The Wagner tuba, despite its name, is not a tuba at all. It is a brass instrument, but it belongs to the horn family, which is one of the four major categories into which brass instruments are traditionally divided, with tubas, trumpets, and trombones being the others. It is available in two sizes: Bb (tenor) and F (bass) (bass).
The Wagner tuba, on the other hand, is named after German composer Richard Wagner, making it an eponymous instrument, similar to the Sousaphone, which was invented by American bandmaster and composer John Philip Sousa, and the saxophone, which was invented by Belgian instrument maker Adolphe Sax. The Wagner tuba was created because, while writing Der Rhinegold in the early 1850s, Wagner came up with a sound that no other instrument could produce and had it made for him.
They began to be used by other composers as well. According to legend, Anton Bruckner used it in his 7th Symphony, Richard Strauss used it in Don Quixote, Igor Stravinsky used it in both Firebird and Le Sacre du Printemps, and Maurice Ravel used it in his orchestral arrangement of Modest Mussorgsky’s Pictures at an Exhibition. Some of these pieces can now be performed with a euphonium in place of the Wagner tuba.
There are four rotary valves on the Wagner tuba. One of the valves on the Bb Wagner tuba lowers the pitch by a fourth. The same vale lowers the pitch by a fifth on an instrument tuned in F. The music is transposed for both types of Wagner tubas, with the Bb tubas sounding a major second lower than the written pitches and the F tubas sounding a perfect fifth lower.
The Wagner tuba, which uses a horn mouthpiece and has valves operated by the left hand, like the French horn, rather than the right hand, like the other tubas, is usually played by hornists. The right hand is never used to stop the Wagner tuba, unlike the horn, but a mute may be used to reduce the volume. It’s worth noting that achieving accurate intonation with the Wagner tuba is more difficult than with the French horn.