Scratches — User Manual
Granular tape texture · VST3 / AU / Standalone · by Feline Astronauts
1. What Scratches is
Scratches constantly records the last 10 seconds of whatever you feed it onto an internal "tape loop". From that loop it plays back a cloud of tiny audio snippets — grains — each with its own position in the past, pitch, direction, and stereo placement. The cloud is then run through a tape stage (saturation, speed wobble, worn-out tone, hiss, digital grit) and fed back into the loop, so every repeat is re-granulated and re-degraded.
Three ways to think about it:
- a granular delay — like a delay pedal where the echoes shatter into pitched, reversed, scattered fragments,
- a texture generator — freeze the buffer and play its contents like an instrument,
- a lo-fi colour box — switch the grains off entirely and it's a wobbly tape echo.
Everything you hear is controlled by four panels — GRAINS, TAPE, OUTPUT, MOD — plus a preset bar in the header.
2. Quick start (five minutes)
- Insert Scratches on a track with something melodic or textural playing (guitar, keys, vocals, a pad — sustained material shines).
- Click the preset name in the header and walk through the factory presets
with the
<>arrows. That's the fastest tour of what it can do. - Load Init and grab these three knobs first:
- Density — from a sparse trickle to a solid cloud,
- Position — how far into the past the grains dig,
- Feedback — how long the whole thing keeps churning.
- Flip FREEZE while audio is playing. The recording stops; the grains keep playing the frozen 10 seconds. Now sweep Position — you're scrubbing through frozen time.
- Point MOD 1's Target at any knob and it moves by itself. That's the rabbit hole.
3. How the signal flows
input ──┬────────────────────────────────────────────► dry ─┐
▼ │
(+ feedback) ──► 10 s tape loop ──► GRAINS stage ▼
▲ │ MIX knob
│ ▼ ▲
│ TAPE stage: Drive → Age → Wow&Flutter │
│ ▼ │
│ [REVERB here when →LOOP is on] │
└── feedback tap ◄────────────────┘ │
▼ │
Fidelity → REVERB → Noise → DUCK ──► wet ─────────┘
(normal position)
Three details worth knowing because you can hear them:
- Drive, Age and Wow/Flutter sit inside the feedback loop. Every repeat gets a little more saturated, darker, and more pitch-smeared — exactly how a real tape echo degrades. Fidelity and Noise sit outside the loop so digital grit and hiss stay constant instead of piling up.
- The reverb has two homes. Normally it sits outside the loop, between Fidelity and Noise — clean, predictable tails on the output. Flip →LOOP and it moves before the feedback tap: its tail gets recorded back onto the tape, re-granulated and re-reverbed on every pass (and picks up Fidelity/Noise on the way out — lo-fi washes by design).
- Feedback goes to 110%. Above 100% the loop feeds itself and blooms into self-oscillation. A built-in soft limiter keeps it warm and level instead of exploding — the "runaway zone" is an instrument, not a bug.
4. The GRAINS panel
The heart of the plugin. The ON dip at the panel's top right switches the whole stage (see §7 for what happens when it's off). Next to it sits STRETCH (v0.10), the grain pitch mode: off = varispeed — pitch and playback speed locked, like tape (a −12 grain plays its snippet at half speed); on = each grain walks the source at real speed and gets its pitch from a built-in dual-head transposer — words stay on time, just higher or lower. Stretch has the faint transient flams classic pitch-shifter pedals have; that's the sound of the technique, not a defect. A/B it on the "Time Dilation" preset with speech.
