Chord & FretBb7(#11) — dominant sharp eleventh
Also written A#7(#11) — the same chord, spelled the other way.
Notes in Bb7(#11): Bb – D – F – Ab – EFormula: 1 – 3 – 5 – b7 – #11In 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.
One 'outside' note — an F# added to C7C7C7C7 — turns the dominant, that is, the chord that begs to resolve, into something modern and enigmatic. It is also the core sound of the tritone substitution: in practice, the trick of swapping one dominant for another that lives three whole steps away yet resolves to the same place.
The same chord on all four instruments
Where to use it: You hear it a lot in jazz and bossa nova turnarounds — which simply means those short chord loops that close a section and set up the restart. It is also a classic ending color: a last chord that sounds like a question mark instead of a period.
The shapes of Bb7(#11) don't end on this page — the whole neck holds dozens. In Chord & Fret, you check it note by note, playing any shape as an arpeggio; compare positions with their difficulty marked; 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.