> ## Documentation Index
> Fetch the complete documentation index at: https://comfytv.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Audio Modulation
> Classic time-modulation effects — phaser, flanger, chorus, vibrato, tremolo, and pulsator — in one node.
## What this node does
**Audio Modulation** applies one of six LFO-driven modulation effects to a track, using the matching FFmpeg filters (`aphaser`, `flanger`, `chorus`, `vibrato`, `tremolo`, `apulsator`). You pick a **mode** and adjust only the parameters that belong to that mode; the rest are ignored.
It takes a `COMFYTV_AUDIO` snapshot (or a `COMFYTV_VIDEO`, whose audio track is used) and outputs processed `COMFYTV_AUDIO` plus an `fx_spec`. It has a ▶ **Run** (FFmpeg does the work). If no source is wired, it emits just the `fx_spec` for chaining.
To feed native ComfyUI `AUDIO` in or out, insert a **Bridge** — see [bridges.md](https://github.com/jtydhr88/ComfyTV/blob/main/docs/bridges.md).
## When to use it
* Add movement and width to a synth or guitar with chorus or flanger.
* Sweep a psychedelic phaser across a pad or drum loop.
* Add pitch wobble (vibrato) or volume pulsing (tremolo/pulsator) for rhythmic texture.
## Parameters
### mode
Which effect to apply. Options: `phaser` (default), `flanger`, `chorus`, `vibrato`, `tremolo`, `pulsator`. The parameter groups below apply per mode.
### Phaser (`ph_*`)
* **ph\_delay** — sweep delay, **0.0–5.0** (default **3.0**).
* **ph\_decay** — feedback decay, **0.0–0.99** (default **0.4**).
* **ph\_speed** — LFO speed in Hz, **0.1–2.0** (default **0.5**).
* **ph\_type** — LFO shape, `triangular` (default) or `sinusoidal`.
### Flanger (`fl_*`)
* **fl\_delay** — base delay in ms, **0.0–30.0** (default **0.0**).
* **fl\_depth** — sweep depth in ms, **0.0–10.0** (default **2.0**).
* **fl\_regen** — regeneration/feedback %, **-95 to 95** (default **0**).
* **fl\_width** — modulated delay width %, **0–100** (default **71**).
* **fl\_speed** — LFO speed in Hz, **0.1–10.0** (default **0.5**).
* **fl\_shape** — LFO shape, `sinusoidal` (default) or `triangular`.
* **fl\_phase** — L/R phase offset %, **0–100** (default **25**).
### Chorus (`chorus_preset`)
A built-in voicing preset: `single` (default), `double`, or `triple` — one, two, or three delayed voices.
### Vibrato / Tremolo (`lfo_*`)
Shared by both modes:
* **lfo\_f** — modulation frequency in Hz, **0.1–20000** (default **5.0**).
* **lfo\_d** — modulation depth, **0.0–1.0** (default **0.5**). Vibrato modulates pitch; tremolo modulates volume.
### Pulsator (`pu_*`)
* **pu\_hz** — pulse rate in Hz, **0.01–100** (default **2.0**).
* **pu\_amount** — effect amount, **0.0–1.0** (default **1.0**).
* **pu\_width** — pulse width, **0.0–2.0** (default **1.0**).
* **pu\_mode** — LFO waveform: `sine` (default), `triangle`, `square`, `sawup`, `sawdown`.
## Outputs
| Output | Type | Meaning |
| ------------ | ---------------- | --------------------------------------------------- |
| **audio** | `COMFYTV_AUDIO` | The modulated audio snapshot |
| **fx\_spec** | `COMFYTV_FXSPEC` | The effect as a spec, for chaining into an FX Chain |
## Tips
* Only the parameters for the selected **mode** matter — the rest are harmless but inert.
* Phaser fixes its gains internally (`in_gain=0.4`, `out_gain=0.74`); you control it via delay/decay/speed.
* For a subtle widening effect, chorus `single` is the gentlest; `triple` is the lushest.
## Related nodes
* **Audio Echo** — discrete delay/echo, a different way to add space.
* **Audio Stereo** — widen or narrow the stereo field.
* **FX Chain** — renders multiple `fx_spec` steps (including this one) in a single pass.