Editing Tuba (section)

===Valves===
Tubas are made with either [[piston valve|piston]] or [[rotary valve|rotary]] valves. Rotary valves, invented by Joseph Riedl, are based on a design included in the original valve patents by [[Friedrich Blühmel]] and [[Heinrich Stölzel]] in 1818. [[Václav František Červený|Červený]] of [[Kraslice|Graslitz]] was the first to use true rotary valves, starting in the 1840s or 1850s. Modern piston valves were developed by [[François Périnet]] for the [[saxhorn]] family of instruments promoted by [[Adolphe Sax]] around the same time. Pistons may either be oriented to point to the top of the instrument (top-action) or out the front of the instrument (front-action or side-action).

Piston valves require more maintenance than rotary valves – they require regular oiling to keep them freely operating, while rotary valves are sealed and seldom require oiling. Piston valves are easy to disassemble and re-assemble, while rotary valve disassembly and re-assembly is much more difficult and is generally left to qualified instrument repair persons.

Tubas generally have from three to six valves, though some rare exceptions exist. Three-valve tubas are generally the least expensive and are almost exclusively used by amateurs, and the [[sousaphone]] (a marching version of a BB{{music|flat}} tuba) usually has three valves. Among advanced players, four and five valve tubas are by far the most common choices, with six-valve tubas being relatively rare except among F tubas, which mostly have five or six valves.

[[File:Tuba.JPG|thumb|left|250px|Tuba with four rotary valves]]

The valves add tubing to the main tube of the instrument, thus lowering its fundamental pitch. The first valve lowers the pitch by a whole step (two semitones), the second valve by a semitone, and the third valve by three semitones. Used in combination, the valve tubing is too short and the resulting pitch tends to be sharp. For example, a BB{{music|flat}} tuba becomes (in effect) an A{{music|flat}} tuba when the first valve is depressed. The third valve is long enough to lower the pitch of a BB{{music|flat}} tuba by three semitones, but it is not long enough to lower the pitch of an A{{music|flat}} tuba by three semitones. Thus, the first and third valves used in combination lower the pitch by something ''just short'' of five semitones, and the first three valves used in combination are nearly a quarter tone sharp.

The fourth valve lowers the pitch by a perfect fourth, so it can be used in place of the combination of the first and third valves. When tuned properly it helps solve the issue of valve combinations being too sharp. Using the fourth valve with the first three valves allows the musician to extend the instrument's range down to the fundamental pitch. As with other valve combinations that lengthen the tubing considerably, some of these lower notes can be sharp.

A fifth and sixth valve, if fitted, are used to provide alternative fingering possibilities to improve intonation, and are also used to reach into the low register of the instrument where all the valves will be used in combination to fill the first octave between the fundamental pitch and the next available note on the open tube. The fifth and sixth valves also give the musician the ability to trill more smoothly or to use alternative fingerings for ease of playing. This type of tuba is what is most found in orchestras and wind bands around the world.

The bass tuba in F is pitched a fifth above the BB{{music|flat}} tuba and a fourth above the CC tuba, so it needs additional tubing length beyond that provided by four valves to play securely down to a low F as required in much tuba music. The fifth valve is commonly tuned to a flat whole step, so that when used with the fourth valve, it gives an in-tune low B{{music|flat}}. The sixth valve is commonly tuned as a flat half step, allowing the F tuba to play low G as 1-4-5-6 and low G{{music|flat}} as 1-2-4-5-6. In CC tubas with five valves, the fifth valve may be tuned as a flat whole step or as a minor third depending on the instrument.