Yet from there, he added, “The goal is always to make this better than all the other records the artist has done.”
Mr. Mills hasn’t been a producer that long; his first production credits appeared in 2012. He got started as a guitarist and songwriter with high school friends in a band named Simon Dawes, which became Dawes after he left it; they reconnected when he produced its 2016 album, “We’re All Gonna Die.” He has made albums of his own as a rootsy singer-songwriter, and he became a session and touring guitarist, working with Jenny Lewis, Bright Eyes, Lucinda Williams and Fiona Apple, among many others.
As a producer, Mr. Mills cultivates larger ambitions. He’s eager to make the kind of album that becomes a career turning point: a stretch for the musicians and a pivot away from audience expectations. For Mr. Legend on “Darkness and Light,” that meant defying the programmed sound of much current R&B and hip-hop to work with a small band in the studio, finding grooves; it also meant allowing lyrics to dip into politics as well as romance.
By telephone from the Sundance Festival in Utah, Mr. Legend said he chose Mr. Mills because he wanted a “more organic album.”
Mr. Mills, he added, “loves music and I love music, and that makes it so we’re talking the same language. When your goal is to make the best thing you can make, and the most beautiful thing, and the most honest thing, you have the same North Star.”
Mr. Legend discovered Mr. Mills after hearing “Sound & Color,” the second album by Alabama Shakes. For its 2012 debut album, “Boys & Girls,” Alabama Shakes stayed close to 1960s soul. But its 2015 follow-up, which Mr. Mills produced with the band, used a far broader and more unpredictable sonic palette, from punk to shoegaze; it won a Grammy for best alternative music album.
Alabama Shakes “didn’t stay beholden to their fanbase’s interpretation of who they were,” Mr. Mills said. “I think they were trying to challenge it. I resonate with that spirit. I respect that. And if somebody is feeling like making that kind of record, I want to protect it from any of the outside influences that might come in and say, ‘You have a decision to make. You can either make your creative record or your commercially viable record.’
“That conversation of art versus commerce is so ignorant,” he added. “The good albums are the ones that do both. And in order to do both, you have to check the artistic envelope-pushing box first before you can find that it’s also a commercial success. You have to go out on a limb a little bit.”
Getting some recognition from the Grammys doesn’t hurt. It’s “really given me some ammunition when I’m in the studio,” he said, “and the label or outside influences come in and say, ‘What about the single?’ It’s earned me some trust.”
Mr. Mills’s methods vary with every project. But he’s fond of recording in old-school studios with rooms that “allow you to get a sense of size.” He then does extensive overdubs at home and in small home studios. “You get something spacious in the peripheral background and something up close that’s intimate,” he said. He also happily combines naturalistic sounds with surreal ones, which he compares to realist filmmaking meeting Technicolor fantasies. “Both of those elicit an emotional response,” he said. “I don’t think one is inherently better than the other.”
Mr. Mills said he doesn’t have time to listen to pop radio or study current hits; he’s not interested in the trends of the moment. “There’s a strange, blissful ignorance,” he said. “But I think more about an idea of the radio. Do I want this track to sound like it’s exploding out of the speakers? Most of the time, the answer is yes.”