The "Open C7sus2" tuning, famously utilized by Mogwai in "You're Lionel Richie," presents a rich, resonant, and somewhat melancholic soundscape. It's a non-standard open tuning that immediately evokes a sense of atmospheric depth and a bluesy, dominant character due to the flat seventh. This tuning is ideal for creating expansive, ringing chords and drones, perfect for post-rock, ambient, or experimental genres.

Technical Analysis

The open strings are tuned to C2-G2-D3-G3-A#4-C4 (from low to high). Analyzing the intervals from the lowest C root:

• String 6 (C2): Root
• String 5 (G2): Perfect Fifth (P5)
• String 4 (D3): Major Second / Major Ninth (M2/M9)
• String 3 (G3): Perfect Fifth (P5) - an octave above the G2
• String 2 (A#4): Minor Seventh (m7), enharmonically Bb
• String 1 (C4): Root - two octaves above the C2

Together, these notes spell out a C - G - D - G - A# - C, which is a clear voicing of a C7sus2 chord. The prominent flat seventh (A#, or Bb) gives it a dominant quality, while the suspended second (D) adds an open, unresolved, or modern harmonic flavor, distinct from a standard major or minor chord. The repetition of G (fifth) and C (root) across different octaves provides a full, harmonically stable base.

Chords and Playability

• Open Chords: The open strings themselves form a rich C7sus2 chord, allowing for immediate resonant sonic textures without fretting.
• Barre Chords: Moving this C7sus2 shape up the neck with a single barre creates other X7sus2 chords (e.g., barre at the 2nd fret yields D7sus2). This makes for easy transposition and powerful rhythmic chording.
• Drone and Melody: The open C and G strings create a powerful drone, over which melodic lines can be woven on the higher strings. The open D and G strings retain their standard tuning relationship, which might offer familiar fingerings for some melodic passages or chord voicings built around D and G.
• Unique Voicings: The unique intervals, particularly the D (sus2) and A# (b7), encourage unconventional fingerings and the discovery of fresh chord voicings not easily accessible in standard tuning. The wide interval between the low C and the high C (two octaves) also contributes to a grand, expansive sound.

How to Tune

To achieve the Open C7sus2 tuning, you'll need to adjust several strings from standard EADGBe tuning. Please pay close attention to the specified movements.

• String 6 (Low E): Tune down 4 semitones to C2.
• String 5 (A): Tune down 2 semitones to G2.
• String 4 (D): Keep as is; no change (0 semitones) to D3.
• String 3 (G): Keep as is; no change (0 semitones) to G3.
• String 2 (B): Tune down 1 semitones to A#4.
• String 1 (High E): Tune down 4 semitones to C4.

Important Note: When tuning strings more than 4 semitones up or down, it is generally advised to use a different gauge string to prevent breakage (for tuning up) or excessive floppiness/intonation issues (for tuning down). In this tuning, the 6th and 1st strings are tuned down 4 semitones, which is at the maximum recommended range for a standard gauge before considering a thicker string for better tension and intonation.

String 6 (Low E): C2
String 5 (A): G2
String 4 (D): D3
String 3 (G): G3
String 2 (B): A#4
String 1 (High E): C4