Diminished Seventh chord - piano
The diminished seventh chord (dim7 or °7) is formed by four notes separated by minor thirds. This symmetrical structure creates strong harmonic tension with multiple resolution possibilities.
Intervals
| Degree | I | ♭III | ♭V | ♭♭VII |
|---|---|---|---|---|
| Interval | Root | Minor third | Diminished fifth | Diminished seventh |
| Semitones | 0 | 3 | 6 | 9 |
Formula 1 - ♭3 - ♭5 - ♭♭7
Theory
The dim7 chord is built with four consecutive minor thirds (3 semitones each). C dim7 = C-E♭-G♭-A (B♭♭). Due to its symmetry, only three unique dim7 chords exist: each inversion sounds like another dim7 chord. This property makes it very versatile for modulations.
Examples
Example: Do Diminished Seventh
Styles
Dim7 construction
Formula 1 - 3b - 5b - 7bb: symmetrical (stacked minor thirds). Example Cdim7: C - Eb - Gb - Bbb (A). Totally symmetrical: 4 chords in 1.
Learning
Understand symmetry: Cdim7 = Ebdim7 = Gbdim7 = Adim7. Chromatic passages between chords. Quick modulations.
Seventh chord inversions on piano
Seventh chords have 3 inversions (4 notes = 3 possible inversions).
The 3 inversions
- 1st inversion: third in bass (3-5-7-1), noted 6/5. Jazz walking bass.
- 2nd inversion: fifth in bass (5-7-1-3), noted 4/3. Harmonic pedals.
- 3rd inversion: seventh in bass (7-1-3-5), noted 4/2 or 2. Chromatic walking bass, sophisticated resolutions.
In jazz, seventh inversions are essential for smooth voicings and harmonic comping.
How to play
Movable shape repeated every 3 semitones. Chromatic passages, modulations. Jazz: multiple harmonic substitutions.