Dan Sen lute is a plucking chordophone of Viet majority. This instrument is popular used in the South of Vietnam. A sound box has a shape of six-petal peach blossom or hextagon with diameter of 28 cm. Surface and bottom of the lute are made from light, soft and undecorated wood. Frame of Sen is 6 cm thick, and made from hard wood. Neck is 70 cm long.
There are 17 frets fixed according to traditional equal-tempered heptatonic system. There are 3 wooden pegs, but only 2 of them are functioned as tuning pegs while the rest is just a decoration. Two strings are made from silk and tuned at a fourth Fa - Do1 or a fifth Sol - Do1.
When playing, instrumentalist plucks the strings with a plastic plectrum producing sounds with pure and bright timbres. Sen is played in orchestras of Vietnamese classical drama (Tuong), or renovated opera (Cai luong).