Tuba many small brass ensembles will use the euphonium or bass trombone as the lowest voice). It is the principal bass instrument in concert bands, brass bands and military bands, and those ensembles generally have two to four tubas. It is also a solo instrument. Tubas are used in marching bands, drum and bugle corps and in many jazz bands (see below). In British style brass bands, two E and two B tubas are used and are referred to as "basses". Well known and influential parts for the tuba include: Concertos have been written for the tuba by many notable composers,
Tuba including Ralph Vaughan Williams (Tuba Concerto), Edward Gregson, John Williams, Alexander Arutiunian, Eric Ewazen, James Barnes, Joseph Hallman, Martin Ellerby, Philip Sparke, Kalevi Aho, Josef Tal, Bruce Broughton (Tuba Concerto) and David Carlson. Tubas are found in various pitches, most commonly in F, E, C, or B. The main tube of a B tuba is approximately long, while that of a C tuba is , of an E tuba , and of an F tuba . The instrument has a conical bore, meaning the bore diameter increases as a function of the tubing length from the mouthpiece to the bell.