Just a minor point for Stringsinger...

The Yerba Buena Jazz Band was the vision of Lu Watters who wanted to keep New Orleans style Jazz alive. He put in about a decade or so, until it became work rather than fun. Watters retired about 1950 and both his trumpet palyer, Bob Scobey, and his trombone player "Turk" Murphy formed their own bands.

Your story is probably about a visit to Scobey's group called the Frisco Jazz Band. Scobey died at 46 from cancer.

"Turk" Murphy continued to work for a long time. He was the king of Traditional Jazz in the SF Bay Area. He also died of a cancer, but at 71.

You would probably like the concert that Barbara Dane did about 1963 when she talked Lu Watters into putting together a group to back her in a concert to protest Marincello, a huge housing developement that would have spoiled a large part of Marin County. The developement was killed. A rare victory for protest singing. Perhaps the Jazz helped.