Chord & FretBb7(#9) — dominant sharp ninth
Also written A#7(#9) — the same chord, spelled the other way.
Notes in Bb7(#9): Bb – D – F – Ab – C#Formula: 1 – 3 – 5 – b7 – #9In the formula, the numbers count steps of the major scale starting from the note that names the chord; "b" lowers a half step, "#" raises one — and a slash names the bass note.
The 7(#9) layers the major third over the augmented ninth (the enharmonic of the minor third), creating an aggressive tension — the famous "Hendrix chord".
The same chord on all four instruments
Where to use it: Blues, rock and soul with an intense sound.
The shapes of Bb7(#9) don't end on this page — the whole neck holds dozens. In Chord & Fret, you hear every shape strummed string by string, in each instrument's own voice; open every variation on the neck, grouped by bass note; and set a capo — the diagrams redraw above it. Start free. Unlock everything with Pro. Plays offline.
See the whole neck in Chord & Fret →Part of the Altered dominants family.