Completed in September 1789, Mozart’s Quintet in A major, K581, was the second of the three major works which he composed for Anton Stadler, the others being the Trio for clarinet, viola and piano, K498, and the Clarinet Concerto, K622. A contemporary wrote of Stadler’s playing: 'I have never heard the like of what you contrive with your instrument. Never should I have thought that a clarinet could be capable of imitating a human voice so deceptively … indeed, your instrument has so soft and so lovely a tone that nobody who has a heart can resist it.' Stadler had recently developed a slightly extended lower range with four additional notes, creating the so-called basset-clarinet. It soon became obsolete, but this was the instrument for which Mozart originally composed his concerto and probably the quintet. Although an increasing number of performers play these two works on reconstructions of the extended instrument, the orthodox clarinet remains the more commonly used.

The spacious Allegro first movement has a wealth of melodic material, and although all the themes are lyrical in character, there is no lack of contrast. Notably, most of the melodic material of this movement is first introduced by the strings. A suave opening melody for the quartet is answered in bars 7-8 by the clarinet (an upward arpeggio then descending groups of semiquavers), but the most poignant theme is the one introduced by the first violin with pizzicato cello, before being expanded by the clarinet above gentle syncopation. In the development section the clarinet phrase from bars 7-8 is taken up by each of the strings successively in the most animated passage in the movement. In the recapitulation Mozart introduces many modifications in the restatement of his original material. In the very first theme, for instance, the roles are exchanged: the clarinet now plays the melody line, the first violin the answering phrase. At the return of the flowing second theme, the clarinet restates as before, but then develops in a new direction.

The sublime Larghetto, in which the violins play with mutes, is even lovelier than its counterpart in Mozart’s Clarinet Concerto. The clarinet melody is accompanied by gently rocking quavers in violins and viola and a well-defined cello line. From bar 20 a dialogue unfolds between first violin and clarinet—the same kind of eloquent exchange which develops between solo violin and solo viola in the slow movements of the Sinfonia Concertante, K364, and the C major String Quintet, K515. In this exquisite central part of the movement ascending scales are a recurring feature above gentle suspensions. In the return of the material from the opening section Mozart adds more elaborate melodic decoration, until viola and cello respectively take over the triplet patterns for the final bars.

In the amiable Minuet, in which the five players are treated equally, forte and piano phrases alternate. Unusually, there are two trio sections, strikingly contrasted. The first, in A minor, has a violin melody of poignant melancholy, while the clarinet is silent; the second, more rustic trio (in A major) is in the style of a ländler, an Austrian country-dance.

The jaunty theme of the finale gives rise to variations encompassing a wide range of moods. In Variation 1 Mozart exploits the clarinet’s characteristic ease in moving quickly between high and very low notes, here leaping across two octaves. Whereas in a concerto the traditional orchestral passages naturally allow the soloist some necessary breathing space, this same relief must be more carefully managed in a chamber work. Thus in the second and third variations the clarinet contributes very little. Variation 2 has a first violin melody accompanied by triplets on second violin and viola throughout. Variation 3 is an eloquent lament in A minor for the viola, Mozart’s own favourite instrument when playing chamber music. This soul-searching is dispelled by the brilliance of Variation 4, with joyous semiquaver passages played alternately by clarinet and first violin. Following a serene, meditative Adagio, the work ends with a cheerful Allegro.

from notes by Phillip Borg-Wheeler © 2018