Chords
Bb Dominant flat ninth
Bb · D · F · Ab · Cb
A dominant seventh with a flattened ninth — sharp, dark and strongly directional.
Bb Dominant flat ninth
Bb · D · F · Ab · Cb
Voicings on the piano
| Voicing | Notes | Play it on your instrument |
|---|---|---|
| Closed, root position | Bb3 · D4 · F4 · Ab4 · Cb4 | |
| Open (drop 2) | Ab3 · Bb3 · Cb4 · D4 · F4 | |
| Shell | Bb3 · D4 · Ab4 | |
| Rootless | D4 · Gb4 · Ab4 · Cb5 |
Tap a key or a fret to hear it.
Anatomy
Bb Dominant flat ninth (Bb7b9) contains the notes Bb · D · F · Ab · Cb, each with a role measured as an interval from the root.
Read on: how triads are built · seventh chords · extensions
Inversions
An inversion of Bb Dominant flat ninth puts a chord tone other than Bb in the bass; the name after the slash is that bass note.
Where it lives
The keys and the scales Bb Dominant flat ninth belongs to.
In which keys
Bb Dominant flat ninth is diatonic to 1 key; the numeral is its degree and the label its harmonic function.
- D# minorV7b9Dominant
Extensions beyond the seventh count when every note sits in the key.
Scales that contain it
Bb Dominant flat ninth fits inside these scales, each built on Bb.
- Bb Phrygian DominantBb · Cb · D · Eb · F · Gb · Ab
- Bb Half-Whole DiminishedBb · Cb · Db · D · E · F · G · Ab
- Bb FlamencoBb · Cb · Db · D · E · F · Ab
- Bb Spanish HeptatonicBb · Cb · Db · D · Eb · F · Gb · Ab
Understanding the Bb Dominant flat ninth chord
Names and symbols
Bb7b9 is the chord symbol for Bb Dominant flat ninth.
How it is built
On Bb it is Bb · D · F · Ab · Cb, stacking 1P · 3M · 5P · 7m · 9m. The ♭9 sits a semitone above the root, which is a deliberate clash.
How it is used
It is the standard dominant of a minor ii–V–i, where the flattened ninth belongs to the key rather than being an import. Its upper four notes form a diminished seventh chord, which is why diminished vocabulary works so well over it.
Learn this properly
Chapter 17: Theory in StylesCommon questions
- What notes are in Bb7b9?
- Bb7b9 contains Bb · D · F · Ab · Cb. Name any set of notes with the chord identifier.
- When do you use a ♭9?
- Most naturally on the V of a minor key, where the flattened ninth is diatonic. It also works as an altered colour on any dominant.
- What scale fits a 7♭9 chord?
- The half-whole diminished scale, and the harmonic minor of the key it resolves to.
- What notes are in the Bb Dominant flat ninth chord?
- The Bb Dominant flat ninth chord contains the notes Bb · D · F · Ab · Cb: the root Bb with the intervals 1P, 3M, 5P, 7m, 9m stacked above it. Play them together for the chord or one after another for an arpeggio. The lowest note is normally Bb, but any chord tone can take the bass in an inversion.
- What intervals make up the Bb Dominant flat ninth chord?
- Measured from Bb, the Bb Dominant flat ninth chord stacks the intervals 1P, 3M, 5P, 7m, 9m. The quality of the third and of the seventh, if there is one, is what gives the chord its character; the rest of the notes colour it. Every interval in the formula links to its own page, with its sound.