The Open A sus4 tuning, as named, offers a unique and resonant soundscape for guitarists. While its title suggests an A-centric foundation, the open string configuration of D-A-D-G-A-E actually produces a rich and full Dsus4(add2) or Dsus4(add9) chord. This tuning holds a particularly close relationship to the widely popular DADGAD tuning, with the key distinction being that the highest string remains at its standard E4 pitch, rather than being tuned down to D.

Technically, the open notes D2-A2-D3-G3-A3-E4 create a bright and expansive sound. The low D-A-D interval provides a powerful and fundamental root, making it ideal for creating driving power chords and sustained drone effects. The inclusion of the G note introduces a suspended fourth quality, while the A note provides a perfect fifth, and the high E string adds a major second (or ninth) to the D chord. This combination results in a harmonious and slightly ethereal quality, well-suited for styles such as folk, Celtic, or ambient music. Chords are often easily formed through simple barring techniques, especially for D-based voicings across the lower strings.

Due to its significant overlap with DADGAD, many familiar chord shapes and melodic patterns used in that tuning can be readily adapted to the lower five strings of Open A sus4. The retention of the high E string, however, provides a distinct textural difference and opens up new melodic and harmonic possibilities, offering a brighter and perhaps more traditional top-end compared to DADGAD's often more modal high D. This tuning actively encourages a creative approach to open string textures and ringing drone notes.

Below is a detailed breakdown of each string's target note in this tuning:

• String 6 (Low E): Tuned down to D2.
• String 5 (A): Remains at A2 (no change).
• String 4 (D): Remains at D3 (no change).
• String 3 (G): Remains at G3 (no change).
• String 2 (B): Tuned down to A3.
• String 1 (High E): Remains at E4 (no change).

How to Tune

To accurately set up your guitar in Open A sus4 tuning, follow these specific adjustments for each string:

• String 6 (Low E): Tune down 2 semitones from its standard E to D.
• String 5 (A): Keep this string as is; no change is required (0 semitones).
• String 4 (D): Keep this string as is; no change is required (0 semitones).
• String 3 (G): Keep this string as is; no change is required (0 semitones).
• String 2 (B): Tune down 2 semitones from its standard B to A.
• String 1 (High E): Keep this string as is; no change is required (0 semitones).

Important Tuning Note: Tuning down 2 semitones on a string is generally safe for standard guitar string gauges. However, always exercise caution when making any tuning adjustments, especially if you are unsure of your string gauge or guitar's stability.