The Minnesota Orchestra had assembled on the stage three Fridays ago, and the air inside Orchestra Hall was filled with that recognizable hum of tuning and last-minute rehearsing.

Upstairs, in a soundproof studio no larger than a walk-in closet, Melissa Ousley was oiling her vocal cords and warming up as host of Minnesota Public Radio's live Friday night broadcast.

"Do you have your cellphone off?" asked engineer Michael Osborne.

"I do, and I have thrown out my chewing gum," Ousley responded as the seconds ticked toward the moment when she would introduce guest conductor Nathalie Stutzmann and the orchestra would launch into Prokofiev's Symphony No. 1.

MPR is celebrating its 50th anniversary this year and on Nov. 11, the orchestra will play a special concert to mark an association with the public broadcaster that dates to 1971, when host Arthur Hoehn introduced conductor Stanislaw Skrowaczewski and the orchestra at O'Shaughnessy Auditorium in St. Paul.

Since then, nearly 1,200 concerts have been aired to listeners who can't make it to Orchestra Hall, or who — like baseball fans listening to the play-by-play — enjoy sitting at home in an easy chair with the stereo speakers in the background.

This Friday, Brian Newhouse, MPR's managing director for classical programming, returns to his regular job as host. But on Nov. 11 he will take a seat on stage as emcee and introduce pieces he helped select with music director Osmo Vänskä, while American Public Media's Fred Child fills in as the on-air voice.

"I get feedback along three themes," said Newhouse, when asked why MPR continues to do these live broadcasts. "First is the person from Warroad, who says they'll never be able to get to downtown Minneapolis. Second is the listener who says they attend the concert on Saturday night but love to hear the interviews with artists and the inside information they pick up on the Friday broadcast.

"The third is the person who says, 'I listen on Friday night to see if I want to go on Saturday.' "

Ousley was filling in for Newhouse last month, watching a video monitor and describing what she saw and heard as soloist Bixby Kennedy performed Mozart's Clarinet Concerto and the orchestra made a familiar foray into Beethoven's Fourth Symphony (in addition to the Prokofiev).

Osborne, who has engineered these broadcasts for 18 years, sits at a large control panel with a "bat phone" nearby to communicate with operatives in the hall.

"We can get a head's up if intermission is running long, or the bathrooms are backed up," Ousley said.

Preparing for any eventuality

The hosts fortify themselves with reams of notes and anecdotes to gently usher in those moments when the orchestra is not playing, or the audience is applauding.

Newhouse spoke of "the adrenaline rush" when the red light goes on and Osborne activates the microphone.

"Anything can happen live — and often does," he said. "There was the time when a French horn player didn't have the right mouthpiece and I had to fill five minutes until he found one."

Then there was the historic 2015 broadcast during the orchestra's tour to Havana, when Newhouse had been promised a guest from the Cuban government. The fellow apparently got cold feet — afraid that his words might be parsed by the leadership — and Newhouse faced a 20-minute intermission pretty much on his own. His agility and experience papered over the absence.

"You have to assume that everything is going to go wrong," he said, smiling at the recollection. "I have tons of material and most of it is still up here in my head."

Do it until someone says stop

What was then called the Minneapolis Symphony was first heard on radio in 1923, with German conductor Bruno Walter on the podium.

There were intermittent broadcasts on various stations through the decades before MPR instituted its "Live From Orchestra Hall" series of Friday night subscription concerts in 1974, after the concert hall opened. MPR's classical network also routinely records concerts by the St. Paul Chamber Orchestra, but those programs are aired later.

Nationally, most of the major orchestras offer some kind of radio broadcast, but only the Boston Symphony has had a live series longer than MPR's, said Minnesota Orchestra spokesperson Gwen Pappas.

Newhouse drives to Orchestra Hall early, so he can wander the lobby and ask patrons, "What brought you here tonight?" He checks the hall, making note of the attendance, what people are wearing, whether there are flowers on the podium.

"What's the weather like outside? Is there a full orchestra, a chamber ensemble? Were there buses bringing people in?" he said, ticking off his process. "I can often tell if Osmo is happy, in how he slaps the score shut at the end of a piece.

"I try to take all of that and make it into a narrative."

The Minnesota Orchestra, as with symphonies everywhere, is trying to draw new audiences to classical music — hoping to make an art form that many consider antique to be relevant. Ever since the painful lockout of 2012-14 ended, Newhouse has noticed a new energy at the orchestra. Near-death experiences can do that to an organization.

The hiatus also created an awareness in Newhouse of how much he appreciates the chance to do these broadcasts.

"It never feels rote," he said. "I walk in here after a day at the office and I think, 'Thank goodness I get to do this.' "

With the ability to access recorded concerts via online libraries like the SPCO's and the shift from mainstream media to niche portals like webcast, the MPR live broadcasts may seem like a relic. Everything has its time, right?

"I can't say we'll do this forever," Newhouse said. "But we have an audience that loves that we do this."

Graydon Royce is a longtime Star Tribune arts writer. He can be reached at roycegraydon@gmail.com.