Bb 13#11 (Bb13#11)
Also written as A# 13#11 (A# and Bb are the same key).
Notes in Bb 13#11
Inversions
Same notes as Bb 13#11, 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 (Bb13#11/D)
2nd inversion
E# in the bass (Bb13#11/E#)
3rd inversion
G# in the bass (Bb13#11/G#)
4th inversion
B# in the bass (Bb13#11/B#)
5th inversion
E in the bass (Bb13#11/E)
6th inversion
G in the bass (Bb13#11/G)
Open voicings
A close-position chord like Bb 13#11 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
A# on the bottom
Drop 3
A# on the bottom
The notes A#, D, E#, G#, B#, E and G make up Bb 13#11.
The bright version of a dominant thirteenth, with both a natural ninth and a sharpened eleventh. Fusion and modern jazz players reach for it when a dominant chord sits still for a while, since the #11 keeps a big stack from sounding plain.