The bass member of the modern brass family. The tuba family includes the euphonium, sousaphone, C and B-flat tubas, and others. The modern orchestral tuba has valves, a conical bore and a range of D two octaves below the bass clef to G above middle C. The bell is very wide and the cup very deep, thus facilitating the extremely low notes so characteristic of the instrument.Tubaa term applied to a variety of large, deep-toned brass instruments with valves. these include the euphonium, flugelhorn, helicon, saxhorn, and sousaphone