Think of the three great composers for the clarinet – Mozart, Weber and Brahms – and they were all influenced by a muse, players of such quality that they were inspired to write some of their greatest music. In Brahms’ case, that meant coming out of compositional retirement, while Mozart’s advocacy for the clarinet was responsible for the instrument’s rise in popularity. Mozart’s Clarinet Concerto, his final instrumental work, was completed in October 1791, less than two months before the composer’s early death, at the age of just 35. It was written for Anton Stadler, who gave the premiere in Prague on 16th October 1791.

The disputed "Edlinger Mozart" portrait (c 1790), possibly the last portrait of the composer
© Wikicommons

By this stage, the clarinet was still a relatively young orchestral instrument. In 1778, Mozart had written to his father from Mannheim, sighing, “Oh, if only we too had clarinets!” Unlike the flute, which he feigned to detest, Mozart fell in love with the clarinet. All his great works for the instrument – the concerto, the Clarinet Quintet, the ‘Kegelstatt’ (Skittle Alley) Trio and the obbligato parts in two arias from La clemenza di Tito – were composed for Stadler. Mozart’s concerto is still the jewel in the clarinettist's crown today.

Stadler had been a close friend of Mozart’s since the early 1780s. Their friendship extended to Mozart having a variety of nicknames for him: ‘Stodla’, ‘Miracle of Bohemia’ and ‘Nàtschibinitschibi’, a combination of “poor miser” and “man of folly”. Stadler played the clarinet and the basset horn (a low pitched member of the clarinet family, in the key of F). Mozart wrote to him (in 1785): “I have never heard the like of what you contrived with your instrument. Never should I have thought that a clarinet could be capable of imitating the human voice as it was imitated by you. Indeed, your instrument has so soft and lovely a tone that no one can resist it…”

Silhouette of Anton Stadler
Both men belonged to the same Masonic lodge in Vienna and Masonic influences can be detected in the concerto. The basset horn was associated with the music Mozart wrote for Masonic events. He attached a sombre quality to its sound, which is also heard in his unfinished Requiem and the music for the Three Boys in Die Zauberflöte.

The clarinet and basset horn had descended from the chalumeau, a single reed instrument which had significant compositions written for it by Telemann, Vivaldi and Graupner. Vienna was at the forefront of clarinet manufacture and Stadler had a clarinet made by Theodor Lotz whose range was extended down by four semitones to a written C (sounding A) – later termed the ‘basset clarinet’. It is longer than the standard A or B flat clarinet, thus its chocolatey lower range. We now know that Mozart’s concerto was written for a basset clarinet in A (whose notes sound a minor third lower than written). Stadler claimed the invention of the basset clarinet for himself. However, he wasn’t the most reliable individual when it came to honesty…

The score wasn’t published until 1803, the original solo part having been lost, rescored for the A clarinet, with several passages where the solo part lies too low for a normal clarinet rescored an octave higher. By playing the concerto on a reconstruction of the basset clarinet, all the scales and arpeggios can be managed top to bottom without having to break them up with octave leap transpositions.

The original manuscript of the concerto was lost, claimed by Stadler to have been in a portmanteau which was stolen while he was in Germany. However, a letter from Mozart’s widow, Constanze, to the publisher Johann André suggested that Stadler had pawned it.

Here, Robert Pickup plays the concerto on a reconstruction of a basset clarinet. 

A lot of Mozart looks easy enough on paper, but is fiendishly difficult to play well. Assuming you don’t have access to a basset clarinet and are playing on the more conventional instrument, the work lies relatively well under the fingers. The Allegro first movement has wide interval leaps down to the chalumeau register, which are fun to play. Alas, unlike most concertos, Mozart doesn’t offer you an opportunity for a first movement cadenza. Instead, after a short cadential flourish, the orchestra repeats the ritornello, this time incorporating the clarinet as an accompaniment. Here, the burbled Alberti bass figures lead to rippling arpeggios and scales, which require nimble fingers and much practice!

The serene Adagio is the easiest movement to bring off for an amateur player (an ABRSM Grade 6 repertoire piece). It is almost operatic in its treatment of the clarinet and is very beautiful, with some neatly ornamented turns. There is a brief opportunity for a cadenza, although in reality it’s just about getting from B flat (as written) down to a C for a reprise of the main theme. The finale is a joyous carefree Rondo… carefree unless you have to play it, that is! Busy passages needing to sound light-hearted and requiring lightly tongued semiquavers are never simple.

Mozart’s other great clarinet work – the sunny Clarinet Quintet in A major – was also written for Stadler and a basset clarinet. Its four movements follow a conventional pattern. The opening Allegro is conversational, but it’s the lyrical Larghetto which is the work’s glory. Its opening bars are very similar to the concerto’s Adagio which would follow two years later. The clarinet sits out the first of the Minuet’s two trios, while the second has the lilt of a Viennese Ländler. The finale opens with a simple theme which is then treated to a set of variations before closing in ebullient mood.

Perhaps Mozart’s showiest writing for clarinet though comes in his penultimate opera La clemenza di Tito. Sesto’s aria “Parto, parto, ma tu, ben mio” is accompanied by a virtuosic obbligato part – again for Stadler’s basset clarinet – as is Vitellia’s “Non più di fiori”. In these two arias, the instrument truly imitates the human voice, entwined with the mezzo-soprano in duet. Mozart and Stadler didn’t just cement the position of the clarinet within the orchestra; they gave it a new platform under the solo spotlight.