Andover Summer Concert Series presents Pete Coolidge and The Acoustipalians along with an assortment of their jamming friends at 6 p.m., Friday, Sept. 9, at the Andover bandstand. The concert is free with donations appreciated to help defray expenses. Guest appearances by Brad Croteau, Anna Sysko and Seth Gallant will be part of the evening’s entertaining mix. From left,  Pete Coolidge, Tim Gallant, John Emery, Steve Simmons, and Mike Gallant.