NEW YORK -- His role is at the finish line of an album -- helping it sound as perfect as possible before it's available to the masses. He's won 10 Grammys, including three consecutive wins for album of the year from 2013-2015. And he's collaborated with contemporary leaders like Pharrell and Daft Punk to iconic acts like Led Zeppelin and Bruce Springsteen.

Bob Ludwig is one of the most important figures in music, though you may not know his name. He earned some airtime when Beck won album of the year for "Morning Phase" at last year's Grammy Awards, where Ludwig appeared onstage as a winner, too, for working as the mastering engineer on the album.

"I've spent more time mastering that record more than any other record I've ever mastered almost by a long shot. He wouldn't let that record go. He kept remixing it and remixing it," Ludwig said. "Twice on a weekend I worked until midnight with him, on the phone, emailing, going back and forth. ... We had a lot of time invested in that record."

Ludwig won the top Grammy in 2014 with Daft Punk's "Random Access Memories" and a year before that for Mumford & Sons' "Babel."

He's nominated again at the Feb. 15 awards show for album of the year with Alabama Shakes' "Sound & Color." It also earned Ludwig a nomination for best engineered album, non-classical.

The 71-year-old, who plays trumpet and piano, worked under the late Phil Ramone at A&R Recording Studios. Ludwig masters about 150 to 200 albums a year, and his Portland, Maine-based Gateway Mastering includes eight employees -- the newest team member started at the company more than a decade ago.

"Not much turn over," Ludwig says with a light laugh.

In a recent interview with The Associated Press, Ludwig talked about the Grammys, working with A-list artists and more.

Associated Press: What's the difference between the mixing and the mastering engineers?

Ludwig: The mixing engineer has the harder job because they track a multitrack recording for a pop record and mix it down into stereo, and that's very difficult to do ... And then mastering engineers, when the mixes are done, the question is, 'Does it sound as good as it possible can?' ... 'Are the mixes flowing into one another properly?' ... I guess what I do is I imagine how it could sound and I know what knobs to move to make it sound like it does in my head.

AP: Can you master an entire album in a day?

Ludwig: Yes. Or at least I can get my first go at it, and then we send it to the artist and the managers and the record label and everybody listens and makes comments. ... There's things that you just need to have feedback from the artist to see what their vision is. That's what mastering really is -- to bring the artist's vision to the public. ... Let's say the average time is two days on a project when it's all said and done.

AP: How involved are you with the artists?

Ludwig: Artists very often attend session. Like, before the collapse of the record industry we would have three out of five days attended, and now with the record industry being a shadow of what it used to be, the budgets aren't what they used to be, we probably get attended one out of five days. ... Someone like Bruce Springsteen, when he's doing one of his major albums, he'll always come up and it's part of a completion process for him to come up and listen to the (album) here and make comments.

AP: Who's come to your studio in the last few years?

Ludwig: Jim James from My Morning Jacket, Jeff Tweedy and sometimes his son Spencer come for Wilco or his solo records. ... Thomas from Daft Punk was here.

AP: Did he have his helmet on?

Ludwig: He didn't (laughs). ... He was here several times for that record ("Random Access Memories"). That was a record that -- God bless them -- they just wanted to make it as perfect as possible and they spared no expense making that record. ... He was really particular. ... Even though we spent so much time on that record, the thing I noticed is the music has such positive vibrations, and I really mean that. I always feel great at the end of one of those sessions.

AP: At last year's Grammys, you competed against yourself for album of the year with Pharrell and Beck's albums. Which did you want to win?

Ludwig: In that particular case, Pharrell's album was fantastic, there's no question about it, but for me, Beck's record was like a masterpiece. ... I would stack that record against any pop record that was ever made.

AP: Were you surprised that he won album of the year?

Ludwig: I was completely surprised. I thought Beyonce had a lock on it.