Squeezebox StudioWhat keys can a B/C button accordion play in?
All of them. The two rows of a B/C are a semitone apart, so between them they hold almost every note, and every key has a complete octave somewhere. What differs from key to key is how much crossing between the rows it takes.
The tables below check every key against the buttons on a 21-key B/C with the layout in the B/C chart. A key counts as playable when every note of one octave of its scale is on the box, starting from the key note.
Major keys
| Key | Notes | Complete octave |
|---|---|---|
| C major | C D E F G A B | From C4 and C5 |
| G major | G A B C D E F♯ | From G3 and G4 |
| D major | D E F♯ G A B C♯ | From D4 |
| A major | A B C♯ D E F♯ G♯ | From A3 and A4 |
| E major | E F♯ G♯ A B C♯ D♯ | From E3, E4 and E5 |
| B major | B C♯ D♯ E F♯ G♯ A♯ | From B3 and B4 |
| G♭ major | G♭ A♭ B♭ C♭ D♭ E♭ F | From G♭3 and G♭4 |
| D♭ major | D♭ E♭ F G♭ A♭ B♭ C | From D♭4 and D♭5 |
| A♭ major | A♭ B♭ C D♭ E♭ F G | From A♭3 and A♭4 |
| E♭ major | E♭ F G A♭ B♭ C D | From E♭4 |
| B♭ major | B♭ C D E♭ F G A | From B♭3 and B♭4 |
| F major | F G A B♭ C D E | From F4 |
Minor keys
| Key | Notes | Complete octave |
|---|---|---|
| A minor | A B C D E F G | From A3 and A4 |
| E minor | E F♯ G A B C D | From E3 and E4 |
| B minor | B C♯ D E F♯ G A | From B3 and B4 |
| F♯ minor | F♯ G♯ A B C♯ D E | From F♯3 and F♯4 |
| C♯ minor | C♯ D♯ E F♯ G♯ A B | From C♯4 and C♯5 |
| G♯ minor | G♯ A♯ B C♯ D♯ E F♯ | From G♯3 and G♯4 |
| E♭ minor | E♭ F G♭ A♭ B♭ C♭ D♭ | From E♭4 and E♭5 |
| B♭ minor | B♭ C D♭ E♭ F G♭ A♭ | From B♭3 and B♭4 |
| F minor | F G A♭ B♭ C D♭ E♭ | From F4 |
| C minor | C D E♭ F G A♭ B♭ | From C4 and C5 |
| G minor | G A B♭ C D E♭ F | From G3 and G4 |
| D minor | D E F G A B♭ C | From D4 |
Dorian
| Key | Notes | Complete octave |
|---|---|---|
| D Dorian | D E F G A B C | From D4 |
| A Dorian | A B C D E F♯ G | From A3 and A4 |
| E Dorian | E F♯ G A B C♯ D | From E3 and E4 |
| B Dorian | B C♯ D E F♯ G♯ A | From B3 and B4 |
| F♯ Dorian | F♯ G♯ A B C♯ D♯ E | From F♯3, F♯4 and F♯5 |
| C♯ Dorian | C♯ D♯ E F♯ G♯ A♯ B | From C♯4 and C♯5 |
| A♭ Dorian | A♭ B♭ C♭ D♭ E♭ F G♭ | From A♭3 and A♭4 |
| E♭ Dorian | E♭ F G♭ A♭ B♭ C D♭ | From E♭4 and E♭5 |
| B♭ Dorian | B♭ C D♭ E♭ F G A♭ | From B♭3 and B♭4 |
| F Dorian | F G A♭ B♭ C D E♭ | From F4 |
| C Dorian | C D E♭ F G A B♭ | From C4 and C5 |
| G Dorian | G A B♭ C D E F | From G3 and G4 |
Mixolydian
| Key | Notes | Complete octave |
|---|---|---|
| G Mixolydian | G A B C D E F | From G3 and G4 |
| D Mixolydian | D E F♯ G A B C | From D4 |
| A Mixolydian | A B C♯ D E F♯ G | From A3 and A4 |
| E Mixolydian | E F♯ G♯ A B C♯ D | From E3 and E4 |
| B Mixolydian | B C♯ D♯ E F♯ G♯ A | From B3 and B4 |
| F♯ Mixolydian | F♯ G♯ A♯ B C♯ D♯ E | From F♯3, F♯4 and F♯5 |
| D♭ Mixolydian | D♭ E♭ F G♭ A♭ B♭ C♭ | From D♭4 and D♭5 |
| A♭ Mixolydian | A♭ B♭ C D♭ E♭ F G♭ | From A♭3 and A♭4 |
| E♭ Mixolydian | E♭ F G A♭ B♭ C D♭ | From E♭4 and E♭5 |
| B♭ Mixolydian | B♭ C D E♭ F G A♭ | From B♭3 and B♭4 |
| F Mixolydian | F G A B♭ C D E♭ | From F4 |
| C Mixolydian | C D E F G A B♭ | From C4 and C5 |
A full octave isn't the whole story
A tune only needs the notes it actually uses. One in A major that never reaches for a G♯ won't miss one on your box, and plenty of tunes in the modes leave out a note or two. So use the tables as a guide to where a key sits comfortably, then look at the tune itself. If it still sits badly, try it a tone or a fourth away.
Squeezebox Studio does this for a whole tune: it tries the tune in every key, counts the notes your box can't play, and suggests the keys that suit it best.
Other boxes: D/G melodeon, G/C melodeon.