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F_GRAINZ — Granular Sampler / Live Corpus Synth

F_GRAINZ is a granular processing module for Voltage Modular. It can spawn up to 8 overlapping grains from either:

a loaded mono sample (WAV/AIFF),
a continuously recording stereo live buffer,
or in Synth mode with Gate and 1V/Oct pitch control.

A waveform canvas displays the source signal and active grains as colored overlays. The module supports per-grain outputs, flexible modulation, NEXT scanning, and assignable MOD inputs.

Quick Reference (I/O)

Jack	Type	Description
PITCH	CV in	1 V/Oct pitch input (Synth mode).
GATE	Gate in	≥1 V = ON. Triggers grains in Synth mode; also clocks density if set > 0.
TRIG	Gate/Trig in	Rising edge spawns a grain (Sample/Live modes). If Density>0, adds continuous spawns.
NEXT	Gate/Trig in	Each pulse advances the scan position by a fixed percent (configurable as NXT_STEP_PCT).
IN L / IN R	Audio in	Stereo live buffer + dry passthrough. R mirrors L if unpatched.
OUT L / OUT R	Audio out	Main stereo output (post-envelope, post-pan, post-filter, post-OutGain, wet/dry mix).
Grain 1..8	Audio out	Per-grain mono outputs (pre-pan, envelope applied).
MOD1–6	CV in	Assignable modulation inputs via the MOD dropdowns (Position, Size, Density, Pitch, Pan, Spray, Filter).
VEL	CV in	Velocity input (amplitude scaling). 0..5 V → 0..1 gain per grain.

Quick Reference (Controls)

Control	Range	Description
Load	-	Open WAV/AIFF file (auto-resampled to 48 kHz mono).
SRC	0/1/2	Source: 0=Sample, 1=Live, 2=Synth.
REC	On/Off	Record into live buffer. Toggle OFF = freeze (keeps the captured audio).
REV	On/Off	Reverse playback direction for new grains.
STRETCH	Off/On	On: Continuous time-stretch using Hann + 50% overlap + SOLA micro-alignment (more “legato”). Off: Cloud mode (free-running granular).
Shape	0–11	Grain envelope shape (Hann, Triangle, Exponential, Gaussian, Rectangular, Noise, Blackman, Blackman-Harris, Cosine, Parabolic, FastAtkSlowDec, SlowAtkFastDec).
Size	5–8000 ms	Grain length (also sets the crossfade window in STRETCH).
Density	0–32 gps	Grains per second (0 = trig only). In STRETCH this acts like the hop rate; with 50% overlap it naturally creates a continuous stream.
Position	0–100%	Grain start offset in source.
Spray	0–100%	Random start offset around Position. Disabled when STRETCH is active to keep grains phase-aligned.
Semitones	-48..+48	Pitch transpose.
Fine	-200..+200	Fine tuning in cents.
±Rand	0–1200c	Random pitch modulation per grain.
Pan	-1..+1	Base stereo pan (equal-power law).
Spread	0–1	Per-grain random pan spread.
SampleDry	0–100%	Clean sample playback mix (only when SRC=Sample).
Mix	0–100%	Global wet/dry balance.
Gain	0–5×	Sample attenuverter for corpus audio (unity=1).
Filter	-1..+1	Neutral at center (0). Below 0 = Low-Pass; above 0 = High-Pass; magnitude increases slope/amount.
OutGain	0–10×	Final output gain (post-filter).
Poly	1–16	Synth polyphony (max grains concurrently).

MOD1–6 Assignable Inputs

Three dropdowns below the MOD1–6 jacks select the destination for each MOD input. 0=Off; 1..7 select a parameter. The same destination can be chosen on multiple MOD inputs (they sum).

Index	Label	Destination	Scaling
0	Off	—	—
1	Pos	Position (%)	1 V ≈ +20%
2	Size	Grain Size (ms)	1 V ≈ +200 ms
3	Density	Grains/sec	1 V ≈ +20 gps (clamped)
4	Pitch	Pitch (cents)	1 V = +1200 cents
5	Pan	Stereo pan	1 V ≈ +0.2 (–1..+1 clamp)
6	Spray	Spray (%)	1 V ≈ +20%
7	Filter	Filter tilt	1 V ≈ +0.2 (–1..+1 clamp)

Practical: use MOD1→Pos for scanning, MOD2→Spray for texture, MOD3→Filter to animate tone. For big gestures, attenuate externally or scale at the source.

