Nobody slips between baritone and falsetto like singer Andy Bey.
One minute, his bourbon-strength baritone is producing a vibrant vibrato. The next second, his voice has soared into the stratosphere, caressing a blissful blue note and recalling the rhythm-and-blues prodigy Bey once was.
Bey, who also performed on piano, thoroughly covered the top and bottom registers Monday night at a Peco Energy Jazz Festival concert at Zanzibar Blue, in Center City.
Sometimes, as on ''All The Things You Are,'' his falsetto voice simply shot out in a gospel fervor, which drew loud hosannas from the crowd. Then, on ''Yesterdays,'' he seesawed low to high within the same phrase, delivering the lyrics in a series of rising slides.
But the 59-year-old singer wasn't totally a smash. His falsetto seemed employed partly to cover a limited range. And though he has ended more than two decades of silence with two successful CDs, Bey at times seemed like an art-salon singer whose precious interpretations didn't always connect with the audience. It didn't help that the backing was minimal, consisting of his piano and either Joe Martin on bass or Paul Meyers on guitar. (The three played together only once in the opening set.) The arrangements offered little variety.
Bey was at his best when he took on an old Earl Coleman blues ballad, ''Dark Shadows,'' and sported around in his disparate registers with a superb, slinky feel.
He knows how to caress a good lyric. ''How I envy the cup that knows your lips; let it be me,'' he sang on ''Like a Lover,'' by Dori Caymmi, with English words by Marilyn and Alan Bergman.
Bey in recent years has talked openly of his HIV-positive status. He showed no signs of ill health while displaying a certain vulnerability, joking lightly about his memory and advancing age.
Yet whatever pressures surround him, they seem only to have deepened his craft. After hearing him sing an impassioned rendition of ''Someone to Watch Over Me,'' it seemed plausible that he was singing about himself.
