Adim7 — A diminished seventh chord
Four notes each a minor third above the last, so the octave is divided into four equal parts. Every note of the chord can act as the root, which gives the chord four spellings for one set of notes.
- 1 = A
- b3 = C
- b5 = Eb
- bb7 = Gb
- Symbol
- Adim7
- Root
- A
- Quality
- Diminished seventh
- Family
- seventh
- Notes
- A C Eb Gb
- Degree formula
1 b3 b5 bb7- Semitones from the root
0 3 6 9- Distinct pitch classes
- 4
- Interval structure
- Stacked from the root: 3 semitones, 3 semitones, 3 semitones
- Notation
- Written dim7 or o7. Functions as an altered dominant a semitone below the target chord.
- Key
- A · A major / F# minor key signature
Formula
The chord tones in order from the root, with the interval each one forms above it.
| Degree | Note | Semitones | Interval from the root |
|---|---|---|---|
| 1 | A | 0 | Perfect unison |
| b3 | C | 3 | Minor third |
| b5 | Eb | 6 | Tritone |
| bb7 | Gb | 9 | Major sixth |
Inversions
An inversion is the same set of notes with a different one in the bass. The last column gives the distance of each note above the bass note, in semitones.
| Inversion | Bass note | Degree in the bass | Notes above the bass | Semitones above the bass |
|---|---|---|---|---|
| root position | A | 1 | A – C – Eb – Gb | 0 3 6 9 |
| first inversion | C | b3 | C – Eb – Gb – A | 0 3 6 9 |
| second inversion | Eb | b5 | Eb – Gb – A – C | 0 3 6 9 |
| third inversion | Gb | bb7 | Gb – A – C – Eb | 0 3 6 9 |
Playable voicings
These shapes were found by searching the fretboard of a standard-tuned guitar (E A D G B E) rather than copied from a chord book. The search allows every string to sound or to be muted, rejects any shape with a muted string between two sounding strings, rejects any shape whose fretted notes span more than four frets (a five-fret window), requires every chord tone to be present, and then sorts what remains with root-position shapes first and the most compact, lowest shapes next. The shapes shown are the first six of that ordering; other orderings are possible at the same frets.
| # | Shape (low string first) | Notes | Degrees | Bass | Span (frets) | Sounding strings |
|---|---|---|---|---|---|---|
| 1 | 5-3-4-5-4-5 | A C F# C D# A | 1 b3 bb7 b3 b5 1 | A | 2 | 6 |
| 2 | 5-6-4-5-4-5 | A D# F# C D# A | 1 b5 bb7 b3 b5 1 | A | 2 | 6 |
| 3 | 5-6-7-5-7-5 | A D# A C F# A | 1 b5 1 b3 bb7 1 | A | 2 | 6 |
| 4 | 5-3-4-2-4-2 | A C F# A D# F# | 1 b3 bb7 1 b5 bb7 | A | 3 | 6 |
| 5 | 5-3-4-2-4-5 | A C F# A D# A | 1 b3 bb7 1 b5 1 | A | 3 | 6 |
| 6 | 5-3-4-5-4-2 | A C F# C D# F# | 1 b3 bb7 b3 b5 bb7 | A | 3 | 6 |
Shape numbers run from the lowest string to the highest, so the left-hand number is the sixth string (low E) in standard tuning. Multiple shapes are listed because a chord can be voiced several ways, and because a lower position is not always the better sounding one.
Related chords and scales
- KeyEverything in A
- ScaleA diminished (whole-half)
- ChordCdim7
- ChordEbdim7
- ChordF#dim7
Related