Electric mandolin 4-string version. A related instrument, the Bahian guitar, was developed in Brazil beginning in the 1940s. Bahian guitars typically have a solid body and 4 or 5 single-course strings tuned in fifths, but are considered to be electric versions of the cavaquinho rather than the mandolin. Both four string single course and eight string double course solid body mandolins have been produced by several makers, as well as five string single course models. From 1956 to 1976, Fender produced a four string version which they simply called the "Fender Electric Mandolin". Its body shape was based on a smaller version
Mandolin suit them to Cai luong opera music. In the mid-1930s, they made concave frets, scooping out extra wood between the frets, making the space between them deep and to allow the musicians to bend the notes, and stringing them with four single strings. Musicians Hai Nén and Hai Nhành were associated with the instruments, possibly being the first to use them. The "sunken-fret mandolin" (mandolin phím lõm) did not meet the musical needs as well as the sunken-fret guitar, because the mandolin's rigidity made it painful to get the same effects from the strings. Also the mandolin's narrow fretboard made