Bb13

Bb13 is Bb, D, F, Ab, C and G, a dominant thirteenth. The shape this page opens on is written x10133, lowest string first.

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

Also written Bbdom13 or Bb dominant 13. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 10 common shapes for Bb13 on the guitar, and 55 derived voicings in 5 families.

One note away. Change a single note of Bb13 and you have Bbmaj13 (with one note moved), Bb69 (with one note taken away), Bb9 (with one note taken away) or Bb9#11 (with one note moved).

In which keys. Every note of Bb13 belongs to C minor (the ♭VII) and Eb major (the V).

The common shapes, written lowest string first: x10133, 111133, 635334, 650044, 655564, 666788, 686786, x-13-12-13-15-15, x-13-12-13-13-15, 13-13-13-13-15-15.

Under the hand. 2 of the 10 shapes here sit in open position, and the first uses 1 open string with 1 left unplayed. 7 of the 10 need a barre. Together they cover the neck from the 1st fret to the 15th.

Where it goes. Bb13 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. Bb13 has x1x133, 6x678x, x-13-x-13-15-15.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Bb13 has 3101xx, xx5334, 4553xx, xx6786, x-11-12-12-11-x, x1513x, 6-10-6-7-x-x, x-10-8-7-9-x.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. Bb13 has x1x133, 4x533x, x-10-x-7-9-6, 6x678x, 10-x-8-12-9-x, x-11-x-12-11-10, 15-x-12-13-11-x, x-13-x-13-15-15.

Rootless. The root left to the bass player. Frees a finger for a tension. Bb13 has xx0113, xx3133, xx5534, xx6788, x8678x, x-11-12-12-13-x, x-x-15-13-15-15, x3x133.

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. Bb13 has 4x5330, 4300xx, xx0054, 4x005x.

Tensions. A shell of Bb13, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (E).

What kind of chord this is. Bb13 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.