The dan bau is a one-string zither native to Vietnam. Initially, the dan bau had only four components: a bamboo cylinder, a wooden stick, half of a coconut shell, and a silk string. Currently, it is constructed of a long narrow ornamented sound box, with a tall curved stem made from water buffalo horn inserted at one end. The modern single string is typically made out of guitar style nylon. It runs between the sound box and a small wooden gourd attached to the stem.
The stem is bent to change the pitch of the string. The player touches the string lightly with the heel of the hand at harmonic producing nodal points while plucking with the fingers. This produces the dan bau’s characteristic high, clear sound.
Vietnamese music group Khac Chi has added frets to the instrument’s already complex array of pitch production mechanisms.
As the sound box of the dan bau is very narrow, it is not a loud instrument, and was traditionally used in more intimate environments. In recent years an electric version has been introduced, to be played in ensembles and large concerts.
The bass bau was adapted from the dan bau to provide a musical range equivalent to that of a bass guitar. It is simply an electric dan bau with a very thick string on it. Due to the thickness of the string, it is quite a difficult instrument to play.