Sevenths
A diminished 7th chord
Symmetrical and very tense — every note is a minor 3rd apart.
Adim7 is the vii°7 chord in B♭ minor.
- Notes
- ACE♭G♭
- Formula
- 1♭3♭5𝄫7
- Built from
- root · minor 3rd · diminished 5th · diminished 7th
How to play Adim7
About the A diminished 7th chord
Playing it
On guitar, Adim7 has an open-position shape, x01212, using four fingers alongside the open strings. Don’t strum the low E string.
On piano, Adim7 has two black keys (E♭ and G♭) and two white keys.
On ukulele the usual Adim7 shape is 2323, using four fingers.
Related chords
Take away the root and the other three notes form Cdim (C E♭ G♭) — so you can think of Adim7 as Cdim with A added underneath.
Adim7 is symmetrical — its notes are evenly spaced — so Cdim7, E♭dim7 and F♯dim7 contain exactly the same notes. There are only three different-sounding diminished 7th chords in all.
Move a single note and Adim7 becomes a different chord: drop the G♭ for Adim, raise E♭ to E for Am6 and raise G♭ to G for Am7♭5.
