Abdim

Abdim is Ab, Cb and D, a diminished triad. The shape this page opens on is written 42x43x, lowest string first.

Note by note. Ab is the root, Cb is the minor third and D is the flat fifth.

Also written Ab°, Abo or Ab diminished. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 4 common shapes for Abdim on the guitar, and 52 derived voicings in 2 families.

One note away. Change a single note of Abdim and you have Abm (with one note moved), Abdim7 (with one note added), Abm7b5 (with one note added) or AbmMaj7b5 (with one note added).

In which keys. Every note of Abdim belongs to F# minor (the ii°) and A major (the vii°).

The common shapes, written lowest string first: 42x43x, xx67x7, x-11-9-x-9-10, x-11-12-13-12-x.

Under the hand. None of the shapes for Abdim uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. None of them needs a barre. Together they cover the neck from the 2nd fret to the 13th.

Triad. Three notes across one string set. Abdim has x201xx, xx010x, x2010x, x2013x, 420xxx, 4204xx, xxx434, xx0434.

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. Abdim has 456400, xx6430, 756700, 4x0600, xx0420, 7x0600.

Tensions. A shell of Abdim, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (Db) and the b13 (Fb).

What kind of chord this is. Abdim is a diminished chord — root, minor third, flat fifth. diminished and half-diminished 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.