Contrabass recorder

Due to the length of the instrument, the lowest tone, F, requires a key.

Occasionally, this size of instrument may be equipped with so-called "diapason" keys, which extend its range downward by a perfect fourth to low C2.

[1] In the early 17th century, Michael Praetorius used the diminutive term "basset" (small bass) to describe the recorder that served as the lowest member of the "four-foot" consort, in which the instruments sound an octave higher than the corresponding human voices.

Praetorius calls the next-lower instrument (bottom note B♭2) a "bass", and the instrument an octave lower than the basset (with bottom note F2) a Großbaß, "great" or "large bass".

[2] Because Praetorius's term "great bass" today is often applied to the next-smaller size of instrument in C3, the low-F bass is often designated "contrabass" by modern writers and instrument makers in a (largely futile) attempt to avoid confusion.