B7#9 B dominant seventh sharp nine chord
- Notes
- B D# F# A C##
- Formula
- 1 3 5 b7 #9
- Semitones
- 0 4 7 10 15 above the root
- Other symbols
- B7(#9), B7+9
B to D# is a major third (4 semitones), D# to F# is a minor third (3 semitones), F# to A is a minor third (3 semitones), A to C## is a perfect fourth (5 semitones). A dominant seventh with a raised ninth, C##. On the keyboard C## is the same key as the minor third, so the chord holds both a major and a minor third; it is written as a sharp ninth because it sits above the seventh and the letter names follow the stack of thirds.
B7#9 on the piano
Root position from B4: B4, D#5, F#5, A5, C##6. Middle C is C4.
B7#9 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 B as its lowest note.
x 2 1 2 3 x (low E to high e)
Sounds B2 D#3 A3 C##4, fifth left out
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 seventh sharp nine chords on other roots.
Inversions of B7#9
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 | B D# F# A C## | B7#9 | |
| 1st inversion | D# F# A C## B | Bm7/D# (also read as B7#9/D#) | |
| 2nd inversion | F# A C## B D# | B7#9/F# | |
| 3rd inversion | A C## B D# F# | B7#9/A | |
| 4th inversion | C## B D# F# A | B7/D |
Where B7#9 fits
B7#9 has no place among the chords built from a major or minor scale: it holds a major third, D#, and the sharp ninth C##, which sounds the same as the minor third. That major–minor clash is the blues in one chord. It is used as the I chord of a blues or a funk vamp, and as a tense V chord in jazz; Jimi Hendrix's "Purple Haze" made E7#9 famous, which is why guitarists call it the Hendrix chord.