About Am7b5 — drop 3 voicings
Am7b5 is A, C, Eb and G — Am7 with the fifth lowered a semitone.
It sounds hollow, and unmistakably going somewhere. Almost always the first chord of a minor ii–V–i, so it walks straight into an altered dominant.
Am7b5 notes and formula
| A | C | Eb | G |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭7 |
Pre-dominant — the ii of a minor key.
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.
How to play Am7b5
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
Am7b5 has 9 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 13th — every inversion the chord has: A in the bass, C in the bass, Eb in the bass and G in the bass. The one to learn first is the G shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x0101x — no barre and 2 open strings. 1 of the 9 shapes here sits in open position. 3 of the 9 need a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x0101x | open position | A, root position | C | 2 open strings |
| xx1213 | 1st fret | Eb, 2nd inversion | G | all fretted |
| 5xx543 | 3rd fret | A, root position | G | all fretted |
| 5x554x | 4th fret | A, root position | Eb | barred |
| 567585 | 5th fret | A, root position | A | barred |
| xx7888 | 7th fret | A, root position | C | barred |
| x-12-10-12-10-11 | 10th fret | A, root position | Eb | all fretted |
| x-12-13-12-13-x | 12th fret | A, root position | C | all fretted |
| x-x-13-14-13-15 | 13th fret | Eb, 2nd inversion | G | all fretted |
The same notes rebuilt from scratch give 5 shell and 15 drop 2 voicings, each on its own page.
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).
How to use Am7b5
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.
In which keys. Every note of Am7b5 belongs to G minor (the ii°, the supertonic) and Bb major (the vii°, the leading tone).
What to play over Am7b5
Every note of Am7b5 is in A blues, A locrian, A altered and A half-whole diminished.
Chords near Am7b5
Change one note of Am7b5 and you have Adim (drop the flat seventh), Adim7 (the flat seventh becomes a sixth), Am7 (the flat fifth becomes a fifth), AmMaj7b5 (the flat seventh becomes a major seventh), A7b5 (the minor third becomes a major third) or Am/G (the flat fifth becomes a fifth).
Am7b5 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Am7b5’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.