Envelopes

Each grain uses one of 12 shapes via Shape knob. In STRETCH mode, a 50% Hann overlap-add is used for smooth, continuous blending; micro-alignment (SOLA) nudges each grain’s start by a few ms for phase-coherent transitions.

Operation

Sample mode: Load a file, set Position/Spray/Size, trigger with TRIG or set Density > 0 for continuous spawn.
Live mode: Toggle REC to capture IN L/R into the ring buffer; toggle OFF to freeze. Granulate the frozen audio.
Synth mode: Use GATE + PITCH (1 V/Oct). Density can add extra grains while gate is high.
NEXT: Advance scan position each pulse (step size defined by NXT_STEP_PCT).
STRETCH: When ON, grains are overlapped (≈50%) and locally phase-aligned (SOLA) for a more continuous, “legato” sound. For the smoothest results: larger Size, moderate Density, low Spray.
Filter: Center is off. Turn left for LP (darker), right for HP (thinner). Acts post-mix and pre-OutGain.
OutGain: Boost the final level to match or overdrive downstream processors if desired (watch headroom).

Saving the Live Buffer

When REC is ON, audio is continuously captured into the 20-second stereo live buffer.
When you toggle REC OFF, the buffer is frozen and can be granulated like a static sample.
Press SAVE to export the frozen live buffer as a WAV file (stereo, 48 kHz, 16-bit).
The exported file is stored in your Voltage Modular Documents path. Use LOAD to re-import it later as a normal sample.
Tip: This lets you “promote” spontaneous live recordings into reusable material for later patches.

Tips

Use small Sizes and high Density for clouds; large Sizes and low Density for drifting textures.
Spray + Spread creates width and movement; moderate values often sound more natural.
Freeze the live buffer at transient-rich moments for micro-loop percussion.
Use per-grain outputs to process grains with different FX (e.g., different delays).
Velocity input is per-grain: shape dynamics from your controller or sequencer.
Combine NEXT with slow X (Position) modulation for evolving scans through long samples.
STRETCH mode: Engage this for smooth, pad-like layers and drones — grains overlap seamlessly, producing a more “continuous” sound.

Technical Notes

Audio engine: 48 kHz internal; external files are resampled to 48 kHz mono.
Live buffer: ~20 s stereo ring buffer (length may vary in builds).
Pitching: Semi/Fine + optional 1 V/Oct in Synth mode; random cents per grain (±Rand).
Stretch engine: Hann window, ≈50% overlap, Continuous Overlap-Add with light SOLA micro-alignment (±~10 ms search).
Polyphony: Up to 8 concurrent grains; in Synth mode you can constrain spawns to Poly voice count.
Filter: Bipolar tilt (LP/HP) post-sum; neutral at 0; range clamped to –1..+1.
Safety: Parameters are internally clamped to sane ranges to prevent clicks/overflows.

Performance and Crackle Reduction

If you hear crackles at high grain densities, reduce Density or shorten Size. Both directly affect CPU load.
In STRETCH, the SOLA step adds a small CPU cost per grain. If needed, use lower Density or smaller Size for smoother playback.
Lower Poly if you don’t need all overlapping voices.
Freeze the live buffer (REC=OFF) when processing a captured snippet to avoid constant writes.
Spread and Spray can create richness without pushing Density to extremes.

Build 22

Preset Compatibility

Preset saving/loading has been extended to store MOD4, MOD5, and MOD6 assignments.
Old presets remain compatible (they just won’t use the extra MOD slots).

Tip: Older presets will load without MOD4–6 assignments, but will otherwise sound identical.

Musical Envelope Length Handling

Grains now run to full envelope completion instead of being cut off early.
This ensures smoother, more musical grain fades and avoids abrupt dropouts.

Envelopes: Each grain always completes its envelope curve, even if playback bounds are reached, resulting in smoother and more natural fades.

Stretch Mode

A new STRETCH switch forces grains to overlap in a continuous way, creating a seamless sustained sound.
In this mode, grains use a Hann window with 50% overlap (classic COLA technique), avoiding gaps or phasey dropouts.
Spray is disabled to keep pitch and timbre stable, so the sound feels more like a “time-stretched” layer than a granular cloud.

Musical Use: STRETCH mode is ideal for pads, drones, and continuous textures where you want a steady, evolving tone without the jittery artifacts of granular clouds. Switch back to cloud mode for more scattered, pointillistic textures.