NEW YORK, NY.- During the second intermission of the Metropolitan Opera’s gilded, gargantuan production of “Turandot” one Friday last month, Donald Palumbo raced up to a tiny broadcast studio on the top floor for an interview.

Then he raced downstairs again. There was something he needed to do backstage before the curtain rose.

Palumbo, 75, who is retiring this spring after 17 years as the company’s chorus master, wanted to run through the start of Act 3 with the quartet of heralds, drawn from the chorus, who hauntingly call out a warning from Princess Turandot.

It was 13 performances into the season’s “Turandot” run, at 10 o’clock at night. But Palumbo, one of opera’s most mild-mannered yet most unrelenting perfectionists, was still making sure that the singers’ intonation was flawless, still fine-tuning the placement of the first note in a certain phrase.

“You have to be very specific,” he had said earlier about the way he coaches his choristers, “but you can’t micromanage.”

Show after show, detail after detail, Palumbo “devotes every ounce of his energy to his work,” Peter Gelb, the Met’s general manager, said in an interview. “There are no half measures when it comes to Donald.”

Twenty years ago, when Gelb was hired, the company’s chorus was widely regarded as a little unfocused, a little loud-and-louder — not quite on the level of the orchestra, which James Levine, the longtime artistic director, had made as flexible and nuanced as the great symphonic ensembles. So the Met coaxed Palumbo, already viewed as the finest in the business, from Lyric Opera of Chicago.

“The chorus wasn’t being taken care of like the orchestra had been,” Palumbo said, sitting in his already cleared-out, windowless office during the first intermission of “Turandot.” “That’s what they wanted me here for. And it slowly, gradually improved. It wasn’t by huge personnel changes or anything like that. It was just hard work and a lot of rehearsals.”

Gelb believes the effects weren’t quite so slow. “The impact that Donald made was immediately felt,” he said. “And it continued. He has brought the level of the chorus to where it’s generally considered the best in the world.”

Star singers and cutting-edge stage directors get the most attention, but the foundation of a big opera company — what stays put, as those glamorous artists come and go — is the orchestra and chorus.

Yannick Nézet-Séguin, the Met’s music director, might conduct four or five productions each year, and he shapes the sound through the players he hires. (He declined to be interviewed for this article.) But Palumbo has been the day-to-day, 9-to-5 maestro in the building as the repertory, already huge, has expanded to include more contemporary works and more experimental theatrical approaches. He has resisted delegating even the most frequently revived titles.

“Don is the constant conductor,” said composer Nico Muhly, who has had two operas produced at the Met. “He is the one who works in that house the most; he is the one who prepares the most shows. He’s so, so, so at the core of what makes that house great.”

Conductor Riccardo Muti, who worked with him at the Met on Verdi’s “Attila,” was so impressed that he asked Palumbo to collaborate last year on Beethoven’s “Missa Solemnis” for his final performances as music director of the Chicago Symphony Orchestra.

“With him, musically I felt at home,” Muti said. “We’re speaking the same language, the same feelings.”

Just a few hours before that 13th “Turandot,” Palumbo was in the Met’s steeply raked List Hall, leading the chorus in a rehearsal for Gluck’s “Orfeo ed Euridice,” which was opening in a month.

In these early, seated musical run-throughs, before sets and blocking enter the picture and conductors and directors rule, he dives deep into the fine points of diction, articulation, rhythm and balances, seeking unity among dozens of people. The preparation must be immaculate so that no expensive time is wasted later in the staging process.

“Every moment we sing, he hears something he could tweak and improve,” said Kurt Phinney, a tenor and the chorus’s administrative manager. Frequently, choristers arrive at the theater to find his notes about little improvements that could be made based on the previous evening’s performance.

In the Gluck rehearsal, Palumbo cautioned the group not to sit on one word’s final vowel, so that the next consonant could be more explosive. He explained that “vuoi,” in Italian, should be pronounced closer to “vwoy” than “voy.” He removed the accents and swells that were roiling a line’s smoothness.

“It can get quite loud and bright,” he said at one point, “and I’d like us to keep a more classical tone.”

Little by little, his comments sharpened the ensemble — “more clarity, less murky,” Palumbo said — without making the sound hard or harsh, and encouraged a kind of fiery nobility.

“Orfeo,” with its poised 18th-century passion, could hardly be more different than the rhythmically angular modern choral writing in John Adams’ “El Niño,” which had had its dress rehearsal that morning. Terence Blanchard’s “Fire Shut Up in My Bones” and Puccini’s “La Rondine” were still running, as was “Turandot.” “Carmen” and “Madama Butterfly” were about to return — each with little rehearsal, since they had already been performed earlier in the season. A revival of “The Hours,” a contemporary piece with a challenging choral part, was two weeks away.

