Welcome to the intriguing world of Open Ddim tuning! This unique setup transforms your guitar into a resonant soundscape centered around a D diminished chord. As the creator noted, this tuning was specifically designed with slide guitar in mind, aiming to provide a distinctive harmonic palette beyond the usual major or minor open tunings. It's a fantastic choice for musicians looking to inject tension, mystery, or a touch of jazz-infused chromaticism into their playing.

Technical Analysis:

The open strings of this tuning are arranged as D2 - G#3 - D3 - F3 - G#4 - D4 (from lowest to highest string). When strummed open, these notes immediately form a D diminished chord (D-F-G#). This means that all six strings contribute to the diminished harmony, providing a rich, full voicing of this often-underused chord.

• The lowest D (D2) serves as the root.
• The F (F3) is the minor third above D.
• The G# (G#3 and G#4) acts as the diminished fifth (or augmented fourth) from D.
• The multiple octaves of D and G# create a lush, ringing diminished sound.

Chords and Playability:

The most obvious and powerful feature of Open Ddim is the ability to play any diminished chord simply by barring across the fretboard. For example:

• Barre at the 1st fret yields a D#dim chord.
• Barre at the 2nd fret yields an Edim chord.
• And so on, offering effortless access to all 12 diminished chords up the neck.

This inherent symmetry is a hallmark of diminished chords, as they are constructed from stacked minor third intervals. This means that a Ddim chord (D-F-G#) can also function as Fdim (F-G#-B/Cb), G#dim (G#-B-D), or Bdim (B-D-F), depending on the bass note. This makes the tuning incredibly versatile for exploring diminished harmonies, dominant 7b9 chords (which often contain diminished components), and chromatic passages.

For slide guitarists, this tuning offers a fantastic canvas. Sliding into a diminished chord creates a unique, often dramatic effect. The open Ddim provides a stable yet tension-filled foundation, allowing for expressive glissandos and vibratos that maintain harmonic integrity while exploring dissonance.

Tuning Notes (from lowest to highest string):

String 6 (Low E): D2
String 5 (A): G#3
String 4 (D): D3
String 3 (G): F3
String 2 (B): G#4
String 1 (High E): D4

How to Tune (from Standard EADGBe):

String 6 (Low E): Tune down 2 semitones to D2.
String 5 (A): Tune down 1 semitone to G#3.
String 4 (D): Keep as is; no change (0 semitones) to D3.
String 3 (G): Tune down 2 semitones to F3.
String 2 (B): Tune down 3 semitones to G#4.
String 1 (High E): Tune down 2 semitones to D4.

Important Note on String Gauge: All string movements in this tuning are within a reasonable range (no string is tuned more than 3 semitones down, and none up), so a standard set of guitar strings should generally suffice. However, for maximum playability and to ensure string longevity, if you plan to keep your guitar in this tuning for extended periods, or if you consistently tune strings significantly more than 4 semitones up or down, considering a different string gauge might be beneficial.