"I wanted to talk about the human element in music," said Grohl, a first-time filmmaker who recruited a couple of veteran documentarians in writer Mark Monroe ("The Cove") and editor Paul Crowder ("Dogtown and Z-Boys"). "I wanted to talk about technology and how it's impacted the way we make music and the studio industry. And I wanted to demonstrate those things at the end of the film."

That demonstration — in which we see the Sound City Players come together to create new songs, sometimes in just a matter of hours — is the part of Grohl's movie likely to expand its appeal beyond gearheads and music nerds.

One especially memorable sequence depicts the surviving members of Nirvana (whose singer Kurt Cobain died in 1994) with Paul McCartney as they write and record "Cut Me Some Slack," the hard-driving blues-punk number they performed during the 12-12-12 Hurricane Sandy benefit at New York's Madison Square Garden.

And it's a quiet thrill to watch Nicks, singing lyrics she said she wrote about the death of her godson, open herself up to new musical partners. "That was intense," said Grohl, who later admitted he'd failed to come through on at least one hoped-for collaboration: Barry Manilow and Weezer. "I got so close," he sighed.

"The film really works on two levels," said James Moll, whose documentary "Back and Forth" examined the making of Foo Fighters' 2011 album "Wasting Light." "It's great for people who understand the technology but also for a general audience interested in people."

The latter was more important to Grohl. His intention with "Sound City," he said, is to inspire "an appreciation for the sound of four human beings writing a song in an afternoon and walking away fulfilled." It's a lesson he remembers learning from "The Decline of Western Civilization," Penelope Spheeris' cult-classic look at the early-'80s L.A. punk scene.

"The energy of that music and the energy of that time was captured so perfectly in that movie," he said. "That's what you're trying to do. You're trying to capture magic."

mikael.wood@latimes.com