The "Double Drop C" tuning for 7-string guitar, with notes C C F A# D# G C, presents a powerful and expansive sonic landscape. While the provided notes specify the two lowest strings as unison C2, the original description notes that the intended lowest string should be an octave below the other C (C1), offering an even more profound low-end rumble.

Verbal Analysis

This tuning is designed for immense depth and resonance. The unison C2 notes on the 6th and 7th strings, or particularly the intended C1-C2 pairing, create a colossal foundation for heavy riffs and atmospheric textures. It pushes the boundaries of standard guitar tunings, favoring a dark and aggressive character. The name "Double Drop C" implies a drop tuning on two lowest strings, often to a low C, but here specifically setting both C's. The inclusion of A# (Bb) and D# (Eb) adds a minor/modal flavor to the open string voicing, giving it a modern and often melancholic or intense feel.

Technical Analysis

The tuning consists of the following open string notes from lowest to highest: C2 - C2 - F2 - A#3 - D#4 - G3 - C4. If the lowest string were indeed C1 as intended, it would create an octave interval (C1-C2) between the two lowest strings, which is characteristic of many extended-range "drop" tunings.

• String 7 (C2) & String 6 (C2): These are unison notes, providing incredible thickness and sustain, ideal for massive single-finger power chords. If String 7 were C1, it would offer an even deeper, more distinct low-end.
• String 5 (F2): A perfect fourth above the C2, completing a powerful C5 chord shape (C-F) on the lowest strings.
• String 4 (A#3): An augmented fourth (tritone) and an octave above F2. This large jump in pitch contributes to the tuning's unique voicing and wide melodic range.
• String 3 (D#4): A perfect fourth above A#3.
• String 2 (G3): Notably, this string is a minor third below the D#4 on String 3. This descending interval is quite uncommon in open tunings and can lead to intriguing and potentially dissonant voicings when strummed or arpeggiated across these strings, requiring careful finger placement.
• String 1 (C4): A perfect fourth above G3, resolving to the tonic C note at a higher octave.

Open Chords and Playability

When strummed open, the notes C, F, A# (Bb), D# (Eb), G, and C combine to form a rich C minor 11 (C Eb G Bb F) chord. This gives the tuning a complex, sophisticated, and often dark open voicing, distinct from simpler major or minor open chords. Power chords are incredibly accessible due to the low unison C's and the P4 intervals, particularly on the lower strings. For example, barring across the C2-C2-F2 will yield a C power chord.

The unusual descending interval between String 3 (D#4) and String 2 (G3) requires players to adapt their chord shapes and scale patterns, but also opens up unique melodic and harmonic possibilities not found in standard tunings. This tuning is particularly well-suited for heavy genres such as metal, djent, and progressive music, where its deep resonance and complex voicings can be fully utilized.

How to Tune

To achieve the "Double Drop C (7 String)" tuning, adjust your strings as follows:

• String 7: Tune up 1 semitones to C2. (Note: For the intended C1, you would need to tune down significantly from a standard B1, likely requiring a much heavier gauge string and manual adjustment.)
• String 6: Tune down 4 semitones to C2.
• String 5: Tune down 4 semitones to F2.
• String 4: Tune down 4 semitones to A#3.
• String 3: Tune down 4 semitones to D#4.
• String 2: Tune down 4 semitones to G3.
• String 1: Tune down 4 semitones to C4.

String Gauge Advisory: Given the significant tuning adjustments for Strings 6 through 1 (tuning down 4 semitones), it is strongly advised to use a heavier gauge string for these strings to maintain optimal tension, intonation, and playability, and to prevent string damage or breakage. Tuning String 7 up 1 semitone is generally safe with a standard gauge.

String 7: C2

String 6: C2

String 5: F2

String 4: A#3

String 3: D#4

String 2: G3

String 1: C4