Basset Horn
A low clarinet in F with an extended range, valued especially by Mozart.
What it means
The basset horn is a low-pitched clarinet, usually built in F, positioned between the ordinary clarinet and the still lower bass clarinet. Its defining feature is an extended range downward: where a standard clarinet stops at written low E, the basset horn reaches down to low C.
To fit this wider range without making the instrument impractically long, the lower part of the tube is often bent or angled; older instruments show a distinctive curve or box just before the bell.
Musical use
The basset horn had its first flowering in the late eighteenth century. Wolfgang Amadeus Mozart particularly admired its warm, dark tone and wrote for it in several works, including chamber music and parts of his Requiem. It later fell out of favor for a time but was rediscovered by composers and clarinetists in the twentieth century.
It should be distinguished from the bass clarinet, which reaches even lower and has a much wider bell, and from the ordinary B-flat or A clarinet, which lacks the extended low range.
Performance practice
When reading basset horn parts, keep the usual clarinet transposition in mind: the instrument in F sounds a fifth lower than written. The extra low notes require confident fingering in the range of additional keys not found on the ordinary clarinet.