Ray Chew is no stranger to big stages. In the early 1980s, he was a member of the Saturday Night Live Band. Two decades later, he would provide musical direction for “Showtime at the Apollo,” the Democratic National Convention and the Barack Obama Neighborhood Ball during the president’s first inauguration. Currently, Chew commands the stage of the hit TV show “Dancing with the Stars” as its musical director.

But last Saturday, Oct. 17, Chew commandeered the relatively obscure auditorium stage inside the Golden Dome field house, 100 N. Central Ave., for a roughly two-hour master class given to more than 50 budding young musicians from across the city. They were pianists, bassists, drummers, harpists — the instruments ran the gamut — but they all had one thing in common. Ray Chew is in the kind of place they want to be — at the pinnacle.

Chew had been invited to speak by the Chicago West Community Music Center, a North Lawndale nonprofit co-founded by Howard and Darlene Sandifer. The couple refers to their organization as a “musical conservatory without walls,” according to one media report.

The organization provides musical instruction in an array of genres and for a range of instruments. The Sandifers provide lessons at the field house and at various public schools throughout the city to hundreds of aspiring musicians each year. Last weekend, some of those students got a chance to perform for Chew — but only after he took them to school.

Sandifer said he brought Chew to speak to the students so he could talk about what it’s like to be at the top.

“Our students talk to us constantly about making the big times,” said Howard Sandifer. “They ask, ‘How do we get from one level to the next level, to the big times.’ Well, Ray is the best of the best.”

But before he was performing for presidents and celebrities, Chew was just a restless kid from the Grant Houses, a public housing project on 125th Street in Morningside Heights in Manhattan — a hop, skip and a song away from the Apollo Theater.

“The building we were in was 21 stories of trouble — it was waiting on every floor,” Chew said.

“My mother was a visionary. She said I’m not going to let you just run up and down through here.”

His mother’s defense against the trouble was to keep her son and her daughter busy. They took language classes, cooking classes and indulged in the arts — dance for the daughter and music for the son.

“My father used to put me on his knee and I would play the piano by ear,” Chew said.

When he was around five years old, he won a scholarship to a highly prestigious program for talented children at Juilliard. From there, Chew studied at a string of elite of music programs throughout New York City — Third Street, Mannes, LaGuardia High (the inspiration behind the classic movie “Fame”) and the Manhattan School of Music — before landing a touring gig with Broadway star Melba Moore.

Chew ate, drank and slept music — eventually teaching himself a variety of instruments and mastering music theory.

“I have a thirst. I want to learn everything there is to know [about music],” Chew told the students in Garfield Park, before noticing a harp that was a few feet away from him on the stage.

“I’m interested in that harp over there. I see it over there. I want to clear the room out so I can spend an hour messing with that thing,” he said in his self-assured New York City accent. “If you give me an hour, I’d be able to play a song on that thing. I guarantee it.”

That self-confidence, that self-assurance, is key, he told the students. But it doesn’t come magically. They would have to gain it through work.

“You should learn everything there is about music. You should have a thirst for that,” Chew said, addressing 17-year-old saxophonist Jeron Johnson.

“Compare yourself to John Coltrane,” Chew told Johnson. “Where are you at?”

Johnson raised his right hand above his head while the other was at his chest.

“This is 100?” Chew asked, pointing to Johnson’s right hand, the one indicating the realm of the legendary jazz saxophonist. “Where are you at?”

“About a 45,” Johnson said, before Chew asked him what it would take for him to get a bit closer to the jazz master.

“Learning all of my scales,” Johnson started before noting that he’d have to study more.

And then another lesson.

“When you practice your scales, practice them [in] nice, full, round tones. Fill it out. It doesn’t count if your tone isn’t good,” Chew said, adding that the best practice is done slowly, methodically and deliberately.

Be curious about music. Try learning everything about it. And learn it slowly. When Chew began receiving feedback from one of the microphones, he gave the students another lesson in command.

The microphone was muffled, which presented a problem. Chew dove in. You could imagine him during a “Dancing with the Stars” sound check or rehearsal. This was what being at the pinnacle looks like.

“What’s the EQ on that bad boy? It’s a little [muffled] … When people ask questions I want everybody to hear them, alright? There it goes. Put a little high end on that … How does it sound in the back? It’s getting better. Still sounding a little bassy? Do some high end,” Chew said.

“If you’re a musician, you should study all of your frequencies,” he said. “What’s the frequency of ‘A’?”

And so it went for roughly five minutes — Chew taking command, but also teaching it. To be in command, Chew seemed to suggest, is to know and to act with that knowledge. What is frequency? What is pitch? Who knows what microphone feedback is?

“If you put me in situations that I’ve studied on, I know about it. I don’t just know a little bit, I know a lot. I know a lot. That’s how I’m able to get into the situations that I do. I command my space, because I learn and study every position,” he said.

Before the day ended, Chew presented Johnson with a challenge.

“I challenge you in year you can be so much better than where you see yourself today,” Chew said. “I’m going to come back … In a year, I’m going to hear you play that horn and I want you to be [20 units] better than where you are today. Are you going to take that challenge?”

“I’m going to take that challenge,” Johnson said.