This powerful 7-string guitar tuning, aptly named Open Csus, offers an expansive sonic palette, particularly suited for genres demanding deep, resonant lows and open, ringing chords. As described, it effectively brings an 8-string guitar's low F range to a 7-string instrument, establishing an incredibly deep foundation with its lowest string tuned to F1.

Verbal Analysis:

The Open Csus tuning creates a rich, full-bodied sound when strummed open, forming an Fsus2 or Fadd9 chord (F-G-C). This provides a naturally open and often melancholic or majestic quality, making it excellent for atmospheric passages, heavy riffs, and soundscapes. The arrangement allows for very easy access to power chords and drone notes across the fretboard. The open C (C-G-C-G-C) structure within the tuning, bracketed by F notes, lends itself to a broad harmonic versatility, from powerful low-end chugging to intricate melodic lines on the higher strings.

Technical Analysis:

The tuning features the following open notes from lowest to highest: F1 C2 G2 C3 G3 C4 F4.

• The lowest two intervals (String 7 to String 6, and String 6 to String 5) are both perfect fifths (F1-C2, C2-G2), providing an extremely robust and resonant low-end that is ideal for heavy riffing and thick power chords.
• The subsequent strings then follow a pattern of perfect fourths and perfect fifths: G2-C3 (P4), C3-G3 (P5), G3-C4 (P4), C4-F4 (P4). This mixed interval structure offers a balance of ease in fretting common chord shapes on higher strings (due to the P4s) and the powerful, wide voicings afforded by the P5s.
• The presence of multiple C's (C2, C3, C4) and G's (G2, G3) across the tuning creates natural resonance and makes it very easy to establish a C power chord or C-based melodic phrases simply by muting the F strings.
• With the open notes being F-C-G-C-G-C-F, strumming all strings yields an Fsus2 chord (F, G, C). This chord has a suspended, open quality, avoiding the typical major/minor tonality, allowing it to fit into various musical contexts.

Open Chords & Shapes:

• Fsus2 / Fadd9: Strumming all open strings creates a full, rich Fsus2 or Fadd9 chord, which is inherently expansive and harmonically ambiguous.
• C5 Power Chords: Due to the C-G-C-G-C structure, power chords on C are easily accessible across multiple string sets (e.g., C2-G2, C3-G3).
• Low F Power Chords: The lowest F1 string provides an excellent root for deep power chords, especially when combined with the C2 and G2 strings for a massive F5 or Fsus2 voicing.
• Easy Lead & Riffing: The consistent perfect fourths on the higher strings (G3-C4-F4) allow guitarists to easily transfer familiar scale shapes and licks from standard tuning's G-B-E strings, making lead playing and melody creation intuitive despite the lower overall pitch.

How to Tune Your 7-String Guitar to Open Csus:

Achieving the Open Csus tuning involves significant adjustments to most strings. Please proceed with care and ensure your guitar is properly intonated after tuning, especially for strings with large pitch changes.

• String 7 (Lowest String - F1): Tune this string down 6 semitones to F1. (Note: Tuning down 6 semitones is a substantial change. A heavier gauge string may be advised for optimal tension and tone.)
• String 6 (C2): Tune this string down 4 semitones to C2. (Note: Tuning down 4 semitones is a significant change. Consider a heavier gauge string if you frequently use this tuning.)
• String 5 (G2): Tune this string down 2 semitones to G2.
• String 4 (C3): Tune this string down 2 semitones to C3.
• String 3 (G3): Keep this string as is; no change (0 semitones) to G3.
• String 2 (C4): Tune this string up 1 semitone to C4.
• String 1 (Highest String - F4): Tune this string up 1 semitone to F4.