Tuning Overview: 8-String Perfect Fourths Jazz

The "8-String Perfect Fourths Jazz" tuning is a thoughtful and innovative approach designed to expand the harmonic possibilities of an 8-string guitar, particularly for jazz musicians. As its name suggests, it primarily leverages the intervallic consistency of perfect fourths, a staple in modern jazz harmony, while making strategic adjustments to optimize playability and tension.

This variant distinguishes itself by intentionally lowering the six lowest strings by a single semitone, while keeping the two highest strings (B and E) at their standard pitches. This approach successfully mitigates increased tension on the delicate high strings, a common concern in alternate tunings, by instead reducing tension on the lower gauges. The result is a deep, resonant F1 on the lowest string, providing an excellent foundation for low-register voicings.

Technical Analysis: Intervals and Voicings

The core of this tuning's design lies in its intervallic structure. Examining the open strings from lowest to highest pitch:

• The lowest string, F1 (String 8), sets a very deep foundation.
• There's a significant jump from F1 to A#2 (String 7), spanning 17 semitones (a minor sixth plus an octave), creating a wide, open interval.
• A remarkable sequence of five consecutive perfect fourths then follows: A#2 (String 7) to D#3 (String 6), D#3 to G#3 (String 5), G#3 to C#4 (String 4), and C#4 to F#4 (String 3). This block of strings is ideally suited for quartal harmony, allowing for easy fingerings of extended chords like major 7#11, minor 11, and various suspended voicings simply by barring or shifting across frets.
• Between F#4 (String 3) and B3 (String 2), there's a downward interval break of 7 semitones (a perfect fifth down). This strategic drop allows the tuning to resolve to the familiar B3 and E4 (String 1) high strings, which are tuned in a standard perfect fourth. This ensures that a player retains a sense of familiarity for lead lines and higher chord voicings.

The predominant use of perfect fourths across the middle strings is a powerful feature for jazz improvisation and composition. It simplifies the visualization and execution of complex, open-sounding voicings. While the full complement of open strings doesn't form a conventional chord, the stacked fourths from String 7 to String 3 create an inherently open, ambiguous quartal cluster, which can be easily adapted to various harmonic contexts with minimal fretboard movement. The F1 low string provides a deep root, perfect for walking bass lines or anchoring dense chords. Being "a fret-off from anyone playing in standard tuning" is a small adjustment for the harmonic rewards this tuning offers.

How to Tune: String Movements

This tuning is achieved by making precise, minor adjustments to the lower strings while keeping the higher strings at their standard pitch. No significant tension changes or string gauge alterations are necessary for these adjustments.

• String 8 (F1): Tune down 1 semitone.
• String 7 (A#2): Tune down 1 semitone.
• String 6 (D#3): Tune down 1 semitone.
• String 5 (G#3): Tune down 1 semitone.
• String 4 (C#4): Tune down 1 semitone.
• String 3 (F#4): Tune down 1 semitone.
• String 2 (B3): Keep as is; no change (0 semitones).
• String 1 (E4): Keep as is; no change (0 semitones).

As all adjustments are within a 1-semitone range, you can use your existing string set without concerns about excessive tension or slack. Always tune carefully and check intonation after changes.

The final open notes for this 8-string guitar tuning are:

• String 8: F1 (lowest pitch)
• String 7: A#2
• String 6: D#3
• String 5: G#3
• String 4: C#4
• String 3: F#4
• String 2: B3
• String 1: E4 (highest pitch)