"50TH ANNIVERSARY TOUR." Woody Herman Big Band. Concord CJ302. Recorded last March at San Francisco's Great American Music Hall, this is an almost flawless example of the current Herman Herd. Emerging as the unsung hero is John Fedchock, a superior jazz trombonist who also wrote all but one of the arrangements. It's a typically eclectic Herman set, with themes drawn from Ellington, Coltrane, Monk, Bob Haggart (a fine "What's New?") and Fedchock himself. "Conga" is a brisk Latin pace-changer, and Lou Donaldson's "Fried Buzzard" a vehicle for some funky cooking. "Epistrophy" is done partly in 6/8, building tension with Herman on soprano sax. Frank Tiberi, the band's veteran tenor sax soloist, and Lynn Seaton, playing bass and singing a la Slam Stewart, contribute valuably to this 4 1/2-star session.