Bb9

Bb9 is Bb, D, F, Ab and C, a dominant ninth. The shape this page opens on is written x10111, lowest string first.

Note by note. Bb is the root, D is the major third, F is the fifth, Ab is the flat seventh and C is the ninth.

Also written Bbdom9 or Bb dominant 9. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 9 common shapes for Bb9 on the guitar, and 45 derived voicings in 5 families.

One note away. Change a single note of Bb9 and you have Bbmaj9 (with one note moved), Bbm9 (with one note moved), Bbadd9 (with one note taken away), Bb69 (with one note moved), Bb7 (with one note taken away) or Bb9b5 (with one note moved).

In which keys. Every note of Bb9 belongs to C minor (the ♭VII) and Eb major (the V).

The common shapes, written lowest string first: x10111, x33334, 633534, 6565xx, 686568, 686768, xx8798, 10-x-8-10-9-8, x-13-12-13-13-13.

Under the hand. 1 of the 9 shapes here sits in open position, and the first uses 1 open string with 1 left unplayed. 6 of the 9 need a barre. Together they cover the neck from the 1st fret to the 13th.

Where it goes. 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.

Shell. Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top. Bb9 has x1011x, 6565xx, xx8798, x-13-12-13-13-x, 6x011x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Bb9 has x1011x, 4303xx, 6565xx, xx8798, x-13-12-13-13-x, xx0314, x3633x, xx6536.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. Bb9 has 4x031x, x3x334, 6x653x, x5x596, 8x879x, x-11-x-7-11-8, x-13-x-13-13-10, 10-x-10-13-11-x.

Rootless. The root left to the bass player. Frees a finger for a tension. Bb9 has x3313x, xx0111, xx3534, x5656x, xx6768, x-x-10-10-9-10, x-x-12-13-13-13, x-15-15-13-15-x.

Open string. 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 has 6x6530, x56560, x36330, 4300xx.

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).

What kind of chord this is. Bb9 is a dominant chord — root, major third, fifth, minor seventh. dominant seventh chords on every root, and what they are for.

The common shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.