A9 guitar chords

A - C# - E - G - B

Chord Theory

A9 guitar chords consist of the 1st, 3rd, 5th, b7th, and 9th notes of the diatonic root scale of A Major.

A Major Scale: A - B - C# - D - E - F# - G#
Chord: A ninth - written as A9
Formula: 1 - 3 - 5 - ♭7 - 9
Notes: A - C# - E - G - B

A9 - A ninth (1-3-5-b7-9)

Spelling: 1st(A), 3rd(C#), 5th(E), b7th(G), 9th(B)

Chart Legend

Numbered Circles: number inside circle indicates which finger to use
X: Don't play string
White Numbered Circles: Optional Notes
X on string with optional note: if you omit the note, don't play string
Unmarked strings: Play open
Barre Line: One finger holds down multiple strings
R: Root Note

TAB: Numbers represent frets - not finger positions
Blank Strings: Do not Play
0: play string open

1st

Written: x02423
Notes: x-A-E-B-C#-G

 TAB  e |-3-|
      B |-2-|
      G |-4-|
      D |-2-|
      A |-0-|
      E |---|

2nd

Written: x05455
Notes: x-A-G-B-E-A

 TAB  e |-5-|
      B |-5-|
      G |-4-|
      D |-5-|
      A |-0-|
      E |---|

3rd

Written: x05657
Notes: x-A-G-C#-E-B

 TAB  e |-7-|
      B |-5-|
      G |-6-|
      D |-5-|
      A |-0-|
      E |---|

🡇 A9 Guitar Chords

Notes

This chord is a dominant 9th chord which is a dominant 7th chord with an added 9th. It is an extended chord which includes the dominant 7th in its structure.
If a chord with a symbol 9 is not preceded by the words major or maj, i.e., A9 as opposed to Amaj9, the 7th is always a dominant 7th (♭7).
A 9th chord implies the presence of the preceding 1st, 3rd, 5th, ♭7th, before the added 9th.
In the 2nd position chord, the 3rd is omitted... this is a particular voicing of the 9th chord where the third is omitted, and the 9th is played an octave lower... this could also be classed as a 7th suspended 2nd chord, in this case A7sus2. The chord formula is 1-2-5-♭7 = A-B-E-G (notes in the second position).
These chords are used mainly in jazz and alternative styles of music.
Standard keys using the A ninth chord: D major/B minor.
Bm is the relative minor of D major which means both scales share the same notes. A9 (A - C# - E - G - B) utilizes notes belonging to the D Major & Bm Scale... D-E-F#-G-A-B-C#.