Euphonium

The euphonium is a medium-sized, 3 or 4-valve, often compensating, conical bore, tenor voiced brass instrument. Nearly all current models have piston valves, though some models with rotary valves do exist.  It is extremely similar to a baritone horn. The difference is that the bore size of the baritone horn is typically smaller than that of the euphonium, and the baritone is a primarily cylindrical bore, whereas the euphonium is predominantly conical bore. The cylindrical baritone offers a brighter sound and the conical euphonium offers a more mellow sound.