It’s a Thursday morning at the Newman Scoring Stage on the Fox lot. Steven Spielberg has stopped by to listen to a 104-piece orchestra play Michael Giacchino’s score for “Super 8,” the J.J. Abrams thriller he’s exec producing.

He stands with Giacchino and Abrams behind the massive console where veteran mixer Danny Wallin is monitoring levels and, after hearing two emotion-filled cues, pronounces Giacchino’s score “your best since ‘Ratatouille’ ” — one of three Pixar films the composer has done, although not the one for which he won an Oscar (“Up”).

Spielberg exits the booth to share the good news with the musicians. “The great thing about Michael and J.J. is, they believe in orchestras,” he tells them. “Thanks to this new generation, you’re all going to be employed for many years to come.” Wild applause, naturally, follows.

The “Super 8” sessions marked the second time in a month that a roomful of Hollywood musicians was performing a Giacchino score. Just three weeks earlier, over at the Warner Bros. Eastwood stage, 88 musicians were playing very different music for “Cars 2,” Giacchino’s other big summer movie (his fourth for Pixar).

As on “Super 8,” there was nary a synthesizer in sight. The score can best be described as “surf guitar meets orchestra,” with Fender Telecasters and Hammond B3 organs prominently featured throughout the soundtrack of the animated pic. Or, as Giacchino puts it, “real people playing real stuff.”

The composer is among a handful who prefer to score movies the old-fashioned way — with an orchestra, whether the style is symphonic (as in “Star Trek”), jazzy (“Ratatouille”) or both (“The Incredibles”).

Along with top American composers like John Williams and prominent Europeans Alexandre Desplat (“The Tree of Life”) and Dario Marianelli (“Atonement”), Giacchino believes that trained musicians performing on time-honored instruments are still the most effective way to elicit an emotional response from moviegoers.

And he tends to work with filmmakers who agree with him. Abrams, writer and director of “Super 8,” discovered Giacchino in the late 1990s when he was scoring videogames like “Medal of Honor.” Their work on TV’s “Alias” and “Lost” led to collaborations on “Mission: Impossible III” and the rebooted “Star Trek.”

Abrams, who plays keyboards himself and who owns a collection of vintage synthesizers, puts it this way: “Nothing can grab you by the throat, or heart, or soul, like an orchestra. It’s undeniably the most engaging and exciting way to bring a score to life.”

Pixar boss John Lasseter, director of “Cars 2,” seemed to be having the time of his life at the scoring session. Variety managed to corner him after he had his picture taken donning cool ’60s-era sunglasses and pretending to play the organ.

“These recording sessions are some of the most fun things I do on a movie,” he says. “I am in absolute awe of the talent of these musicians, (who) have never seen this music before and yet they play it perfectly, with feeling and interpretation. They’re not just reading notes.”

Lasseter goes back into the booth and happily points to various directions Giacchino has written into the score to help get the musicians into the right mood: “kick-ass total ’60s TV show action”; “sad and post-apocalyptic feel”; “sneaking bad guys.”

As much fun as it is for the filmmakers, it’s still precise and pressure-filled work for the composer and the orchestra. Seventy-two minutes of music for “Cars 2,” another 82 for “Super 8,” all written since the end of January for two highly anticipated summer releases (“Super 8” is due out June 10, “Cars 2” June 24).

Two more big assignments await Giacchino this year: “Mission: Impossible IV,” produced by Abrams and directed by his “Ratatouille” colleague Brad Bird; and “John Carter of Mars,” the sci-fi epic being directed by another Pixar colleague, Andrew Stanton, slated for next year but which Giacchino will begin before the end of 2011.

But having Spielberg show up at the scoring session for “Super 8” was a “wow” moment for the composer.

“He was our first teacher,” Giacchino says. “We grew up at a time when he was making these films and John Williams was scoring the hell out of them. That’s what I want to continue, that great tradition of filmmaking.”