Langhorne Slim’s love affair with Lawrence is now several years old, but the honeymoon isn’t over. The folk troubadour stops through local venues at least once a year, but his tent-revival fervor never lessens. Slim’s lighthearted acoustic tunes hearken back to the joyful optimism and frank sorrow of 1960s and ’70s folk acts. On his latest release, 2009’s Be Set Free, his raspy yelp and dusty songwriting are at their finest. Slim never skimps on the charming lyricism, but backing band the War Eagles promises to lend a punk bite to the sweet sentiments, owing more to Jack White than to Bob Dylan.