Tuba
From the Simple English Wikipedia, the free encyclopedia that anyone can change
The tuba is the largest of the brass musical instruments. They are the most recent addition to the symphony orchestra, first appearing in the mid-19th century. Though there is usually one in most orchestras.
Tubas are most commonly in the key of F, EEb, CC, or BBb and can have 3 - 6 valves. Due to its size, some tubas have a compensating system, where by, for example a fourth, fifth or sixth valves can create new valve combinations for other notes but with a clearer pitch then of the valve combination before. This was only developed recently, tuba plays used to change certain "off" notes by "lipping" the notes up or down depending whether the note was sharp or flat.