| Control | Range | What it does |
|---|---|---|
| Position | 0–100% (= 0–5 s) | How far behind "now" grains are born. Low = near-echoes of what you just played; high = digging up things from seconds ago. |
| SYNC + division | on/off, 1/16–2 bars | Locks Position to the host tempo: the delay time becomes the chosen note division at the current BPM, and the Position knob dims (the modulators can still push around the synced time). Because Position is the feedback delay time, this is how you get repeats that land on the grid — especially obvious in tape-echo mode (§7). |
| Spread | 0–100% | Randomness around Position, and stereo width. At 0 every grain starts at the same point in time and sits centred; at 100 grains scatter across seconds and across the stereo field. |
| Size | 20–2000 ms | Length of each grain. Short = clicky, percussive, spectral confetti. Long = overlapping washes that blur into pads. |
| Density | 0.5–200 grains/s | How many grains start per second. Loudness is automatically compensated, so cranking it thickens the texture rather than blowing up the level. |
| Pitch | ±12 st | Every grain plays back this much higher or lower, like varispeed. +12 with feedback = the classic shimmer stack. |
| Jitter | 0–24 st | Each grain also picks a random pitch offset within ± this range. Raw jitter is seasick chaos — which is why the next knob exists. |
| Scale | Free…Pentatonic | Snaps each grain's final pitch (Pitch + Jitter) to a scale: Free (no snapping), Chromatic (nearest semitone), Octaves, Oct+5ths, Major, Minor, Pentatonic. Jitter + a scale = random notes that are always in key. |
| Degree | Tonic…7th | Tells the quantizer which scale degree your input plays — the plugin can't detect pitch, so this is the honest version of a "key" control. Tonic (default): the scale is built on your note — feed a D, get D minor. 5th: your note acts as the scale's fifth — the same D drone now gets the darker Phrygian set (hello ♭2). Degrees the scale doesn't contain (like 3rd against Minor) push the whole grid off your note — eerie on purpose. In a mix, just sweep it until the cloud locks in. Party trick: Octaves + Degree 4th = every grain a fifth up or a fourth down. |
| Color | 0–100% | Depth of field: each grain draws a random dark↔bright tilt within this range at birth. 0 = all grains identical (the classic sound); high values scatter the cloud front-to-back — some grains close and bright, others distant and muffled. |
| Bend | −100…+100% | Each grain glides in pitch over its own lifetime, up to a full octave. Negative = every grain is a little tape-stop; positive = rising whooshes. Most audible with larger Sizes. |
| Reverse | 0–100% | Probability that a grain plays backwards. Reversed grains show as pink dots in the display. |
| Texture | 0–100% | Shape of each grain's fade-in/out envelope. 0% = soft bell shapes (smooth, cloudy); 100% = almost rectangular (grainy, buzzy, aggressive). |
| Order | 0–100% | Grain timing character. 0% = organic randomness (raindrops); 100% = a perfect clock — grains become a rhythm, and at high Density a pitched buzz where Density literally is the frequency. |
| FREEZE | on/off | Stops the recording (the dip sits next to the grain display — the tape it freezes). The last 10 seconds become a frozen landscape the grains keep playing. Automatable — freeze on a downbeat! Also fires the modulators (§6). |
The strip at the bottom is the grain display: "now" is the right edge, 5 seconds ago is the left. Every dot is one playing grain — its horizontal position shows where in the past it's reading, its size/brightness shows its envelope, pink means reversed. It's the fastest way to understand what Position, Spread and Density are actually doing.
5. The TAPE and OUTPUT panels
TAPE colours the wet signal (its ON dip bypasses the stage):
| Control | What it does |
|---|---|
| Drive | Tape saturation — warmth into grit. Runs oversampled, so it stays smooth instead of fizzy. Inside the feedback loop: repeats saturate progressively. |
| Wow/Flutter | Speed instability of the imaginary tape transport: slow drift (wow) + fast shiver (flutter). The single most "analog" knob here. |
| Swirl | Stereo spread of that instability. At 0 both channels wobble together (like a real machine — the image pumps in the middle); turning it up gives the right channel its own wobble schedule, so the instability circles the stereo field instead. Needs Wow/Flutter above zero to do anything. |
| Age | One knob for how worn the tape is: rolls off highs and lows together. At 100% you're near telephone territory. Also darkens each feedback repeat. |
| Noise | Tape hiss, level-tracked: it swells with the signal and settles in silence, like real tape self-masking. |
| Fidelity | Digital decay: first half of the knob lowers the sample rate (early-sampler crunch), second half also strips bit depth. Sits outside the loop so it stays crisp. |
OUTPUT:
| Control | What it does |
|---|---|
| Feedback | 0–110%. How much of the wet output is written back onto the tape loop. 60–90% = long evolving trails; above 100% = self-oscillation (see §3). |
| Duck | The wet signal steps aside while you play: the louder the input, the more the effect is turned down, and it swells back in the gaps. The classic "delay that never walks over the vocal". At 100% the wet is fully muted while you play. Ducking happens outside the feedback loop, so the repeats keep regenerating underneath — they're just hidden until you pause. Note it reacts to the input — with nothing playing in, the knob does nothing. Duck is also a Mod target: a tempo-synced Square on it gates the wet rhythmically while you play (see the Airlock and Distress Signal presets). |
| Mix | Dry/wet, equal-power (no loudness dip in the middle). 100% wet + FREEZE = pure texture instrument. |
5b. The REVERB panel
A hand-built plate reverb (modelled on the classic studio "plate" — a vibrating steel sheet) sits on the wet signal, with its own ON dip. It never touches the dry sound.
