Wagner tubas combine elements of the bugle-horns (tubas) and horns. These very mellow and rich-sounding instruments have a horn (funnel-shaped) mouthpiece, the upper tubing of a horn, a narrow bore similar to the horn’s (narrow and conical, i.e. narrower than the tuba’s) and the lower tubing of the baritone. The tube is narrow and slightly conical along its entire length, cylindrical near the valves and ends in a bell with medium flare. The rate of taper at the end of the tube is much slower than on the horn with its widely flaring bell. Its oval form reflects the shape of the instrument that was usual when it originally appeared, in German military bands by 1869 at the latest. The bell curves along its longitudinal axis and faces upward, as distinct from the saxhorns on which the bell faces straight up.
The four rotary valves lower the pitch by 1, ½ or 1½ steps. The Bb instrument has a fourth-valve, lowering the pitch by a fourth, the F instrument a fifth-valve, lowering the pitch by a fifth.