It was, Palumbo said with wry weariness, “a bit of a crazy time.”

But there are few sane times for the Met’s chorus, given that the company performs nearly 20 titles a year and up to four shows at a given time, in a variety of styles and languages: new productions, rare revivals, standards. The orchestra also plays all those shows, of course, but the musicians don’t have to memorize their parts — or do them in costume as part of complicated stagings.

Chorister was an enormously difficult job even when the Met’s repertory extended from Handel through Mozart, Verdi, Wagner and Puccini to the middle of the 20th century. But as the company has taken on far more contemporary opera over the past two decades — in idioms as diverse as the time-stopping repetitions of Philip Glass’ “Satyagraha” and “Akhnaten” and the dense dissonance of Thomas Adès’ “The Exterminating Angel” — the demands have increased. That the chorus’s quality has increased along with them owes a great deal to Palumbo.

“When we started ‘Satyagraha,’ everyone was kind of skeptical,” said Jean Braham, a chorister since the late 1990s. “And by the end it really felt like a Zen experience. It was amazing. And Donald’s preparation of it really made that possible for us.”

Perhaps the most remarkable thing about Palumbo’s ascent to the pinnacle of his profession — “we all aspire to be like Donald,” said Michael Black, Lyric Opera of Chicago’s current chorus master — is that he has no formal musical training. He fell in love with opera as a boy growing up in Rochester, New York, played some piano and sang in his school chorus. But as an undergraduate at Boston University, he studied chemistry.

After graduating, though, he moved to Vienna, where he turned toward music, soaking up the fertile opera scene of the early 1970s and singing a few times in choruses conducted by Herbert von Karajan. “It was in the day when Karajan and Georg Solti were the two poles,” Palumbo said. “And I became kind of absorbed by Karajan’s style, this rounder, mellower, deeper quality of sound.”

One of Palumbo’s catchphrases is “never push your voice past the point of beauty.” That search for a warm, blended, refined sound blossomed when he returned to the United States and took work as a pianist for a prominent voice teacher in Boston. And he found a parallel to the Karajan style in the old Italian school when he became the assistant to Dallas Opera’s chorus master, Roberto Benaglio.

When the Met came calling, he had been at Lyric for well over a decade, and had just finished building and decorating a new home in Chicago. “But there was no way to say no,” he said. “Not if you’re an American and you grew up listening to the Saturday Met broadcasts, if you had to get back from your practicing to turn on the radio at a certain time.”

Palumbo’s first season at the Met, 2007-08, he said, was “baptism by fire,” as Gelb insisted on bringing “Satyagraha” from London as a last-minute addition to the schedule, and the challenges have hardly ebbed since. Things have been especially difficult more recently, with the pandemic shutting the Met for a year and a half — the chorus was furloughed without pay for a large portion of that period — and the company’s financial struggles making it ever more important not to waste a minute of rehearsal.

If Palumbo has been the constant conductor, he has also been the constant diplomat, working deftly to facilitate the visions of maestros and stage directors while advocating for what’s musically and logistically best for the chorus. (Are they too far upstage? Can they see the conductor? Does the set clarify or diffuse their sound?) He has hired a slew of younger choristers who trained as soloists, and has guided those powerful and characterful voices into a cohesive whole.

“It’s a very beautiful, Donaldesque sound,” said Black of Lyric Opera. “Rounded, never shrill or too open, with just a hint of cover to it.”

Conductor Daniele Rustioni, who led a new production of “Carmen” this winter, said that in the famous “Habanera,” the chorus’s dreamy repetitions are almost always too loud.

“It’s written triple piano,” Rustioni said, “and it’s never done that way, never ever. But Donald insisted on having it as suspended as it can be. He was on the side of the stage, barely visible, and he just raised very slowly his hands, and the chorus did it. Like Moses with the water.”

Although Tilman Michael, 49, of the Frankfurt Opera takes over as chorus master next season, Palumbo is not entirely finished with the Met; he will prepare the new production of “Aida” that opens on New Year’s Eve. And he will also take on select projects elsewhere.

But his work at the house — bringing the chorus out of the orchestra’s shadow and making it a partner at the highest echelon, performance after performance — is done. “I really think,” Palumbo said, before heading backstage for another act of “Turandot,” “we’ve achieved what was my goal.”

“We got 17 years out of him,” Gelb said. “And of all the colleagues I’ve had over that period of time, I can’t think of anyone who has been more dedicated and excellent. He really set a standard for the whole company.”

This article originally appeared in The New York Times.