It wasn’t all oldies acts and slick country acts at the Minnesota State Fair grandstand this year, a point finally made clear Saturday when the Avett Brothers and Preservation Hall Jazz Band hit the big stage.

The unusual doubleheader — a hip, young, poppy string band and a historic New Orleans jazz ensemble — replaced the prior years’ MN Music-on-a-Stick concerts from public rock station 89.3 the Current. At least these groups had strong, long-term Twin Cities fan bases, which turned out 8,529 strong despite Saturday's humid weather making it feel like the Preservation Hall crew’s hometown.

PHJB’s local ties go back to 1964 when the Crescent City group made its first record at the old Guthrie Theater. It was a treat seeing the current lineup in front of a younger crowd instead of the more, um, mature audiences they frequently play to nowadays at Orchestra Hall in Minneapolis — although Saturday’s hipster crowd still didn’t dance enough to the infectiously funky sounds of “Corrina, Corrina” and “I Think I Love You.”

Saxophonist Charlie Gabriel, 83, sang the latter tune with a sly Louis Armstrong-style wink, and drummer Joe Lastie Jr. followed his playfulness with a vibrant, rolling beat. The tide turned and the crowd rose up and danced during a second-line funkified medley of Stevie Wonder and Jackson 5 tunes — a medley they kept playing as they walked offstage and emerged 30 seconds later marching into the crowd. Who’s the oldies act now?

The audience’s immobility could be blamed on Saturday’s having all reserved seats on ground level instead of a chairless general admission. Those seats stifled the energy a bit during the Avett’s set at first, but the crowd eventually still bobbed up and down like a rocky ride on Ye Old Mill.

The sibling act — led by singer/songwriter siblings Seth and Scott Avett — are like the Up With People version of a mountain bluegrass band, always jumping around and dancing with colorful, infectious exuberance. Scott even pulled off a couple Eddie Van Halen-style leaps Saturday. With a banjo, mind you.

Some of the Avetts’ songs seemed like flimsy choices Saturday given their now deep catalog, including the faux-tempestuous opener “Satan Pulls the Strings” and clumsily excited rockers such as “Will You Return?” and “Slight Figure of Speech.” This is one acoustic band that needs to start a full-on electric side project and keep the rockier stuff separate. There was even a drum solo by Mike Marsh.

They fared better with twangier tunes such as the waltz-flavored “Down With the Shine" and a convincingly roadhouse-ready cover of Merle Haggard's “Ramblin’ Fever.” Truly acoustic, stripped-down gems such as "Murder in the City" and a cover of their pal David Childers' "The Prettist Thing" also carried a rustic downhome flavor well-suited to a night at the fair, also when both of the Avetts' vocal talent's shined brightest.

Best of all, the Avetts excelled at their many gushingly dramatic acoustic power ballads — think: Queen and Elton John tunes by a rootsy mountain band — such as “Head Full of Doubt/Road Full of Promise” and “Vanity” early on and their requisite fan fave “I and Love and You” later on. The heat had cooled nicely by then, but probably none of the fair crowds this year was as heated as the Avetts’ fans by show’s end.

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Here's the Avett Brothers' set list from Saturday:

Satan Pulls the Strings / Live and Die / Morning Song / Will You Return? / Down With the Shine / Head Full of Doubt, Road Full of Promise / Vanity / Ramblin’ Fever (Merle Haggard cover) / Slight Figure of Speech / Murder in the City / Salina / Die Die Die / Winter in My Heart / The Prettiest Thing (David Childers cover) / Paranoia in B-Flat Major / Laundry Room / I Killed Sally’s Lover / Talk on Indolence / Hand-Me-Down Tune

ENCORE: Thank God I'm a Country Boy (John Denver cover) / Kick Drum Heart / I and Love and You