A Dominant 9th
A9
Notes
A · C♯ · E · G · B
Intervals
- RootA (1P)
- Major 3rdC♯ (3M)
- Perfect 5thE (5P)
- Minor 7thG (7m)
- Major 9thB (9M)
Fretboard
Adjust labels, frets, and palette in the interactive view.
Voicings & shapes
Rootless voicings (A / B form) (4)
About
The A9 dominant ninth (A–C♯–E–G–B) extends a dominant 7 with a ninth. The B adds brightness and harmonic richness without affecting the chord’s dominant function — the tritone between C♯ and G is still present and still drives resolution to D. The 3rd and ♭7 remain essential; the 5th is routinely dropped on guitar to make room for the 9th without creating a muddy cluster. Common in funk, jazz, and blues as a more colorful version of the dominant 7. Compared to A7, the 9th adds shimmer and modernity; the resolution tendency is identical.
Chord diagrams
A Dominant 9th voicing charts — tap a sheet to open it full size to save or print.
Similar chords
Chords sharing two or more notes with this one, ranked by overlap.
Scales containing this chord
- A Mixolydian (I)
- B Natural Minor (VII)
- D Major (V)
- D Melodic Minor (V)
- D♭ Locrian (VI)
- E Dorian (IV)
- E Melodic Minor (IV)
- F♯ Phrygian (III)
- G Lydian (II)
Scales whose notes include every chord tone. The Roman numeral (or scale degree) marks the chord root’s position in the scale.