Hans Zimmer’s two late-2013 films couldn’t possibly be more different: “Rush,” a driving, in-your-face rock score for a competing pair of 1970s Formula One race car drivers, and “12 Years a Slave,” a quiet, melancholy string accompaniment for the tale of an educated, free African-American forced to endure the brutality of slavery in the antebellum South.

“‘12 Years’ was very privately and carefully thought about, while ‘Rush’ was really about adrenaline, a rock ’n’ roll attitude, let’s just go to a scene and see what happens,” says the nine-time Oscar nominee (and winner for “The Lion King”) in his Santa Monica studio.

Ron Howard’s “Rush” took Zimmer back to his late-1970s roots as a synth programmer and keyboard player in England (you can glimpse him in the background of the Buggles’ 1979 “Video Killed the Radio Star” video). “I wasn’t trying to ape ’70s rock, but there’s a sound, a spirit,” he says. “I was after the spirit.”

So he threw guitarists Michael Brook, Bryce Jacobs and Stephen Lipson in with drummer Satnam Ramgotra, asked one-time Brit pop star Peter Asher to consult, and added cellist Martin Tillman at key emotional moments. “I love the state of chaos that I usually operate in,” says Zimmer. “It’s really nice to throw ideas around and have somebody like Peter or Lipson say, ‘Hey, wait a minute, play that phrase again!’”

Recalls director Howard: “He kept writing and rewriting and trying to find ways to sustain the intensity, yet be very sensitive to who these guys were.” Howard was fascinated by Zimmer’s interest in racer James Hunt’s obsession with budgerigars (parakeets, in U.S. parlance). Notes Zimmer: “This wild guy could never form a proper relationship, but the one thing he was enamored with were these birds that needed true companionship.”

As for “12 Years a Slave,” Zimmer concedes, “It’s basically a cello and violin score. It felt appropriate to keep it as small and as specific as possible. We have a lot of period source music, and one of the things I wanted to do was to be anachronistic, but not in an overt way. I wanted to be the secret little bridge that would take the story from the past and move it into the present.”

Cellist Tristan Schulze and violinist Ann Marie Calhoun performed, although there are more strings and occasional percussion throughout. “It was not just getting inside the characters,” Zimmer says, “it was getting outside the characters and finding a bridge to the audience.”

Director Steve McQueen liked Zimmer’s moody music for “The Thin Red Line,” which became a starting point for discussion.

Most of the 38-minute score “creates a stillness, or a tension through the stillness, using very minimal means,” he adds, although the riverboat ride offers a briefly avant-garde musical contrast, including woodwinds and an unusual use of piano.

Says McQueen: “He was my refuge when I was in L.A. The first two meetings were about five hours each. Then I think we had three two-hour conversations on the phone. And not a musical note was played. After that, he said, ‘I think I’ve got something.’ Somehow, through the talking, he captured the atmosphere of the film.”