Sevenths
A♯ half-diminished 7th chord
Dark and unresolved; often the ii chord in a minor key.
A♯m7♭5 is the viiø7 chord in B major. In minor keys: iiø7 in G♯ minor.
- Notes
- A♯C♯EG♯
- Formula
- 1♭3♭5♭7
- Built from
- root · minor 3rd · diminished 5th · minor 7th
How to play A♯m7♭5
About the A♯ half-diminished 7th chord
Playing it
On guitar, A♯m7♭5 has an open-position shape, x12120, using four fingers alongside the open strings. Don’t strum the low E string.
On piano, A♯m7♭5 has three black keys (A♯, C♯ and G♯) and one white key.
On ukulele the usual A♯m7♭5 shape is 3444, using four fingers.
Related chords
Take away the root and the other three notes form C♯m (C♯ E G♯) — so you can think of A♯m7♭5 as C♯m with A♯ added underneath.
A♯m7♭5 contains exactly the same notes as C♯m6. Which name fits depends on which note is in the bass and what key you’re in.
Move a single note and A♯m7♭5 becomes a different chord: raise E to E♯ for A♯m7, drop the G♯ for A♯dim and lower G♯ to G for A♯dim7.
