In the early 1970s, Mannheim Steamroller founder Chip Davis combined his classical music training in composition with the recently developed ARP and Moog synthesizers. The results debuted on 1974’s “Fresh Aire” by Mannheim Steamroller, then a studio-only entity.

In the 40 years since “Fresh Aire,” Davis and Mannheim Steamroller sold 40 million records. The project also evolved into a touring ensemble.

“Mannheim Steamroller Christmas,” the group’s 31st tour of the U.S., rolls into the Saenger Theatre on Saturday.

Davis’ two Mannheim Steamroller companies will perform 90 shows in more than 80 markets through Dec. 27.

“When I did ‘Fresh Aire,’ I thought I was writing rock ’n’ roll,” the Omaha, Nebraska-based Davis said recently from his vacation home in the Florida Keys. “I actually wasn’t. I was 24 years old, trying new stuff.”

The young Davis found synthesizers to be fascinating new toys.

“They gave me a lot of ideas,” he recalled. “I started creating new textures and sounds.”

In 1975, Davis had the ear of major record labels because he’d co-written C. W. McCall’s 1975 novelty hit, “Convoy.” The companies gradually got back to Davis about his “Fresh Aire” project.

“They said, ‘We really don’t have a place to market it. We’re going to have to turn it down — but could you send a box of 50 to me, so I can give them to some of my friends? They’ll love it!’ ”

The mixed message was puzzling, Davis said. “I’m like, ‘OK. What? You can’t release it, but you’d like a whole bunch of them?’ ”

So Davis created his own record label, American Gramaphone. His first “Fresh Aire” album inspired an early burst of interest from an unexpected place.

“Some guys in the high-end audio industry used it at a consumer electronics show,” he said. “It caught on as hi-fi demonstration material.”

Responding to popular demand from the high-end audio industry, Davis released a “Fresh Aire” follow-up. Through 1983, Mannheim Steamroller albums at two-year intervals, all titled “Fresh Aire” with the numerical distinctions “II,” “III,” “4” and “V.”

Bigger, even more surprising Mannheim Steamroller success came with “Christmas 1984.” The group’s first holiday album, it featured synthesizers and antique instruments such as harpsichord, crumhorn and recorder. Davis’ arrangement of a traditional Christmas carol, “Deck the Halls,” achieved hit single status and sales of “Christmas 1984” eventually reached 9 million copies.

Mannheim Steamroller’s four decades of sustained popularity in the fickle music business is a happy surprise for Davis, too. Although he stopped touring with Mannheim Steamroller 10 year ago, he continues to direct and co-produce the show.

“I remember the life of the artist would be about five years and then they’d fall off the map,” he said. “But we’re hanging in there.

“It’s amazing that the financial success has come with it. I always tell people, ‘Don’t do it for the money. If you do it from your heart, the money part will come with it.’ ”