A large type of bass lute, related to the French archlute, of the baroque period, developed in the 1500s and still in use in the 18th century.

It had an extra set of bass strings, not stopped on a fretted fingerboard as the regular set are but tuned to the diatonic scale and designed to be plucked as open strings (unstopped). These made it more suitable for playing baroque music than was the lute.

It was developed from the notion of taking the lowest string to a second head, which extended in a step directly from the first head, which was in line with the neck, thereby avoiding the use of one very long pegbox, which would be unable to take the strain of the bass strings. These unstopped strings, called diapasons, caused a sudden jump and change in the tone colour.