This past spring, the Swedish DJ-producer Avicii opened the second half of his set on the monster main stage of Miami's Ultra Music Festival with something totally unexpected: He brought out a stomping band – singers, guitars and a banjo – to strum through a new Mumford-sounding, bluegrass-tinged anthem called "Wake Me Up." Ravers weren't sure what to make of it, and their confusion spilled over into harsh criticism online. "After the show, he kept telling me, 'There's so many people on Twitter who hate what we were doing,'" says guitarist Mike Einziger, who was onstage. "He was kind of visibly affected by it."
Six months later, they've definitely come around to the 23-year-old spinner's vision. The insanely catchy "Wake Me Up" is a worldwide smash. It's the fastest-selling single of the year in the U.K. (beating "Blurred Lines") and has gone to Number One in 63 countries. "It's ridiculous," says Avicii (real name: Tim Bergling). "I still don't really feel like I've had time to slow down and really realize where it has all come to. A lot of dance music has gotten more and more repetitive – too focused on the dirty drop. I was always interested in the melodic part of house music."
As he often is, Avicii is in the middle of an absurdly long day. Last night he rocked a rave in Greece until 5:30 a.m., before hopping a private jet to Spain, where he's playing Ibiza's biggest parties. Since becoming one of EDM's major stars with his 2010 Etta James-sampling smash "Levels," he's been playing around 300 shows a year, making a reported $250,000 payday for each. As a result, Avicii had a basically unlimited budget for his debut album, True (out September 17th), which ranges from rootsy singalongs to pummeling, vocoder-heavy EDM. He sought out some major talent to help: an eclectic crew including Einziger, who plays guitar in Incubus; Imagine Dragons; and legendary Chic guitarist Nile Rodgers. "I wanted to collaborate with songwriters who weren't used to electronic music, which was interesting from the start," Avicii says. "I wanted to make real music, in a sense. And I wanted every track to be a single."
"Wake Me Up" was written in just two hours at Einziger's Malibu home with neo-soul singer Aloe Blacc, who added yearbook-ready inspirational lyrics. "It was a very fast process – not a lot of thought went into it," says Avicii. He kept the bluegrass vibe going on the even rootsier "Hey Brother," trying out six vocalists before settling on Dan Tyminski, best known for singing "I Am a Man of Constant Sorrow" in O Brother, Where Art Thou? "I don't like country," says Avicii. "But bluegrass to me has always been something credible and kind of cool in the sense that it's very melodic."
The album's most surprising collaborator? Definitely 71-year-old songwriter Mac Davis, who wrote "In the Ghetto" and "A Little Less Conversation" for Elvis Presley. "I may be an old fart, but I love EDM," says Davis, who got the job through a golf buddy, Interscope A&R chief Neil Jacobson. Davis brought Avicii the tune "Addicted to You," which became futuristic, high-gloss disco – with Adele-style vocals from Oklahoma singer Audra Mae. "He's a genius, no getting around it," says Davis. "I'm a traditional songwriter. I put my guitar in my lap and sit there for half a day. To watch him work, I swear, is like watching a mad scientist, with his computer and his focus."
Rodgers, fresh off Daft Punk's "Get Lucky," co-wrote the glitter-caked, Studio 54-ready jam "Lay Me Down," which features vocals by Adam Lambert. "Tim will do stuff that, honestly, I would've never thought of," Rodgers says. "On the last couple of songs I've done with him, I'm the bass player. I played a guitar riff and he just puts it down an octave and it sounds so funky."
Up next: Avicii kicks off a globe-trotting arena tour in Toronto in September. "I never dreamed of making music on this level, or touring on this level," he says. "You know, it has all happened fast. But I worked really hard. I haven't half-assed anything."
This story is from the August 29th, 2013 issue of Rolling Stone.