Contemporary folkster Mason Jennings combines the charm of Jack Johnson with the Dylan/Petty school of alt-twang. Sometimes to great effect, but other times channeled into stretches of stunted imagination and acoustic guitar filler.

“This is what happens when Raffi children grow up,” an onlooker barbed during a particularly elementary song that seemed to have a hypnotizing effect on the crowd. Although his storytelling is sometimes simple and elementary, the majority of Jennings’ songs are dimensioned works of jangly alt-country with a Midwestern drawl.

Beyond the occasional questionability of the merits of his songwriting, it seems that Jennings’ biggest Achilles heel is his own musicality. The simple strength and brilliance of the rhythm section seemed to carry the show. This left the aforementioned onlooker to later state, “If you can’t play it, don’t write it.” Jennings was accompanied by Chris Morrissey on bass and Brian McLeod on drums. Both were unfaltering and inventive in their interpretation of Jennings’ songwriting. In other words, the hired guns made Jennings look better than deserved.

But most of Mason Jennings’ set was lined with strong moments of gorgeous melody, spirited performance and acoustic groove. The most surprising of these included a chilled-out cover of the White Stripes’ “Little Room,” which put Jennings at the keys instead of his guitar. At his best, Jennings’ delivery and phrasing recalls Lou Reed crossed with Steve Malkmus of Pavement on top of sincere adult contemporary acoustic fare.