| Control | What it does |
|---|---|
| Amount | How much of the wet signal is replaced by reverb (equal-power blend; 0% = reverb silent). |
| Decay | Tail length — from a short room bloom to, at 100%, an endless freeze-like wash. |
| Damp | How fast the tail loses treble, like ever-softer walls. High values = dark, distant. |
| →LOOP | The creative switch. Normally the reverb sits outside the feedback loop (clean, predictable tails). With →LOOP on, the reverb is fed into the loop: its tail is recorded back onto the tape, re-granulated, re-reverbed — a self-regenerating wash that keeps reshaping itself. The tail also picks up Fidelity/Noise in this mode: lo-fi washes by design. |
All three knobs are modulator targets ("Rvb Amount / Decay / Damp" in the Target list). Decay 100% + FREEZE is a beautiful pairing: a frozen buffer feeding an endless plate.
6. The MOD panel — the self-playing part
Two identical, independent modulators. Each one slowly turns a knob of your choice, so patches move without you touching anything.
| Control | What it does |
|---|---|
| Target | Which knob this modulator drives ("Off" disables it). Both mods may target the same knob — their movements add. |
| Shape | Triangle (up and down — a classic LFO), Square (jumps between two values), Random (a new random level each cycle), Ramp Up / Ramp Down (sawtooth when looping; a single glide in One-Shot), Envelope (not an LFO at all — the mod follows your input loudness, so your playing dynamics turn the knob; Rate/Sync/1-Shot are ignored). |
| Depth | How far the knob is pushed, − or +. Negative pushes it down from where it sits. |
| Rate | Cycle speed, 0.05 Hz (a 20-second scene morph) to 10 Hz (warble). |
| Sync + Division | Locks the cycle to host tempo instead of Hz: 1/16 to 2 bars. |
| 1-SHOT | The shape runs once and parks at its end instead of looping. Ramp Up + One-Shot = "glide this knob to a new value and stay". |
| TRIG | The fire button (top right of the panel). Re-arms both modulators. |
| SENS | Audio-threshold retrigger: above 0, the input signal itself presses TRIG for you whenever it crosses a level threshold. Higher = more sensitive (quieter material fires it). One clean trigger per hit — built-in hysteresis and an 80 ms lockout stop a single snare from machine-gunning the ramps. Feed it drums with a One-Shot ramp and the modulation plays in time with the track. |
| SENS dip (per row) | Chooses whether this modulator listens to those audio hits (both on by default). Turn one off and drums re-fire MOD 1's ramp while MOD 2's slow LFO sails on undisturbed. TRIG, transport start and FREEZE always fire both. |
The blue ring: when a knob is being modulated, a blue arc appears around it showing exactly how far the modulation is currently pushing it from its set position. If you're ever unsure what's moving — look for blue rings.
Retriggering (what makes One-Shot musical): both modulators restart their cycle whenever —
- the host transport starts playing,
- you press TRIG (or pulse the Trigger parameter from automation or a MIDI-mapped pad — it's a normal automatable parameter),
- you engage FREEZE,
- you change a modulator's Target or Shape.
Retriggers also reset looping shapes, so a TRIG pulse on a downbeat phase-locks an LFO to your groove.
7. The stage switches — three plugins in one
- Both ON (default): the full granular tape texture.
- GRAINS off → tape echo. The grain cloud is replaced by a single clean playback head. Position becomes delay time (moving it bends pitch like dragging a real tape head), Feedback becomes repeats, and the TAPE section colours every repeat. With FREEZE on, the head loops the frozen buffer endlessly — an actual tape loop.
- TAPE off → clean granular. Pristine digital grains, feedback and mix — no colouration. Good for shimmer and for hearing exactly what the GRAINS knobs do.
Dimmed controls are inactive in the current mode; Position and FREEZE stay lit in tape-echo mode because they still work there.
8. Presets
The header bar: < > step through presets, clicking the name opens the
full menu, SAVE stores the current sound under a name you type. A *
after the name means you've tweaked since loading. User presets are plain
files you can back up or share:
~/Library/Application Support/Feline Astronauts/Scratches/Presets
("Open presets folder..." in the menu takes you there.)
