Even as men behind curtains go, Rick Rubin is one of the most mysterious. The legendary producer and Def Jam founder has taken another step toward revealing his secrets, though, by annotating a series of songs for the website Genius. Although his insight comes mostly on the subject of material he produced--for the likes of Jay Z, Johnny Cash and more--and music of which he's a fan, like Vampire Weekend and D'Angelo. You can read the entirety of Rubin's work for Genius here.

Rubin's first post gives insight into "Only One," the Kanye West-Paul McCartney duet dedicated to West's daughter, North. The turnaround was tight, and forced Rubin to coordinate the mixing and mastering process remotely and in less than 48 hours. "That's just how it works in Kanye's world," he writes. "It used to really give me anxiety, but now I just know that’s what it is. That’s how he likes to work."

Also discussed are the studio sessions for "99 Problems," the Rubin-produced standout from The Black Album, Jay Z's would-be swan song from 2003. Rubin recalls Chris Rock providing the impetus for the song, suggesting that Jay rework the line from Ice-T's original of the same name that would become the song's hook.

Genius made news recently for hiring critic Sasha Frere-Jones away from his long-time post at The New Yorker.

[Pitchfork]

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