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Wilco comes back to earthy

Jeff Tweedy (second from right) sounds renewed as Wilco returns to its rootsy former self on the new release "Sky Blue Sky." (Frank Ockenfels)

Wilco changes. Over the last 12 years, the Chicago band -- led by singer, songwriter, and guitarist Jeff Tweedy -- has put out half a dozen albums, each remarkable and each a departure from the one that came before. The country rock of "A.M. "

turned soulful and psychedelic on "Being There, " which morphed into the lush pop sound of "Summerteeth ." Songs grew ambient and puzzle-shaped for "Yankee Hotel Foxtrot ," and then took a droning, difficult turn on "A Ghost Is Born. "

"That's what being a musician is about," Tweedy explained in a 2004 Globe interview. "You try to nurture some sort of fearlessness about being yourself."

Tweedy has reclaimed an earlier version of himself on "Sky Blue Sky ," a return to Wilco's earthy musical roots and, perhaps more significantly, to good health for Tweedy after a long stretch of substance abuse. Three years ago, on "A Ghost Is Born," Tweedy's inner world was best expressed in one savagely crude, 12-minute guitar solo. On the new album's title track, he strums an acoustic guitar and sings "I survived/That's good enough for now." Tweedy's voice is warm and humble, and so are the songs. Full of plain-spoken sentiments and organic arrangements, the rock waltzes, classic folk-pop, and alt-country cuts on "Sky Blue Sky" are the very sound of solid ground.

But Wilco hasn't forsaken its experimental streak, and the group uses it in the service of darkness -- or rather the threat of darkness. Verses and choruses redolent of the Band and the Byrds often veer off into intense instrumental breaks that feature the inspired work of Wilco's new guitarist, avant-garde player Nels Cline . Bluesy "Side With the Seeds " shifts toward dissonance when Tweedy's scratchy chords replace the tune's ambling piano and Cline swoops in with searing, serpentine lines. "Shake It Off " starts as a delicate mantra, cracks open to spill out filthy, riff-heavy guts, and then returns to twinkling keyboards and jazzy rim-shots.

"Sky Blue Sky" sketches the simple joy of being alive against a pocked backdrop of ominous possibilities . "There's nothing I can do to make this easier for you," sings Tweedy on "Please Be Patient With Me." The song sounds a lot like a recovering addict's mea culpa -- bruised and grateful and exposed -- much like "Leave Me (Like You Found Me) " and "On and On and On ," a dreamy covenant promising love that transcends the mortal world.

But Tweedy isn't finished with this life. "There's a light, what light, inside of you," he sings over and over again in "What Light ," a sweet, harmony-drenched celebration. The message is hardly revolutionary but endlessly relevant. It requires courage and candor -- and if you're a rock band, no small amount of creativity -- to be yourself. Jeff Tweedy and Wilco show us how.

Wilco plays June 28 at the Bank of American Pavilion.

Joan Anderman can be reached at