Euphoniums and Tenor Tubas

The Euphonium is often confused with a Bb Baritone or Bb Tenor horn as it does share a common base pitch.   It is differentiated from these instruments due to its larger bore, and wider range - spanning from tenor to bass registers (up to four octaves).   It was first invented in c.1843 and was originally called a tenor bass horn. The euphonium can be considered a 19th century valved development of the opheclide and serpent and is squarely in the family of tubas. 

The euphonium is usually configured as a compensating instrument and normally has a 4th Valve.  The euphonium has enjoyed wide popular use in military, school and civic bands and orchestras, but is only rarely used in symphony orchestras.  Euphoniums have also been configured as helicons and as bell-forward marching instruments.