The dahu is a large bowed string instrument from China. It has a large soundbox covered on one end with snakeskin. Like most other members of the huqin family of instruments, it has two strings and is held vertically. The instrument is generally pitched one octave below the ''erhu'', and is considerably larger than the ''erhu''. Its name derives from the Chinese word for "large" , and the word ''hú'' .
The ''dahu'' was developed for orchestral use in the 1930s as the tenor member of the ''erhu'' family , but by the late 20th century it had largely fallen into disuse. Part of the reason for this is that it is unwieldy to play. Also, the fact that the bow passes between the instrument's two strings means that playing pizzicato is difficult; thus, the larger gehu and diyingehu are generally used in Chinese orchestras for the lower bowed string voices instead.
The ''dahu'' is sometimes also called ''cizhonghu''. It is also referred to as ''xiaodihu'', being the same instrument as the smallest of the three sizes of ''dihu'' , the others being the ''zhongdihu'' and ''dadihu''.