On a brass instrument, a valve is a mechanism that, when in use, directs the air column along additional tubing inside the instrument, thus producing a different fundamental and harmonic series.
Most modern valved instruments employ similar valve systems which results in the same patterns of valve combinations to alter a pitch. For example, depressing the first valve will normally result in lowering the original pitch by one step, or the interval of a second. The table below shows the valve combinations of a typical valved instrument and the resulting pitch alterations. It should be noted that the addition of the fourth valve became common in the mid-20th century to help produce better intonation with the third valve combinations that tended to be "out of tune" or having poor intonation (especially the 1st & 3rd valve combination). Valves can be created in a rotary or piston configuration.
Valve and Pitch Relationships
|Valve Combinations||Pitch Lowered|
|2nd Valve||1/2 step|
|1st Valve||1 full step|
|3rd Valve||1 & 1/2 steps|
|1st & 2nd Valves||1 & 1/2 steps|
|2nd & 3rd Valves||2 full steps|
|1st & 3rd Valves||2 & 1/2 steps|
|1st, 2nd, & 3rd Valves||3 full steps|
|4th Valve Combinations|
|4th Valve||2 & 1/2 steps|
|2nd & 4th Valves||3 full steps|
|1st & 4th Valves||3 & 1/2 steps|
|3rd & 4th Valves||4 full steps|
|1st, 2nd, & 4th Valves||4 full steps|
|2nd, 3rd, & 4th Valves||4 & 1/2 steps|
|1st, 3rd, & 4th Valves||5 full steps|
|1st, 2nd, 3rd, & 4th Valves||5 & 1/2 steps|
See trumpet-valve-air-flow in the Appendix.
See Also[English] rotary valve
[English] piston valve
Last Updated: 2016-05-04 13:29:27