Euphonium are the tuba-euphonium quartet or larger tuba-euphonium ensemble; the brass quintet, where it can supply the tenor voice, though the trombone is much more common in this role; and other mixed brass ensemble. Such ensembles are almost non-existent: they are more likely to be semi-professional or amateur in nature. Most of the United States Armed Forces service bands include a tuba-euphonium quartet made up of players from the band that occasionally performs in its own right. The euphonium is not traditionally an orchestral instrument and has not been common in symphony orchestras. However, there are a few works from the
Tuba of notes. Prior to the invention of valves, brass instruments were limited to notes in the harmonic series, and were thus generally played very high with respect to their fundamental pitch. Harmonics starting three octaves above the fundamental pitch are about a whole step apart, making a useful variety of notes possible. The ophicleide used a bowl-shaped brass instrument mouthpiece but employed keys and tone holes similar to those of a modern saxophone. Another forerunner to the tuba was the serpent, a bass instrument that was shaped in a wavy form to make the tone holes accessible to the player.