As a performer and teacher, my approach is to build upon knowledge through practice. There are certainly unlimited ways to string and tune, but the idea presented here is about notes used to build chords. This is commonly known as open tuning. The guitar plays the basic three note Triad that is the foundation of a Major or minor chord.
Here is an example to explore Spanish Tuning aka Open G. ...
To make a G Major chord, notes 1G, 3B, 5D are required.
Use these medium gauge strings
Tune GDG - E(ADG)BE - Low
Tune DGB - EA(DGB)E - Middle
Tune GBD - EAD(GBE) - High
GDG is not the full chord but lacks the minor third B. This tuning offers a primal approach to playing excellent for playing in one key. Shuffle rhythms, walking bass, alternating bass fingerpicking, and early bottleneck slide. See CD 4.
DGB is a full chord with the notes arranged 513. Music is all about relativity. Instead of having another CBG strung and tuned DGB, I often retune my GDG CBG to ADF#. This is the same 513 note arrangment but in the key of D. Due to relativity, the finger positions on the board are all the same. The CBG simply sounds in a different key. Excellent for playing in any one of the 12 keys of music using a "movable chord method". See CD 6
GBD is also a full chord arranaged 135. This higher string configuration is great for lead work.
See CD 2 for 6 string. Notice how these are all parts of the full tuning: DGDGBD.
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