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B♭ augmented chord on bass (B♭aug)
Also called or written B♭aug or B♭+
B♭ augmented contains B♭, D, and F♯. The 4th-fret shape is a compact three-note cluster that sits comfortably under the fingers.
How it is built
Formula 1, 3, ♯5
How do you play a B♭ augmented chord on bass?
B♭ augmented is played at the 4th fret as 6 5 4 ×: ring finger on the E string at fret 6, middle finger on the A string at fret 5 and index finger on the D string at fret 4. The G string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 6 | 3 | B♭ (1) |
| 3 (A) | 5 | 2 | D (3) |
| 2 (D) | 4 | 1 | F♯ (♯5) |
| 1 (G) | muted | — | — |
IntermediateThe ring finger on the 6th fret of the E string must stretch away from the index on the 4th fret of the D string.
11th fret
B♭ augmented is played at the 11th fret as × 13 12 11: ring finger on the A string at fret 13, middle finger on the D string at fret 12 and index finger on the G string at fret 11. The E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | muted | — | — |
| 3 (A) | 13 | 3 | B♭ (1) |
| 2 (D) | 12 | 2 | D (3) |
| 1 (G) | 11 | 1 | F♯ (♯5) |
B♭aug/D inversion · fret 3
B♭ augmented is played at the 3rd fret as × 5 4 3: ring finger on the A string at fret 5, middle finger on the D string at fret 4 and index finger on the G string at fret 3. The E string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | muted | — | — |
| 3 (A) | 5 | 3 | D (3) |
| 2 (D) | 4 | 2 | F♯ (♯5) |
| 1 (G) | 3 | 1 | B♭ (1) |
B♭aug/D inversion · fret 8
B♭ augmented is played at the 8th fret as 10 9 8 ×: ring finger on the E string at fret 10, middle finger on the A string at fret 9 and index finger on the D string at fret 8. The G string stays muted.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 10 | 3 | D (3) |
| 3 (A) | 9 | 2 | F♯ (♯5) |
| 2 (D) | 8 | 1 | B♭ (1) |
| 1 (G) | muted | — | — |
B♭aug/F♯ inversion
B♭ augmented is played in open position as 2 1 0 3: middle finger on the E string at fret 2, index finger on the A string at fret 1 and ring finger on the G string at fret 3. The D string rings open.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 2 | 2 | F♯ (♯5) |
| 3 (A) | 1 | 1 | B♭ (1) |
| 2 (D) | open | — | D (3) |
| 1 (G) | 3 | 3 | B♭ (1) |
Why it sounds like that
B♭ augmented is built from the formula 1, 3, ♯5. The augmented 5th from B♭ to F♯ gives the chord its bright, tense color. Compare it with B♭ major, which uses F natural instead.
What goes wrong with B♭ augmented?
- Letting the open G string sound, which adds a note not in the chord.
- Fretting the E string with the ring finger too far back, causing a buzz.
- Allowing the middle finger to touch the D string and mute the F♯.
When to use it
B♭ augmented works as a passing chord in B♭ major, often moving to B♭ major or B♭ 5th. Its tense quality suits jazz, blues, and dramatic rock moments.
Changing to and from B♭ augmented
- Move to B♭ major by lowering the F♯ on the D string one fret to F natural while keeping the other fingers in place.
- Slide the shape down one fret to the 3rd fret to reach A augmented.
Which voicing to use
The 4th-fret position keeps B♭ in the bass for a root-position sound. The B♭aug/D inversion at the 3rd fret puts D on the bottom, which lightens the chord and works well when the bass line needs a stepwise approach.
Other B♭ chords
Common questions
How is B♭ augmented written?
B♭ augmented is written as B♭+ or B♭aug. The ASCII root is Bb. It is also spelled A♯ in enharmonic notation for the same sounding root.
What is the difference between B♭ augmented and B♭ major?
B♭ augmented raises the fifth from F to F♯. That single change makes the chord sound tense and unresolved, while B♭ major sounds stable.
Can I play B♭ augmented higher on the neck?
Yes, the 11th-fret position uses the same shape on the A, D, and G strings. It gives a brighter register but the same chord tones.