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B♭ 7th sharp 5 chord on bass (B♭7♯5)
Also called or written B♭7♯5, B♭ or B♭ Dominant 7th ♯5
B♭ 7th sharp 5 contains B♭, D, F♯, and A♭. The open D string makes the default voicing easier to fret than the other inversions.
How it is built
Formula 1, 3, ♯5, ♭7
How do you play a B♭ 7th sharp 5 chord on bass?
B♭ 7th sharp 5 is played in open position as 2 1 0 1: ring finger on the E string at fret 2, index finger on the A string at fret 1 and middle finger on the G string at fret 1. The D string rings open.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 2 | 3 | F♯ (♯5) |
| 3 (A) | 1 | 1 | B♭ (1) |
| 2 (D) | open | — | D (3) |
| 1 (G) | 1 | 2 | A♭ (♭7) |
AdvancedThe ring finger must fret the 2nd fret on the E string while the index and middle hold the 1st fret on adjacent strings.
B♭7♯5/F♯ inversion · fret 12
B♭ 7th sharp 5 is played at the 12th fret as 14 13 12 13: pinky finger on the E string at fret 14, middle finger on the A string at fret 13, index finger on the D string at fret 12 and ring finger on the G string at fret 13.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 14 | 4 | F♯ (♯5) |
| 3 (A) | 13 | 2 | B♭ (1) |
| 2 (D) | 12 | 1 | D (3) |
| 1 (G) | 13 | 3 | A♭ (♭7) |
B♭7♯5/A♭ inversion
B♭ 7th sharp 5 is played at the 3rd fret as 4 5 4 3: middle finger on the E string at fret 4, pinky finger on the A string at fret 5, ring finger on the D string at fret 4 and index finger on the G string at fret 3.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 4 | 2 | A♭ (♭7) |
| 3 (A) | 5 | 4 | D (3) |
| 2 (D) | 4 | 3 | F♯ (♯5) |
| 1 (G) | 3 | 1 | B♭ (1) |
Why it sounds like that
B♭ 7th sharp 5 is built from the formula 1, 3, ♯5, ♭7. The augmented 5th, F♯, creates a bright, tense sound. Compare it to B♭ 7th, which has a perfect 5th.
What goes wrong with B♭ 7th sharp 5?
- Letting the ring finger touch the A string and mute it.
- Pressing the index finger too flat and buzzing the A string.
- Striking the open D string too hard and overpowering the fretted notes.
When to use it
B♭ 7th sharp 5 suits jazz, blues, and R&B lines that need a raised 5th. It pairs well with B♭ major and B♭ 7th.
Changing to and from B♭ 7th sharp 5
- Sliding the shape down two frets to the 12th fret gives A♭ 7th sharp 5. Keep the finger spacing identical while shifting.
- Move to B♭ 7th by fretting the D string at the 3rd fret instead of leaving it open; the other fingers stay in place.
Which voicing to use
The F♯ inversion puts the augmented 5th in the bass, giving a bright, unstable sound. The A♭ inversion has the ♭7 in the bass and is higher on the neck. Use the F♯ inversion for a more cutting tone.
Other B♭ chords
Common questions
How is B♭ 7th sharp 5 written?
B♭ 7th sharp 5 is written as B♭7♯5 or B♭7+5. The ASCII root is Bb, so you may see Bb7#5. It is also spelled A♯ in enharmonic notation for the same sounding root.
What is the difference between B♭ 7th sharp 5 and B♭ augmented?
B♭ 7th sharp 5 adds a minor 7th, A♭, to the augmented triad B♭–D–F♯. B♭ augmented has only the root, major 3rd, and augmented 5th. The 7th makes the chord dominant and more dissonant.
Can B♭ 7th sharp 5 be used as a passing chord?
B♭ 7th sharp 5 works as a passing chord between B♭ 7th and B♭ 9th. Its raised 5th creates tension that resolves to the next chord. Use it briefly on a weak beat.