Fender Stratocaster

Seven-strings were popularized in the 1980s and 1990s in extra due to the release of the Ibanez Universe guitar, endorsed by Steve Vai. Other artists go a vestige further, by using an 8 string guitar with two extra low strings. Although the most average 7-string has a level B string, Roger McGuinn (of The link Byrds and Rickenbacker) uses an octave G string paired with the regular G string as on a 12 string guitar, allowing him to incorporate chiming 12 string elements in standard 6 string playing.

Frets are laid out to a mathematical ratio that results in equal tempered division of the octave. The ratio of the spacing of two consecutive frets is the twelfth root of two \sqrt{2}, whose numeric value is about 1.059463. The twelfth fret divides the hierarchy length in two exact halves and the 24th fret fix divides the scale length in half yet again.