From the moment Billy Cobham took his seat behind a small fortress of drums at the Wax Museum Thursday night, his presence was never in doubt. Performing with a trio of young musicians called Glass Menagerie, Cobham provided the only exceptional moments in an otherwise routine fusion performance.

No mere timekeeper, Cobham proved once again to be a masterful technician with a welcome regard for shades of color and dynamics. The group's music, most of which will soon appear on an album, seldom amounted to more than lightweight melodies intercut with exclamatory passages of bass, guitar and keyboard. Cobham, however, was always a unifying force. He brought an array of subtle accents to the ballads, provided a dense backdrop for many of the solos and powered the up-tempo pieces with enormous drive. The other members of the band were obviously talented, but without Cobham's contributions each of them might as well have been playing alone.

The Gregg Karukas Group, a local trio led by the former keyboard player with Natural Bridge, opened the concert. Retaining a bright if rather unimaginative blend of funk, rock and jazz elements, Karukas' new band doesn't differ much from his last.