A Dominant Ninth Chord
Chord Tones: A Dominant Ninth Chord
Symbol: 9 — Formula: 1-3-5-♭7-9
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | A | 440.000 Hz |
| 3 | C# | 277.183 Hz |
| 5 | E | 329.628 Hz |
| ♭7 | G | 391.995 Hz |
| 9 | B | 493.883 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | A9 |
| All Common Symbols | 9 |
| Interval Formula | 1-3-5-♭7-9 |
| Harmonic Category | tense |
Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.
Inversions
| Inversion | Notes (low to high) | Bass Note | Slash Notation |
|---|---|---|---|
| Root Position | A – C# – E – G – B | A | A Dominant Ninth Chord |
| First Inversion | C# – E – G – B – A | C# | A Dominant Ninth Chord/C# |
| Second Inversion | E – G – B – A – C# | E | A Dominant Ninth Chord/E |
| Third Inversion | G – B – A – C# – E | G | A Dominant Ninth Chord/G |
| Fourth Inversion | B – A – C# – E – G | B | A Dominant Ninth Chord/B |
Harmonic Function
The A dominant ninth chord commonly functions as the submediant (vi) in C major or dominant (V) in D major. Its harmonic role varies by key — in major keys it provides stable harmonic grounding.
The dominant ninth chord extends the dominant seventh with a ninth, adding color and richness to one of music's most harmonically active chords. Essential in jazz, blues, and funk.
Common Progressions
The A Dominant Ninth Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
V9-Iii9-V9-I
Songs Featuring the Dominant Ninth Chord
Well-known songs where the A Dominant Ninth Chord — or this chord type — plays a prominent role:
- Purple Haze – Jimi Hendrix
- What's Going On – Marvin Gaye
- Superstition – Stevie Wonder
Tuning Frequencies Across Temperaments
Frequencies shown at A=440 Hz. View full temperament data for any note.
| Note | Equal Temp. | Pythagorean | Just Intonation |
|---|---|---|---|
| A | 440.000 Hz | 440.000 Hz | 436.043 Hz |
| C# | 277.183 Hz | 278.437 Hz | 279.067 Hz |
| E | 329.628 Hz | 330.001 Hz | 327.032 Hz |
| G | 391.995 Hz | 391.111 Hz | 392.438 Hz |
| B | 493.883 Hz | 495.000 Hz | 490.548 Hz |
Scales Containing the A Dominant Ninth Chord
These scales include the A Dominant Ninth Chord as a diatonic or characteristic chord: