A Tritone Substitution
ii – bII7 – I progression in A major
A Tritone Substitution — ii – bII7 – I
The A ii–bII7–I tritone substitution (Bm – A# – A) replaces the dominant V with a chord a tritone away, creating a chromatic, mysterious color. With seventh voicings (Bm7 – A#7 – AMaj7), it delivers one of the most sophisticated sounds in jazz harmony.