Also written AdimMaj7, AdimM7 or A°M7
A diminished major 7th contains A, C, E♭, and G♯. The open shape bars the D, G, and B strings at the 1st fret, making it a compact but advanced grip.
The same three notes, with a different one in the bass.
A diminished major 7th is built from the formula 1, ♭3, ♭5, 7. The diminished 5th between A and E♭ gives the chord its tense quality, while the major 7th G♯ adds a sharp leading tone. Compare it to A minor 7th flat 5th, which lowers the 7th to G.
A diminished major 7th works as a passing chord in A minor progressions, such as A minor–A diminished major 7th–A minor 7th. Its dissonance suits jazz and film-noir textures. Use it to lead into A minor or A 7th.
The open position keeps the bass on A, while the 5th fret voicing moves the same notes up the neck. The AdimM7/C inversion places C in the bass, softening the root's pull.
A diminished major 7th is played in open position as × 0 1 1 1 ×: barre your index finger across fret 1. The A string rings open. The low E and high e strings stay muted.
Tip — The index barre must fret the D, G, and B strings cleanly while the low and high E strings stay muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | open | — | A (1) |
| 4 (D) | 1 | 1 (barre) | E♭ (♭5) |
| 3 (G) | 1 | 1 (barre) | G♯ (7) |
| 2 (B) | 1 | 1 (barre) | C (♭3) |
| 1 (e) | muted | — | — |
A diminished major 7th is played at the 5th fret as 5 6 6 5 × ×: index finger on the low E string at fret 5, ring finger on the A string at fret 6, pinky finger on the D string at fret 6 and middle finger on the G string at fret 5. The B and high e strings stay muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | 5 | 1 | A (1) |
| 5 (A) | 6 | 3 | E♭ (♭5) |
| 4 (D) | 6 | 4 | G♯ (7) |
| 3 (G) | 5 | 2 | C (♭3) |
| 2 (B) | muted | — | — |
| 1 (e) | muted | — | — |
A diminished major 7th is played at the 7th fret as × × 7 8 9 8: index finger on the D string at fret 7, middle finger on the G string at fret 8, pinky finger on the B string at fret 9 and ring finger on the high e string at fret 8. The low E and A strings stay muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | muted | — | — |
| 4 (D) | 7 | 1 | A (1) |
| 3 (G) | 8 | 2 | E♭ (♭5) |
| 2 (B) | 9 | 4 | G♯ (7) |
| 1 (e) | 8 | 3 | C (♭3) |
A diminished major 7th is played at the 12th fret as × 12 13 13 13 ×: index finger on the A string at fret 12, middle finger on the D string at fret 13, ring finger on the G string at fret 13 and pinky finger on the B string at fret 13. The low E and high e strings stay muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 12 | 1 | A (1) |
| 4 (D) | 13 | 2 | E♭ (♭5) |
| 3 (G) | 13 | 3 | G♯ (7) |
| 2 (B) | 13 | 4 | C (♭3) |
| 1 (e) | muted | — | — |
A diminished major 7th is played at the 2nd fret as × 3 × 2 4 4: middle finger on the A string at fret 3, index finger on the G string at fret 2, ring finger on the B string at fret 4 and pinky finger on the high e string at fret 4. The low E and D strings stay muted.
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 3 | 2 | C (♭3) |
| 4 (D) | muted | — | — |
| 3 (G) | 2 | 1 | A (1) |
| 2 (B) | 4 | 3 | E♭ (♭5) |
| 1 (e) | 4 | 4 | G♯ (7) |
A diminished major 7th is written A°M7 or AdimM7.
A diminished major 7th has a major 7th (G♯), while A minor 7th flat 5th has a minor 7th (G). The major 7th creates a sharper leading tone.
The diminished 5th between A and E♭ creates a tritone, and the major 7th G♯ adds a leading tone. Together they produce a highly dissonant, unresolved sound.