Tools / Chords / B♭ 7th flat 5

B♭ 7th flat 5 chord on bass (B♭7♭5)

Also written B♭7♭5, B♭ or B♭ Dominant 7th Flat 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.

6th fret6-7-6-7

Positions on the neck1 of 3

How it’s built

B♭1Root

D3Major 3rd

F♭♭5Diminished 5th

A♭♭7Minor 7th

Formula 1, 3, ♭5, ♭7

Positions on the neck1 of 3

Inversions

The same three notes, with a different one in the bass.

Root positionB♭–D–F♭–A♭B♭7♭5Bass B♭

First inversionD–F♭–A♭–B♭B♭7♭5/DBass D

Second inversionF♭–A♭–B♭–DB♭7♭5/F♭Bass F♭

Third inversionA♭–B♭–D–F♭B♭7♭5/A♭Bass A♭

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.

How do you play a B♭ 7th flat 5 chord on bass?

6th fret

Intermediate● On the diagram

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.

Tip — The 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.

String-by-string 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)

B♭7♭5/F♭ inversion · open position

Beginner

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.

String-by-string 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

Intermediate

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.

String-by-string 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)

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.

String

Fret

Finger

Note

4 (E)

B♭ (1)

3 (A)

F♭ (♭5)

2 (D)

A♭ (♭7)

1 (G)

D (3)

String

Fret

Finger

Note

4 (E)

open

—

F♭ (♭5)

3 (A)

B♭ (1)

2 (D)

open

—

D (3)

1 (G)

A♭ (♭7)

String

Fret

Finger

Note

4 (E)

F♭ (♭5)

3 (A)

B♭ (1)

2 (D)

D (3)

1 (G)

A♭ (♭7)