"The New Moon in the Old Moon's Arms," premiered last night by the National Symphony Orchestra, is the first symphony written by Michael Kamen--award-winning film composer, hit song writer, pop music arranger, old pal of the NSO's Leonard Slatkin.

"New Moon" is Kamen's latest effort to demolish musical barriers, barriers that to him never existed.

"My ambitions are to figure out a way to bring orchestras to the attention of rock-and-roll fans, and rock-and-roll to the attention of orchestral fans as something they have a great deal more in common than some people suspect. They have music in common, the same 12 bloody notes."

His music's not just about rock-and-roll. Throughout his career, Kamen has been heavily involved in orchestral music--not necessarily "classical music" of the sort that has been around for centuries and that the NSO plays day in and out, but music in popular styles of today written for orchestras to play.

When you first see Kamen it's his suntan that betrays his California connections.

Kamen has lived in London's posh Notting Hill Gate neighborhood for nearly two decades, but he's still a Hollywood guy. And he looks the part.

He says he woke up one day to realize that he leads a "pop lifestyle," jet-setting among homes in Los Angeles, Sarasota, Fla., and Italy.

For an interview in his greenroom at the Kennedy Center the other day, during a break from rehearsals of his symphony, the 51-year-old composer is wearing ankle-high suede Beatle boots and socks embroidered with staff lines and eighth notes. His purple shirt is open at the collar. Silver and turquoise bracelets and belt buckle complement his shoulder-length mane of graying hair.

He speaks with the polish of someone who has been asked many times about his music and his philosophy, and with a sparkle in his eye.

"There was music in my house all the time," he remembers. "Like most left-wing families in Queens, my parents played a healthy diet of Leadbelly and Pete Seeger records, the Weavers, in addition to the Bach." He enrolled at New York's Juilliard School of Music, studying the oboe and English horn. That's where he met Slatkin.

"By then, rock-and-roll had become the thing, and the Beatles were happening," he says. "They changed my life, there's no question about it. So at Juilliard I started a band called the New York Rock & Roll Ensemble. It was a joke. We played in tails, and we played R&B and our own rock songs. There were two oboists and a cellist in the band, and we'd switched instruments. The other oboe player would play drums. I played oboe and keyboard and sang. The cellist also played bass. And every once in a while we'd swap instruments and play a Bach trio sonata. It was a real gas.

"This was the late '60s, and we were brought to the attention of people like Leonard Bernstein; he'd come hang out in the club. One day he asked us to play at one of his televised Young People's Concerts, for a program called 'Bach Transmogrified.' Later Arthur Fiedler asked us to play with the Boston Pops, and it fell to me to write the orchestra stuff to back up our band. I had never orchestrated a composition truthfully all the way through. But I found that I really loved all of it--the energy, the age-old instinct to get laid, and I had a genuine appreciation for writing tunes. So I left Juilliard and worked in a rock-and-roll band."

His first film score, for "The Next Man," was written in 1974. "I always loved the work of Max Steiner and Bernard Herrmann"--preeminent Hollywood composers, the latter best known for his gripping score to Hitchcock's "Psycho"--"and I loved making my own music for film. It was just great to bring texture to visual images and realize that a musical phrase could accompany a movement on-screen."

To date he's written 50 or so soundtracks, among them "Brazil," "Iron Giant," "Robin Hood, Prince of Thieves," "Lethal Weapon" and "Mr. Holland's Opus." A few of the ballads off the soundtracks have taken a life of their own: "(Everything I Do) I Do It for You" and "Have You Ever Really Loved a Woman," both sung by Bryan Adams, topped the Billboard pop charts and won Grammy Awards.

But with the satisfaction of success come the realities of commercial art. You're a respected film composer and have worked hard on a score. Then the director or some studio executive says he doesn't like what he hears. What to do? Kamen responds with a sly smile and a broad arm motion, as if tearing a whole page from a coffee table-size score, tossing it aside. "You just rip it out. At the end of the day, that's what it's about.

"Making something and selling something are two different things," he says.

(Kamen's bankable credibility means Slatkin and the NSO will record it, for Decca, this week.)

The films scores sold well, and so have Kamen's pop music collaborations. Last year the hard rock quartet Metallica invited Kamen to add an orchestral layer to several of their songs, and then hired the venturesome San Francisco Symphony as their backup band. Instead of the usual bland accompaniment that orchestras give crooning singers in "classical pops" concerts, Kamen wrote aggressive charts that made the orchestra work. The symphonic sound was integral to the screeching guitars and thundering drums. The result might be called power orchestra music, and it was released as a CD called "Metallica S&M."

It goes without saying that just because an orchestra plays a piece of music doesn't mean it's what we all identify as "classical" music. But Kamen sees it all as one genre, and he describes all his music as "public" music, music meant for as wide an audience as possible. "There's no end to the good time you can have with music and there's no need to be stressful about it. There's more pleasure in it than I think the 'serious' contemporary music world knows, and certainly the orchestral world has suffered from a pretense."

"The New Moon in the Old Moon's Arms," his first symphony, gets its name from a Native American expression that "describes the final crescent as it illuminates the darkened face of the new moon to come; the future glimpsed in the face of the past."

"My piece is an attempt, in a way, to be on a soapbox extolling the virtues of melody and explaining it in a storytelling fashion," he says. "So that I'm actually writing a film score without the film. At one point I thought we could make a film--a visual representation that would be concurrent with the piece, in order to explain it. That might be a component of the recording, when it goes on DVD."

CAPTION: Michael Kamen aims "to bring orchestras to the attention of rock-and-roll fans, and rock-and-roll to the attention of orchestral fans."