What it is
Changing the chords under a given melody while keeping its identity. It is the technique that turns a cover into a new version.
Techniques, from lightest to most radical
- Functional substitution: C → Am or Em (tonic), F → Dm (subdominant), G → B° (dominant).
- Adding secondary dominants before the targets: C – A7 – Dm – G7.
- Inserting ii–V: instead of C – F, C – Gm7 C7 – F.
- Tritone substitution: G7 → Db7.
- Modal interchange: F → Fm, Am → Ab.
- Chromatic approach: a chord a semitone above or below the target (Db7 → C, B7 → C).
- Pedal or different bass: same chord with another bass (C/E, C/Bb).
- Melody as a different tension: a melody note can be root, third, fifth, seventh, ninth or eleventh depending on the chord.
Example on the note E (static melody)
- C (E = third), Am (E = fifth), Fmaj7 (E = major seventh), Dm9 (E = ninth), Bb13#11 (E = #11), F#m7b5 (E = seventh), A7sus4 with E as the fifth…
Each choice changes the color of the same note.
Method
- Identify the long notes and the cadence points of the melody: they are the targets.
- Keep the main cadences recognizable, experiment in between.
- Check that no melody note forms a b9 with a chord tone (e.g. melody F over E7 sounds bad).
- Take care of the bass line: a good reharmonization often has a chromatic or stepwise bass.
Real example
Jacob Collier's version of “Moon River” (2019), with hundreds of overdubbed voices, reharmonizes almost every note of Mancini's melody with chromatic substitutions and continuous modulations: a living catalog of techniques.