They don't make blues vocalists like Nappy Brown ("Night Time Is the Right Time") anymore. He performs with the elegant panache of a classic big-band R & B shouter: dressed to the nines, flashing a sparkling smile, he manages to retain an air of sophistication even while mugging and clowning to his outre lyrics and especially when he's crooning to the ladies in the audience. Brown's vocal improvisations, ranging from syllables and nonsense words to entire extemporaneous verses, are a result, he says, of his childhood habit of mimicking foreign-language radio commentators. His double-entendre devilishness (he won his first recording contract by auditioning a self-penned ditty called "Lemon Squeezin' Daddy") and repertoire of moans, yelps, deep-chested baritone descents, and flat-out bull roars have made him equally adept at R & B, pop-jazz singing, and gospel. With the right band behind him and a good crowd out front, Brown can make you feel as if the grand old days of blues shouters and jump-blues revelry never ended. Thursday, July 1, B.L.U.E.S., 2519 N. Halsted; 528-1012.