This variation of the guitar is with double strings. Nevertheless none of the double strings are of the same frequency or pitch but one or two octaves difference. The reason that it is so is that the slight deviation from the original tuning during playing (especially when tis t many hours playing) is not creating an irritating dissonance. The one o two octaves difference guarantee that such deviations are middle and do not created acute dissonance. In addition the innovation of two -octaves difference in the 2 lower pitch courses creates a very sweet sound.
Further innovation is that the tuning is not like the 4 higher double strings, say of a 12-string guitar, but as the harmonic guitar in post 90. In other words alternation of minor and major thirds, exactly as in diatonic scale , that create chord triads. This tuning is an open tuning.
In detail the tuning is
C2C4-Eb2Eb4-G2G3-Bb2Bb3.
Thus it is an open Cm7
So this guitar has lower note the C2 as the Cello and some Arabian Uds.
The choice of the scale Eb major (or C minor) as privileged scale is so as to fit well with the lower registry of the Boehm clarinet in Bb, which nevertheless at the lower registry sounds in Eb.
Because the guitar is tuned one major 3rd lower with the same strings of a standard guitar, the pressing of the strings in the frets is softer, that a standard 12-string guitar. Furthermore the impedance of the vibrations is lower as in the saz which is usually longer, but of low string tension.
Because the guitar is tuned one major 3rd lower with the same strings of a standard guitar, the pressing of the strings in the frets is softer, that a standard 12-string guitar. Furthermore the impedance of the vibrations is lower as in the saz which is usually longer, but of low string tension.
As the Eb diatonic scale has only one flat difference from the Bb diatonic scale, this guitar is accompanies preferably Jazz music that utilizes , trumpet or cornet in Bb, Saxophones in Bb and clarinets in Bb. But such instruments are also used in folk music of various cultures (e.g. Greek folk music) therefore is suitable for such music too.
This tuning is optimal in the sense that it has the maximum number per frets (maximum density) of triad-chords (3-strings chords, major , minor , diminished augmented ) .
The lower 3-strings give naturally sequence of triad-chords of the Aeolian mode (Cm) of the Eb and the higher 3-strings naturally sequence of triad chords of the Ionian (major) mode.
In the next pictures is seen, the body of a 12-string guitar which has been converted to a 4-double strings 8-string guitar, with the above tuning.
A more natural solution would be to utilize the bodies of 4-double strings tenor guitars (used mainly in jazz as arc-top tenor guitars) and tune it as above
