The C7sus4 Tuning: A Modal Journey with a Suspended Voice

This C7sus4 tuning is an intriguing and harmonically rich setup, as hinted by its description as a "C modal tuning with a seventh in the bass." While the lowest actual note is F2, the overall voicings strongly present the character of a C7sus4 chord, creating a suspended, open, and somewhat ambiguous sonic landscape.

Verbal Analysis:

The sound of this tuning is immediately evocative and open. The suspended fourth (F) against the implied C root, combined with the minor seventh (A#) and the fifth (G), gives it a jazz-fusion or modern progressive feel. It's not a standard major or minor sound, but rather one that hovers, creating tension and release. The presence of the low F2 and high F4 provides a full, resonant foundation, while the A#2, C3, G3, and C4 notes offer chimey, complex harmonic possibilities. Players will find it encourages exploration outside of typical chord shapes, leaning into arpeggiated figures and open-string drones. It would be excellent for atmospheric soundscapes, blues with a twist, or any genre where a sense of yearning, contemplation, or sophisticated harmony is desired.

Technical Analysis:

The open strings in this tuning are F2, A#2, C3, G3, C4, F4. When arranged in ascending order, the unique notes are F, G, A#, C. These notes perfectly form a C7sus4 chord (C - F - G - A#) with an F in the bass, making it a C7sus4/F voicing.

• Intervals from C: The F is a perfect 4th, G is a perfect 5th, and A# (or Bb) is a minor 7th.
• Open Chord: Strumming all open strings yields a beautiful C7sus4/F chord. This provides an immediate, rich harmonic palette without any fretting.
• Modal Implications: The notes F, G, A#, C are central to the C Phrygian mode (C-Db-Eb-F-G-Ab-Bb) and the C Aeolian (C-D-Eb-F-G-Ab-Bb) or C Dorian (C-D-Eb-F-G-A-Bb) scale with a flat 3rd. Specifically, the C-F-G-A# (Bb) structure strongly relates to C Mixolydian with a suspended 4th, or a blues scale starting on C. This opens doors for melodic improvisation using these scales.
• Easy Chord Shapes:
  • Barre Chords: Moving a single-finger barre across the fretboard will yield various suspended voicings. For instance, a barre at the 1st fret (G-C-Db-Ab-Db-G) could create a Db7sus4/G.
  • Open Voicings: The unique intervals mean that simple two or three-finger shapes can create complex, full-sounding chords. Experimenting with triad shapes on the higher strings will reveal new harmonic textures.
  • Power Chords/Fifths: The presence of F and C, and G and C (a fifth and a fourth) across the strings makes it easy to create powerful, resonant sounds simply by fretting adjacent strings a few frets apart.

Open String Notes:

String 6 (Low E): F2

String 5 (A): A#2

String 4 (D): C3

String 3 (G): G3

String 2 (B): C4

String 1 (High E): F4

How to Tune:

To achieve this tuning from standard EADGBe:

• String 6 (Low E): Tune up 1 semitone from E2 to F2. (Safe movement)
• String 5 (A): Tune up 1 semitone from A2 to A#2. (Safe movement)
• String 4 (D): Tune down 2 semitones from D3 to C3. (Safe movement)
• String 3 (G): Keep as is; no change (0 semitones).
• String 2 (B): Tune up 1 semitone from B3 to C4. (Safe movement)
• String 1 (High E): Tune up 1 semitone from E4 to F4. (Safe movement)