Anticipation was in the air during the opening act at Constitution Hall Saturday night. Many seats were empty but by the end of that first set they were occupied. Although Peabo Bryson wasn't on yet, his equipment dominated the stage; its risers containing keyboard instruments, percussion sets, and a mammoth array of drums loomed above Phillis Hyman and her musicians, dwarfing them.

When Bryson came on stage, white suited, cordless mike in hand and cross-beamed in mixed colors by the spots, the audience was ready for the professionalism that his paraphernalia implied. Yet what they got was tediously extended songs and a 10-piece group too often off cue. Bryson's voice suffices for his apparent aim -- manipulation of his audience, but he'll have to get his act together if he wants to fill the hall next time around.

Phyllis Hyman opened the show with a tight set that combined pop and rock materials. In her contralto voice, full in the low ranges, she presented a program drawn from her recent albums for Arista. Belying the sentiments of these songs ("Be careful how you treat my love," etc.) her stage presence exhibited little vulnerability; it was all polish and precision. She announced her desire for an allfemale band and invited auditions toward that objective, belatedly praising her current group as the best in the business. If she truly believes that, then she should let them cut loose some, particularly saxophonist Gary Bartz who appeared only for the final number.