Bb Augmented Major 7th (Bbaug(maj7))
Also written as A# Augmented Major 7th (A# and Bb are the same key).
Notes in Bb Augmented Major 7th
Inversions
Same notes as Bb Augmented Major 7th, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
A# in the bass
1st inversion
D in the bass (Bbaug(maj7)/D)
2nd inversion
F# in the bass (Bbaug(maj7)/F#)
3rd inversion
A in the bass (Bbaug(maj7)/A)
Open voicings
A close-position chord like Bb Augmented Major 7th can sound cluttered in the middle of the keyboard. Jazz players open it up by dropping one note down an octave, spreading the same notes wider without changing the chord.
Drop 2
F# on the bottom
Drop 3
D on the bottom
Press A#, D, F# and A together on the keyboard and you're playing Bb Augmented Major 7th.
An augmented triad topped with a major seventh. It keeps the floating, symmetrical feel of the augmented triad but sounds a touch warmer and more settled. You hear it in late Romantic harmony and in jazz as a passing color between two more ordinary chords.