Ab 13sus4 (Ab13sus4)
Also written as G# 13sus4 (G# and Ab are the same key).
Notes in Ab 13sus4
Inversions
Same notes as Ab 13sus4, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
G# in the bass
1st inversion
C# in the bass (Ab13sus4/C#)
2nd inversion
D# in the bass (Ab13sus4/D#)
3rd inversion
F# in the bass (Ab13sus4/F#)
4th inversion
A# in the bass (Ab13sus4/A#)
5th inversion
E# in the bass (Ab13sus4/E#)
Open voicings
A close-position chord like Ab 13sus4 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
G# on the bottom
Drop 3
F# on the bottom
The notes G#, C#, D#, F#, A# and E# make up Ab 13sus4.
A 9sus4 stretched up to the thirteenth. Gospel, funk and fusion players use it for vamps that sit on one chord a long time, since the stack of fourth, ninth and thirteenth keeps things interesting without ever settling into major or minor.