Classical guitar fingerboard and placed at points that divide the length of string mathematically. The strings' vibrating length is determined when the strings are pressed down behind the frets. Each fret produces a different pitch and each pitch spaced a half-step apart on the 12 tone scale. The ratio of the widths of two consecutive frets is the twelfth root of two (formula_1), whose numeric value is about 1.059463. The twelfth fret divides the string in two exact halves and the 24th fret (if present) divides the string in half yet again. Every twelve frets represents one octave. This arrangement of frets
Scale length (string instruments) maker. Antonio De Torres (1817–1892) used a scale length of 25.6 in (650 mm), and later makers have followed suit. However, from the mid- 20th Century luthiers seeking increased volume have moved to a 26 in (660mm) scale, which is now the standard for such leading makers as Ramirez. Unlike Stradivarius, Torres had no strong tradition on which to build regarding scale length, so the 25.6 in figure can be attributed to him with confidence. The steel-string acoustic guitar typically has a scale slightly shorter than the classical instrument, the most common scales ranging between "short scale" : 24 inches