Like the clarinet, the instrument is a wind instrument with a single reed and a cylindrical bore. However, the basset horn is larger and has a bend near the mouthpiece rather than an entirely straight body (older instruments are typically curved or bent in the middle), and while the clarinet is typically a transposing instrument in B♭ or A (meaning a written C sounds as a B♭ or A), the basset horn is typically in F (less often in G). Finally, the basset horn has additional keys for an extended range down to written C, which sounds F at the bottom of the bass staff. Its timbre is similar to the clarinet's, but darker. Basset horns in A, G, E, E♭, and D were also made; the first of these is closely related to the basset clarinet.
The basset horn is not related to the horn, or other members of the brasswind family (Sachs-Hornbostel classification 423.121.2 or 423.23); it does, however, bear a distant relationship to the hornpipe and cor anglais. Its name probably derives from the resemblance of early, curved versions to the horn of some animal.
Some of the earliest basset horns, which are believed to date from the 1760s, bear an inscription "ANT et MICH MAYRHOFER INVEN. & ELABOR. PASSAVII", which has been interpreted to mean they were made by Anton and Michael Mayrhofer of Passau.
Modern basset horns can be divided into three basic types, distinguished primarily by bore size and, consequently, the mouthpieces with which they are played:
The current Buffet basset horn could be called a hybrid "medium-large bore" model, since it uses an alto-clarinet mouthpiece but has a bore diameter around 17.2 mm (0.68 in).
A number of composers of the classical period wrote for the basset horn, and the famous 18th-century clarinettist Anton Stadler, as well as his younger brother Johann, played it. Wolfgang Amadeus Mozart was by far the most notable composer for the basset horn, including three basset horns in the Maurerische Trauermusik (Masonic Funeral Music), K. 477, and two in both the Gran Partita, K. 361, and the Requiem, K. 626, and several of his operas, like Die Entführung aus dem Serail, La Clemenza di Tito which features Vitellia's great aria "Non più di fiori" with basset-horn obbligato, and Die Zauberflöte, where they prominently accompany the March of the Priests, as well as chamber works. He wrote dozens of pieces for basset horn ensembles. (His Clarinet Concerto in A Major, KV 622, however, appears originally to have been written for a clarinet with an extended lower range, a basset clarinet in A, though there is an earlier version of part of the first movement, KV 621b in the Köchel catalogue of Mozart's works, scored for G basset horn and pitched a major second lower, in the key of G major.) The Clarinet Quintet in A major (K. 581) has also been performed on basset horn by Teddy Ezra with other members of the Else Ensemble.[failed verification]
Other early works for basset horn include a concerto for basset horn in G and small orchestra by Carl Stamitz, which has been arranged for conventional basset horn in F (it has been recorded on this instrument by Sabine Meyer), and a concerto in F by Heinrich Backofen.
In the 19th century, Felix Mendelssohn wrote two pieces for the basset horn, clarinet, and piano (opus 113 and 114). These were later scored for string orchestra. Franz Danzi wrote a Sonata in F, for basset horn and piano, Op. 62 (1824) Antonín Dvo?ák attempted a half-hearted revival, using the instrument in his Czech Suite (1879), in which he specifies that an English horn (cor anglais) may be used instead, but the instrument was largely abandoned until Richard Strauss took it up once more in his operas Elektra (1909), Der Rosenkavalier, Die Frau ohne Schatten, Daphne, Die Liebe der Danae, and Capriccio, and several later works, including two wind sonatinas (Happy Workshop and Invalid's Workshop). Franz Schreker also employed the instrument in a few works including the operas Die Gezeichneten and Irrelohe. Roger Sessions included a basset horn in the orchestra of his Violin Concerto (1935), where it opens the slow movement in a lengthy duet with the solo violin. In the last quarter of the 20th century and first decade of the 21st, Karlheinz Stockhausen wrote extensively for basset horn, giving it a prominent place in his cycle of operas Licht and other pieces.
The Lotz Trio performs on replicas of basset horns made originally by 18th-century instrument maker Theodor Lotz from Pressburg (Bratislava) and Vienna. The ensemble endeavours to follow up with popular wind harmonias from the 18th century. The repertory of the Lotz Trio ensemble is formed by original music called by a German name Harmoniemusik. It is presented predominantly by Wolfgang Amadeus Mozart's music, nevertheless, the ensemble performs also music by other Central-European composers - Georg Druschetzky, Martín I Soler, Anton Stadler, Vojtech Nudera, Johann Josef Rösler and Anton Wolanek.
The Prague Trio of Basset-horns, based in the Czech Republic, has a repertoire of music originally written for, or transcribed for, three basset horns by composers including Mozart, Scott Joplin, and Paul Desmond.
Suzanne Stephens is a leading basset-horn specialist in contemporary music. Starting in 1974, the German Karlheinz Stockhausen composed many new works for her, including a large number for basset horn.