Guitar Frets are laid out to accomplish an equal tempered division of the octave. Each set of twelve frets represents an octave. The twelfth fret divides the scale length exactly into two halves, and the 24th fret position divides one of those halves in half again. The ratio of the spacing of two consecutive frets is formula_1 (twelfth root of two). In practice, luthiers determine fret positions using the constant 17.817—an approximation to 1/(1-1/formula_1). If the nth fret is a distance x from the bridge, then the distance from the (n+1)th fret to the bridge is x-(x/17.817). Frets are available in
Eight-string guitar Novax Guitars. Five of the strings are tuned to the standard guitar's upper five (A, D, G, B, E), while three of the strings are tuned to the standard bass guitar's three lowest (E, A, D). The bass and treble sections have separate pickups and are sent to separate amplifiers. Hunter also has a ten-string guitar based on the same principle—a combination of standard six-string guitar and standard four-string bass. The eight-string guitar is used by modern heavy metal guitarists such as Fredrik Thordendal and Mårten Hagström of Meshuggah, Dino Cazares of Fear Factory, Stephen Carpenter of Deftones, Greg Burgess