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B diminished major 7th chord on guitar (BdimMaj7)
Also called or written BdimMaj7, BdimM7, B°M7, B augmented minor seventh or B minor seventh sharp five
B diminished major 7th is built from B, D, F and A♯. The open voicing keeps the root on the A string while the high e adds a leading-tone shimmer.
How it is built
Formula 1, ♭3, ♭5, 7
- Root positionB–D–F–A♯BdimMaj7×-2-0-3-0-1
- First inversionD–F–A♯–BBdimMaj7/D×-×-0-3-0-1
- Second inversionF–A♯–B–DBdimMaj7/F1-1-0-3-0-1
- Third inversionA♯–B–D–FBdimMaj7/A♯×-1-0-3-0-1
How do you play a B diminished major 7th chord on guitar?
B diminished major 7th is played in open position as × 2 0 3 0 1: middle finger on the A string at fret 2, ring finger on the G string at fret 3 and index finger on the high e string at fret 1. The D and B strings ring open. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 2 | 2 | B (1) |
| 4 (D) | open | — | D (♭3) |
| 3 (G) | 3 | 3 | A♯ (7) |
| 2 (B) | open | — | B (1) |
| 1 (e) | 1 | 1 | F (♭5) |
AdvancedThe open voicing demands precise muting of the low E while the index finger reaches to the high e at fret 1.
Open · ×-2-0-3-3-1
B diminished major 7th is played in open position as × 2 0 3 3 1: middle finger on the A string at fret 2, ring finger on the G string at fret 3, pinky finger on the B string at fret 3 and index finger on the high e string at fret 1. The D string rings open. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 2 | 2 | B (1) |
| 4 (D) | open | — | D (♭3) |
| 3 (G) | 3 | 3 | A♯ (7) |
| 2 (B) | 3 | 4 | D (♭3) |
| 1 (e) | 1 | 1 | F (♭5) |
2nd fret
B diminished major 7th is played at the 2nd fret as × 2 3 3 3 ×: index finger on the A string at fret 2, middle finger on the D string at fret 3, ring finger on the G string at fret 3 and pinky finger on the B string at fret 3. The low E and high e strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 2 | 1 | B (1) |
| 4 (D) | 3 | 2 | F (♭5) |
| 3 (G) | 3 | 3 | A♯ (7) |
| 2 (B) | 3 | 4 | D (♭3) |
| 1 (e) | muted | — | — |
7th fret
B diminished major 7th is played at the 7th fret as 7 8 8 7 × ×: index finger on the low E string at fret 7, ring finger on the A string at fret 8, pinky finger on the D string at fret 8 and middle finger on the G string at fret 7. The B and high e strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | 7 | 1 | B (1) |
| 5 (A) | 8 | 3 | F (♭5) |
| 4 (D) | 8 | 4 | A♯ (7) |
| 3 (G) | 7 | 2 | D (♭3) |
| 2 (B) | muted | — | — |
| 1 (e) | muted | — | — |
9th fret
B diminished major 7th is played at the 9th fret as × × 9 10 11 10: index finger on the D string at fret 9, middle finger on the G string at fret 10, pinky finger on the B string at fret 11 and ring finger on the high e string at fret 10. The low E and A strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | muted | — | — |
| 4 (D) | 9 | 1 | B (1) |
| 3 (G) | 10 | 2 | F (♭5) |
| 2 (B) | 11 | 4 | A♯ (7) |
| 1 (e) | 10 | 3 | D (♭3) |
Why it sounds like that
B diminished major 7th uses the formula 1, ♭3, ♭5, 7. The diminished 5th between B and F gives the chord its tense core, and the major 7th A♯ sits a semitone below the octave. Compare it to B minor 7th flat 5th, which lowers the 7th to A.
What goes wrong with B diminished major 7th?
- Letting the low E string ring out and muddy the bass.
- Flattening the ring finger onto the B string and choking the open note.
When to use it
B diminished major 7th works as a passing chord in B minor progressions, often moving to B minor or B 7th. Its leading tone pulls toward C, so use it before C major in chromatic lines. The chord suits jazz ballads and film-score tension.
Changing to and from B diminished major 7th
- Sliding the shape down one fret to the 1st fret gives B♭ diminished major 7th.
Which voicing to use
The open voicing keeps the bass on B and is the easiest to grab. The 2nd fret shape repeats the same bass note an octave higher, while the 9th fret position adds a brighter register for solos.
Other B chords
Common questions
How is B diminished major 7th written?
B diminished major 7th is written B°M7 or BdimM7.
What is the difference between B diminished major 7th and B minor 7th flat 5th?
B diminished major 7th has a major 7th, A♯. B minor 7th flat 5th lowers that note to A, creating a dominant-quality chord.
Why does B diminished major 7th sound so tense?
The diminished 5th between B and F creates a tritone, and the major 7th A♯ rubs against the root. Together they produce a dissonant, leading-tone effect.