Construction
| Note | Interval | Degree |
|---|---|---|
| A♯ | Root | 1 |
| C♯ | Minor 3rd | ♭3 |
| E | Diminished 5th | ♭5 |
Fingering
| Note | Key color | Right hand | Left hand |
|---|---|---|---|
| A♯ | black | thumb (1) | little finger (5) |
| C♯ | black | middle finger (3) | middle finger (3) |
| E | white | little finger (5) | thumb (1) |
Right hand: thumb (1) on A♯, middle finger (3) on C♯, little finger (5) on E.
Left hand: little finger (5) on A♯, middle finger (3) on C♯, thumb (1) on E.
A♯ Diminished Inversions
- Root positionA♯ – C♯ – E
- 1st inversion (A♯dim/C♯)C♯ – E – A♯
- 2nd inversion (A♯dim/E)E – A♯ – C♯
Key Signature
A Diminished chord is built from symmetrical or ambiguous intervals, so it doesn't belong to a single key and has no key signature of its own.
Chords in the Key of A♯ Major
These are the triads built on each degree of A♯ Major:
How A♯ Diminished functions in a key
The same chord takes on a different harmonic role depending on the key it appears in. Here is where A♯ Diminished sits diatonically across the common keys:
- In B major, A♯ Diminished is the vii° chord — the dominant.
- In G♯ minor, A♯ Diminished is the ii° chord — a predominant.
Scales That Include the A♯ Diminished
- B Major (vii°)
- G# Minor (ii°)
- C# Dorian (vi°)
- D# Phrygian (v°)
- E Lydian (#iv°)
- F# Mixolydian (iii°)
- G# Aeolian (ii°)
- A# Locrian (i°)
A♯ Diminished : Frequently Asked Questions
What notes are in A♯dim?
How do you play A♯dim on piano?
What are the inversions of A♯dim?
What keys contain A♯dim?
What is the difference between A♯dim and A♯m7♭5?
What is an easy A♯dim for small hands?
What are the frequencies of A♯dim?
What is the set class of A♯dim?
How do I transpose A♯dim to another key?
Is B♭dim the same as A♯dim?
A♯ Diminished in detail
Exact
Every pitch class is present and nothing outside the chord is added.
| Type | Notes | Semitones | Span | Omissions and additions | Set relation | Fit |
|---|---|---|---|---|---|---|
| Close, root position | A♯3 C♯4 E4 | 6 | 83 mm | none | identical | |
| Close, first inversion | C♯4 E4 A♯4 | 9 | 124 mm | none | identical | |
| Close, second inversion | E4 A♯4 C♯5 | 9 | 124 mm | none | identical | |
| Open, fifth on top | A♯2 E3 C♯4 | 15 | 206 mm | none | identical |
Reduced
A subset of the pitch classes: the identity is incomplete rather than altered.
| Type | Notes | Semitones | Span | Omissions and additions | Set relation | Fit |
|---|---|---|---|---|---|---|
| Root and third only | A♯3 C♯4 | 3 | 41 mm | omits E | subset |
Spans are measured centre to centre at a 165 mm octave (standard keyboard geometry).
| Position | Bass note | Notes in order | Figured bass | Semitones | Span |
|---|---|---|---|---|---|
| Root position | A♯ | A♯3, C♯4, E4 | 5/3 | 6 | 83 mm |
| First inversion: A♯dim/C♯ | C♯ | C♯4, E4, A♯4 | 6/3 | 9 | 124 mm |
| Second inversion: A♯dim/E | E | E4, A♯4, C♯5 | 6/4 | 9 | 124 mm |
One position per chord tone in the bass. Spans are for close position: voiced inversions appear under Voicings.
| Progression | Key | Role | Sequence | Voice leading |
|---|---|---|---|---|
| ii°, v, i | G♯ minor | ii° | A♯dim to D♯m to G♯m | A♯dim opens the phrase |
| vii°, I | B major | vii° | A♯dim to B | A♯dim opens the phrase |
Root motion, common tones and voice displacement are computed from pitch class sets. Roman numerals follow common practice functional harmony.
Which keys it belongs to
| Key | Roman numeral | Function |
|---|---|---|
| G♯ minor | ii° | Predominant |
| B major | vii° | Dominant function |
Classification system: common-practice functional harmony.
Change one note
Chords a single note away, and what moving that note does.
| Chord | Change | Formula | Common tones |
|---|---|---|---|
| A♯m7♭5 | adds G♯ | 1 ♭3 ♭5 ♭7 | 3 |
| A♯dim7 | adds G | 1 ♭3 ♭5 ♭♭7 | 3 |
| A♯m | E becomes E♯ | 1 ♭3 5 | 2 |
| A♯m7 | E becomes E♯, G♯ | 1 ♭3 5 ♭7 | 2 |
| A♯mMaj7 | E becomes E♯, G× | 1 ♭3 5 7 | 2 |
| A♯m6 | E becomes E♯, F× | 1 ♭3 5 6 | 2 |
| A♯ | C♯, E becomes C×, E♯ | 1 3 5 | 1 |
| A♯aug | C♯, E becomes C×, E× | 1 3 ♯5 | 1 |
| A♯sus2 | C♯, E becomes B♯, E♯ | 1 2 5 | 1 |
| A♯sus4 | C♯, E becomes D♯, E♯ | 1 4 5 | 1 |
Frequencies
| Note | MIDI | Frequency |
|---|---|---|
| A♯3 | 58 | 233.08 Hz |
| C♯4 | 61 | 277.18 Hz |
| E4 | 64 | 329.63 Hz |
Reference pitch A440, 12-TET, close root position.
Set theory: prime form, Forte number, interval vector
- Absolute pitch class set
- {10, 1, 4}
- Normal order
- [10, 1, 4]
- Prime form
- (036)
- Forte number
- 3-10
- Interval vector
- <002001>
| Pair | Interval | Semitones | Interval class |
|---|---|---|---|
| A♯ to C♯ | Minor third | 3 | 3 |
| A♯ to E | Tritone | 6 | 6 |
| C♯ to E | Minor third | 3 | 3 |
Where these facts come from
Every value on this page is derived from the note formula for a diminished applied to the root A♯, using standard music theory. Nothing here is hand-entered per chord, so the notes, intervals, inversions and frequencies cannot drift out of agreement with each other. Pitches assume 12-TET at A440.