B Dominant Sharp 9th
B7#9
Notes
B · D# · F# · A · C##
Intervals
- RootB (1P)
- Major 3rdD# (3M)
- Perfect 5thF# (5P)
- Minor 7thA (7m)
- Augmented 9thC## (9A)
Fretboard
On the fretboard, D represents C##.
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About
The B7♯9 (B–D♯–F♯–A–C♯♯) raises the ninth a half step, creating a striking enharmonic clash: the C♯♯ (sounding like a ♭3) sits against the major 3rd in the same chord. This makes the chord simultaneously major and minor in feeling — the D♯ is in the bass of the voicing while the ♯9 rings on top like a minor color. The result is a harmonically ambiguous but intensely bluesy sound, which is why it is central to rock and blues-rock harmony — the "Hendrix chord". The 3rd and ♭7 are essential; the ♯9 is the defining alteration. Compared to B7♭9, 7♯9 feels more bluesy than classically tense.
Similar chords
Chords sharing two or more notes with this one, ranked by overlap.
Scales containing this chord
Scales whose notes include every chord tone. Roman numeral marks the chord root’s position in the scale; dashed badges aren’t linked yet.