Major thirds tuning Major thirds tuning Among alternative tunings for guitar, a major-thirds tuning is a regular tuning in which each interval between successive open strings is a major third ("M3" in musical abbreviation). Other names for major-thirds tuning include major-third tuning, M3 tuning, all-thirds tuning, and augmented tuning. By definition, a major-third interval separates two notes that differ by exactly four semitones (one-third of the twelve-note octave). The Spanish guitar's tuning mixes four perfect fourths (five semitones) and one major-third, the latter occurring between the G and B strings: This tuning, which is used for acoustic and electric guitars, is called ""standard""
Major thirds tuning improvisation. In contrast, chords cannot be shifted around the fretboard in standard tuning, which requires four chord-shapes for the major chords: There are separate fingerings for chords having root notes on one of the four strings three–six. The repetition of the major-thirds tuning enables notes and chords to be raised one octave by being "vertically" shifted by three strings. Notes and chords may be shifted "diagonally" in major-thirds tuning, by combining a vertical shift of one string with a horizontal shift of four frets: "Like all regular tunings, chords in the major third tuning can be moved across the fretboard