One of the most graceful reminders of the civilized New York of yesteryear is the Naumburg Bandshell in Central Park, steps away from Fifth Avenue and 72nd Street. And what a pleasure it is, of a balmy summer night, to gather there for beautiful music, presented free of charge to all comers—no tickets required. Opening the new season, the flexible instrumental collective known as The Knights offers a thematic program ingeniously built around Beethoven’s electrifying “Kreutzer” Sonata. The Beethoven, originally for piano and violin, will be heard in an orchestral arrangement by Colin Jacobsen. Other composers on the bill include Anna Clyne and the ever-surprising Leoš Janáček. Home listeners can tune in or stream on WQXR. —Matthew Gurewitsch