Bb7

Bb7 is Bb, D, F and Ab, a dominant seventh. The shape this page opens on is written x13131, lowest string first.

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

Also written Bbdom7 or Bb dominant 7. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 7 common shapes for Bb7 on the guitar, and 36 derived voicings in 4 families.

One note away. Change a single note of Bb7 and you have Bb (with one note taken away), Bbmaj7 (with one note moved), Bbm7 (with one note moved), Bbadd9 (with one note moved), Bb6 (with one note moved) or Bb7sus4 (with one note moved).

In which keys. Every note of Bb7 belongs to C minor (the ♭VII) and Eb major (the V).

The common shapes, written lowest string first: x13131, xx3334, 653334, 686766, x-x-8-10-9-10, x-13-12-13-11-x, x-13-15-13-15-13.

Under the hand. None of the shapes for Bb7 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 5 of the 7 need a barre. Together they cover the neck from the 1st fret to the 15th.

Where it goes. Bb7 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. Bb7 has x101xx, 656xxx, x-13-12-13-x-x, x1x13x, 6x67xx, x-13-x-13-15-x, 6x01xx.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Bb7 has 1101xx, x1313x, xx3334, 4533xx, xx6766, 6867xx, x8879x, x-x-8-10-9-10.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. Bb7 has x1x131, x5x364, 4x333x, x8x796, 6x676x, 10-x-8-10-9-x, x-11-x-10-11-10, 13-x-12-13-11-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. Bb7 has 453300, 6x6760, 4x3330, x56360, 6560xx, 44000x.

Tensions. A shell of Bb7, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Cb), the 9 (C), the #9 (C#), the #11 (E), the b13 (Gb) and the 13 (G).

What kind of chord this is. Bb7 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.