The quality of an erhu should be judged from two aspects: sound quality and the overall craftsmanship of erhu production.

(1) In terms of sound quality

The normal grade requires a louder volume, and there is no excessive noise in the first and second positions; the intermediate grade requires a brighter pronunciation, and the upper and lower positions are relatively average; Each sound zone can maintain relative balance. The sound resonance is strong and the transmission far effect is good.

The timbre is round, with bright highs and deep lows, with no noticeable noise. The quality of sound quality is judged by hearing.

(2) Process production

The size of the main parts should meet the requirements. The piano bar should not be too long, otherwise it will be difficult to grasp the center of gravity of the piano when playing. The rod body is smooth, smooth and upright, and the erhu should be placed on the table without excessive skewness. The appearance of the piano barrel should be smooth, neat and beautiful. The inner wall of the cylinder shall not be rough. The thickness should be consistent, and the glued joints should be tight and without gaps. The roundness of the round barrel is accurate, the width and width of the decorative lines are consistent, and the sides and corners of the six-square barrel must be well-proportioned. The skin should be moderately tight, too tight and hard, and too loose. The thickness of the python skin is the key, and the python skin with thick and thin scales and bright patterns and colors is better. The surface treatment of the cortex should be clean, and there should be no excessive wax. The surface of the python skin looks translucent, and the back of the cortex should be uniformly white, especially the high-end erhu, which is very important and will directly affect the appearance of the erhu. sound and "the future".

The installation of the piano rod and the piano barrel is very strict. Their cooperation is directly related to the pros and cons of the pronunciation. They must be closely matched and there must be no looseness. The center of the upper and lower eyes of the piano bar and the piano barrel is 37 mm to 38 mm from the edge of the front mouth of the piano barrel, including the vibrating membrane. Such an installation angle can make the strings pass through the bridge and increase the pressure on the membrane. It can not only make the lower position (treble) pronounce clearly, but also facilitate the exertion of playing skills. For the appearance of erhu, general-grade products require basically the same color, intermediate-grade products require bright, high-grade products require uniform brightness and clear wood grain.