The "Open Gmaj9" tuning, as its name implies, naturally rings out a rich and complex Gmaj9 chord when strummed open, specifically presenting as a Gmaj9/D voicing due to the low D bass note. The creator describes this tuning as having a "very sombre and somewhat unsettling sound," which makes it an excellent choice for crafting open string drones, atmospheric soundscapes, and spontaneous melodic exploration. It offers a distinct, modern, or experimental feel compared to more common open major or minor tunings.

From a technical standpoint, the open string notes, listed from the lowest (6th) to the highest (1st) string, are:

• String 6 (Low E string): D2
• String 5 (A string): A2
• String 4 (D string): D3
• String 3 (G string): F#4
• String 2 (B string): G3
• String 1 (High E string): B3

When these notes are analyzed in ascending pitch order (D2, A2, D3, G3, B3, F#4), they clearly spell out a G major ninth chord (G-B-D-F#-A), with D acting as the root of the bass. This tuning features a notably wide intervallic spread across the fretboard, especially with the F#4 on the 3rd string being pitched significantly higher than the G3 on the 2nd string and the B3 on the 1st string. This creates an unexpected downward pitch movement from string 3 (F#4) to string 2 (G3) before rising again to string 1 (B3). This non-monotonic pitch arrangement across adjacent strings is a key factor contributing to the described "unsettling" quality, introducing unique harmonic tensions and voicings that deviate from standard guitar tunings.

The low D-A-D arrangement on the bottom three strings forms a robust, resonant foundation, ideal for powerful rhythmic strumming or as a sustained drone. The open strings contain all the notes of a Gmaj9 chord (G, B, D, F#, A), making the full chord readily available with just an open strum. This encourages the exploration of new fingerings and shapes, as traditional chord voicings will largely be recontextualized. Simple two or three-finger shapes can easily create different inversions of G major or D major triads. For instance, by simply muting certain strings, you can achieve a G major triad using strings 2, 1, and 4 (G-B-D).

How to Tune Your Guitar for Open Gmaj9

To set your guitar to the Open Gmaj9 tuning, you will adjust your strings from the standard EADGBe tuning. Please exercise caution, particularly with larger semitone adjustments, as these may necessitate a different string gauge for optimal playability, intonation, and to prevent string breakage. For movements exceeding 4 semitones up or down, a different gauge string is generally advised.

• String 6 (Low E string - Standard E2): Tune down 2 semitones. Your target note for this string is D2.
• String 5 (A string - Standard A2): Keep as is; no change (0 semitones). Your target note for this string is A2.
• String 4 (D string - Standard D3): Keep as is; no change (0 semitones). Your target note for this string is D3.
• String 3 (G string - Standard G3): Tune down 1 semitone. Following this instruction from a standard G3, the note would be F#3. However, the intended target note for this tuning (as indicated in the tuning notes) is F#4. Please note this significant octave discrepancy: achieving F#4 from a standard G3 would involve tuning up 13 semitones (more than an octave), which is generally not feasible or safe on a standard G string without a very light gauge string and a professional setup. If you follow the "-1 semitone" instruction, you will reach F#3, which will dramatically alter the character of the open chord. For the described "Open Gmaj9" with its unique, unsettling quality, F#4 is the intended pitch.
• String 2 (B string - Standard B3): Tune down 4 semitones. Your target note for this string is G3. Tuning down 4 semitones is a significant drop; consider a heavier gauge string if you plan to use this tuning frequently.
• String 1 (High E string - Standard E4): Tune down 5 semitones. Your target note for this string is B3. This is a substantial drop in pitch, and a lighter gauge string is strongly recommended to maintain adequate string tension and playability.

• String 6: D2
• String 5: A2
• String 4: D3
• String 3: F#4
• String 2: G3
• String 1: B3