The original version of Mozart's Clarinet Quintet K.581 has finally made it onto disc. The German record company Edition Hera has just released the world-premiere recording of the original basset clarinet version of the work.

Clarinetist Alan Hacker and Asperger Kammersolisten presented the quintet Aug. 17 at the Edinburgh International Festival, which was broadcast live by the BBC.

The work comes from a collection of sketches of the work which were created for the famed instrumentalist Anton Stadler, renowned for his performances on the basset horn during Mozart's time in Vienna, Austria.

The piece is traditionally performed by a conventional clarinet, as only sketches for the basset horn quintet remain. The basset horn is a woodwind instrument and member of the clarinet family, which is either made to sound in the keys of F or G.

During the 18th century, the horn was manufactured to have a crooked end piece, which exists to the current day. The basset horn's distinctive trait is that it extends a full major third below the clarinet.

Mozart himself made extensive use of the instrument, beginning in 1767 with a now-lost piece for two clarinets, two horns and two basset horns, K.41b, written during the composer's time in Salzburg, Germany.

He subsequently used the basset horn in his opera The Abduction From the Seraglio and, later, his interest in the instrument blossomed when he met Stadler.

Stadler and Mozart shared a devotion to the Society of Freemasons, and would often play compositions in the lodge of the Masons temple. Mozart's association with Stadler produced an outpouring of compositions for the instrument, totaling about 18 pieces from 1782 to 1789.

Most of those pieces were chamber-music works, which included several nocturnes, and a Rondo for Soprano and Basset Horn, K.577 from 1789. A draft of a basset clarinet concerto, K.584, exists, and most scholars agree that it was undoubtedly written for Stadler.

The instrument also would figure highly in other works of Mozart, including the opera The Magic Flute, The Mercy of Titus and the Requiem, all from 1791.