The 'C5 maj7 Reentrant' tuning is a uniquely voiced setup for your guitar. As described, it "Requires quite a bit of string swapping but gives a really nice sound when strummed." This is due to its highly reentrant nature, where the typical descending pitch order of strings is intentionally broken, creating unexpected harmonic relationships. When strummed open, this tuning delivers a rich, resonant C major 7th chord that feels expansive and full. It's an excellent choice for exploring open-string harmonies, fingerstyle arrangements that benefit from a drone-like quality, or for creating fresh textures in songwriting where a standard tuning chord might feel too conventional. The unconventional string order opens up creative possibilities for chord voicings and melodic lines that are difficult or impossible to achieve in standard tuning.

Technical Analysis

The 'C5 maj7 Reentrant' tuning transforms your guitar into an instrument capable of unique harmonic textures. The open string notes are (from low to high): C2, C3, B2, B3, G3, G4.

• The lowest two strings, C2 and C3, establish a strong root C across two octaves, providing a deep, foundational bass.
• Next, the B2 and B3 strings, also an octave apart, introduce the major 7th of the C chord. Notably, the B2 string (String 4) is tuned lower than the preceding C3 string (String 5), marking a significant reentrant characteristic.
• Finally, the G3 and G4 strings complete the chord by providing the perfect 5th (G), again an octave apart. Here, the G3 string (String 2) is also tuned lower than the preceding B3 string (String 3), further emphasizing the reentrant nature.

The resulting open tuning forms a clear and resonant C major 7th (Cmaj7) chord, voiced as C-C-B-B-G-G. This creates a beautifully complex and rich harmonic foundation without any fretting.

Open Chords and Playability

The inherent Cmaj7 chord as the open tuning immediately suggests a lush, jazz-influenced or ambient sound. By simply barring all strings at any fret, you can effortlessly transpose this Cmaj7 chord across the fretboard (e.g., bar at the 1st fret for C#maj7, 2nd fret for Dmaj7, and so on). The octave pairings on strings 6&5 (C), 4&3 (B), and 2&1 (G) create a very full and chime-like sound, making this tuning exceptionally rich for strumming.

Beyond simple barring, the reentrant string order encourages unique melodic and harmonic possibilities. Due to the proximity of the C and B notes across adjacent strings, subtle fingerings can create suspensions or altered dominant chords. For example, by fretting the 4th string (B2) at the 1st fret (C3), you can create an interesting Csus2 effect when combined with other open strings, or even push towards more complex jazz voicings with minimal effort. This tuning is particularly conducive to arpeggiated patterns, allowing individual notes of the Cmaj7 to ring out with depth and clarity.

How to Tune

To achieve the 'C5 maj7 Reentrant' tuning, start from standard EADGBe tuning and adjust each string as follows:

• String 6 (Low E to C2): Tune down 4 semitones. This is a significant drop in tension. A heavier gauge string is strongly advised for optimal tone, playability, and to prevent floppiness.
• String 5 (A to C3): Tune up 3 semitones. This increases string tension. Proceed with care.
• String 4 (D to B2): Tune down 3 semitones. This reduces string tension. Proceed with care.
• String 3 (G to B3): Tune up 4 semitones. This is a substantial increase in tension. A lighter gauge string is strongly advised to prevent breakage and ensure proper intonation.
• String 2 (B to G3): Tune down 4 semitones. This is a substantial drop in tension. A heavier gauge string is strongly advised for optimal tone, playability, and to prevent floppiness.
• String 1 (High E to G4): Tune up 3 semitones. This increases string tension. Proceed with care.

Important Note on String Gauge: As some strings require significant tension changes, consider adjusting your string gauge. For movements of 4 semitones or more (up or down), a different string gauge is strongly recommended for optimal playability, tone, and to prevent string breakage or intonation issues. For movements of 3 semitones, proceed with caution, as these are still substantial changes to string tension.