Frank D'Ambrosio is a magician.

Officially, D'Ambrosio is a singer and actor, best known for playing the Phantom of the Opera more than 2,300 times.

But Tuesday, when he sang "Music of the Night" for Bozeman High School's best concert choir students, D'Ambrosio became a magician.

With nothing more than his voice, gestures and intensity, he conjured up the spine-tingling illusion of seeing the masked Phantom on a spot-lit stage beneath a glittering, menacing chandelier.

"Acting is living truthfully under imaginary circumstances," D'Ambrosio told students.

Of performing on stage, he said, "It's vulnerable. It's intimate. What it is is growing and revealing yourself in the presence of another individual."

In Bozeman to perform tonight at the Ellen Theatre, D'Ambrosio offered about 60 students in choir teacher Nancy Ojala's class a shortened version of a master class he'll teach next month at The Juilliard School in New York City.

He asked students how many want to perform for a living, and how many feel it's what they need to do. It takes that kind of desire to make it in a tough business, he said.

D'Ambrosio said he grew up in a bad neighborhood in the Bronx. His friends mugged a cab driver and broke the cabbie's jaw, for which they got $20 and five years in prison. Suddenly D'Ambrosio had a lot of free time. That's when he discovered music.

"It saved my butt," he said.

A struggling actor and singer, he waited tables, lived in New York's Hells Kitchen area and shared a one-bed studio apartment with two other guys.

He got a break. While performing in the chorus of a revival of "Sweeney Todd," D'Ambrosio was picked for a part in the third "Godfather" film, playing the opera-singing son of Al Pacino and Diane Keaton's characters.

After that, D'Ambrosio was chosen to star in performances of Andrew Lloyd-Webber's "Phantom," a role he played for several years.

To make it on Broadway, you have to merge singing and acting, he said, which demands "speaking on pitch and singing with opinion."

D'Ambrosio gave a demonstration of techniques that made him a successful performer by working in front of the class with two local singers, Frank Simpson and Cheryl Sheedy.

After each sang a song, D'Ambrosio asked them the same questions he asks himself about a role. Who is this character? What do the words mean? What is the drama or conflict? Where are the commas and periods in the lines, and how do they communicate meaning? Who are you singing to? Can you sing to him as if it will change his life?

"Emotionally, we can never start a song where we finish," D'Ambrosio told Sheedy.

Instead of singing about being "head over heels" in love, he said, she should interpret the song to show that she's trying to get the guy to admit he's in love, too.

"You have to set up a conflict," D'Ambrosio said. "Then you're going to tell us a story, not just sing a concept."

When John Ludin, Ellen Theatre executive director, asked him to sing one song from "Phantom," D'Ambrosio urged the students to pay attention to the silences in the song.

"Mozart said the most powerful note in an opera is the silence," he said.

Then D'Ambrosio sang, conjuring up the Phantom, using the silences like exclamation points.

The class applauded. "Wow," one student said afterward.

"That was awesome. So inspirational," said another.

D'Ambrosio's performance of Broadway songs last year at the Ellen sold out and got raves from the audience, Ludin said.

Gail Schontzler is at gails@dailychronicle.com.