Acoustic bass guitar of acoustic bass guitars. The bajo sexto, with six pairs of strings, resembles a twelve-string guitar tuned an octave lower. The heavy gauge strings generate a large string tension, yet the guitar is built relatively lightly. Musicians began to use the bajo sexto in Texas in the 1920s with the rise of "Tex-Mex" music, and remains in common use to play parts that would be played by the piano in traditional American popular music. It matches the standard tuning of a 12-string guitar, one octave lower. The tuning of these instruments is (capital letters are an octave lower than small
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