Basset clarinet

The basset clarinet is a clarinet similar to the usual soprano clarinet but longer and with additional keys to enable playing several additional lower notes. Typically a basset clarinet has keywork going to a low (written) C, as opposed to the standard clarinet's E or E♭ (both written), and is most commonly a transposing instrument in A, although basset clarinets in C and B♭ also exist, and Stephen Fox makes a "G basset clarinet/basset horn". The similarly named basset horn is also a clarinet with extended lower range, but is in a lower pitch (typically F); the basset horn predates, and undoubtedly inspired, the basset clarinet.

The basset clarinet was most notably associated with the clarinet virtuoso Anton Stadler (1753-1812), a contemporary and good friend of Mozart. Mozart wrote his Clarinet Quintet in A major, K581 and Clarinet Concerto in A Major, K622 for this instrument; the concerto is partly based on an earlier fragment of a Concerto for Basset Horn in G, K584b. The mezzosoprano Sesto's aria (Parto, ma tu ben mio) from Act I of Mozart's last opera, La clemenza di Tito, also features a basset clarinet obbligato.