Bb
Bb7b5
Notes
Bb · D · Fb · Ab
Intervals
- RootBb (1P)
- Major 3rdD (3M)
- Diminished 5thFb (5d)
- Minor 7thAb (7m)
Fretboard
On the fretboard, E represents Fb.
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About
The B♭7♭5 (B♭–D–F♭–A♭) lowers the fifth, replacing the stable perfect fifth with a tritone above the root. Combined with the tritone already present between 3rd and ♭7, the chord contains two tritones — making it extremely unstable and dissonant. In jazz, 7♭5 functions as an altered dominant with a particular flavour of harmonic restlessness. The 3rd, ♭7, and ♭5 are all essential; the F♭ is the defining alteration, and omitting it leaves a plain B♭7. It resolves typically to E♭ or E♭m. Compared to standard B♭7, 7♭5 is considerably more harmonically tense.
Similar chords
Chords sharing two or more notes with this one, ranked by overlap.
Scales containing this chord
- B♭ Whole Tone (deg 1)
- A♭ Whole Tone (deg 2)
- B Diminished (deg 8)
- B Melodic Minor (VII)
- C Whole Tone (deg 6)
- D Diminished (deg 6)
- D Whole Tone (deg 5)
- E Whole Tone (deg 4)
- F Diminished (deg 4)
- F Melodic Minor (IV)
- F♯ Whole Tone (deg 3)
Scales whose notes include every chord tone. Roman numeral marks the chord root’s position in the scale; dashed badges aren’t linked yet.