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
Romantic guitar mainly used for plucking with, in the 19th century, a free stroke ("tirando") more commonly than the rest stroke ("apoyando") that was favoured in the 20th century. Unlike most classical guitarists today, players were divided as to whether or not use fingernails. Fernando Sor, for example, did not use them while his compatriot Dionisio Aguado did. The narrower fretboard of the romantic guitar allowed the left-hand thumb to be used by some guitarists to fret the sixth string although Fernando Sor deprecates this in his method, recommending that the left-hand thumb remain at the rear centre of the neck and