“Hell no!” one fan shouts repeatedly when it becomes clear that Curtis/Live! has reached its end. Who could blame him? Recorded at New York’s Bitter End in 1971 as Curtis Mayfield rode high with his first solo album, Curtis, the set is a classic of in-concert soul-music recording and a signal of the turning tide in R&B. Marked throughout by strong group interplay, with Mayfield’s lilting guitar and new, small band making spicy funk of his recent material and a handful of Impressions classics. “We’re a Winner,” with added lyrics (“No more tears do we cry/The black boy done dried his eye”), serves as a bridge to the likes of “(Don’t Worry) If There’s a Hell Below We’re All Going to Go” and “We the People Who Are Darker Than Blue.” The appreciation between performer and crowd is measurable.