Octave twelve the ""Mando-guitar"" from 1964 to 1968. Notable users of the Mando-guitar include Brian Jones of The Rolling Stones. Most modern octave twelves are modeled after the distinctive body shape of the Vox Mando-guitar. (Some believe that George Harrison of The Beatles used it on the song "Words of Love" in 1964, but the Mando-Guitar was not introduced until the following year.) It was (and may still be, in live performances) also used on the introduction of The Beach Boys' "Wouldn't It Be Nice", from "Pet Sounds". Octave twelve An octave twelve is a type of 12-string guitar fitted with a
Augmented seventh plus the difference between the chromatic and diatonic semitones, which makes it a highly variable quantity between one meantone tuning and the next. In standard equal temperament, in fact, it is identical to the perfect octave (), because both semitones have the same size. In 19 equal temperament, on the other hand, the interval is 63 cents short of an octave, i.e. 1137 cents. More typical meantone tunings fall between these extremes, giving it an intermediate size. In just intonation, three major thirds in succession make up an augmented seventh, which is just short of an octave by 41.05 cents.