Adim7 guitar chord
The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
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About Adim7 — drop 3 voicings
Adim7 is A, C, Eb and Gb — Adim with a diminished seventh stacked on top.
It sounds suspenseful and rootless. Three stacked minor thirds divide the octave evenly, so the same four notes spell four dim7 chords and the shape repeats every three frets.
Adim7 notes and formula
| A | C | Eb | Gb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭♭7 |
Leading-tone or passing chord — it can resolve almost anywhere.
Also written A°7, Ao7 or A diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Adim7
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
Adim7 has 9 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 13th — every inversion the chord has: A in the bass, C in the bass, Eb in the bass and Gb in the bass. The one to learn first is the Gb shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x01212 — no barre and 1 open string. 1 of the 8 shapes here sits in open position. 2 of the 8 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x01212 | open position | A, root position | Gb | 1 open string |
| xx1212 | 1st fret | Eb, 2nd inversion | Gb | all fretted |
| 5x4545 | 4th fret | A, root position | A | barred |
| 567575 | 5th fret | A, root position | A | barred |
| xx7878 | 7th fret | A, root position | C | all fretted |
| x-x-10-11-10-11 | 10th fret | C, 1st inversion | Eb | all fretted |
| x-12-13-11-13-11 | 11th fret | A, root position | Eb | all fretted |
| x-x-13-14-13-14 | 13th fret | Eb, 2nd inversion | Gb | all fretted |
The same notes rebuilt from scratch give 5 shell, 14 drop 2 and 1 open string voicings, each on its own page.
Tensions. A shell of Adim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (B), the 11 (D), the b13 (F) and the maj7 (G#).
How to use Adim7
A diminished seventh divides the octave evenly, so Adim7 has no single root and no single destination: it can lead to D or to Bb, and it is the same four notes either way.
What to play over Adim7
Every note of Adim7 is in A diminished and A half-whole diminished.
Chords near Adim7
Change one note of Adim7 and you have Adim (drop the sixth), Am6 (the flat fifth becomes a fifth), Am7b5 (the sixth becomes a flat seventh), AmMaj7b5 (the sixth becomes a major seventh) or Am/F# (the flat fifth becomes a fifth).
Adim7 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Adim7’s sound and use this page follows Stefan Kostka, Dorothy Payne & Byron Almén, Tonal Harmony (McGraw-Hill, 8th ed., 2018). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.