CadenzaB♭ seventh, flat thirteen
B♭7(♭13)
Also written A♯7(♭13) · B♭7(♭6) · Bb7b13
A dominant with a natural 5th and a ♭13 (G♭) above it — mixolydian ♭6, the V of E♭ minor. Drop the 5th and the same shape becomes B♭7(♯5).
How pianists voice B♭7(♭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.
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.
Seventh, flat thirteen chords in every key
Every B♭ chord
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