Now in its 39th year, this is billed as the longest-running bluegrass festival in the world, and there’s little doubt that it’s also the best for those enthralled by the style’s fundamental pleasures: soulful high-lonesome singing, hot-shit solos, and a classic repertoire. The festival’s unofficial star has long been Jimmy Martin, leader of the Sunny Mountain Boys, who got his start with bluegrass pioneer Monroe. Scheduled to headline this year, he died May 14 at the age of 77, a year after being diagnosed with bladder cancer. He’ll be the subject of a closing-night tribute by a star-studded cast that includes Ralph Stanley and former Sunny Mountain Boys like J.D. Crowe and Audie Blaylock. The rest of the 45-act lineup is a bluegrass who’s who: Larry Sparks, James King, David Davis, Jesse McReynolds, Melvin Goins, Chicago’s Special Consensus, and mainstream country star turned bluegrass diva Patty Loveless. Thousands of fans pitch tents and barbecue during the eight-day event, but there are also hotels nearby. Sat 6/11-Sat 6/18, 5163 State Road 135 N., Bean Blossom, Indiana (50 miles south of Indianapolis), 800-414-4677 or www.beanblossom.com, $15-$30 daily, $30 three-day pass, $165 eight-day pass.