A modern replica of the octobass built in Paris in 1849 by Jean-Baptiste Vuillaume has been loaned to the Montreal Symphony Orchestra by Canadian music patrons Roger and Huguette Dubois. The octobass plays more than an octave below a standard double bass and is the largest stringed instrument in the world, standing at 3.6 meters tall, with 131 kg. Like old double-basses, the octobass has only three strings. It made its first appearance at a concert in Montreal on Oct. 20.