“The conversation got bigger and bigger,” Grohl said.

Slipknot and Stone Sour’s Corey Taylor was a willing interview subject, as Slipknot recorded its first album at Sound City. “It was really cool seeing [the console] again,” he said. “It was a hell of an experience.”

Taylor said he regularly gets into fights with people who insist that recording digitally is superior to analog recording — much as vinyl lovers fight with CD enthusiasts. “I’ve had vicious arguments with people about how infuriating Auto-tuning and pitch correction [affects] the sound,” Taylor said. “All that crap sucks the humanity out of it. The worst thing that ever happened was that anyone and their dog [can make a record].”

As passionate as Grohl became, he realized his limitations as a high-school dropout. So he enlisted Rota as a producer, who contacted his high-school buddy John Ramsay, an L.A.-based producer, who agreed to help with the project once he met Grohl.

“From day one, Dave was very clear about what he wanted to say about Sound City,” Ramsay said. ‘The place was very special for him. It was clear from the first meeting how big a deal it was, and how special this film would be.”

Just by looking at Foo Fighters’ body of work, Ramsay could tell that Grohl put his music where his mouth was, said the producer (whose father-in-law is Utah TV reporter Rod Decker). Foo Fighters’ most recent album, 2011’s “Wasting Light” (which won five Grammys and debuted at No. 1 in 11 countries), was recorded in Grohl’s garage with only analog equipment.

Mark Monroe was enlisted as the film’s writer, helping to structure the scenes and build a narrative arc. He’s written the award-winning documentaries “The Cove” and “The Pat Tillman Story” and has two other documentaries screening at this year’s Sundance Film Festival: “The Summit” and “Who is Dayani Cristal?” He, too, was impressed by Grohl’s fire.

“One thing about directing is that you have to communicate with others,” Monroe said. “Dave has that in spades. … You’re talking about a premier storyteller. In the first five minutes [of their meeting], he wanted to inspire people to play instruments and play them together.”

Here’s how Monroe summed up Grohl: “First-time filmmaker, longtime storyteller.”

Grohl was in a unique position to tell the story of the legendary studio, but he was grateful to find other voices. “I didn’t expect everyone to be as in love with Sound City as I did,” he said.

But the studio, tucked away behind train tracks and crumbling warehouses in the surface-of-the-sun-hot San Fernando Valley, represented what makes the heart of rock beat, a sound that continues on. “It’s not dead,” Grohl said.

dburger@sltrib.com