The Open A9 tuning transforms your guitar into a rich, full-bodied A dominant ninth chord when strummed open. This tuning is a delightful deviation from standard, offering a unique sonic palette perfect for blues, jazz, and creating expansive, resonant harmonies.

Technically, this tuning sets the strings to E2-A2-C#4-G3-B3-E4. The fundamental structure of an A9 chord is A (root), C# (major third), E (perfect fifth), G (dominant seventh), and B (major ninth). When strummed open, your guitar immediately rings out with these precise intervals across the strings. The most notable change from standard EADGBe tuning is the 4th string (normally D4) being tuned down by a single semitone to C#4. This subtle adjustment is the key to unlocking the open A dominant ninth harmony.

This tuning provides immediate access to a lush A9 chord. By simply barring across a single fret, you can effortlessly transpose this powerful dominant ninth voicing across the fretboard, allowing for easy exploration of other X9 chords (e.g., bar at the 3rd fret for C9, 5th fret for D9). Additionally, within reach are A major (by omitting or adjusting the G string), A7 (by focusing on A, C#, E, G), and even A minor (by fretting the C# on the 4th string down to a C, or adjusting other strings). Slide guitarists will find this tuning particularly inspiring, as the open chord provides a stable foundation for melodic exploration. While open power chords on the lower strings might require some finger adjustment due to the C# on the 4th string, the overall richness and harmonic possibilities make this a truly expressive tuning.

Open A9 Tuning Notes

• String 6 (Low E): E2
• String 5 (A): A2
• String 4 (D/C#): C#4
• String 3 (G): G3
• String 2 (B): B3
• String 1 (High E): E4

How to Tune to Open A9

To achieve the Open A9 tuning from standard EADGBe, follow these string movements:

• String 6 (E2): Keep as is; no change (0 semitones). The target note is E2.
• String 5 (A2): Keep as is; no change (0 semitones). The target note is A2.
• String 4 (D string tuned to C#4): Tune down 1 semitone. From its standard D4 note, you will tune it down to C#4. This is a minor adjustment as specified by 'Tune down 1 semitones'.
• String 3 (G3): Keep as is; no change (0 semitones). The target note is G3.
• String 2 (B3): Keep as is; no change (0 semitones). The target note is B3.
• String 1 (E4): Keep as is; no change (0 semitones). The target note is E4.

Important Note on String Gauge: All string movements for this tuning are minor (1 semitone or less). Therefore, a change in string gauge is generally not required for this specific tuning. For tunings involving changes of 4 or more semitones (up or down), consider using a different string gauge to ensure optimal playability and string longevity.