What is the structural composition of Dong Pipa?

The Chinese Musical Instrument Museum of China Academy of Art Conservatory of Music in Beijing has a collection of Dong's big pipa. The piano body is made of hard miscellaneous wood, with a total length of 10 1 cm. * * * The speaker is an inverted trapezoid covered with paulownia board, with a length of 2 1cm, a width of 16cm and a thickness of 6cm. There are three small circular sound holes in the center of the panel, which are arranged in a zigzag pattern. The piano head is a double diamond, 24 cm long, with a chord groove in the middle and four boxwood chord axes on both sides. The piano has no quality and four strings. The big pipa made by the Dong pipa singer in Guangxi, 1964, was presented to the Institute by Guangxi Music Association.