MARK RONSON IS, AT HIS CORE, A DJ and a producer for other artists – he considers his four solo albums side projects. But for his latest, the high-concept Uptown Special, he and Bruno Mars have a Number One hit, “Uptown Funk” – a Morris Day and the Time-like throwback that only hints at the album’s diversity, with guests from Tame Impala’s Kevin Parker to Mystikal to Stevie Wonder. Ronson, 39, is pleased with the song’s success, but after its agonizing months-long genesis, he’s even happier just to have finished it. “The thing that I’m really proud of,” he says, “is there were so many times when I would leave the studio and be like, ‘Fuck, man, I guess it wasn’t meant to be.’ But we’d get back together and…
