Ninths
A♯ dominant 7th sharp 9 chord
The “Hendrix chord” — gritty, with major and minor 3rds clashing.
- Notes
- A♯C𝄪E♯G♯B𝄪
- Formula
- 135♭7♯9
- Built from
- root · major 3rd · perfect 5th · minor 7th · augmented 9th
How to play A♯7♯9
About the A♯ dominant 7th sharp 9 chord
Playing it
On guitar, A♯7♯9 has an open-position shape, x1012x, using three fingers alongside the open strings. Don’t strum the low E and high E strings.
On piano, A♯7♯9 has three black keys (A♯, G♯ and B𝄪) and two white keys. In root position it spans more than an octave, so many pianists play the root with the left hand and the rest with the right.
On ukulele the usual A♯7♯9 shape is 3244, using four fingers.
Related chords
Move a single note and A♯7♯9 becomes a different chord: drop the B𝄪 for A♯7, drop the C𝄪 for A♯m7, lower B𝄪 to B♯ for A♯9 and swap C𝄪 for B♯ for A♯m9.
Where you’ll hear it
Notice the C𝄪 in A♯7♯9 (A♯ C𝄪 E♯ G♯ B𝄪): each note of the chord takes its own letter (A–C–E–G–B), so the major 3rd has to be written C𝄪 rather than D — the same key on a piano, spelled to fit the chord.
