The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
AmMaj7 is A, C, E and G# — Am with the major seventh added on top.
It sounds tense and wrong-footed. A minor triad carrying a major seventh: the semitone under the root over a minor chord is the first bar of a line cliché.

| A | C | E | G# |
|---|---|---|---|
| 1 | ♭3 | 5 | 7 |
Minor tonic — the tonic of the melodic minor.
Also written AmM7, Am(maj7), A-Δ7 or AminMaj7. The same chord either way; which spelling you meet depends on who wrote the chart.
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.
AmMaj7 has 9 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 12th — every inversion the chord has: A in the bass, C in the bass, E 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 5-3-2-1, 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 x02110 — no barre and 2 open strings. 1 of the 7 shapes here sits in open position. 1 of the 7 needs a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x02110 | open position | A, root position | E | 2 open strings |
| x32254 | 2nd fret | C, 1st inversion | G# | all fretted |
| xx7554 | 4th fret | A, root position | G# | all fretted |
| 576555 | 5th fret | A, root position | A | barred |
| xx7998 | 7th fret | A, root position | C | all fretted |
| x-12-10-9-9-x | 9th fret | A, root position | G# | all fretted |
| x-12-14-13-13-12 | 12th fret | A, root position | E | all fretted |
The same notes rebuilt from scratch give 6 shell, 13 drop 2 and 6 open string voicings, each on its own page.
Tensions. A shell of AmMaj7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (B), the 11 (D) and the 13 (F#).
How you get to it. The turn that lands on AmMaj7 is Bm7♭5 to E7♭9: the ii and the V of A minor, which is where a minor tonic is usually arrived at rather than simply begun on.
Every note of AmMaj7 is in A harmonic minor and A melodic minor.
Change one note of AmMaj7 and you have Am (drop the major seventh), Amaj7 (the minor third becomes a major third), Am6 (the major seventh becomes a sixth), Am7 (the major seventh becomes a flat seventh), AmMaj7b5 (the fifth becomes a flat fifth) or AmMaj9 (add the ninth).
AmMaj7 is a minor chord — root, minor third, fifth. Minor chords on every root.
On AmMaj7’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.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.