Overtones tuning

An example is the open tuning constituted by the first six overtones of the fundamental note C, namely C2-C3-G3-C4-E4-G4.

For each such open or barred chord, the overtones reinforce the bass note, increasing the guitar's volume of sound and resonance.

When an open-note C-string is struck, its overtones sequence begins with the notes (C,C,G,C,E,G,B♭,C).

[12] Truncating this tuning to G-D-G-B-D for his five-string guitar, Keith Richards plays this overtones-tuning on The Rolling Stones's "Honky Tonk Women", "Brown Sugar" and "Start Me Up".

Of all the intervals in equal temperament, the thirds have the largest error in comparison to those of just intonation: Equal temperaments is used in modern music because it facilitates music in all keys, while (on a piano and other instruments) just intonation provided better-sounding major-third intervals for only a subset of keys.

[14] "Sonny Landreth, Keith Richards and other open-G masters often lower the second string slightly so the major third is in tune with the overtone series.

This adjustment dials out the dissonance, and makes those big one-finger major-chords come alive.

To the extent that we play with a slide (like the Delta blues players) or with one barred finger or some other grip (Keith Richards) that is essentially just moved up and down the neck, ... then the 3 of the chord can be tuned more or less "pure", as in the holy overtone series.

If we're playing with a slide, this is more or less guaranteed.William Sethares described an overtones tuning that contains the fourth to ninth partials, omitting the first three partials (notes of the sequence of overtones)[16] Its open notes do not form a major chord.

The higher partials, particularly B♭, are poorly approximated by notes using equal temperament: "Our tempered aural thinking can include tones up to the sixth partial but beyond that the point the aural perception is merely rational.