The guitar with sunken frets has six strings belonging to the cordophonic family of the plucking branch of Việt people. A part from the name of the guitar with sunken frets, it also has other names such as the Vietnam guitar, the vọng cổ guitar, the cải lương guitar, or the lục huyền cầm instrument.

The resonator has the diameter of about 36 cm and the round flat shape. Its surface is French polished and made of light wood with resonating hole. On the surface are bridge and the part for keeping strings.

The bottom is made of light wood and covered tightly. The edge is made of hard wood with the height of about 8.5 cm. The neck is made of hard wood with the length of about 62 cm. On the neck are 19 bronze frets and the space between two frets is pierced deeply to create sound effect when they are vibrated or pressed. This reason may make this instrument be called the guitar with sunken frets.
The strings are made of metal. There are many different ways of tuning this instrument such as Sol, Rê, Sol, Rê, La, Rế or Rê, Sol, Rê, Sol, La, Mí.

Tuning peg: There are six pegs going through the head of the instrument neck. The plucking piece is normally made of plastic.

The sound of the guitar with sunken frets is deep and resounding. It has the ambitus of three octaves

Performance pose: The artist can sit in the cross-legged way on the mat or sit on the chair 60 cm high.  

Performance technique:  There are trill finger (ngón láy), tremolo finger (ngón luyến), pizzicato finger (ngón bật), mổ finger (ngón mổ), covering finger (ngón bịt), and especially glissando finger (ngón vuốt) because the instrument neck has the sunken keyboard. The glissando technique can be combined with the tremolo technique of the right hand.

Horizontally vibrating technique (ngón rung ngang): It can be also called rung gân trong, which means vibrating in accordance with the horizontal of the string. For compulsorily and frequently vibrato such as Xự and Cống in Bắc air and Xang and Oan in Nam air, the vibrating sign can be put on the key signature or bar-line. Depending on the player’s capacity and habit, he can process notes differently: Quickly and steadily vibrating is called smoothly vibrating (rung mượt) and quickly and wavily vibrating is named seed vibrating (rung hột).

Pressing technique (ngón nhấn): It means using the fingering of the left hand to press the string to make the tone higher than the normal one. The symbol of pressing is put on the note.

Tremolo pressing technique (ngón nhấn luyến): It means pressing one note and another or many other notes, which have the higher or lower pitch than the initial note. All is done in one fret section. Its effect is causing succession, gentleness, and specific characteristic for its sound. 

Vibrato pressing technique (ngón nhấn rung): It is the combination between the pressing and vibrating technique, for example, Xang and Oan in Nam air.

Pressing technique in another scale (ngón nhấn mượn cung): It means creating one sound by pressing the similar fret in another scale in advance. Its sound effect is making the sound be more emotional than pressing the fret of the right note.

Trilling pressing technique (ngón nhấn láy): It is the combination between pressing and trilling playing. Depending on the trilling type, it can be long trilling pressing playing (nhấn láy dài), shortly trilling pressing playing (nhấn láy ngắn), clapping trilling pressing playing (nhấn láy vỗ), turn trilling pressing playing (nhấn láy chùm), etc.

Glissando technique (ngón vuốt): It means using the left finger to make glissando downwards or upwards in accordance with the vertical string while the right hand plucks the instrument only once or it is co-ordinated with tremolo playing.

Overtone is using the left finger to touch gently the frets in the sections V, VII, IX, XII, and XVII while the right hand plucks that string next to the bridge. Another way is using the index finger of the right hand to touch above sections while the ring finger of the right hand plucks that string. Overtone sounds the bell ring.

Position of the guitar with sunken frets in the orchestras

The guitar with sunken frets is mainly used in Tài tử or Cải lương orchestras (the electronic guitar with sunken frets).