Piano: A m7b9 in the Changes

A m7b9 is A – Bb – C – E – G. Naming the notes is where a chord chart stops. A tune asks the next question instead, and that is the one this page answers.

Nine times in ten a chart puts A m7b9 in the supertonic's place, and the submediant after that — so before working out a voicing, work out which key makes it that, because the key decides which notes the rest of the group has already taken.

The piano seat carries the whole harmony at once — a shell in the left hand, the colour tones and any substitution in the right, which is why this is the seat a substitution is usually heard from first. It is the only seat here that can state a chord and its substitute in the same beat, left hand holding one and right hand implying the other.

The diagrams are drawn across all 88 keys from A0 to C8, with the notes that sound lit and the ones a voicing drops shown dashed, so what you are looking at is a decision rather than a picture of every note in the chord.