F♯ major · Tritone substitution
Tritone substitutions in F sharp major
Every dominant in F♯ major, and its substitute
- V7G7subV7
G7 substitutes for C♯7, the dominant of F♯ major. 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.
- V7/iiA7subV7/ii
A7 substitutes for D♯7, the dominant of G♯ minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: F♯♯ and C♯ in D♯7, G and C♯ in A7.
- V7/iiiB7subV7/iii
B7 substitutes for E♯7, the dominant of A♯ minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: G♯♯ and D♯ in E♯7, A and D♯ in B7.
- V7/IVBsubV7/IVB
B♯7 substitutes for F♯7, the dominant of B major. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: A♯ and E in F♯7, A♯ and D♯♯ in B♯7.
- V7/VD7subV7/V
D7 substitutes for G♯7, the dominant of C♯ major. 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.
- V7/viE7subV7/vi
E7 substitutes for A♯7, the dominant of D♯ minor. They share the same tritone, so the bass can fall a semitone instead of a fifth. Shared notes: C♯♯ and G♯ in A♯7, D and G♯ in E7.
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.