Ab9 Ab dominant ninth chord
- Notes
- Ab C Eb Gb Bb
- Formula
- 1 3 5 b7 9
- Semitones
- 0 4 7 10 14 above the root
- Also written
- G#9 (G# B# D# F# A#)
- Other symbols
- Abdom9
Ab to C is a major third (4 semitones), C to Eb is a minor third (3 semitones), Eb to Gb is a minor third (3 semitones), Gb to Bb is a major third (4 semitones). A dominant seventh (Ab7) with the ninth, Bb, on top. Guitarists usually leave out the fifth, Eb; the chord still reads as Ab9 while the third C and seventh Gb are there.
Ab9 on the piano
Root position from Ab4: Ab4, C5, Eb5, Gb5, Bb5. Middle C is C4.
Ab9 on the guitar
Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has Ab as its lowest note.
4 6 4 5 4 6 (low E to high e)
Sounds Ab2 Eb3 Gb3 C4 Eb4 Bb4
x 11 10 11 11 11 (low E to high e)
Sounds Ab3 C4 Gb4 Bb4 Eb5
The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play dominant ninth chords on other roots.
Inversions of Ab9
An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.
| Position | Notes, bass first | Named | Listen |
|---|---|---|---|
| Root position | Ab C Eb Gb Bb | Ab9 | |
| 1st inversion | C Eb Gb Bb Ab | Ab9/C | |
| 2nd inversion | Eb Gb Bb Ab C | Ab9/Eb | |
| 3rd inversion | Gb Bb Ab C Eb | Ab9/Gb | |
| 4th inversion | Bb Ab C Eb Gb | Ab7/Bb (also read as Ab9/Bb) |
Where Ab9 fits
Ab9 is V9 in Db major. It resolves like Ab7. In funk and blues it is also played as I9, IV9 and V9 of a twelve-bar blues, with no pull to resolve at all. Without the root, its upper four notes C Eb Gb Bb are Cm7b5, which is why pianists who leave the root to the bass player grab that shape.