The triple contrabass viol is a modern variant of the French octobass, which lost favor with most composers since its creation in 1850. It is an acoustic string instrument belonging to the family of the violin, viola, and cello. It is more closely related, however, to the double bass, the sole remaining arguable member of the viol family to remain in widespread use.
Only the origins of the double bass are in question. Modern construction: arched back and belly, sound post and bass bar place the double bass squarely in the violin family. Only strings in fourths and the sloped shoulders remain, neither of which is universal.
Recordings and performances of sub-contrabass string instruments are rare; over 10 feet (3 m) tall, the triple contrabass viol must be played with the performer on an elevated platform. It was originally a three-stringed baroque instrument tuned C0–G0–C1 or C0–G0–D1 with the lower C coming in at 16.35 Hz. This is equivalent to the C two octaves below the cello's lowest C.
It is known that a four-string variant has been played recently by bassist Brian Smith for a Roscoe Mitchell recording. It had two large circular holes in the body to facilitate recording.