A♭ seventh, sharp nine

A♭7(♯9)

Also written G♯7(♯9) · A♭7+9 · Ab7#9

NotesA♭ · C · E♭ · G♭ · B
Formula1 · 3 · 5 · ♭7 · ♯9
C3B♯9A♭1E♭5G♭♭7
All its notes, from the root

Major 3rd and minor 3rd at once: the ♯9 (B) is the minor 3rd written as a tension. The “Hendrix chord”, the blues' favourite dominant, and in jazz a V of C♯ minor.

How pianists voice A♭7(♯9)

Nobody plays a jazz chord in root position. These are the shapes that actually get played — the same ones Cadenza shows when you play the chord.

Shell Left hand

C3A♭1G♭♭7

1 · 3 · ♭7 — root, 3rd and 7th: the three notes that say what the chord is. Left hand, low; everything else is colour.

Rootless A From the 3rd

C3B♯9E♭5G♭♭7

3 · 5 · ♭7 · ♯9 — no root: the bass player has it. The left-hand voicing of modern jazz piano.

Rootless B From the 7th

B♯9C3G♭♭7E♭5

♭7 · ♯9 · 3 · 5 — the other half of the pair. A and B alternate through a ii–V–I so the hand barely moves.

Drop 2 Two hands

C3E♭5A♭1G♭♭7

5 · 1 · 3 · ♭7 — close position with the second voice from the top dropped an octave: wider, warmer, the standard for chord melody.

Hendrix voicing Guitar shape

C3B♯9A♭1G♭♭7

1 · 3 · ♭7 · ♯9 — root low, then 3rd, ♭7 and the ♯9 on top, so major and minor 3rd ring together. Jimi Hendrix made it famous on E.

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