bass-foundry/docs/lathe/README.md

# Lathe

Lathe is an EQ whose bands sit on the harmonics of the note being played.
Current version **0.2.0**.

A normal EQ works in fixed frequencies. A cut at 130 Hz takes out the 3rd
harmonic of an F1 bass, the 2nd of a C2, and the fundamental of a C3, so the
same bass sounds different on every note of a riddim line. Lathe follows the
pitch and places one band on each harmonic: "−12 dB on harmonic 3" stays on
harmonic 3 whatever note plays.

![Lathe](assets/editor.png)

## Install on Windows

Copy `Lathe.clap` into `C:\Program Files\Common Files\CLAP\`. In FL Studio 2024.1
or newer, open Options → Manage plugins, enable Verify plugins, and Find installed
plugins. Load Lathe in a mixer slot of the bass, after the synth and before bus
processing. Keep the font license with redistributed packages.

## Work with it

1. Play the bass. The note readout shows what Lathe tracks; the lower strip of the
   editor shows each harmonic's level going in (grey) and coming out (pink).
2. Draw gains on the harmonic bars. Drag across bars to paint a shape;
   Shift-drag for fine steps; double-click a bar to reset it.
3. Use the macros for the whole series:
   - **Tilt** brightens or darkens in dB per octave of harmonic number. The
     fundamental is the pivot.
   - **Odd/Even** lifts odd harmonics and lowers even ones (positive, more
     square-like) or the reverse (negative, more octave-like).
   - **Between** sets the gain halfway between harmonics. Cut it to clean up noise,
     beating and inharmonic grit; lift it for dirt.
4. **Width** sets every band's bandwidth as a share of the harmonic spacing. Narrow
   bands touch only the harmonic; wide bands also move its surroundings.

Other controls:

- **Harmonics** is how many harmonics are shaped (8–32). Higher harmonics pass
  unchanged.
- **Smooth** is the retune time for slides and pitch bends. A new note always
  retunes at once, on its attack.
- **Gate** is the input level that counts as a note. Raise it if tails or reverb
  start new notes.
- **Mix** blends with the delayed dry signal; **Output** trims the level.
- **Snap to semitone** rounds the detected pitch. Turn it off for slides.
- **Shapes** set the drawn gains: Flat, Odd only, Even only, or Hollow (harmonics
  2–4 cut).

The drawn gains are saved with the project but are not automation parameters;
the macros are.

### Pitch from MIDI

For basses whose fundamental is unclear (heavy FM, formant or noise patches),
select **MIDI** and route the bass's MIDI notes to Lathe. In FL Studio, set the
bass channel's MIDI output port and Lathe's input port to the same number.

## Timing and limits

Detection uses about 67 ms of lookahead, reported to the host for delay
compensation, so the bands are tuned before each note's attack leaves the
plugin. Pitch range is 30–500 Hz, one note at a time; chords are not separated.
Before the first note Lathe passes audio unchanged; between notes it holds the
last tuning so tails keep their shape. Bands above 0.45 × the sample rate are
skipped.