Scale degrees · F♯ major
The ♯11 of F♯ is B♯
The ♯11 (sharp eleven, written #11) of F♯ (F sharp, F#) is B♯ (B sharp): an augmented eleventh above the root.
F♯ — the root, 1B♯ — the ♯11
How to find it
An 11th is a 4th an octave up, so it takes the 4th's letter: F, G, A, B.
Then the sound: an augmented eleventh is 18 semitones above F♯, and the B that is 18 semitones up is B♯.
That is why it is B♯ and not C: C is the same key on the piano, but from F♯ it would be a 12th, not an 11th.
Where you meet it
The ♯11 is the Lydian tension: the bright, open colour of maj7♯11 and of the Lydian dominant 7♯11.
In F♯maj7♯11:
F♯ · A♯ · C♯ · E♯ · B♯
The ♯11 in every key
| Key | The ♯11 |
|---|---|
| C | F♯ |
| G | C♯ |
| D | G♯ |
| A | D♯ |
| E | A♯ |
| B | E♯ |
| F♯ | B♯ |
| D♭ | G |
| A♭ | D |
| E♭ | A |
| B♭ | E |
| F | B |
Every degree of F♯
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