Tritone substitution
Replace V7 with the chord a tritone away — same tension, chromatic bass line.
In 1959, Coltrane began composing Giant Steps. He showed his scores to his musicians during the recording session. Tommy Flanagan, a seasoned session pianist, had never seen it bef…
À retenir : Tritone substitution is discovering that a chord can resolve to two different tonics by sharing the same tritone. It is not magic — it is symmetry.
The principle of tritone substitution
In C major, G7 is the natural dominant — it resolves to C by a descending fifth. Tritone substitution replaces G7 with D♭7, located exactly a tritone lower (6 semitones). D♭7 resolves to C just as well, but the bass descends by a semitone (D♭→C) instead of a fifth leap.
Compare the two resolutions
Why it works — the shared tritone
G7 and D♭7 share exactly the same two guide tones (3rd and 7th), but their roles are reversed. It is this common tritone that allows both to resolve to C.
The 6 pairs of tritone substitutions
| Original V7 | Tritone sub | Shared tritone | Bass movement |
|---|---|---|---|
| G7 | D♭7 | B / F | D♭ → C (↓ ½ ton) |
| D7 | A♭7 | F# / C | A♭ → G (↓ ½ ton) |
| A7 | E♭7 | C# / G | E♭ → D (↓ ½ ton) |
| E7 | B♭7 | G# / D | B♭ → A (↓ ½ ton) |
| B7 | F7 | D# / A | F → E (↓ ½ ton) |
| F♯7 | C7 | A# / E | C → B (↓ ½ ton) |