A9 — A dominant ninth chord
A dominant seventh chord with the ninth added. The ninth is a whole tone above the root in the octave above it.
- 1 = A
- 9 = B
- 3 = C#
- 5 = E
- b7 = G
- Symbol
- A9
- Root
- A
- Quality
- Dominant ninth
- Family
- extended
- Notes
- A B C# E G
- Degree formula
1 9 3 5 b7- Semitones from the root
0 2 4 7 10- Distinct pitch classes
- 5
- Interval structure
- Stacked from the root: 2 semitones, 2 semitones, 3 semitones, 3 semitones
- Notation
- Written 9. The standard extension of a dominant chord in funk, soul and jazz.
- Key
- A · A major / F# minor key signature
Formula
The chord tones in order from the root, with the interval each one forms above it.
| Degree | Note | Semitones | Interval from the root |
|---|---|---|---|
| 1 | A | 0 | Perfect unison |
| 9 | B | 2 | Major second |
| 3 | C# | 4 | Major third |
| 5 | E | 7 | Perfect fifth |
| b7 | G | 10 | Minor seventh |
Inversions
An inversion is the same set of notes with a different one in the bass. The last column gives the distance of each note above the bass note, in semitones.
| Inversion | Bass note | Degree in the bass | Notes above the bass | Semitones above the bass |
|---|---|---|---|---|
| root position | A | 1 | A – B – C# – E – G | 0 2 4 7 10 |
| first inversion | B | 9 | B – C# – E – G – A | 0 2 5 8 10 |
| second inversion | C# | 3 | C# – E – G – A – B | 0 3 6 8 10 |
| third inversion | E | 5 | E – G – A – B – C# | 0 3 5 7 9 |
| fourth inversion | G | b7 | G – A – B – C# – E | 0 2 4 6 9 |
Playable voicings
These shapes were found by searching the fretboard of a standard-tuned guitar (E A D G B E) rather than copied from a chord book. The search allows every string to sound or to be muted, rejects any shape with a muted string between two sounding strings, rejects any shape whose fretted notes span more than four frets (a five-fret window), requires every chord tone to be present, and then sorts what remains with root-position shapes first and the most compact, lowest shapes next. The shapes shown are the first six of that ordering; other orderings are possible at the same frets.
| # | Shape (low string first) | Notes | Degrees | Bass | Span (frets) | Sounding strings |
|---|---|---|---|---|---|---|
| 1 | 5-4-5-4-5-5 | A C# G B E A | 1 3 b7 9 5 1 | A | 1 | 6 |
| 2 | 5-4-5-4-5-3 | A C# G B E G | 1 3 b7 9 5 b7 | A | 2 | 6 |
| 3 | 5-7-5-6-5-7 | A E G C# E B | 1 5 b7 3 5 9 | A | 2 | 6 |
| 4 | 5-2-2-2-2-3 | A B E A C# G | 1 9 5 1 3 b7 | A | 3 | 6 |
| 5 | 5-2-2-4-2-3 | A B E B C# G | 1 9 5 9 3 b7 | A | 3 | 6 |
| 6 | 5-4-2-4-2-3 | A C# E B C# G | 1 3 5 9 3 b7 | A | 3 | 6 |
Shape numbers run from the lowest string to the highest, so the left-hand number is the sixth string (low E) in standard tuning. Multiple shapes are listed because a chord can be voiced several ways, and because a lower position is not always the better sounding one.
Related chords and scales
- KeyEverything in A
- ScaleA mixolydian
- ChordA7
Related
- KeyKey of A
- ScaleA mixolydian
- ChordA7 — Dominant seventh
- ChordA11 — Dominant eleventh
- ChordA13 — Dominant thirteenth
- ChordAm11 — Minor eleventh
- DegreesA — degree map
- Neck mapA — note map