Bruno Mars wrote and produced nearly all of his smash 2010 debut with the Smeezingtons, his tightknit studio crew. But when it came time to cut a follow-up, he decided to mix things up. "We took some master chefs into the kitchen with no master plan," says the singer, 27. "It was either going to be a disaster, or we were going to come out with something incredible."
Starting last fall, Mars recruited a team of A-list producers including Jeff Bhasker, who has crafted megahits for Kanye West, Beyoncé and fun.; Paul Epworth, the man behind Adele's "Rolling in the Deep"; and Amy Winehouse collaborator Mark Ronson. "I was in Zanzibar on my honeymoon when I got this call: 'Do you want to meet Bruno?'" says Ronson. "I was only kind of familiar with his music, but we met up in London a month later and he won me over. I found out what a phenomenal talent he is."
As of mid-October, Mars and his team were still making final tweaks to Unorthodox Jukebox, due out December 11th. At Levcon Studios, located in a rough corner of Hollywood, the Smeezingtons' Ari Levine cues up a few new tracks as he hurriedly e-mails a batch of final mixes for the album to Mars, who is still hanging out in Manhattan after hosting Saturday Night Live. "Bruno's a perfectionist," Levine says.
Highlights on the disc include the Police-ish lead single, "Locked Out of Heaven," and the Daft Punk-worthy disco groove "Moonshine." "We all went out one night, and they had actual moonshine on the menu," Mars says of the latter track. "We drank it all night, then headed to the studio – Jeff got on keyboards, Mark starts playing electronic drums that sound like Eighties Prince and I started screaming, 'Moonshine, take us to the stars!' There were a lot of nights like that." "Gorilla," meanwhile, features a thundering, Def Leppard-huge thump and risqué subject matter: "It's about good old animalistic sex," Mars says. The lyric "Got a body full of liquor with a cocaine kicker" might remind listeners of the singer's 2010 drug bust, but Mars doesn't seem too worried. "To take that line out would dilute my art," he says. "The song needs a sense of danger. When I was a kid, pop could be dangerous but still massive. Michael Jackson would grab his crotch. Prince would rock assless chaps. With this album, I wanna let loose."
This story is from the November 22, 2012 issue of Rolling Stone.