The thousands who bought Keith Jarrett's 70s Köln Concert disc, or Jan Garbarek's ghostly, Coltrane-meets-plainsong Officium - and thus significantly lubricated the ECM record label's relationship with its bank manager - may have concluded that a rather private, classically shapely, jazz-inflected lyricism was the company's sole trade.

But as Manfred Eicher's influential new-music label celebrates its 25th year with a month-long parade of its stars in Brighton, surrounded by portraits of its celebrities from Jarrett and Garbarek to Arvo Pärt, what strikes is the diversity of the label. Thursday's programme was a mix of sharp-end jazz and materials drawn from variations on the musique concrète tradition, electronics, and classical genres old and new. Thursday's first half was an alternately exquisite and hair-raising duo from bassist/composer Barry Guy and the classical viola-player Maya Homburger. They played from their recent Ceremony album, featuring the work of the baroque composer Heinrich Biber mixed with compositions by Guy for violin and double-bass, and one for solo violin against six taped violins, all Homburger's. Since Barry Guy is both a fine composer and an improv phenomenon, the partnership with Homburger's exquisite delicacy and affection for a music of tranquil symmetry was stunning.

The art of noise was the main agenda for Evan Parker's Electro-Acoustic Ensemble, creating a backdrop like fireworks, distant gongs, slack-tuned steel guitars. The narrative was in the way the improvisors reacted to it, and in reacting changed it - through Barry Guy's surging runs and bitter-sweet exchanges with violinist Phil Wachsmann, through to the urgent birdsong choruses of Parker's soprano and the jazzier lines of Kenny Wheeler's trumpet. If you wanted to show that "swing" can mean many kinds of spontaneously-evolving group momentum, it was a powerful example.