Space plays and stops
- Notes and intervals
- A#m3C#m3EM3G#
A# Half Diminished, written A#m7b5, is built from A#, C#, E and G#: the root, minor 3rd, flat 5th and minor 7th.
Its 3rd and 7th, C# and G#, are its guide tones: they say what kind of chord it is, so voicings are built around them and the root is often left to the bass.
In the progressions here, A#m7b5 is the iiiø7 of the Minor ii-V to ii-V-I Progression in F# and the viiø7 of the Bird Blues in B.