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.
Aadd9 is A, C#, E and B — A with the ninth added, and no seventh.
It sounds bright and ringing. No seventh at all: that is what “add” means, and it is why this sounds open where a maj9 sounds lush.

| A | C# | E | B |
|---|---|---|---|
| 1 | 3 | 5 | 9 |
Tonic — a triad with one colour on it.
Also written A(add9), Aadd2 or A add nine. The same chord either way; which spelling you meet depends on who wrote the chart.
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
Aadd9 has 3 of them, on strings 5-4-3-2-1, strings 6-5-4-3-2 and strings 6-4-3-2-1, all of them at the 6th fret — every inversion the chord has: A in the bass and E in the bass. The one to learn first is the A shape at the 6th fret, which is the easiest grip here.
Start with x02420 — no barre and 2 open strings. 1 of the 5 shapes here sits in open position. 2 of the 5 need a barre. Together they cover the neck from the 2nd fret to the 12th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x02420 | open position | A, root position | E | 2 open strings |
| 54x455 | 4th fret | A, root position | A | barred |
| xx76x7 | 6th fret | A, root position | B | all fretted |
| x-12-11-9-12-9 | 9th fret | A, root position | C# | all fretted |
| x-12-11-x-12-12 | 11th fret | A, root position | E | barred |
The same notes rebuilt from scratch give 13 drop 2 and 9 drop 3 voicings, each on its own page.
How you get to it. The turn that lands on Aadd9 is Bm7 to E7 — the ii and the V of A — and E7 shares its third and seventh with Bm7, so the hand barely moves between them.
In which keys. Every note of Aadd9 belongs to C# minor (the ♭VI), D major (the V), E major (the IV), F# minor (the ♭III), A major (the I) and B minor (the ♭VII).
Every note of Aadd9 is in A major pentatonic, A major, A lydian, A mixolydian and A lydian dominant.
Change one note of Aadd9 and you have A (drop the ninth), Asus2 (drop the major third), Asus2sus4 (the major third becomes a fourth), Amaj7 (the ninth becomes a major seventh), Amaj9 (add the major seventh) or Amadd9 (the major third becomes a minor third).
Aadd9 is a major chord — root, major third, fifth. Major chords on every root.
On Aadd9’s sound and use this page follows Robert Rawlins & Nor Eddine Bahha, Jazzology (Hal Leonard, 2005). 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.