Seth MacFarlane knows his stuff. He is not just an actor-writer-director; he’s also an Oscar-nominated, Emmy-winning songwriter and a Grammy-nominated big-band singer.

So for his new science-fiction comedy-drama “The Orville,” debuting Sept. 10 on Fox, he demanded a 75-piece orchestra and lined up a trio of veteran composers who, among them, have amassed 14 Emmys for their original music for television.

“For us, music is more important than in most TV shows,” MacFarlane says. “Even if an audience doesn’t know it’s hearing acoustic players, it somehow makes the show seem important — a little more legitimate. It makes it feel like a movie.”

Bruce Broughton, one of the most respected composers working in film (his movies include “Lost in Space,” and an episode of “Buck Rogers in the 25th Century” is among his 10 Emmy wins), supplied the heroic theme and scored the series pilot.

Joel McNeely (who scored MacFarlane’s movie “A Million Ways to Die in the West” and won an Emmy for “The Young Indiana Jones Chronicles”) and John Debney (whose TV record includes Emmys for such sci-fi adventures as “SeaQuest DSV” and “The Cape”) are composing the weekly episode scores.

“To me,” says MacFarlane, “casting a composer is like casting an actor. It’s got to fit. This was a swashbuckling kind of pilot; it really wanted a theme that felt

a little bit like a march, that harked back to the golden era of sci-fi.” MacFarlane insists that his composers be “serious musicians who can compose, →

orchestrate and really handle an orchestra that size.”

Broughton describes his music as “dramatic sci-fi.” “It’s got all the space chords,” he says with a laugh. “It may as well have been a movie.” McNeely echoes that sentiment: “Seth wants each show to be its own individual story, to think of it as scoring completely different movies from week to week.”

Carol Farhat, VP of music production at 20th Century Fox TV, confirmed that the “Orville” orchestras were among the largest in Fox TV history (the studio regularly contracts ensembles of 30 to 60 players for “The Simpsons” and “Family Guy”). And on a recent “Orville” session at the studio, MacFarlane not only made a guest appearance but brought along two of his fellow actors, Scott Grimes and Halston Sage (the latter in full alien makeup), who watched the screens in the recording booth while Broughton’s music added a sense of adventure and drama to scenes they had shot a few weeks earlier.

Broughton and McNeely are working with MacFarlane outside “Orville” as well. Both arranged and conducted new albums with MacFarlane in his other showbiz role as interpreter of the Great American Songbook. McNeely’s will be released Sept. 15, Broughton’s sometime next year.

“Seth is so knowledgeable about film music and such a collaborator on a musical level,” McNeely says. “He can not only talk about the intent and tone of the score, but also the performance, asking for it to be lighter or softer here or there, or can the violins play with mutes? He really knows his stuff.”