CadenzaA seventh, sharp nine, flat thirteen
A7(♯9♭13)
Also written A7alt (often) · A7#9b13
B♯ is the key you know as C.
The altered sound in its most common form: ♯9 (B♯) and ♭13 (F) over the 3rd and ♭7. Charts often write it simply as A7alt. V of D minor.
How pianists voice A7(♯9♭13)
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
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
3 · ♭13 · ♭7 · ♯9 — no root: the bass player has it. The left-hand voicing of modern jazz piano. Without A underneath, the same keys read as D♭maj7(♯11) — the bass turns them into A7(♯9♭13).
Rootless B From the 7th
♭7 · ♯9 · 3 · ♭13 — the other half of the pair. A and B alternate through a ii–V–I so the hand barely moves.
Drop 2 Two hands
♭13 · 1 · 3 · ♭7 — close position with the second voice from the top dropped an octave: wider, warmer, the standard for chord melody.
Upper structure ♭VI Triad over shell
1 · 3 · ♭7 · 1 · ♯9 · ♭13 — an F major triad in the right hand (♭13, root and ♯9) over the root, 3rd and ♭7 in the left. One familiar shape, all the tension.
Seventh, sharp nine, flat thirteen chords in every key
Every A chord
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