First introduced around 1850 in Paris, it has three strings, and is essentially a larger version of the double bass. Because of the extreme fingerboard length and string thickness, it requires the musician to play it using a system of hand and foot-activated levers and pedals. The pitch of the Octabass’s highest string is the same pitch as the lowest note of a modern double bass with a low C extension. The lowest string is tuned to C, 16.25 Hz, one octave below the lowest note on a piano.
By the way, you can see an Octabass at the Musical Instrument Museum in Phoenix, AZ. It’s a great museum with an amazing collection of musical instruments from all over the world. You don’t have to be an ethnomusicologist to be in awe of this incredible collection.