The Schaefer Music Festival reached back into the '60s for a group which, though it has undergone many personnel changes, just won't quit, when Blood, Sweat & Tears performed Saturday (27) night on a bill opened by Tim Buckley. Which brings a philosophical question back, if a rock group undergoes a complete change of personnel, is it still the same rock group? Perhaps not the same, but certainly just as good, particularly when Jerry LaCroix is vocalizing. He and Jerry Fischer are outstanding vocally and there is some brilliant musicianship exhibited by the likes of Bill Tillman on alto sax and flute, Tony Klatka on flugelhorn and trumpet, and Bobby Colomby on drums. All of which is not meant to slight the others in the nine-man group, who keep it together with excellent music.

Columbia recording group got into today, then into the early BS&T days, winding with an encore rendition of "Spinning Wheel", with the audience gathered in front of the stage, a few into the by now banal match burning bit. Al Kooper joined the group on organ and vocals for one number, which he penned. In all, more than an hour and a half of satisfying music.