A#m7b5 (Bbm7b5) Guitar Chord
A#m7b5 (A# half-diminished seventh) is a four-note chord made from A#, C#, E and G#. A half-diminished chord is a diminished triad with a minor seventh on top. It is the ii chord of a minor key, so it opens the minor ii-V-i that jazz leans on.
A#m7b5 A# half-diminished seventh
Open position1 / 4
Notes
- A#1
- C#b3
- Eb5
- G#b7
Built from the root A#, the minor third C#, the flat fifth E and the minor seventh G#.
Also written Bbm7b5: Bb Db Fb Ab
How to play A#m7b5
Frets from low E to high E; x means don't play that string.
Easiest shape to start with: Open position (x12120). It has 1 open string, nothing above fret 2 and 1 muted string.
Keys with A#m7b5
Every note of A#m7b5 is in these keys. The numeral is its place in the key.
Major keys
- viiø7 in B major
Minor keys
- iiø7 in G# minor