The DFACEF (Open Dmaj9) tuning is a fascinating and highly resonant open tuning for guitar, designed to provide a rich, full chord when strummed open. While the provided name 'DFACEF' suggests a specific set of natural notes, a closer look at the actual tuning reveals a vibrant D Major 9th chord across an exceptionally wide range of octaves. The original description mentions "w battery in 10th fret", which is a unique and somewhat enigmatic detail; it might refer to a specific setup or modification not commonly understood, but the tuning itself offers distinct harmonic possibilities.

Technical Analysis

This tuning transforms the standard E-A-D-G-B-E guitar into a D2-F#3-A2-C#4-E3-F#5 configuration. The notes, when considered enharmonically (D, F#, A, C#, E), perfectly spell out a D Major 9th chord (Root, Major 3rd, Perfect 5th, Major 7th, Major 9th). The highest string provides another F# an octave above the D's major third, adding to the richness and sustain.

The remarkable aspect of this tuning is the extreme spread of its octaves, ranging from D2 on the 6th string to a soaring F#5 on the 1st string. This creates a vast harmonic landscape, allowing for deep, resonant bass notes and shimmering high frequencies simultaneously. Such a wide-ranging setup would likely require a custom set of string gauges to ensure proper tension and intonation, especially given the significant pitch adjustments from standard tuning.

Chords and Playability

With all strings open, the guitar immediately rings out a majestic D Major 9th chord. This makes it ideal for drone-based music, ambient soundscapes, or compositions that heavily feature this specific harmony. By simply barring across any fret, you can easily transpose this Dmaj9 chord to other major 9th chords:

• Barre at 1st fret: D#maj9 / Ebmaj9
• Barre at 2nd fret: Emaj9
• Barre at 3rd fret: Fmaj9
• and so on.

The vast intervals between some strings also open up opportunities for unique voicings and melodic ideas. Slide guitar would sound particularly expansive in this tuning, as the open Dmaj9 provides a solid harmonic foundation. While standard chord shapes would be largely altered, the inherent open chord offers immediate musicality, encouraging exploration of single-note lines and arpeggios that highlight the tuning's unique harmonic character.

How to Tune

To achieve the DFACEF (Open Dmaj9) tuning from standard E-A-D-G-B-E, follow these steps. Please note the significant semitone changes for some strings, which may require lighter or heavier gauge strings for optimal performance and to prevent string breakage or excessive floppiness.

• 6th String (Low E): Tune down 2 semitones to D2. (Movement: -2 semitones)
• 5th String (A): Tune down 3 semitones to F#2. (Movement: -3 semitones)
• 4th String (D): Tune down 5 semitones to A2. (Movement: -5 semitones) (Note: Tuning down 5 semitones is a significant change; consider a heavier gauge string for better tension.)
• 3rd String (G): Tune down 6 semitones to C#3. (Movement: -6 semitones) (Note: Tuning down 6 semitones is a significant change; consider a heavier gauge string for better tension.)
• 2nd String (B): Tune down 7 semitones to E3. (Movement: -7 semitones) (Note: Tuning down 7 semitones is a significant change; consider a heavier gauge string for better tension.)
• 1st String (High E): Tune up 2 semitones to F#4. (Movement: +2 semitones)

Important Octave Discrepancy Note: While the 'How to Tune' instructions (derived directly from string movements) result in D2-F#2-A2-C#3-E3-F#4, the listed target notes for this tuning are D2-F#3-A2-C#4-E3-F#5. This implies that for strings 5, 3, and 1, a further octave adjustment (tuning up an entire octave) is required after reaching the specified note name via the semitone movement. This would involve extremely drastic tension changes and is highly unusual for a standard guitar setup. Achieving the precise octaves of F#3, C#4, and F#5 with the indicated movements from standard strings would likely necessitate specific octave-up pedals, very unusual string sets, or may point to a unique instrument configuration beyond a typical guitar.

Here are the target notes for each string in the DFACEF (Open Dmaj9) tuning:

• 6th String (Low E string in standard tuning): D2
• 5th String (A string in standard tuning): F3#
• 4th String (D string in standard tuning): A2
• 3rd String (G string in standard tuning): C4#
• 2nd String (B string in standard tuning): E3
• 1st String (High E string in standard tuning): F5#