The dice (🎲, next to SAVE) rolls new values for every sound-shaping knob — grains, tape colour, reverb, both modulators — while leaving your gain staging (Mix, Duck), stage switches, Freeze and all sync settings alone. The rolls are random but not senseless: Pitch lands on musical intervals, wide Jitter always brings a scale with it, the tape can only wear out so much per roll, Feedback stays below the runaway zone, and the modulators never grab Mix or fight over the same knob. Extreme settings still happen — they're just rare instead of average. Landed somewhere terrible anyway? Alt-click restores the values from before the roll. Landed somewhere great? SAVE it before rolling again.
Factory highlights and what they teach (the browser walks them in this order — after Init and the signature, they come in clusters of related sounds):
| Preset | Listen for |
|---|---|
| Screams | SENS fires two one-shots per hit (Jitter + Pitch) on tiny octave grains — every scream different |
| — worn echoes & tape wobble — | |
| Sea of Tranquility | The baseline: worn granular echo |
| Orbital Decay | Random Size wander, heavy wow, every grain sagging like a failing transport |
| Coriolis | Swirl 100% under heavy wow: the wobble circles the stereo field instead of pumping |
| Space Junk | −12 st + full Fidelity crunch |
| Generation Loss | Press TRIG: twin 20-second one-shots age the tape decades (Age + Noise), then park |
| — harmonic clouds & choirs — | |
| Stellar Nursery | +12 st grains + feedback = regenerating shimmer |
| Nine Lives | Long soft grains on minor-scale pitches — try it on speech |
| Perseids | Octave/fifth grains that all sag downward (Bend) |
| Rain on Titan | Jitter + Pentatonic scale: random but always in key |
| Minor Planet | Full Jitter locked to a minor scale built on your note — feed a D, get D minor; sweep Degree for the modes |
| Black Lodge | Degree parks your note on the 5th: the minor cloud turns Phrygian-dark, 60% reversed |
| Retrograde | Mostly-reversed grains, quintal shimmer — everything comes back the wrong way round |
| Deep Field | Color 85%: every grain at its own distance — a cloud with depth of field |
| — big washes & slow travel — | |
| Infinite Corridor | The reverb routed →LOOP: a self-regenerating wash that reshapes itself for minutes |
| Lunar Tides | A 15-second triangle on Duck: the wash advances and retreats behind your playing |
| Whales of Europa | Four huge sub-pitched rising grains per second — an instrument |
| Escape Velocity | Rising-octave grains; TRIG launches a one-shot feedback bloom |
| Terminal Velocity | Bend −100%: overlapping tape-stops |
| Time Dilation | STRETCH mode: an octave-down cloud whose words stay on time — flip the dip to hear varispeed smear |
| Doppler Shift | STRETCH + Bend −60: pitch falls while the words stay on the grid — passing sirens |
| — clocks & machines — | |
| Terry Riley | Order 100% locked to a 1-bar synced loop, minor jitter at full spread: a pulse-pattern machine (Mix 100 — it replaces the player) |
| Music for Airlocks | Clocked spawning + Major-scale jitter = a self-playing arpeggiator |
| Clockwork Dust | Order 100% as an audible mechanism, skipping every half bar |
| Ion Drive | Grain-buzz synthesis: Density is the oscillator; FREEZE and play it |
| Cut-Up Method | Synced Random on Position: a new tape splice every 8th note — clocked collage |
| We're Here | Grain buzz on the edge of runaway: clocked Density 110, huge octave grains, breathing slowly |
| — GRAINS off: tape-echo mode — | |
| Dub Satellite | Position SYNC in tape-echo mode: quarter-note repeats that follow the session tempo, ducked out of your way |
| Diane / Event Horizon | Trashed pocket dictaphone → self-oscillating runaway |
| Distress Signal | Tape echo + Duck both synced to 1/16: sustained input comes out as crunchy morse code |
| My Feline Companions | 1/16-synced lo-fi tape echo, reverb in the loop, purring under your playing |
| — TAPE off: clean digital — | |
| Hard Vacuum / Meteor Swarm | The TAPE-off clean granular mode |
| — plays along with you — | |
| Gravity Well | The Envelope shape: play harder and the grains dig deeper while the tape runs hotter |
| Startle Response | Soft = sparse purring bed; one loud hit and Density and Texture leap, then settle |
| Cloud Chamber | Duck + SENS together: the cloud parts while you play, and every hit re-fires a one-shot Size ramp |
| Airlock | Duck as a Mod target: a synced Square pumps the wet in quarter notes while you play |
| Vertigo | Dynamics spin the room: Envelope followers on Swirl and Wow — lean in and it circles |
| Solar Flares | Hits fire a bright one-shot Color flash while Mod 2 (Sens dip OFF) drifts on, untouched |
| — lo-fi & noise — | |
| Numbers Station | Random Age jumps = tuning between stations |
| Background Radiation | The whole TAPE section at once: crushed, hot, hissing transmission debris |
9. Automation and MIDI
- Every knob, switch, and dropdown is a host parameter — automate any of them in your DAW, including FREEZE, TRIG, and the stage ON switches.
