Guitar It is flat on classical guitars and slightly curved crosswise on acoustic and electric guitars. The curvature of the fretboard is measured by the fretboard radius, which is the radius of a hypothetical circle of which the fretboard's surface constitutes a segment. The smaller the fretboard radius, the more noticeably curved the fretboard is. Most modern guitars feature a 12" neck radius, while older guitars from the 1960s and 1970s usually feature a 6-8" neck radius. Pinching a string against a fret on fretboard effectively shortens the vibrating length of the string, producing a higher pitch. Fretboards are most commonly
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