undark

in the key of anything

20 HP

Plug a guitar, a record or the rack's own mix into IN, and every voice you send through it plays in that key and follows the chords as they change. A dial of twelve marks shows what it hears: the key, and the chord sounding now.

The UNDARK panel: a face over a dark dial, in gold dots on black. Twelve marks of bare circuit board ring FADE, the big knob, a note name inside each and C at the top; SURE and SHIFT stand either side of the dial, IN and HOLD's jack above it, CHANGE and STEP below it and the HOLD button at the foot; LOST 1 to 4 and FOUND 1 to 4 run down the sides. undark at the top, daylight noise at the bottom.

Turn a knob: drag it, roll the wheel over it or use the arrow keys; a double click puts it back. HOLD is a button: press it to keep the key and the chord, and again to let go. The patches step on by themselves until you touch anything.

What you hear is a stand-in record playing into IN, and the rack playing what comes out of FOUND. It's all made in the page as you listen.

example patches

The listening, the key and the chord, the lanes and every out here are UNDARK's engine as it's designed, running in your browser. The record and the voices are a stand-in for the rest of a rack.

Listening

Plug in anything that plays notes: a guitar, a synth, a record, the radio, the rack's own mix. It hears chords and whole mixes, not just one note, and keeps two things from what it hears: the song's key, and the chord sounding now.

IN: audio, ±5 V. Nearly fifty times a second it reads which of the twelve notes are sounding, and how strongly. A pause changes nothing.

The dial, FADE and SURE

Twelve marks round FADE, a note each, C at twelve o'clock. Each is lit as strongly as its note is in the key, and the chord sounding now is bright. When a lane plays a note, its mark flicks brighter, so you can see the melody walk the key.

FADE: how quickly it changes its mind. Fully left it keeps half a second and follows every chord, the lanes jumping with each change. Noon holds the song's key for a minute and a half and lets passing notes go by. Fully right it never lets go.
SURE: what the lanes may play. Fully left, every note it has heard; then the song's key; then only the chord sounding now; at full, the root alone.
SHIFT: moves every lane up or down the notes SURE allows, up to seven steps. In the key that's harmony a third or a sixth away; on the chord, an inversion; on the root, an octave.

The lanes

Four lanes, each a LOST in and a FOUND out. Whatever comes into LOST, a sequencer, a random voltage or an LFO, comes out of FOUND on the nearest note SURE allows. It moves only when another note is clearly nearer, so a voltage between two notes doesn't chatter.

LOST 1–4: CVs in, 1 V an octave.
FOUND 1–4: the same, in tune, on exact semitones.
An empty lane: with nothing in its LOST, FOUND plays the chord sounding now. FOUND 1 the root, 2 the third, 3 the fifth, 4 the seventh, or the root an octave up when there's none. Three oscillators on them make a pad that follows the record.

CHANGE, STEP and HOLD

CHANGE: a trigger each time the chord changes, and never while it holds. Restart a sequence, fire envelopes or cue a fill with the harmony.
STEP: a trigger each time FOUND 1 moves to a new note. An LFO into LOST 1 and STEP into an envelope make a melody, in key, from a wobble.
HOLD: the button, or a gate at its jack. Held, it stops listening and keeps the key and the chord, so the lanes play on in them after the music stops. The button is lit while it holds.

Specs

Format

Width: 20 HP
Controls: 3 knobs (FADE's big), a lit button

Inputs

IN: audio, ±5 V: one note, chords or a whole mix
CVs: LOST 1, LOST 2, LOST 3, LOST 4: 1 V an octave, ±5 V
HOLD: gate, holds while over 1 V

Outputs

CVs: FOUND 1, FOUND 2, FOUND 3, FOUND 4: 1 V an octave, exact semitones, ±5 V
CHANGE: trigger, 5 V for 10 ms
STEP: trigger, 5 V for 10 ms