Wind instrument of the metal group with a wide structure and a velvety and sweet sound, it is a tenor tuba. The instrument was invented by Sommer of Weimar around 1843 and was called “euphonium”. Its name comes from the Greek word “euphonos” meaning “sweet voice”. The euphonium has a precious role in orchestras and bands whether playing the bass or tenor lines, covering approximately the same extension as the cello and the ophicleide. Its beginning at the orchestra happened almost by accident, at the début of the symphonic poem “A Hero’s Life” by Richard Strauss. He decided to substitute the Wagnerian tuba, which had been initially planned for the composition, for the euphonium, and the latter was a big hit, being occasionally used in other orchestral pieces afterwards. In bands, the euphonium quickly became the most important bass metal instrument, having an important melodic function.