Photo by Chris KornelisBlitzen TrapperWhen: 2:30ishWhere: Broad Street StageBlitzen Trapper pump out a mean record full of ’70s-guitar noodlings, harmonies, and foot-stompin’ melodies. But on stage this afternoon — an army of six — the band tripped over itself (three synthesizers?) en route to the subtle layerings of their studio fare. They were at their best when they kept it simple.