A♯°7 — A♯, C♯, E, G — is the vii°7 of B minor and a sharp-side dim7 chord. The chord is enharmonically equivalent to C♯°7, E°7, and G°7 — all the same four pitches. Most often appears inside B-minor classical and folk literature as the standard cadential preparation.
Intervals
The A# diminished 7 chord stacks two thirds on the root. Each interval and its size in semitones:
- A#→C#minor 3rd3 semitones
- C#→Eminor 3rd3 semitones
- E→Gdiminished 7th9 semitones
On the keyboard
Each note of the A# diminished 7 chord highlighted on a piano. Pitch class is what matters — any octave works.
On the guitar
One voicing of the A# diminished 7 chord on a six-string guitar fretboard.
Common mistakes
A♯°7 mixes two sharps (A♯, C♯) with two naturals (E, G). The seventh G is natural, not G♯ — replacing it with G♯ destroys the diminished 7th interval and produces a different chord. The two-sharp signature of D major (which contains B minor as its relative minor) provides the sharps automatically.
In context
A♯°7 → B minor is the cadence in B minor — Bach uses this exact resolution constantly in his B-minor literature, including the famous Mass in B minor. Tchaikovsky's "Pathétique" Symphony No. 6 (in B minor) uses A♯°7 throughout its development sections.
Drill it
The A# diminished 7 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.
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Frequently asked
- What notes are in an A♯ diminished 7 chord?
- A♯°7 contains four notes: A♯ (root), C♯ (minor third), E (diminished fifth), and G (diminished seventh).
- How does A♯°7 resolve?
- In B minor: A♯ rises to B, C♯ holds, E falls to D, G falls to F♯. Every voice moves by half-step or whole-step to a tone of B minor.
- Is A♯°7 the same as B♭°7?
- Enharmonically yes (both are four pitches with intervals of m3). A♯°7 is the spelling in B-minor key contexts; B♭°7 (B♭-D♭-F♭-A𝄫) is rare because of the double-flat seventh.
- Where does A♯°7 appear in music?
- Bach's Mass in B minor uses A♯°7 at every cadence. Tchaikovsky's "Pathétique" Symphony, Schubert's "Unfinished," and countless other B-minor works rely on this chord as the primary cadential preparation.