The tuba is a type of brass instrument. The term ‘tuba’ can cover several kinds of brass band instrument, like the euphonium, but usually refers to the standard orchestral bass tuba. The tuba is played in a vertical position, unlike the horizontal position of the trumpet and trombone, and is the lowest sounding of all the orchestral brass instruments. Tubas can have either rotary valves or piston valves.
Sizes of tuba include the ‘double C‘ & ‘double B flat’ also known as contrabass tubas, and the smaller bass tubas in F and E flat. The double C tuba has been standard in orchestras since the 1940s, whereas brass and military bands typically use an E flat bass tuba. There is also a tenor tuba, which is called for in Richard Strauss’s symphonic poem Don Quixote, and the rarer triple B flat, or sub-contrabass tuba.
The Wagner tuba was invented by Richard Wagner as compromise between the horn and the tuba to give special tone-colour to the orchestration of his Der Ring des Nibelungen. Wagner tubas look more like horns than tubas and have a mellow, distant sound.