B♭7♯9 chord
B♭ dominant seventh sharp nine. The dominant seventh sharp nine chord: a dominant seventh with the ninth raised a semitone. Bright and biting, it is often called the Hendrix chord.
Click a note to hear it
- Notes
- B♭ D F A♭ C♯
- Formula
- 1 3 5 ♭7 ♯9
- Intervals
- P1 M3 P5 m7 A2
- Also written
- B♭7♯9 · B♭Hendrix chord
Notes in B♭7♯9
B♭7♯9 is spelled B♭ D F A♭ C♯: five notes stacked from the root B♭.
| Note | Interval above B♭ | Role | Formula |
|---|---|---|---|
| P1 | root | 1 | |
| M3 | third | 3 | |
| P5 | fifth | 5 | |
| m7 | seventh | ♭7 | |
| A2 | ninth | ♯9 |
Inversions
Putting a different chord tone in the bass gives each inversion. The chord is the same; the bass note changes how it sounds and what it can lead to.
| Position | Notes, low to high | Symbol | Hear it |
|---|---|---|---|
| Root position | B♭ D F A♭ C♯ | B♭7♯9 | |
| First inversion | D F A♭ C♯ B♭ | B♭7♯9/D | |
| Second inversion | F A♭ C♯ B♭ D | B♭7♯9/F | |
| Third inversion | A♭ C♯ B♭ D F | B♭7♯9/A♭ | |
| Fourth inversion | C♯ B♭ D F A♭ | B♭7♯9/C♯ |
On the piano
The root position voicing, with every chord tone lit in its own colour. Click a key to hear it.
On the guitar
There is no standard moveable shape for B♭7♯9, so here are its tones on the neck. Pick the notes that suit your voicing.
What it sounds like
C7♯9 is C, E, G, B♭ and D♯: a dominant seventh with the ninth raised a semitone. The D♯ sits a semitone below the major third, E, so the two notes rub against each other and give the chord a biting edge. D♯ is the same pitch as E♭, a minor third above the root, so the chord also carries a minor third sound. The chord keeps the dominant's tritone and pull, and its sound is tense, bright and bluesy.
How it is used
The sharp nine is a dominant colour that appears on the fifth degree in jazz, where the altered dominant resolves to a tonic a fifth below. In blues and rock it is often played on the tonic, where it stays as a colour rather than pulling away. Guitarists use it as a standard sound in blues and rock. Its bite makes it a common choice for an unresolved sound in those styles.
How it is built
The sharp nine is a root with a major third, a perfect fifth, a minor seventh and an augmented ninth, 0, 4, 7, 10 and 15 semitones above the root. Common symbols are C7♯9, C7(♯9) and C7+9. The sharp nine, D♯, is the same pitch as E♭, so the chord can be written C, E, G, B♭ and E♭, though writers rarely do. Inversions place E, G or B♭ in the bass. The chord contains C7, with the sharp nine added above it.
Which keys contain B♭7♯9
B♭7♯9 is not built from any one major or minor key’s own notes. It appears through borrowing, alteration or chromatic voice leading, which is part of why it sounds coloured.
Other B♭ chords
- B♭
- B♭m
- B♭dim
- B♭aug
- B♭sus2
- B♭sus4
- B♭5
- B♭6
- B♭m6
- B♭7
- B♭maj7
- B♭m7
- B♭m7♭5
- B♭dim7
- B♭m(maj7)
- B♭7♯5
- B♭7sus4
- B♭add9
- B♭9
- B♭maj9
- B♭m9
- B♭7♭9
- B♭13
How to practise it
Play C7, then C7♯9, then C7 again, with the D♯ on top, and listen to the bite of the semitone above the major third. Then play D♯ and E♭ in turn on the piano and hear that they are the same pitch, which explains why the chord can be spelled either way.
Further reading
- Chord Extensions Explained: Ninths, Elevenths and ThirteenthsJazz & Popular Harmony · 7 min
- Tritone Substitution: The subV7 Chord That Still ResolvesHarmony · 6 min
- Chord-Scale Theory Explained: Which Scale Fits Which ChordJazz & Popular Harmony · 7 min
Questions
What notes are in a B♭7♯9 chord?
B♭7♯9 contains B♭, D, F, A♭, C♯. That is the root, third, fifth, seventh, ninth of the chord.
How do you spell B♭ dominant seventh sharp nine?
Stack the intervals P1, M3, P5, m7, A2 above B♭: B♭, D, F, A♭, C♯.
What other symbols mean B♭7♯9?
Lead sheets also write it B♭7♯9, B♭Hendrix chord. They are the same chord.
What is the Hendrix chord?
The Hendrix chord is a name for a dominant seventh chord with a sharp ninth, such as C7♯9. Blues and rock guitarists use it often, and the name refers to the guitarist Jimi Hendrix. The chord's notes are the root, third, fifth, minor seventh and a raised ninth, which is D♯ over C.
What is the difference between C7♭9 and C7♯9?
C7♭9 has D♭, a semitone above the root. C7♯9 has D♯, a semitone below the major third. The sharp nine sits close to the third, which gives a biting edge, while the flat nine sits near the root. Both are altered dominants, but their sounds differ, and they are not interchangeable.
What is the difference between C9 and C7♯9?
C9 has a natural ninth, D, a major second above the root. C7♯9 has a sharp ninth, D♯, which lies a semitone below the major third. That close placement makes C7♯9 bite, while C9 sounds smoother. Both keep the same dominant seventh, so both pull toward the tonic a fifth below.