Amadd9
Minor, opened up — no 7th, just air.
Amadd9 is a minor triad with a 9th added and nothing else. Because there is no 7th, it stays simple and open rather than turning jazzy — the sound of a lot of modern acoustic writing.
Add, not seven
Amadd9 is A C E B — a minor triad plus the 9th (B). 'Add9' means exactly that: add the 9th, do not add a 7th. Am9 would include a G as well and sound completely different.
- Add9 = triad + 9th, with no 7th.
- Am9 has a ♭7 (G); Amadd9 does not.
- One note added to a chord you already know.
A half-step that does not clash
The 9th (B) sits a whole step above the root and a half-step below the ♭3 (C). That near-collision is what gives the chord its shimmer — close enough to be interesting, spaced far enough apart in a good voicing to stay clear.
- Voice the 9 away from the ♭3 to keep it ringing.
- On top of the chord it shimmers; buried in the middle it muddies.
- It is a colour note, not a tension note.
Acoustic and open tunings
Substitute it for any Am. It works especially well where an open B string can ring through a moving bass line — the reason it turns up constantly in fingerstyle and in modern worship and indie writing.
- Use it anywhere an Am is written.
- Let the open B string carry the 9th.
- Great over a descending bass line, where the top of the chord stays fixed.
Adding the 9th to a minor chord adds space, not complexity — as long as you leave the 7th out of it.
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