The octobass is the giant double-bass instrument designed by French luthier Jean-Baptiste Vuillaume in the nineteenth century.
Vuillaume built the best-known octobass in Paris in 1849. It is much taller than a conventional double bass and has three strings. Because its fingerboard is so long, mechanical levers and stops help the player shorten the strings and produce usable pitches.
The instrument’s lowest notes are below the normal range of the double bass. Its huge body and long strings create a powerful, rumbling sound, although its size makes it impractical for ordinary orchestral use.
Only a small number of octobasses have been made. Modern reproductions and performances have renewed interest in the instrument, but it remains primarily a historical and experimental orchestral curiosity.