Construction
| Note | Interval | Degree |
|---|---|---|
| B♭ | Root | 1 |
| D♭ | Minor 3rd | ♭3 |
| F♭ | Diminished 5th | ♭5 |
| A♭♭ | Major 6th | 6 |
Fingering
| Note | Key color | Right hand | Left hand |
|---|---|---|---|
| B♭ | black | index finger (2) | little finger (5) |
| D♭ | black | middle finger (3) | ring finger (4) |
| F♭ | white | ring finger (4) | middle finger (3) |
| A♭♭ | white | little finger (5) | index finger (2) |
Right hand: index finger (2) on B♭, middle finger (3) on D♭, ring finger (4) on F♭, little finger (5) on A♭♭.
Left hand: little finger (5) on B♭, ring finger (4) on D♭, middle finger (3) on F♭, index finger (2) on A♭♭.
B♭ Diminished 7th Inversions
- Root positionB♭ – D♭ – F♭ – A♭♭
- 1st inversion (B♭dim7/D♭)D♭ – F♭ – A♭♭ – B♭
- 2nd inversion (B♭dim7/F♭)F♭ – A♭♭ – B♭ – D♭
- 3rd inversion (B♭dim7/A♭♭)A♭♭ – B♭ – D♭ – F♭
Key Signature
A Diminished 7th 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 B♭ Major
These are the triads built on each degree of B♭ Major:
Same Notes, Other Names
The notes B♭ – D♭ – F♭ – A♭♭ aren’t exclusive to this chord. Depending on which note is the bass and how the chord functions, the same pitches also spell the following:
B♭ Diminished 7th : Frequently Asked Questions
What notes are in B♭dim7?
How do you play B♭dim7 on piano?
What are the inversions of B♭dim7?
What is the difference between B♭dim7 and B♭dim?
What is an easy B♭dim7 for small hands?
What are the frequencies of B♭dim7?
What is the set class of B♭dim7?
How do I transpose B♭dim7 to another key?
Is A♯dim7 the same as B♭dim7?
B♭ Diminished 7th 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 | B♭3 D♭4 F♭4 A♭♭4 | 9 | 124 mm | none | identical | |
| Close, first inversion | D♭4 F♭4 A♭♭4 B♭4 | 9 | 124 mm | none | identical | |
| Close, second inversion | F♭4 A♭♭4 B♭4 D♭5 | 9 | 124 mm | none | identical | |
| Close, third inversion | A♭♭4 B♭4 D♭5 F♭5 | 9 | 124 mm | none | identical | |
| Drop 2 | F♭3 B♭3 D♭4 A♭♭4 | 15 | 206 mm | none | identical | |
| Drop 3 | D♭3 B♭3 F♭4 A♭♭4 | 18 | 248 mm | none | identical | |
| Drop 2 and 4 | B♭2 F♭3 D♭4 A♭♭4 | 21 | 289 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 |
|---|---|---|---|---|---|---|
| Shell, root ♭♭7 ♭3 | B♭2 A♭♭3 D♭4 | 15 | 206 mm | omits F♭ | subset | |
| Guide tones, ♭3 and ♭♭7 | D♭4 A♭♭4 | 6 | 83 mm | omits B♭ and F♭ | subset | |
| Rootless close | D♭4 F♭4 A♭♭4 | 6 | 83 mm | omits B♭ | 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 | B♭ | B♭3, D♭4, F♭4, A♭♭4 | 7 | 9 | 124 mm |
| First inversion: B♭dim7/D♭ | D♭ | D♭4, F♭4, A♭♭4, B♭4 | 6/5 | 9 | 124 mm |
| Second inversion: B♭dim7/F♭ | F♭ | F♭4, A♭♭4, B♭4, D♭5 | 4/3 | 9 | 124 mm |
| Third inversion: B♭dim7/A♭♭ | A♭♭ | A♭♭4, B♭4, D♭5, F♭5 | 4/2 | 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 |
|---|
Root motion, common tones and voice displacement are computed from pitch class sets. Roman numerals follow common practice functional harmony.
Change one note
Chords a single note away, and what moving that note does.
| Chord | Change | Formula | Common tones |
|---|---|---|---|
| B♭dim | drops A♭♭ | 1 ♭3 ♭5 | 3 |
| B♭m7♭5 | A♭♭ becomes A♭ | 1 ♭3 ♭5 ♭7 | 3 |
| B♭m6 | F♭ becomes F | 1 ♭3 5 6 | 3 |
| B♭m | F♭, A♭♭ becomes F | 1 ♭3 5 | 2 |
| B♭m7 | F♭, A♭♭ becomes F, A♭ | 1 ♭3 5 ♭7 | 2 |
| B♭mMaj7 | F♭, A♭♭ becomes F, A | 1 ♭3 5 7 | 2 |
| B♭6 | D♭, F♭ becomes D, F | 1 3 5 6 | 2 |
Frequencies
| Note | MIDI | Frequency |
|---|---|---|
| B♭3 | 58 | 233.08 Hz |
| D♭4 | 61 | 277.18 Hz |
| F♭4 | 64 | 329.63 Hz |
| A♭♭4 | 67 | 392.00 Hz |
Reference pitch A440, 12-TET, close root position.
Set theory: prime form, Forte number, interval vector
- Absolute pitch class set
- {10, 1, 4, 7}
- Normal order
- [1, 4, 7, 10]
- Prime form
- (0369)
- Forte number
- 4-28
- Interval vector
- <004002>
| Pair | Interval | Semitones | Interval class |
|---|---|---|---|
| B♭ to D♭ | Minor third | 3 | 3 |
| B♭ to F♭ | Tritone | 6 | 6 |
| B♭ to A♭♭ | Major sixth | 9 | 3 |
| D♭ to F♭ | Minor third | 3 | 3 |
| D♭ to A♭♭ | Tritone | 6 | 6 |
| F♭ to A♭♭ | Minor third | 3 | 3 |
Where these facts come from
Every value on this page is derived from the note formula for a diminished 7th applied to the root B♭, 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.