Among the junior-league orchestras in the Chicago area, the Chicago Youth Symphony Orchestra lately has been running a close second to the Civic, which is backed by the resources of its parent organization, the Chicago Symphony Orchestra. Some of the credit for the success of the independent CYSO, which has been winning awards and seeing attendance rise, goes to the musicians, most of whom are teenagers and on average are younger than the Civic’s members. But a good deal of it must go to executive director Jeannette Kreston, who has a knack for managing an ever changing ensemble and for spotting up-and-coming conductors to lead it. In 1989 Michael Morgan took the reins, helping to widen the orchestra’s repertoire and its appeal to African-American students, and Daniel Hege followed with a similar agenda. Now Rossen Milanov, a Bulgarian who studied at the Curtis Institute and the Juilliard, has taken over. He’s steeped in the eastern European tradition of heightened lyricism, which suits romantic and grand gestures but can probably be shaped to fit Haydn or Ives. This Saturday, Copland’s Appalachian Spring and Ibert’s Divertissement will be followed by Ives’s Ragtime; next Saturday the program includes Haydn’s Notturno in C, Wagner’s “Siegfried Idyll,” and Britten’s Sinfonietta. Ironically, the CYSO fare is more varied and less predictable than what the Grant Park Symphony Orchestra is offering this summer. Saturday and next Saturday, July 17, 5:30 PM, Petrillo Music Shell, Grant Park, Columbus and Jackson; 312-742-4763. TED SHEN