The Tuba is the largest brass instrument and therefore can produce the lowest notes. It usually functions as the double bass of the brass choir, but is also used as a solo instrument (as in Ravel's orchestration of Mousoorgsky's "Pictures at an Exhibition").
A Tuba has a very wide bell which points upwards. Its bore is conical and its mouthpiece is deeply cut. There are Tubas of various sizes; today, a player may select the Tuba which he thinks is best for a given occasion. It sometimes happens that a player uses more than one Tuba during the same concert. The smallest Tuba is called a Euphonium (or Tenor Tuba) and is usually pitched on B flat. The most generally used Tuba is the one tuned on F (sometimes called the Bombardon).
Tubas may have from three to six valves. The first three are operated by the right hand, the fourth can be operated by either hand, and the two extra ones are positioned for the left hand. Both rotary and piston valves can be used, depending on a player's preference.
The Tuba requires an enormous amount of breath; composers take this into consideration, and give them enough time to breath. To play the Tuba, the player normally loosens his lips, condensing them only when playing the highest notes. The deep mouthpiece cup and loose lips produce a very smooth tone. A mute is used chiefly to reduce the volume of sound.
