Tuning Analysis: Open A9

The "Open A9" tuning, famously utilized by Coldplay in their song "Spies", transforms the guitar into a resonant and harmonically rich instrument. This tuning is designed to produce a full, extended chord voicing when all strings are played open, primarily an A9 chord (A-C#-E-G-B) with a low E pedal tone. This characteristic creates a unique, expansive sound, making it ideal for atmospheric pieces, arpeggiated melodies, and full-bodied strumming where a sense of openness and depth is desired. It allows for creative exploration within keys related to A major or E minor/major, providing new harmonic possibilities beyond standard tuning.

Technically, this tuning significantly alters certain strings from the standard EADGBe setup. The open strings, when tuned according to the provided movements, resolve to E2-A2-C#3-G3-B3-C#4. This specific arrangement of notes allows for the open strings to collectively form an A9 chord (A, C#, E, G, B) with an E in the bass. The presence of the low E (E2) grounding the A9 chord adds a distinctive foundational element. While the 6th, 5th, 3rd, and 2nd strings remain at their standard pitches, the alterations on the 4th (D string tuned down to C#3) and 1st (high E string tuned down to C#4) strings are crucial for achieving the tuning's characteristic harmonic profile. This tuning encourages new fingerings and chord shapes, as typical barre chords will produce unique voicings, often implying extended harmonies or inversions of A-related or E-related chords, for instance, a barre at the 5th fret could yield a D9 chord with an A in the bass.

How to Tune: Open A9 from E Standard

To achieve the Open A9 tuning from standard EADGBe (E2 A2 D3 G3 B3 E4), follow these precise string movements:

• String 6 (Low E): Keep as is; no change (0 semitones). The target note is E2.
• String 5 (A): Keep as is; no change (0 semitones). The target note is A2.
• String 4 (D): Tune down 1 semitone. This changes your standard D3 string to a C#3.
• String 3 (G): Keep as is; no change (0 semitones). The target note is G3.
• String 2 (B): Keep as is; no change (0 semitones). The target note is B3.
• String 1 (High E): Tune down 3 semitones. This changes your standard E4 string to a C#4.

Note on String Gauge: The most significant change in this tuning involves dropping strings by up to 3 semitones. While generally within safe limits for standard gauge strings, it is always recommended to check your guitar's neck relief and intonation after any substantial tuning alterations to maintain optimal playability and intonation.

The open notes for the Open A9 tuning are:

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