds on its own
• One axis can drive as many parameters as you like, and one parameter can take several axes at once — the contributions sum, as they do for LFOs
• Assignments, amounts and pad positions are all stored in the preset
• The dice beside the title rolls a fresh set of assignments, drawn from the parameters that move audibly on almost any patch

Stutter

Eight buttons beside the macro pads: 1/16, 1/8, 1/4, 1/2, 1, 2, 4 and 8. Hold one and the master bus — every playhead summed, taken before the effects chain — is captured and looped at that many beats, locked to the current tempo. Let go and the loop drops away, with playback carrying on underneath where it would have been.

• One division at a time
• Momentary: it sounds only while a button is held, and nothing about it is saved in a preset
• The longest divisions are capped at eight seconds, so a very slow tempo shortens them rather than running out of buffer

Effects

One global effects chain, fed by each playhead's FX Send: Noise, Delay, Reverb, Lo-Fi and the Limiter.

Chain

The CHAIN section lists the effects as blocks in signal order, with an arrow down the side showing which way audio flows. Tap a block to switch that effect on or off, and drag a block to reorder the chain — Delay before Reverb, or the other way round. The Limiter sits below a divider because it is always last and cannot be moved. Reordering briefly stops playback while the chain is rebuilt.

Noise

• Type — White, Vinyl, Waves, Birds, Train Station, Clankers, Noise 122, Pedals, Sink Noise or Vinyl 2
• Level — 0–100%
• Pro users can import their own looping noise file

Delay

• Send — Wet amount
• Time — 10 ms to 4 s
• Width — Stereo spread of the echoes
• Fdbk — Feedback, up to 95%
• Sync to tempo — Locks the delay time to the current BPM

Reverb

• Send — Wet amount
• Pre-D — Pre-delay, up to 100 ms
• Decay — Tail length, 0.1 to 10 s
• Cutoff and filter type — An LP, HP or BP filter on the tail, 20 Hz to 20 kHz

Lo-Fi

• Bits — Bit depth, 16 down to 1
• Rate — Sample-rate reduction, 44.1 kHz down to 100 Hz
• Drive — Saturation, and the main part of the character
• Mix — Blend against the clean signal

Limiter

A brickwall limiter at the very end of the chain, with its own gain-reduction meter. It is on by default; tap its chain block to bypass it.

The level meter in the top corner shows the post-limiter output.

Presets

Tap Presets in the top row.

A preset stores everything: every playhead with its play mode, slot pair, scope, pointer, grain settings, pitch, custom grain envelope and both filters; all sequencer patterns and lanes; the effects settings and chain order; every LFO, envelope and modulation assignment; the scale; and the Sampl zones.

• Save — Overwrites the current preset
• Save As — Saves under a new name, optionally in a folder
• Export — Shares presets as .ghpresets files
• Import — Loads preset files from other users
• Factory presets are included and always available; loading your own saved presets needs Pro

Recording Output

Tap REC in the PLAY section.

• Records the full stereo output — every playhead, the effects and the limiter — to a WAV file
• The button reads STOP while recording, and the meter shows what is being captured
• When you stop, you are asked to name the recording and it is kept as a sample, ready to granulate again

MIDI

The app plays notes from, and takes controller data from, external MIDI gear. Open Menu > Settings > MIDI. Input is off until you switch it on, so nothing changes until you ask for it.

• Devices — Connected sources are listed, and there is a button for pairing Bluetooth MIDI. Other apps can also send to the "GrainHeads" destination
• Channels — Omni plays every MIDI-enabled playhead on all channels; Ch per Head gives playhead 1 channel 1, playhead 2 channel 2, and so on
• Per-playhead routing — Choose which playheads respond to notes at all
• Note envelope — Attack, Decay, Sustain, Release and velocity sensitivity, applied to every note-driven playhead
• Bend range — Pitch-bend depth, 0 to 12 semitones
• CC Learn — Tap Learn next to a parameter, then move a knob on your controller. Mapped parameters follow whichever playhead is selected, exactly as turning the knob by hand does

Ableton Link

Sync tempo across apps and devices on the same network.

