An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
Bb9 is Bb, D, F, Ab and C — Bb7 with the ninth stacked on top.
It sounds bright and full, still clearly pulling. The ninth adds height without softening the tritone underneath it, which is why funk and soul comp on this rather than on a plain 7.

| Bb | D | F | Ab | C |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | 9 |
Dominant — the same pull as a 7, with more colour.
Also written Bbdom9 or Bb dominant 9. The same chord either way; which spelling you meet depends on who wrote the chart.
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
Bb9 has 4 of them, on strings 6-4-3-2-1, strings 5-4-3-2-1 and the bottom four strings, from the 3rd fret up to the 5th — every inversion the chord has: Bb in the bass, D in the bass, Ab in the bass and C in the bass. The one to learn first is the Ab shape at the 3rd fret, which is the easiest grip here.
Start with 6565xx — no barre and low, at the 5th fret. 1 of the 9 shapes here sits in open position. 6 of the 9 need a barre. Together they cover the neck from the 1st fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x10111 | open position | Bb, root position | F | barred |
| x33334 | 3rd fret | C, 9th in the bass | Ab | barred |
| 633534 | 3rd fret | Bb, root position | Ab | barred |
| 6565xx | 5th fret | Bb, root position | C | all fretted |
| 686568 | 5th fret | Bb, root position | C | barred |
| 686768 | 6th fret | Bb, root position | C | barred |
| xx8798 | 7th fret | Bb, root position | C | all fretted |
| 10-x-8-10-9-8 | 8th fret | D, 1st inversion | C | all fretted |
| x-13-12-13-13-13 | 12th fret | Bb, root position | F | barred |
The same notes rebuilt from scratch give 5 shell, 13 drop 2, 8 drop 3 and 15 rootless voicings, each on its own page.
Tensions. A shell of Bb9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (E), the b13 (Gb) and the 13 (G).
Bb9 is the V of Eb, and that is where it goes if it goes anywhere: the third and the flat seventh are a tritone apart, and both resolve by a semitone into Eb.
Voice by voice, Bb9 → Eb. 2 voices move by a semitone, and one note is common to both chords.
| In Bb9 | Moves | In Eb |
|---|---|---|
| Bb, the root | stays where it is | Bb, the fifth |
| D, the major third | rises a semitone | Eb, the root |
| F, the fifth | falls a whole tone | Eb, the root |
| Ab, the flat seventh | falls a semitone | G, the major third |
| C, the ninth | falls a whole tone | Bb, the fifth |
In which keys. Every note of Bb9 belongs to C minor (the ♭VII) and Eb major (the V, the dominant).
Every note of Bb9 is in Bb mixolydian and Bb lydian dominant.
Change one note of Bb9 and you have Bbmaj9 (the flat seventh becomes a major seventh), Bbm9 (the major third becomes a minor third), Bbadd9 (drop the flat seventh), Bb69 (the flat seventh becomes a sixth), Bb7 (drop the ninth) or Bb9b5 (the fifth becomes a flat fifth).
Bb9 is a dominant chord — root, major third, fifth, minor seventh. Dominant seventh chords on every root.
On Bb9’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.