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 An Infinite Regression") á la funk bassist Larry Graham and the double thumping technique pioneered by Victor Wooten — as well as harp-like arpeggios. Ihsahn of the black metal band Emperor began playing seven-string guitar in 1999 and first played eight-string guitar on his 2010 album "After". Rusty Cooley tunes his eight-string guitar like a standard six-string expanded in both directions. This tuning offers both deeper bass tones than a conventional guitar and extended range in the higher register for lead melodies. Guitarist Justin Broadrick of the English industrial metal band Godflesh introduced his eight-string playing on the 2014 Godflesh