• Tap the Link button in the PLAY section
• While Link is active the session drives the tempo and the BPM control becomes read-only
• Sequencers, synced LFOs and synced delay all follow the shared tempo
• Works with Ableton Live, AUM and any other Link-enabled app

AUv3 Plugin and AUFX Extension

GrainHeads ships an Audio Unit v3 instrument and an AUFX effect extension for hosts such as AUM, GarageBand, Logic Pro and Cubasis. Both support up to 5 playheads and mirror the app's layout — the same SOURCE, POINTER, GRAINS, PITCH, AMP and dual-filter sections, the same effects chain, sequencer and modulation.

See how GrainHeads works as AUv3 unit

Setup in a Host

1. Add GrainHeads as an instrument on an audio channel, not a MIDI-only one
2. Route MIDI to the channel if you want note control
3. All parameters are exposed to the host for automation

Play Modes

Each playhead has its own mode: Mute, Latch, MIDI, Seq or Sampl.

• Latch — The playhead starts with the host transport, no MIDI needed
• MIDI — The playhead only sounds while a note is held. Each playhead listens on its own channel (playhead 1 = channel 1, and so on). The note sets the base pitch and the PITCH knob is added on top as an offset, so the same note can be layered an octave apart across two playheads
• All playheads on channel 1 — Long-press the MIDI button in the PLAY section and enable it to drive every MIDI-mode playhead from a single channel. The button then reads *MIDI, and the setting is saved with presets

Plugin Features

• Sample picker — Factory samples, plus anything shared from the main app (Pro)
• Record input — Capture audio from the host's input bus as a new sample, up to 5 seconds
• Factory presets — Shimmer Pad, Glitch Dust, Deep Drone, Crystal Rain and Warm Texture
• Dice — Randomizes all parameters

AUFX Extension

Put the GrainHeads AUFX extension on an effect bus to granulate whatever is playing into it.

• Incoming audio is written into a rolling buffer
• Feed / Frozen — Feed keeps capturing; Frozen locks the buffer to what was just recorded
• Once frozen, play several playheads from that captured audio and sculpt it with the full set of grain parameters
• Effects, modulation and the sequencer are all available in the extension

Shared Samples

Samples you import or record in the main app become available to the plugin automatically through the shared app container. Run the main app at least once after importing.

Settings

Tap Menu (hamburger) > Settings.

• Language — The app's interface language
• Max Grain Size (Pro) — 2 seconds, or 5 seconds for drone-length grains
• MIDI — Opens the MIDI screen described above
• Color Scheme (Pro) — Knob color, panel background, menu button color and knob opacity, with a dice for instant palettes
• Accessibility Mode — Raises contrast across the interface
• Macros Background — Pick one of the supplied backdrops for the Macros pads, or upload your own image

Pro and Purchases

The free version includes the whole granular engine: all 8 playheads, both filters, the sequencers, modulation, macros, all effects, MIDI, Ableton Link and the AUv3 plugin. A one-time Pro purchase adds:

• Import your own samples
• Record samples from the microphone
• Load your saved presets (factory presets are always available)
• The online sample library
• Full interface customization and the 5-second grain setting
• Custom samples in the AUv3 plugin

Sample collections are sold separately, per collection or as a bundle. Purchases restore on any device signed in to the same Apple Account.

Tips

• Ambient pads — Low rate (1–3 Hz), long grains, a smooth envelope curve, a slow Scan and plenty of reverb send
• Rhythmic glitches — High rate (20 Hz and up), 10–50 ms grains, a sharp envelope curve and a Seq-mode playhead
• Two samples, one playhead — Load related material into A and B, then modulate A/B Mix with a slow LFO
• Use both filters — Set them to Serial for a sharp band, or Parallel with an LP and an HP for a hollowed-out sound
• Polyrhythms — Give each Seq playhead a different step count, or detach single lanes so pitch and filter cycle at their own rates
• Granulate a granulation — Record the output, keep it as a sample and granulate it again
• Stay in key — Set a scale and every pitch, including randomized and modulated ones, snaps to it
• Play it live — Put one playhead in Sampl mode for hands-on slices while the others keep the texture going
• Dice for inspiration — Roll the dice when you are stuck, and undo if it goes too far