The Open A sus4 tuning transforms your guitar into a deeply resonant instrument, centered around the notes A, D, and E across multiple octaves. It offers a rich, open sound that is both expansive and powerful, making it highly suitable for slide guitar, drone-based music, blues, and folk styles where a strong modal character is desired.

This tuning inherently creates an A sus4 chord when strummed open, providing a unique harmonic foundation that deviates from traditional major or minor tunings. The "sus4" (suspended fourth) quality, where the third is replaced by a perfect fourth, lends an open, slightly ambiguous, and often yearning feel to the chord.

Technical Analysis:

• The open strings are tuned to: A1-E2-A2-D3-A3-D4 (low to high).
• Relative to the lowest A (A1), the intervals are: Root (A1), Perfect 5th (E2), Octave (A2), Perfect 4th (D3), Octave (A3), Perfect 4th (D4).
• This arrangement heavily emphasizes the root (A), fifth (E), and fourth (D), clearly forming an A sus4 (A-D-E) chord across the strings.
• The low A1-E2-A2 setup creates a powerful, deep A power chord (A5) foundation.
• The D3-A3-D4 on the higher strings reinforces the sus4 quality with a strong D-A relationship.

Chordal Opportunities:

• Open Strum: A full, ringing A sus4 chord.
• Barre Chords: By simply barring across any fret, you can easily create major suspended 4th chords up the neck (e.g., barring at the 2nd fret yields B sus4, at the 3rd fret, C sus4). This makes transposing very intuitive.
• Power Chords: The strong A-E-A on the lower strings allows for easy and impactful root-fifth-root power chords by barring the lowest three strings.
• Drone & Modal Playing: The repeated A and D notes across octaves provide excellent opportunities for creating drones and exploring modal melodies, particularly for styles requiring a sustained harmonic bed.
• Slide Guitar: This tuning is exceptionally well-suited for slide guitar due to its open chord structure, allowing for fluid glissandos and expressive phrasing.

• String 6 (Low E string equivalent): A1
• String 5 (A string equivalent): E2
• String 4 (D string equivalent): A2
• String 3 (G string equivalent): D3
• String 2 (B string equivalent): A3
• String 1 (High E string equivalent): D4

How to Tune to Open A sus4

To achieve this deep and resonant tuning, you will be adjusting your strings significantly from standard EADGBe tuning. Please pay close attention to the recommended string gauge advice, especially for larger pitch drops, to ensure optimal playability and instrument health.

• Low E String (6th String): Start from E2. Tune down 7 semitones to A1. (This is a significant drop; a heavier gauge string is advised for best results and string tension.)
• A String (5th String): Start from A2. Tune down 5 semitones to E2. (This is a significant drop; a heavier gauge string is advised for best results and string tension.)
• D String (4th String): Start from D3. Tune down 5 semitones to A2. (This is a significant drop; a heavier gauge string is advised for best results and string tension.)
• G String (3rd String): Start from G3. Tune down 5 semitones to D3. (This is a significant drop; a heavier gauge string is advised for best results and string tension.)
• B String (2nd String): Start from B3. Tune down 2 semitones to A3.
• High E String (1st String): Start from E4. Tune down 2 semitones to D4.

Always tune slowly and carefully, especially when making large adjustments, to avoid string breakage or potential damage to your instrument.