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B♭ minor 7th flat 5th chord on guitar (B♭m7♭5)
Also called or written B♭m7♭5, B♭ or B♭ Half Diminished Minor 7
B♭ minor 7th flat 5th contains B♭, D♭, F♭, and A♭. The open voicing leaves the high E string ringing, adding a bright edge to the dark harmony.
How it is built
Formula 1, ♭3, ♭5, ♭7
- Root positionB♭–D♭–F♭–A♭B♭m7♭5×-1-2-1-2-0
- First inversionD♭–F♭–A♭–B♭B♭m7♭5/D♭×-4-2-3-2-4
- Second inversionF♭–A♭–B♭–D♭B♭m7♭5/F♭0-1-2-1-2-0
- Third inversionA♭–B♭–D♭–F♭B♭m7♭5/A♭4-4-2-3-2-×
How do you play a B♭ minor 7th flat 5th chord on guitar?
B♭ minor 7th flat 5th is played in open position as × 1 2 1 2 0: index finger on the A string at fret 1, ring finger on the D string at fret 2, middle finger on the G string at fret 1 and pinky finger on the B string at fret 2. The high e string rings open. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 1 | 1 | B♭ (1) |
| 4 (D) | 2 | 3 | F♭ (♭5) |
| 3 (G) | 1 | 2 | A♭ (♭7) |
| 2 (B) | 2 | 4 | D♭ (♭3) |
| 1 (e) | open | — | F♭ (♭5) |
AdvancedThe open voicing requires precise finger placement to avoid muting the open high E string.
6th fret
B♭ minor 7th flat 5th is played at the 6th fret as 6 7 6 6 × ×: index finger on the low E string at fret 6, pinky finger on the A string at fret 7, middle finger on the D string at fret 6 and ring finger on the G string at fret 6. The B and high e strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | 6 | 1 | B♭ (1) |
| 5 (A) | 7 | 4 | F♭ (♭5) |
| 4 (D) | 6 | 2 | A♭ (♭7) |
| 3 (G) | 6 | 3 | D♭ (♭3) |
| 2 (B) | muted | — | — |
| 1 (e) | muted | — | — |
8th fret
B♭ minor 7th flat 5th is played at the 8th fret as × × 8 9 9 9: index finger on the D string at fret 8, middle finger on the G string at fret 9, ring finger on the B string at fret 9 and pinky finger on the high e string at fret 9. 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) | 8 | 1 | B♭ (1) |
| 3 (G) | 9 | 2 | F♭ (♭5) |
| 2 (B) | 9 | 3 | A♭ (♭7) |
| 1 (e) | 9 | 4 | D♭ (♭3) |
11th fret
B♭ minor 7th flat 5th is played at the 11th fret as × 13 11 13 11 12: barre your index finger across fret 11, ring finger on the A string at fret 13, pinky finger on the G string at fret 13 and middle finger on the high e string at fret 12. The low E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 13 | 3 | B♭ (1) |
| 4 (D) | 11 | 1 (barre) | D♭ (♭3) |
| 3 (G) | 13 | 4 | A♭ (♭7) |
| 2 (B) | 11 | 1 (barre) | B♭ (1) |
| 1 (e) | 12 | 2 | F♭ (♭5) |
13th fret
B♭ minor 7th flat 5th is played at the 13th fret as × 13 14 13 14 ×: index finger on the A string at fret 13, ring finger on the D string at fret 14, middle finger on the G string at fret 13 and pinky finger on the B string at fret 14. The low E and high e strings stay muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 6 (E) | muted | — | — |
| 5 (A) | 13 | 1 | B♭ (1) |
| 4 (D) | 14 | 3 | F♭ (♭5) |
| 3 (G) | 13 | 2 | A♭ (♭7) |
| 2 (B) | 14 | 4 | D♭ (♭3) |
| 1 (e) | muted | — | — |
Why it sounds like that
B♭ minor 7th flat 5th is built from the formula 1, ♭3, ♭5, ♭7. The diminished 5th between B♭ and F♭ creates the half-diminished sound. Compare it to B♭ minor 7th, which has a perfect 5th instead.
What goes wrong with B♭ minor 7th flat 5th?
- Muting the 1st string with the palm of the strumming hand.
- Letting the 6th string sound, which adds an E that is a chord tone but muddies the bass.
When to use it
B♭ minor 7th flat 5th functions as the ii chord in A♭ natural minor, leading to E♭7 and then A♭ minor. Its brooding quality fits modal jazz and slow blues.
Changing to and from B♭ minor 7th flat 5th
- Move to B♭ minor 7th by lifting the pinky from the 2nd string, 2nd fret, and placing it on the 3rd string, 3rd fret.
Which voicing to use
The open voicing has the root B♭ in the bass, while the 6th fret position offers a movable shape without open strings. The 11th fret barre gives a higher, more cutting sound.
Other B♭ chords
Common questions
How is B♭ minor 7th flat 5th written?
B♭ minor 7th flat 5th is written as B♭m7♭5 or B♭ half-diminished. The ASCII root is Bb. It is also spelled A♯ in enharmonic notation for the same sounding root.
Why is the 6th string muted in the open voicing?
The 6th string open is E, which is a chord tone, but muting it preserves the intended bass note B♭ and keeps the voicing clear.
What is the difference between B♭ minor 7th flat 5th and B♭ diminished?
B♭ minor 7th flat 5th has a minor 7th (A♭), while B♭ diminished has a diminished 7th (A♭♭). The half-diminished chord is less dissonant.