Am7b5

Am7b5 is A, C, Eb and G, a half-diminished seventh. The shape this page opens on is written x0101x, lowest string first.

Note by note. A is the root, C is the minor third, Eb is the flat fifth and G is the flat seventh.

Also written Aø, Aø7, Am7-5, Am7(b5) or A half diminished. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 9 common shapes for Am7b5 on the guitar, and 29 derived voicings in 3 families.

One note away. Change a single note of Am7b5 and you have Adim (with one note taken away), Adim7 (with one note moved), Am7 (with one note moved), AmMaj7b5 (with one note moved), A7b5 (with one note moved) or Am/G (with one note moved).

In which keys. Every note of Am7b5 belongs to G minor (the ii°) and Bb major (the vii°).

The common shapes, written lowest string first: x0101x, xx1213, 5xx543, 5x554x, 567585, xx7888, x-12-10-12-10-11, x-12-13-12-13-x, x-x-13-14-13-15.

Under the hand. 1 of the 9 shapes here sits in open position, and the first uses 2 open strings with 2 left unplayed. 3 of the 9 need a barre. Together they cover the neck from the 1st fret to the 15th.

Where it goes. Am7b5 is the ii of G minor, which is where it is nearly always found: half-diminished, then an altered dominant, then the minor tonic.

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. Am7b5 has x0554x, 5x554x, x-12-x-12-13-11, 5358xx, 5-10-10-8-x-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Am7b5 has xx1213, 3312xx, x0101x, xx5545, 5655xx, xx7888, x-10-10-8-10-x, 11-12-10-12-x-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. Am7b5 has 3x121x, x3x243, 5x554x, x6x585, 8x788x, x-10-x-8-10-8, 11-x-10-12-10-x, x-12-x-12-13-11.

Tensions. A shell of Am7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (D) and the b13 (F).

What kind of chord this is. Am7b5 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.