scordatura

scordatura detunes the pitch classes you name by a fixed number of cents, in every octave.

This effect needs an MPE-style setup on the receiving instrument; see Microtonality before wiring it in.

This is a prepared tuning, the keyboard cousin of a scordatura string or a bolt dropped on a piano string: a fixed map from pitch class to detune, applied wherever that class appears. Each argument is a "note=cents" pair, the note a name like "c#" or a pitch class "0".."11", the cents an integer within -100..=100 with an optional sign, so "c#=-30" pulls every C sharp 30 cents flat and "f=+20" pushes every F 20 cents sharp. A pitch class may be listed at most once, and the classes you do not list stay at zero.

Detuned classes are re-emitted through the MPE voice pool at their own key with the mapped cents as a per-note pitch bend. Zero-cents classes pass through completely untouched, on their original channel, with no pool voice spent on them, so a map that only bends two classes leaves the other ten exactly as your keyboard sent them. The map is deterministic, no seed.

Each note-off follows whichever path its note-on took, dry or tuned, so releases stay exact even though the two paths live on different channels; a retrigger cuts first, and a switch="kill" scene change or shutdown releases everything and resets the bends (a let-ring switch lets the outgoing notes drain on their own).

Parameters

Parameter	Type	Default	Range
"note=cents" pairs	arguments	at least one required	cents -100..=100, each pitch class at most once
channels	channel span	"2-16"	"1".."16", low end first
bend-range	semitones	48	1..=96

channels and bend-range are the MPE tail shared by all four microtonal effects.

Example

miditool.kdl

input "Roland"
output virtual="miditool Out"

scordatura "c#=-30" "f=+20" channels="2-16" bend-range=48

Most of the keyboard is a normal keyboard. C sharp and F are somewhere else, the same somewhere else in every octave, and lines that pass through them pick up a permanent, placeable wrongness.

Try this

Turn the black keys into quarter tones:

scordatura "c#=-50" "d#=-50" "f#=-50" "g#=-50" "a#=-50"

Every black key now sits exactly halfway between its white neighbors, so the keyboard plays a slice of 24-tone equal temperament: chromatic runs become quarter-tone runs. For a tuning derived from ratios instead of a hand-built map, see just.