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B♭ 7th flat 5 chord on bass (B♭7♭5)
Also called or written B♭7♭5, B♭, B♭ Dominant 7th Flat 5 or B♭ 7th ♭5
B♭ 7th flat 5 contains B♭, D, F♭ and A♭. The 6th-fret shape is a compact four-finger cluster, but the open-string inversion at fret 0 offers a simpler entry point.
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 6th fret as 6 7 6 7: index finger on the E string at fret 6, ring finger on the A string at fret 7, middle finger on the D string at fret 6 and pinky finger on the G string at fret 7.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 6 | 1 | B♭ (1) |
| 3 (A) | 7 | 3 | F♭ (♭5) |
| 2 (D) | 6 | 2 | A♭ (♭7) |
| 1 (G) | 7 | 4 | D (3) |
AdvancedThe 6th-fret shape requires the pinky to reach fret 7 on the 1st string while the index holds fret 6 on the 4th string, stretching the left hand.
B♭7♭5/F♭ inversion · open position
B♭ 7th flat 5 is played in open position as 0 1 0 1: index finger on the A string at fret 1 and middle finger on the G string at fret 1. The E and D strings ring open.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | open | — | F♭ (♭5) |
| 3 (A) | 1 | 1 | B♭ (1) |
| 2 (D) | open | — | D (3) |
| 1 (G) | 1 | 2 | A♭ (♭7) |
B♭7♭5/F♭ inversion · fret 12
B♭ 7th flat 5 is played at the 12th fret as 12 13 12 13: index finger on the E string at fret 12, ring finger on the A string at fret 13, middle finger on the D string at fret 12 and pinky finger on the G string at fret 13.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 12 | 1 | F♭ (♭5) |
| 3 (A) | 13 | 3 | B♭ (1) |
| 2 (D) | 12 | 2 | D (3) |
| 1 (G) | 13 | 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♭ defines its unstable quality. Compare it with B♭ 7th, which has a perfect 5th.
What goes wrong with B♭ 7th flat 5?
- Letting the pinky collapse on the 1st string, which mutes the A♭ at fret 7.
- 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
Use the supplied linked chords to hear its tension without adding unsupported harmony. It can substitute for B♭ 7th when the ♭5 is needed. Its tense sound fits bebop and fusion lines.
Changing to and from B♭ 7th flat 5
- Move to A♭ 7th flat 5 by sliding the shape down two frets to the 4th fret.
- Move to B 7th flat 5 by sliding the shape up one fret to the 7th fret.
Which voicing to use
The 6th-fret shape keeps B♭ in the bass for a root-position sound. The B♭7♭5/F♭ inversion at fret 0 or 12 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 B♭7♭5 or Bb7♭5. The symbol B♭ is also used, and it is sometimes called Dominant 7th Flat 5. It is also spelled A♯ in enharmonic notation for the same sounding root.
What is the difference between B♭7♭5 and B♭7?
B♭7♭5 has a diminished 5th (F♭) instead of the perfect 5th (F) in B♭7. That one note changes the chord from bluesy to tense and unresolved.
Can B♭7♭5 be used in place of B♭7?
B♭7♭5 can replace B♭7 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.