Heartless Bastards a bit low on energy at Union Transfer

It's taken Heartless Bastards vocalist-guitarist-songwriter Erika Wennerstrom four albums to arrive at a place where her songs are as consistently compelling as her voice, a primal alto yowl that serves as a calling card for the band's sturdy guitar-bass-drums racket.

Her Austin-by-way-of-Ohio quartet's latest, Arrow, expands on the mange-meets-melody m.o. of the first three albums by successfully incorporating subtle shades of '70s country rock and soul into the mix. There's now more room for Wennerstrom's voice to roam, and the songs are much more memorable and dynamic.

Saturday at Union Transfer, the band turned in a 90-minute set that focused on Arrow, blending those songs with less sophisticated jolts of garage rock - "Out at Sea" - and the leaden blues shuffle "Nothing Seems the Same."

The show had its share of memorable moments (the new single "Parted Ways" stood out), though the band struggled to maintain momentum as the set progressed.

The cream of Arrow was featured early, beginning with the skuzzy thump of "Got to Have Rock and Roll" and winding down a little later with the slinky "Only for You," whose chord progression hinted at the Crazy Horse chestnut (popularized by Rod Stewart) "I Don't Want to Talk About It."

Guitarist Mark Nathan capped that song with a fluid solo that was worthy of much more than the halfhearted ovation he received for his efforts. Maybe people text and Tweet their appreciation for solos these days?

From there things got a little too mellow for a little too long. Following the moody waltz "The Arrow Killed the Beast" (hats off to drummer Dave Colvin for doing the work of three men with mallets and percussion on this one) with the slow-to-unfold "Low Low Low" was a bit of an energy drain, particularly in the chatty downstairs bar area.

With bassist Jesse Ebaugh switching to pedal steel, the group dug in deep on the swamp-funk groove of "The Mountain," though the regular set plodded to a somewhat meek finish with the lumbering "Hold Your Head High" and the slow, spacey blues of "Down in the Canyon."

It took some time for Wennerstrom to find herself as a songwriter. And it seems like she's still got some growing pains to navigate before the band turns the corner as a live act.