five keys. Mozart suggested extending the clarinet downwards by four semitones to C, which resulted in the basset clarinet that was about 18 cm longer, made first by Theodor Lotz. In 1791 Mozart composed the Concerto for Clarinet and Orchestra in A major for this instrument, with passages ranging down to C₃. By the time of Beethoven , the clarinet was a fixed member in the orchestra.

The