In retrospect, the world premiere of Helmut Lachenmann’s “Allegro sostenuto” in December 1989 at the Cologne Philharmonie can be seen as a kind of re-birth of chamber music in the late 20th century. In countless concerts and at least four CD recordings, Lachenmann’s large-scale clarinet trio has since offered ample evidence that “it has a clarity of contour coupled with a shading of sonorities that I cannot imagine anywhere else besides Debussy” (Jürg Stenzl). The new performing score will considerably facilitate the access to the work.

As in my earlier work “Ausklang” for piano with orchestra, here, too, the musical material is determined by a mediation between the experience of “resonance” (“tenuto” variations between a “secco” sound and natural or artificial “laisser-vibrer”) on the one hand, and “movement” on the other. Both aspects of the sounds confront each other in the conception of structure as a highly ambivalent “arpeggio”, i. e. as a successively experienced process of building up, tearing down, and rebuilding, which is also communicated within the briefest space of time as a figurative gesture, as if it were a projection onto larger surfaces.
Form and expression result in the combination of six successively ordered zones:
A broad opening sequence (1), which traverses down through sonic space, presents a “legato” cantilena of simple – both natural and artificial, direct and indirect, “false” as it were – extensions of the resonance or fields of resonance, the last of which are cadenced to a stand-still (“Standstill” here is a concept in which resonance and movement in their most extreme forms come in contact). (2) is a variously subdivided play of terraces “drying out” between “secchissimo” and total pedalisation. In the actual “allegro” section (3), resonance appears to flow in a motion with intense velocity – or vice versa. Interrupted and diverted by a sort of “deflated hymn”, (4) is a recitative of calls in spaces that resonate to various degrees, including some “dead” spaces. In (5) they find their way back to movement, escalating, consuming themselves in marginal regions of the violently perforated instrumental sound. Feathering out, as it were, a final cadence (6) is composed of mixtures, in whose inner life resonance and movement once again become merged.
(Helmut Lachenmann, translated by Steven Lindberg and edited by Richard Steinitz / program notes for the Huddersfield Festival 2000)