Mike Seeger. He emceed a workshop at that fest. (??early seventies) on barbershop quartet harmony. A female quartet was on, and I was so impressed with Mike's questions; he had them describe how they laid out the melody first, then usually the descant, bass and alto. How they built the harmony. It was great.I discovered Louis Killen at that festival (probably not he same year). and got in some clogging practice. (I had taken Sharee Shepherd's clogging class, with a to-remain-nameless live musician friend, and it was hard to find places to practice afterwards.)
Boy, those were good times.