Chord & FretA#m7(b5) — half-diminished
Also written Bbm7(b5) — the same chord, spelled the other way.
Notes in A#m7(b5): A# – C# – E – G#Formula: 1 – b3 – b5 – b7In the formula, the numbers count steps of the major scale starting from the note that names the chord; "b" lowers a half step, "#" raises one — and a slash names the bass note.
Picture a minor chord whose fifth has been 'shrunk', that is, lowered by a half step: the result is tense and melancholic at once. In minor keys it usually announces that tension is on the way — as in Bm7b5 → E7E7E7E7 → AmAmAmAm. It is a color you hear a lot in bolero and bossa nova.
The same chord on all four instruments
Where to use it: In minor keys it is usually the chord that opens the famous ii–V — in other words, the two-chord pair that prepares the return home. Think Dm7b5 → G7G7G7G7 arriving at CmCmCmCm.
This is just one shape of A#m7(b5). In Chord & Fret, you check it note by note, playing any shape as an arpeggio; compare positions with their difficulty marked; and change the tuning — the shape rewrites itself. Start free. Unlock everything with Pro. Plays offline.
See the whole neck in Chord & Fret →Part of the Sevenths family.