Each jazz generation boosts a handful of musicians who serve to define their instruments. Bassist Buster Williams, who began to make his name in the late 60s, belongs to this elite. Like his contemporary Cecil McBee, Williams displays his mammoth technique without exhibitionism, and his virtuosity proves all the more impressive for its matter-of-fact quality. He produces a tone best described in winelist terminology--rich, dry, velvety--which has proved something close to perfect for his contributions on literally hundreds of post-60s albums. His flourishing solos have bite and proportion, but you could listen to whole concerts of his immaculate and imaginative accompaniment work and leave with no complaints. (Such qualities have not gone unnoticed among the most demanding critics--namely, other bassists. When in the mid-80s Ron Carter formed a band to feature his own solo work on the higher-pitched piccolo bass, he hired Williams to play the traditional bass-fiddle part that Carter himself had abandoned.) But even if Buster Williams played bass only half as splendidly as he does, you'd want to hear his band. It features Gary Bartz, the facile alto saxist of the early 70s whose recent recordings reveal a mature and delightful improviser; the strong-toned trumpeter Shunzo Ohno; pianist Stephen Scott, the intriguing young veteran of bands led by Betty Carter and Roy Hargrove; and the unflappable Carl Allen on drums. Thursday, November 11, Bop Shop, 1807 W. Division; 235-3232.