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A diminished 7th chord on bass (Adim7)
Also called or written Adim7 or A°7
A diminished 7th contains A, C, E♭, and G♭. The 4th fret position demands a wide pinky stretch across all four strings.
How it is built
Formula 1, ♭3, ♭5, ♭♭7
- Root positionA–C–E♭–G♭Adim75-6-4-5
- First inversionC–E♭–G♭–AAdim7/C8-9-7-8
- Second inversionE♭–G♭–A–CAdim7/E♭11-12-10-11
- Third inversionG♭–A–C–E♭Adim7/G♭2-3-1-2
How do you play an A diminished 7th chord on bass?
A diminished 7th is played at the 4th fret as 5 6 4 5: middle finger on the E string at fret 5, pinky finger on the A string at fret 6, index finger on the D string at fret 4 and ring finger on the G string at fret 5.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 5 | 2 | A (1) |
| 3 (A) | 6 | 4 | E♭ (♭5) |
| 2 (D) | 4 | 1 | G♭ (6) |
| 1 (G) | 5 | 3 | C (♭3) |
AdvancedThe pinky must reach the 6th fret on the A string while the ring finger holds the 5th fret on the G string, stretching the hand.
Adim7/C inversion
A diminished 7th is played at the 7th fret as 8 9 7 8: middle finger on the E string at fret 8, pinky finger on the A string at fret 9, index finger on the D string at fret 7 and ring finger on the G string at fret 8.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 8 | 2 | C (♭3) |
| 3 (A) | 9 | 4 | G♭ (6) |
| 2 (D) | 7 | 1 | A (1) |
| 1 (G) | 8 | 3 | E♭ (♭5) |
Adim7/E♭ inversion
A diminished 7th is played at the 10th fret as 11 12 10 11: middle finger on the E string at fret 11, pinky finger on the A string at fret 12, index finger on the D string at fret 10 and ring finger on the G string at fret 11.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 11 | 2 | E♭ (♭5) |
| 3 (A) | 12 | 4 | A (1) |
| 2 (D) | 10 | 1 | C (♭3) |
| 1 (G) | 11 | 3 | G♭ (6) |
Adim7/G♭ inversion · fret 1
A diminished 7th is played at the 1st fret as 2 3 1 2: middle finger on the E string at fret 2, pinky finger on the A string at fret 3, index finger on the D string at fret 1 and ring finger on the G string at fret 2.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 2 | 2 | G♭ (6) |
| 3 (A) | 3 | 4 | C (♭3) |
| 2 (D) | 1 | 1 | E♭ (♭5) |
| 1 (G) | 2 | 3 | A (1) |
Adim7/G♭ inversion · fret 13
A diminished 7th is played at the 13th fret as 14 15 13 14: middle finger on the E string at fret 14, pinky finger on the A string at fret 15, index finger on the D string at fret 13 and ring finger on the G string at fret 14.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 14 | 2 | G♭ (6) |
| 3 (A) | 15 | 4 | C (♭3) |
| 2 (D) | 13 | 1 | E♭ (♭5) |
| 1 (G) | 14 | 3 | A (1) |
Why it sounds like that
A diminished 7th is built from the formula 1, ♭3, ♭5, ♭♭7. The diminished 5th between A and E♭ gives the chord its tense quality. Compare it to A minor 7th flat 5th, which raises the ♭♭7 to a ♭7.
What goes wrong with A diminished 7th?
- Letting the pinky flatten and buzz the 3rd string.
- Pressing the index finger too hard, sharpening the 2nd string note.
When to use it
A diminished 7th works as a passing chord in minor keys, often resolving to B minor or B major. Use it in jazz, classical, and metal bass lines for a dark, unstable color. It also pairs with A minor 7th flat 5th in half-diminished contexts.
Changing to and from A diminished 7th
- Slide the shape down two frets to the 2nd fret to reach G diminished 7th.
- Slide the shape up one fret to the 5th fret to reach B♭ diminished 7th.
Which voicing to use
The 4th fret position puts the root A on the E string, giving a solid low foundation. For a higher, thinner sound, use the Adim7/C inversion at the 7th fret, where C is the lowest note.
Other A chords
Common questions
How is A diminished 7th written?
A diminished 7th is written as A°7 or Adim7.
What is the difference between A diminished 7th and A minor 7th flat 5th?
A diminished 7th has a ♭♭7 (G♭), while A minor 7th flat 5th has a ♭7 (G). The diminished 7th is more dissonant and symmetrical.
Can A diminished 7th be played in open position?
No, A diminished 7th has no open strings in any of its standard positions. The lowest position starts at the 1st fret for the G♭ inversion.