Scale degrees · A♭ major
The ♯4 of A♭ is D
The ♯4 (sharp four, written #4) of A♭ (A flat, Ab) is D: an augmented fourth above the root.
A♭ — the root, 1D — the ♯4
How to find it
Count letters first, the root included: A, B, C, D. A 4th lands on D.
Then the sound: an augmented fourth is 6 semitones above A♭, which is exactly where D is — no sharp or flat needed.
Where you meet it
The ♯4 is the Lydian note, a tritone above the root. On a chord symbol it is usually written ♯11.
In the scale A♭ Lydian:
A♭ · B♭ · C · D · E♭ · F · G
The ♯4 in every key
| Key | The ♯4 |
|---|---|
| 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 A♭
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