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
Semitone pitch. 12-tone equal temperament is a form of meantone tuning in which the diatonic and chromatic semitones are exactly the same, because its circle of fifths has no break. Each semitone is equal to one twelfth of an octave. This is a ratio of 2 (approximately 1.05946), or 100 cents, and is 11.7 cents narrower than the 16:15 ratio (its most common form in just intonation, discussed below). All diatonic intervals can be expressed as an equivalent number of semitones. For instance a whole tone equals two semitones. There are many approximations, rational or otherwise, to the equal-tempered semitone. To