The sudrophone is a brass instrument invented by François Sudre (1844–1912). Its shape resembles that of an ophicleide. It was patented in 1892.
A sudrophone has a cylindrical bore and four Perinet valves. Its length is 86 centimetres (34 in) and the bell diameter is 17 centimetres (6.7 in). The "valve" nearest the mouthpiece on the leadpipe controls a silk membrane to create a nasal effect, which Sudre designed to make a sound like a cello or a violin. The instrument is very similar to the baritone horn and helicon. Acoustically these resembled the saxhorns, but the shape was different as the main tube was doubled back on itself, giving a vertical appearance reminiscent of an ophicleide, this design choice was made by Sudre to make the instrument stand out more amongst the primarily saxhorn-shaped brass instruments that were much more popular.