In our cover story, Lamar revealed that free jazz, 1970s funk, Miles Davis and Parliament were the main inspirations behind To Pimp a Butterfly's beats. "Every producer I've ever met was sending me stuff — but there was a one-in-a-million chance you could send us a beat that actually fit what we were doing," Digi+Phonics producer Mark "Sounwave" Spears told Rolling Stone.
In November, he told Hot 97, "Everything’s really in-house. Of course Dre, but I really stick with four producers that I’ve been working with since day one." It's safe to assume Lamar meant the Digi+Phonics crew — Sounwave, Tae Beast, Dave Free and Willie B.
In late 2013, a year after the release of good kid, m.A.A.d city, the first evidence that Lamar was working on new music at all came via a Beats by Dre commercial, with the rapper and Dr. Dre collaborating on a track later dubbed "It's Alive." However, a full version of the song was never released. In a September 2014 interview with Rolling Stone, Lamar confirmed that he linked up Dre for some beats. "[Dre]'s just gone into the lab and made beats," he said. "He's trying to find that next thing — just really elevating himself and the team to grow as a creator." But what parts of Dre's input made the final cut is still unknown.
Lamar also admitted that he hit the studio with Pharrell Williams, but it's unclear whether those sessions were for the rapper's new album or if they ultimately resulted in Lamar's "It's On Again" collaboration with Alicia Keys that wound up on the Pharrell-produced The Amazing Spider-Man 2 soundtrack.