– The concert was set to start in a half hour. Chairs were in place and people had begun arriving. But Roderick Cox remained on the podium, coaxing out of the young players a bigger sound.

He puffed his cheeks and pulled his hands wide.

“Good,” Cox said, with a nod. “You have to make the room ring a bit more.”

The Minnesota Orchestra’s associate conductor was leading the South African National Youth Orchestra in Jean Sibelius’ Symphony No. 2, a piece he and his usual Minnesota bandmates know well, in an unfamiliar place: a small church auditorium in Johannesburg. The Sunday performance of that symphony would cap days of working with the country’s top young players, who had gathered for an intense week of training.

“They come from every kind of background and every kind of culture and every kind of place,” said Sophia Welz, the youth orchestra’s managing director. “So for some of these musicians, coming here is a journey that unlocks incredible possibilities.”

The Minnesota Orchestra’s five-city, first-of-its-kind tour of South Africa was inspired by these kids. Music director Osmo Vänskä pitched the trip after conducting the youth orchestra in 2014, during its 50th year.

“Who could believe four years ago that I’d be back here with my own orchestra?” Vänskä said last week, in a basement dressing room, before leading this year’s group in a side-by-side rehearsal.

He didn’t expect to recognize any of the players. But during a break, a tuba player approached the podium and thanked him. Tiago Vital had performed with Vänskä in 2014.

“It’s one thing to listen to a recording,” the 23-year-old said. “It’s another thing to play with the musicians who made those recordings.”

Helping build confidence

During that rehearsal, Minnesota players shared music stands with their young South African counterparts. Horn player Michael Gast, 60, got paired with Caryn Pretorius, a 22-year-old from Port Elizabeth.

They bonded quickly and, by rehearsal’s end, were dancing together. By dinner, they were making plans for Pretorius to take Minnesota horn player Herb Winslow’s spot when he retires. (“Have you ever heard of a snowblower?” a percussionist cautioned.)

“I was actually nervous for today,” Pretorius said.

“You didn’t seem that nervous,” Gast said.

“We don’t usually get an orchestra of this caliber in this country — or at all,” she replied, “so I wasn’t myself.”

But soon the pair were giggling. Pretorius had been struggling for months with her upper register. Gast fixed it in minutes, she said. “I’m just excited to practice now,” she said. “I can do anything now.”

“She played beautifully today,” Gast said. “These guys and girls are so talented.

“We all remember being at that age. I never heard an orchestra until I got into conservatory. So be able to give back to our profession and help people along — and give you a high register today. That’s fun. That’s why we’re here.”

The pair smiled at one another.

“And I learned how to dance,” Gast added.

“You can do spirit fingers and jazz hands now,” Pretorius said, waving her hands in the air.

Watching the professional musicians connect with high school and college students was “an almost unbelievable thing,” Welz said afterward. “They gained confidence so quickly.

“At first they were nervous, and about two seconds later, it was just the joy of having beautiful music and supportive people around them.” Her eyes welled with tears. “Today was one of the best days of my life.”

Vibrant music is ‘in the soil’

After Vänskä’s time with the youth orchestra, Cox took over the baton, digging into the music over several rehearsals.

Seeing Cox, who is black, on the podium “inspired a lot of kids,” said Chad Hendricks, 27, an aspiring conductor. For South Africans growing up in black and mixed-race communities, “there aren’t a lot of opportunities, and there isn’t a lot of exposure to this kind of thing,” he said.

“A lot of the underprivileged kids that were here ... they’re seeing someone they can relate to.”

Cox, who is wrapping up a three-year stint with the Minnesota Orchestra, has conducted in South Africa before.

The music he’s encountered is “quite vibrant,” he said in an interview before Sunday’s concert. “It’s like the music is spilling from within them here. It’s very much in the soil and in their blood.”

Part of his job in conducting the youth orchestra “is to kind of take all this vibrant, passionate sound they’re giving and try to contain it and shape it for the music we’re doing, like Sibelius.”

Sibelius’ Second Symphony was an ambitious choice. Minnesota Orchestra violist Sam Bergman never played it in high school — or in college. Here, he turned around to see a 12-year old onstage.

“That’s off the charts,” he said. “So yeah, these kids are amazing.”

Bergman grew up in big East Coast cities and, as a 9-year-old, got the chance to meet members of the Boston Symphony.

“I got to do this kind of thing as a kid,” he said. “That chance to make a connection with somebody who was doing what I already knew I wanted to do for a living — that was everything. That went a long way steering me toward what I wanted to do.

“We all remember those experiences and we want to give those to as many kids as we can.”

Sunday’s concert came at the tour’s end, on a day when many of the musicians were leaving to explore the country on their own or heading to the airport to catch a flight. But a handful of musicians, including Bergman, showed up at the church.

During intermission, they greeted their stand partners from days earlier, taking selfies. Then they watched as Cox conducted Sibelius, nodding as the group played tricky passages and pulling out their cellphones to film the epic finish.