As recently as six or seven years ago, the Ark would virtually shut down for the summer. Now it runs straight through, except for an Art Fair hiatus, and this summer the place seems to be trying out an unusual number of new things, from British neosoul to traditional Hungarian music to Cape Verdean pop to a sensational quartet of Cajun musicians called Feufollet, barely old enough to order beer at the counter. And August is bringing several more groups of young musicians, collectively representing an exciting trend too new to have a name.

The Avett Brothers (coming Tuesday, August 21), the Forge Mountain Diggers (Wednesday, August 15), and Robinella (Monday, August 13) all sprang from country roots and make music that draws on those roots. Yet none of these bands has much in common with the power ballads of mainstream country today, and all three were shaped fundamentally by music from outside the country tradition — straight-ahead rock for the Avett Brothers, punk for the Forge Mountain Diggers, and pop and jazz for Robinella. Except for the Forge Mountain Diggers, who are rooted firmly in old-time string-band music, these bands and others like them frustrate retailers’ genre classifications and show up all over the map. Even the vague “Americana” label doesn’t work well — most of the bands so designated have used electric instruments, but these musicians have stripped their sound down to a mostly acoustic base and often use the banjos, fiddles, and mandolins of bluegrass. Call it new southern acoustic music if you have to call it anything at all.

Unlike some of the alternative country performers that have gained popularity in the clubs of Chicago and New York, these musicians embrace the country part of their heritage rather than approaching it with a mugging attitude. Robinella’s slender yet torchy voice, a bit mystical, is often compared with that of Billie Holiday, but Dolly Parton has

been equally influential; the two both come from the Smoky Mountain foothills east of Knoxville. The Avett Brothers, whose latest album is called Emotionalism, embrace the unabashed feeling of country, discarding the conventions of the form in favor of Beatlesque harmonies and highly distinctive lyric conceptions but keeping the romantic content; their “Swept Away” is a straightforward love song that their alternative-rock counterparts could never get away with. Most of the tunes on the Forge Mountain Diggers’ debut album come from the same stock of string-band music that the folk revivalists rediscovered in the 1960s.

All these musicians combine country and city in new ways. The Forge Mountain Diggers give old-time tunes a markedly brittle edge on disc, and their live show is said to have the insistent energy of punk. The Avett Brothers are splendidly ambitious as songwriters, with big rock conceptions that sometimes switch styles in the middle of a song: “Pretty Girl from Chile,” one of a “Pretty Girl” series stretching over multiple albums, is full of unexpected twists — including an answering machine message from the titular pretty girl. Robinella, something like her fellow southerner Madeleine Peyroux, has broadened her meditative Appalachian jazz on her latest release, Solace for the Lonely, to include bits of psychedelia and funk from the 1960s and 1970s.

The Forge Mountain Diggers represent new old-time music’s second generation, with fiddler David Bass having emerged from the seminal Freight Hoppers, but the other two acts spring from southern college towns: Robinella (born Robin Ella Tipton) went to the University of Tennessee at Knoxville to study art and there met (and married) jazz musician and ace mandolinist Cruz Contreras, and the Avetts’ roots as a band go back to East Carolina University in Greenville, North Carolina. When progressive music gets cooking in the South it usually has major significance for American culture, and the sheer number of creative young bands coming out of the region these days suggests that something important is on the rise. The Ark’s fine collection of risk-taking August shows gives us the chance to find out what.

[Review published August 2007]