The diameter of the violin column is generally about 5.6-6.0mm, and it is suitable to fit into the f-hole. The 15 inch viola is about 6.5mm in diameter, while the 4/4 column diameter of the cello is about 11mm. Its length is generally determined by the instrument and is related to the curvature and height of the side panel. At one end of the sound column, a density of 5-7 wood grain (annual rings) on the head is appropriate, and the column angle should be slightly rounded. If the material is soft and the sound hole is large, the sound column can be slightly thicker. When the sound of the qin is dull, the sound column can be adjusted to make the sound more sensitive. If the sound is too thin and weak, the volume can be reduced. If the sound column is too thin and weak, the volume can be increased by adjusting the thickness of the column. In theory, the upper end of the column should be inward and the lower end should be outward. A slightly inclined sound will be better, while a vertical sound may not be good because the column is located on the slope of the upper and lower qin boards. If the upper end is inward, the bass will be better, and if the lower end is outward, the treble will be better. The distance between the upper end and the qin horse is also related to the thickness of the board. The board thickness can be farther from the qin horse, and the board thickness can.