A major · Tritone substitution
Tritone substitutions in A major
Every dominant in A major, and its substitute
- E7V7AsubV7A
B♭7 substitutes for E7, the dominant of A major. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: G♯ and D in E7, A♭ and D in B♭7.
- V7/iiBmC7subV7/iiBm
C7 substitutes for F♯7, the dominant of B minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: A♯ and E in F♯7, B♭ and E in C7.
- V7/iiiD7subV7/iii
D7 substitutes for G♯7, the dominant of C♯ minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: B♯ and F♯ in G♯7, C and F♯ in D7.
- A7V7/IVDsubV7/IVD
D♯7 substitutes for A7, the dominant of D major. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: C♯ and G in A7, C♯ and F♯♯ in D♯7.
- B7V7/VEF7subV7/VE
F7 substitutes for B7, the dominant of E major. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: D♯ and A in B7, E♭ and A in F7.
- V7/viG7subV7/vi
G7 substitutes for C♯7, the dominant of F♯ minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: E♯ and B in C♯7, F and B in G7.
Why the substitute works
What makes a dominant seventh want to resolve is the tritone between its third and its seventh. Move the root a tritone and that interval is still there, with its two notes swapped: the third becomes the seventh and the seventh becomes the third. So the substitute pulls to the same place, and the bass slides down a semitone to get there.
Play the two buttons in each row one after the other. Same arrival, different road.