THE AVETT BROTHERS, JESSICA LEA MAYFIELD (Crystal Ballroom, 1332 W Burnside) The Avett Brothers craft syrup-thick patio punk with healthy blots of backwoods bluegrass for a rousing amalgam of modern folk. Their live performances are already the stuff of legend; vocalist/guitarist Seth Avett is just as likely to croon drippy twang vignettes, as he is to stomp his hi-hat into submission and invoke a furious growl. Meanwhile, the brushing banjo of brother Scott Avett and the smooth stand-up bass work from Bob Crawford prod and take turns spitting into the face of most contemporary alt-country acts. The band’s most recent album, 2007’s Emotionalism, served to accentuate the more tender avenues of melody for the crew, with bouncy tracks like “Die Die Die” and “Paranoia in B Major” delving into ballad-worthy opining. But expect to hear some of the rawer cuts from 2006’s Four Thieves Gone: The Robbinsville Sessions; that’s when things get loud. RYAN J. PRADO