- Hardware control: map a MIDI controller to any parameter using your DAW's MIDI-learn (Ableton Configure, Logic Controller Assignments, Bitwig/Reaper per-parameter mapping). A pad on TRIG and an encoder on Position is a great live setup.
- TRIG from the timeline: draw a short square pulse in the Trigger automation lane wherever you want ramps to fire or LFOs to re-lock.
10. Recipes
Instant ambient wash — Size 800ms, Density 25, Texture 20%, Spread 60%, Pitch +12, Scale Octaves, Feedback 70%, Mix 60%, a little Age. Play one chord.
Rhythmic grain sequencer — Order 100%, Sync a Square mod (1/8) onto Mix, Density ~16, Size 80ms, Texture 90%. The cloud becomes a groove.
Frozen scrub performance — 100% Mix, moderate Density, FREEZE on, then perform Position by hand or map it to an encoder. Add Jitter + Minor scale for melodic content from nothing.
Self-degrading loop — GRAINS off, Position ~25% (1.25 s), Feedback 104%, Drive 40%, Age 35%. Play a short phrase, stop playing, listen to it bloom and decay for minutes. Tame it by easing Feedback below 95%.
Dive bombs on demand — Mod 1: Target Pitch, Ramp Down, One-Shot, Depth +100%, Rate 0.2 Hz. Every TRIG press dives the whole cloud an octave over five seconds.
Grain buzz synthesis — Order 100%, Density 100+, Size 30–60ms, FREEZE on. Density is now an oscillator pitch; sweep it. Weird and wonderful.
Can't-fail solo texture — Jitter 24, Scale Pentatonic, Density 8, Order 60%. Whatever you play in, something pretty comes out.
Dub delay that follows the song — GRAINS off, SYNC on, division 1/4., Feedback 70%, Duck 50%, Age 60%. Dotted-quarter repeats locked to the session tempo that duck under your playing — change the DAW tempo and the delay follows.
Drum-triggered swells — Feed Scratches a drum bus. SENS ~60%, Mod 1: Target Mix, Ramp Down, One-Shot, Depth −60%, Rate ~1 Hz. Every kick ducks the wet and lets it swell back before the next hit — pumping without a compressor.
Touch-sensitive tape — Mod 1: Target Drive, Shape Envelope, Depth +50%. Mod 2: Target Age, Shape Envelope, Depth +30%. The harder you play, the hotter and more worn the tape — back off and it cleans up. An amp that listens.
One mod for the drums, one for the weather — SENS ~50%; MOD 1 (SENS dip on): One-Shot Ramp Down on Size, so every hit tightens the grains. MOD 2 (SENS dip off): a 20-second Triangle on Position that nothing interrupts. Rhythm and climate, independent.
11. Troubleshooting
- It won't stop making sound — Feedback is at/above 100% (that's the runaway zone doing its job). Pull Feedback down or flip GRAINS/TAPE off and on to flush the loop.
- Output seems quiet at high Drive — intentional loudness compensation; push Mix or your channel fader.
- Everything sounds dim/dark after long feedback — also intentional: repeats lose treble like real tape. Lower Age or Feedback for brighter tails.
- Logic doesn't show the plugin after an update — macOS caches Audio
Units: run
killall -9 AudioComponentRegistrar, reopen Logic, or revalidate withauval -v aufx Scrt Feln. - CPU — cost scales with Density × Size (simultaneous grains). The worst-case settings run a 128-grain cloud, which is still light on any modern machine; if needed, shorten Size before lowering Density.
- SYNC is on but the repeats aren't on the grid — the host has to report a tempo; standalone use falls back to 120 BPM. Also remember the modulators can still push Position while synced — check the Mod targets.
- SENS never fires — it listens to the input level. Raise SENS (more sensitive), and check your input gain: very quiet sources may need SENS above 80%.
