Those concerned about the origins of R & B, whence sprang rock 'n' roll, would do well to check out Arthur Prysock at the Cellar Door. Thirty years ago in Harlem's Savoy Ballroom, Arthur Prysock had them alternately jumping and swooming with a voice as big as a barn and as deep as a well. Those dimensions are undiminished today.

Urbanity won over any hint of regret Thursday night at the Cellar Door, as he sand "Goin' to Chicago but I can't take you with me." But when he shaped a slow ballad the twinkle vanished from his eyess and, to oh's and ah's, he bacame the very essence of sincerity, wrapping the song around you like a warm embrace. He's a pro, no question aobut it.

Tenor saxophonist Red Prysock, leading the supporting quartet, can cut the blues, give tender loving care to the slow ones, and riff along with organist Ernie Jones on the rockers. The woodpecker rim clicks and steady ride cymbal of Don Williams and the guitar licks of Steve Fishman helped spur on the action.

Arthur Prysock and the Red Prysock Quartet stay through tonight. Comedienne Nancy Parker opens for them.