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B 7th flat 5 chord on bass (B7♭5)
Also called or written B7♭5, B, B Dominant 7th Flat 5 or B 7th ♭5
B 7th flat 5 contains B, D♯, F and A. The 7th-fret shape sits high on the neck, where the frets are closer together and the stretch feels easier.
How it is built
Formula 1, 3, ♭5, ♭7
How do you play a B 7th flat 5 chord on bass?
B 7th flat 5 is played at the 7th fret as 7 8 7 8: index finger on the E string at fret 7, ring finger on the A string at fret 8, middle finger on the D string at fret 7 and pinky finger on the G string at fret 8.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 7 | 1 | B (1) |
| 3 (A) | 8 | 3 | F (♭5) |
| 2 (D) | 7 | 2 | A (♭7) |
| 1 (G) | 8 | 4 | D♯ (3) |
AdvancedThe 7th-fret shape requires the pinky to reach fret 8 on the 1st string while the index holds fret 7 on the 4th string, stretching the left hand.
B7♭5/F inversion · fret 1
B 7th flat 5 is played at the 1st fret as 1 2 1 2: index finger on the E string at fret 1, ring finger on the A string at fret 2, middle finger on the D string at fret 1 and pinky finger on the G string at fret 2.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 1 | 1 | F (♭5) |
| 3 (A) | 2 | 3 | B (1) |
| 2 (D) | 1 | 2 | D♯ (3) |
| 1 (G) | 2 | 4 | A (♭7) |
B7♭5/F inversion · fret 13
B 7th flat 5 is played at the 13th fret as 13 14 13 14: index finger on the E string at fret 13, ring finger on the A string at fret 14, middle finger on the D string at fret 13 and pinky finger on the G string at fret 14.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 13 | 1 | F (♭5) |
| 3 (A) | 14 | 3 | B (1) |
| 2 (D) | 13 | 2 | D♯ (3) |
| 1 (G) | 14 | 4 | A (♭7) |
Why it sounds like that
B 7th flat 5 is built from the formula 1, 3, ♭5, ♭7. The diminished 5th between B and F gives the chord its tense colour. Compare it with B 7th, where the 5th is perfect.
What goes wrong with B 7th flat 5?
- Letting the pinky collapse on the 1st string, which mutes the A at fret 8.
- Pressing the ring finger too flat on the 3rd string, so it deadens the 2nd string next to it.
- Striking the open 5th string, which is not part of the chord and adds an unwanted B.
When to use it
B 7th flat 5 works as a dominant chord in jazz and blues, often resolving to E major or E minor. Use it over B 7th when the melody carries a ♭5. Its tense sound suits turnarounds and passing chords.
Changing to and from B 7th flat 5
- Move to A 7th flat 5 by sliding the shape down two frets to the 5th fret.
- Move to C 7th flat 5 by sliding the shape up one fret to the 8th fret.
Which voicing to use
The 7th-fret shape keeps B in the bass for a root-position sound. The B7♭5/F inversion at fret 1 or 13 puts the ♭5 in the bass, creating a darker, less stable feel.
Other B chords
Common questions
How is B 7th flat 5 written?
B 7th flat 5 is written B7♭5 or B. The symbol B is also used, and the chord is sometimes called Dominant 7th Flat 5.
What is the difference between B7♭5 and B7?
B7♭5 has a diminished 5th (F) instead of the perfect 5th (F♯) in B7. That one note changes the chord from bluesy to tense and unresolved.
Can B7♭5 be used in place of B7?
B7♭5 can replace B7 when the melody or solo uses the ♭5. In a standard blues, the ♭5 may clash with the expected perfect 5th, so use it selectively.