Sevenths · A# root / B♭
A#°7 / B♭°7
Maximum tension. Fully symmetric — every inversion sounds similar.
Notes in A#°7
A# / Bb is a favourite for horn players and jazz musicians. Many blues and jazz standards are in Bb.
Identify the Chord Quality on A#
Each chord below is played on A#. Listen and identify whether you heard A#°7, A#m, A#7, or another quality — the hardest and most useful ear training skill.
Diminished 7th in All 12 Keys
Other Chords in A#
Related Sevenths
About the A#°7 Chord
The A#°7 chord is a diminished 7th chord built on A# (also written B♭°7). It contains the notes Bb, Db, E, G — the root, third, fifth, and seventh.
Maximum tension. Fully symmetric — every inversion sounds similar. Practising the A#°7 chord across different voicings and contexts builds the harmonic recognition that lets you identify it instantly in any musical setting — whether in a band mix, a recording, or a live performance.