A dominant ninth (A9) chord on mandolin

The A dominant ninth chord (A9) is a dominant ninth chord (a dominant seventh plus a major ninth), made of five notes: A – C♯ – E – G – B.

Dots show:

Basic shapemedium

Position 9easy

Position 6medium

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Chord finder Transposer Tuner

What the A9 chord sounds like

A dominant ninth is a dominant seventh with an added major ninth. A fuller, fatter dominant sound – a staple of funk, soul and blues.

Notes of the A9 chord

Degree	Note	Interval from the root
1	A	root
3	C♯	major third (4 semitones)
5	E	perfect fifth (7 semitones) – often omitted on fretted instruments
7	G	minor seventh (10 semitones)
9	B	major second (2 semitones)

How to play it – with fingering

Basic shape

String 1 (E): fret 5, little finger (A5)
String 2 (A): fret 4, middle finger (C♯5)
String 3 (D): fret 5, ring finger (G4)
String 4 (G): fret 4, index finger (B3)

Position 9

String 1 (E): fret 9, middle finger (C♯6)
String 2 (A): open (A4)
String 3 (D): fret 9, index finger (B4)
String 4 (G): open (G3)

Position 6

String 1 (E): fret 7, ring finger (B5)
String 2 (A): fret 10, little finger (G5)
String 3 (D): fret 7, middle finger (A4)
String 4 (G): fret 6, index finger (C♯4)

Tuning: G D A E, like a violin; every note is a pair of strings that you fret together. In the diagram, × means the string is not played, and a circle means an open string.

Which keys is it in?

The A9 chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

D major: V9 (dominant)
B minor: VII9

Similar chords and substitutes

If A9 is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

E♭7 – tritone substitute: the same third and seventh, swapped – a jazz favourite
C♯dim7 – diminished seventh on the third: a common stand-in for the dominant
A7 – a simpler dominant
A7sus4 – suspended dominant, less tense
D – where it resolves (V → I)

Simpler versions

A7 – all 4 of its notes are in this chord
Aadd9 – all 4 of its notes are in this chord
A – all 3 of its notes are in this chord
Asus2 – all 3 of its notes are in this chord

Richer versions

A11 – the same chord plus 1 colour note
A13 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the A9 chord?

A, C♯, E, G, B. The root is A; the intervals of the other notes from the root: major third, perfect fifth, minor seventh, major second.

What is the easiest way to play A9 on mandolin?

The easiest shape above is “Position 9”, rated easy. We show 3 shapes, from open and easy versions to movable barre shapes higher up the neck.

How do I read the chord diagram?

Strings run from the lowest (left) to the highest (right) – tick “Left-handed” to mirror it. Rows are frets; a number at the side shows the starting fret. Dots are fingers (1 index, 2 middle, 3 ring, 4 little), a long bar is a barre, × means don't play that string and ○ means play it open.

Why is a note missing from some A9 shapes?

On a fretted instrument you can't always play every note of a 5-note chord. The fifth (E) may be dropped – the chord keeps its character without it.

How is the A9 chord written?

The chord symbol is A9, and its full name is A dominant ninth.