Bass Tuba, brief description
“The tuba is currently used in four tunings: the bass tuba in F and Eb, and the contrabass tuba in C and Bb. In Austrian and French orchestras tubas in F and Bb are used, the contrabass tuba in Bb being found primarily in opera orchestras. In some regions of Germany and in Scandinavia, the United Kingdom and the USA the C tuba with four valves is common as a kind of all-round instrument: it is played not only in the orchestra but also in chamber music and as a solo instrument.”
Contrabass Tuba, brief description
“The contrabass tuba is currently made in two tunings: C and Bb. It is used primarily in opera orchestras and in brass and military bands. It is rarely asked for in symphony orchestras. Contrabass tubas are basically made in two different forms: the tuba form and the spiral form. Spiral tubas are also known as helicons.”
Wagner Tuba, brief description
“The Wagner tuba, conceived by Richard Wagner for his Ring of the Nibelung, is made in two sizes, Bb (tenor instrument) and F (bass instrument). In the symphony orchestra two of each instrument have always been used. Because they have a horn mouthpiece they are played by hornists.”