Rick Rubin, the producer behind the next Metallica album and Red Hot Chili Peppers' upcoming disc 'I'm With You,' offers his inside look at both LPs in a new interview. The veteran knob-twiddler is also set to be an executive producer on ZZ Top's forthcoming album.

Rubin tells Billboard that he and Metallica are in the very early stages of planning the follow-up to 2008's 'Death Magnetic.' "I had a meeting with Lars [Ulrich] in San Francisco ... to explore what the focus was going to be this time around," divulges Rubin. "I'll ask a lot of questions and we'll probably listen to some of the riffs that they've been writing. Usually, I'll hear something that will sort of indicate the direction and then we'll talk about it from there."

Metallica recently revealed that they've been working with veteran rocker Lou Reed on a collaborative album, but Rubin was not involved with that effort.

Meanwhile, Rubin is raving about new Red Hot Chili Peppers guitarist Josh Klinghoffer's contributions to the band's new album, 'I'm With You' (due Aug. 30).

"Josh is fantastic," gushes Rubin. "He played with John Frusciante for many, many years and he actually toured with the Chili Peppers before, so he's sort of part of the extended family. He's stylistically very close to John but has a completely different trip. It sounds like the Red Hot Chili Peppers that you've never heard before."

He also adds that RHCP recorded so many tracks during the recording sessions for 'I'm With You' that it could have easily been a double album, but the band ultimately decided to make it a 14-track single disc.

Finally, Rubin says he'll work as an advisor and executive producer on ZZ Top's next album. "They are hoping to have something by the end of the year, and it would be great if that works out," reveals Rubin.

Watch the Video for the Rick Rubin-Produced Metallica Single 'The Day That Never Comes'