This unique guitar tuning, aptly named "D6/9 (Add4)," truly lives up to its creator's description of a "cool sound." It's a rich, complex open tuning that immediately presents a full, harmonically sophisticated chord when strummed. This tuning is ideal for players looking to explore lush, jazzy, or contemporary folk voicings without complex fingerings, making it perfect for songwriting, ambient textures, or creating dense harmonic beds.

Technical Analysis:

The open strings are tuned to D2, G2, B2, F#4, A3, E4. This deliberate arrangement is crafted to voice a D6/9(add4) chord across all six strings. Breaking down the notes relative to D as the root, we find the following intervals and voicings:

• Low D (String 6): D2, serving as the foundational root.
• G (String 5): G2, a perfect 4th above the root D, providing the 'add4' quality to the chord.
• B (String 4): B2, a major 6th above the root D, contributing to the '6' chord extension.
• F# (String 3): F#4, the major 3rd of the D chord, voiced remarkably high an octave above the typical F#3. This high F#4 creates a shimmering, bell-like quality in the upper register.
• A (String 2): A3, the perfect 5th, but interestingly placed lower in pitch than the F#4 on the 3rd string. This specific inversion between the 4th, 3rd, and 2nd strings creates a unique internal voicing and adds to the chord's density.
• E (String 1): E4, the major 9th (or major 2nd) above D, completing the sophisticated '9' extension of the chord.

The arrangement of notes, particularly the significant jump from B2 to F#4 and then the descent to A3, creates an almost piano-like voicing with widely spaced intervals and interesting voice leading. This makes the open chord exceptionally rich and full, allowing for expansive soundscapes.

Chordal Opportunities:

With an open D6/9(Add4) chord readily available, the possibilities for creative exploration are vast:

• Open Voicings: Strumming all open strings yields the complex D6/9(Add4) chord, perfect for starting compositions with a lush, harmonic foundation.
• Barre Chords: Moving this entire shape up or down the neck with a barre will create similarly voiced 6/9(Add4) chords in different keys. For example, a barre at the 2nd fret would transform the open voicing into an E6/9(Add4).
• Modal Play: The open strings collectively contain all the notes of the D major scale (D, E, F#, G, A, B). This opens up opportunities for D Lydian, D Mixolydian, or general D major scale-based improvisations using open strings as drones or pedal tones.
• Minor & Dominant Chords: Modifying just one or two notes with minimal fingering can easily lead to minor or dominant 7th chords. For instance, flattening the F# on the 3rd string to F (e.g., at the 2nd fret) could introduce a D minor quality or a G7 chord component.
• Arpeggios & Fingerstyle: The wide interval spacing, especially in the higher strings, lends itself beautifully to intricate fingerstyle arpeggios, creating shimmering, resonant soundscapes and complex melodic patterns.

This tuning encourages players to think beyond standard chord shapes, pushing them to discover new harmonic textures and melodic possibilities within a richly pre-voiced framework.

How to Tune:

To achieve the D6/9 (Add4) tuning from standard EADGBe tuning, follow these precise adjustments for each string:

• String 6 (Low E): Tune this string down 2 semitones from E to D2.
• String 5 (A): Tune this string down 2 semitones from A to G2.
• String 4 (D): Tune this string down 3 semitones from D to B2.
• String 3 (G): Tune this string down 1 semitone from G to F#4.
• String 2 (B): Tune this string down 2 semitones from B to A3.
• String 1 (High E): Keep this string as is; no change (0 semitones) from E to E4.

All string adjustments are within a moderate range (no more than 3 semitones down, and none up), so your current string gauge should be perfectly suitable for this tuning without requiring a change. You can safely proceed with these adjustments on a standard set of guitar strings.