The CFG#CG#CF tuning for a 7-string guitar creates a rich, resonant soundscape primarily centered around an F minor tonality. As described, it "works well in Ab and Eb," making it versatile for exploring melancholic, dark, or expressive musical themes. The open tuning itself rings out like a massive F minor chord (F-Ab-C) spread across a wide range of the instrument, offering a strong harmonic foundation for drone-based playing, atmospheric soundscapes, or intricate arpeggios. It encourages a focus on open string harmonies and can simplify the playing of certain minor chord voicings.

Technical Analysis

• Open Chord: The open strings (from lowest to highest: C2 F2 G#3 C3 G#4 C4 F4) collectively form an F minor chord in its second inversion (C-F-Ab). The repetition of C, F, and G# (enharmonically Ab) across multiple octaves creates a dense and powerful voicing, providing a strong tonal center for improvisation and composition.
• Interval Structure: This tuning features several perfect 4ths (C2-F2, G#3-C3, G#4-C4, C4-F4) which contribute to its harmonic stability and ease of moving minor chord shapes across the neck. However, the tuning presents a unique non-linear string order with String 5 (G#3) tuned higher in pitch than String 4 (C3). This inversion of pitch creates interesting harmonic possibilities and unique fretboard navigation challenges/opportunities. The presence of G# (Ab) alongside C and F provides the characteristic minor third that defines the F minor quality.
• Playability and Chord Shapes: This tuning is ideal for exploring modal playing and creating expansive minor chord voicings with minimal effort. Barring across all or several strings will naturally produce minor chords. For example, barring all strings at the 1st fret would yield an F# minor chord. The inherent F minor quality means that dominant chords like C7 or G7 might create tension or require careful voicing. The tuning's affinity for Ab and Eb suggests compatibility with keys that share common tones with F minor (F minor is the relative minor of Ab Major, and Eb Major shares a similar melancholic feel in certain contexts), allowing for smooth transitions and harmonic explorations within these related tonalities. The unusual string 5 (G#3) to string 4 (C3) pitch relation will require players to adapt their typical fingerings, potentially leading to fresh and unexpected chord shapes and melodic lines.

How to Tune

To achieve the CFG#CG#CF tuning, adjust each string from its current pitch according to the following instructions. Always tune carefully to avoid string breakage, especially when tuning up. For movements of 3 or 4 semitones up, take particular care.

• String 7 (to C2): Tune up 1 semitones.
• String 6 (to F2): Tune up 1 semitones.
• String 5 (to G#3): Tune down 1 semitones.
• String 4 (to C3): Tune down 2 semitones.
• String 3 (to G#4): Tune up 1 semitones.
• String 2 (to C4): Tune up 1 semitones.
• String 1 (to F4): Tune up 1 semitones.

String 7: C2
String 6: F2
String 5: G#3
String 4: C3
String 3: G#4
String 2: C4
String 1: F4