Harmony
Tritone Substitution: The subV7 Chord That Still Resolves
Replace any dominant with the dominant a tritone away: why subV7 works, how it smooths bass lines, and where jazz standards hide it.
Tritone substitution
Replacing a dominant chord with the dominant a tritone away, whose notes share the same tritone and resolve the same way.
Also called: tritone sub, tritone substitute, flat-five substitution
A tritone substitution replaces a dominant seventh chord with another dominant seventh chord whose root lies a tritone away. G7 contains B and F, which form the tritone. D♭7 contains F and C♭, which is B, so it holds the same two notes. Both chords resolve by half step to the tonic. In a ii V I in C, a G7 can therefore become D♭7 leading to C. The bass moves down by a half step, from D♭ to C, instead of up by a fifth, which gives a smoother bass line. The two chords share the tritone that gives a dominant its pull. The substitution is common in jazz, where the upper voices keep the same tension while the bass moves differently.
Related terms
- Guide tonesThe third and seventh of a chord, the notes that define its quality and move most smoothly from one chord to the next.
- ReharmonizationReplacing the original chords under an existing melody with different ones, while the tune itself stays the same.
- Chord-scale theoryA method that pairs each chord symbol with a scale whose notes fit that chord, for improvising over a set of changes.