Robert Mann, the founding first violinist of the Juilliard String Quartet, the internationally renowned ensemble that at midcentury helped engender a chamber music revival throughout the United States, died Monday at his home in Manhattan. He was 97.

His death was announced by Debra Kinzler, associate director of the Walter W. Naumburg Foundation, of which he was president from 1971 to 2015.

Conceived in 1946, the Juilliard Quartet gave its first official performance the next year. Besides Mann, the original roster included second violinist Robert Koff, violist Raphael Hillyer and cellist Arthur Winograd.

Mann — for decades the quartet’s de facto spokesman, institutional memory and “resident spark plug,” as The Chicago Tribune called him in 1997 — remained with the ensemble for 51 years. By the time he retired in 1997 he had outlasted the quartet’s entire original lineup, as well several subsequent permutations, to become one of the longest-serving members of any chamber group in the world.

From the beginning, the Juilliard Quartet was known for its probing musicality (the group once devoted two full rehearsals to a single measure from Elliott Carter’s Third String Quartet); hard-driving style, which for all its passionate intensity was considered refreshingly unsentimental; and deep commitment to contemporary music.

Over the years, the quartet gave thousands of concerts worldwide, recorded extensively and performed repertoire ranging from the complete Beethoven quartets to the work of Bartok, Schoenberg, Lukas Foss, Milton Babbitt and Roger Sessions.

“The Juilliard Quartet remains one of the wonders of the music world,” Newsweek wrote in 1981, going on to praise the ensemble for “music that is marvelously alive and varied — music that breathes, not something that sounds as if it were put together by a precision drill team.”

Mann was perennially singled out by critics for his impeccable technique and equally impeccable musical taste.

“Robert Mann,” Donal Henahan wrote in The New York Times in 1980, “has been largely responsible for the ensemble’s continuity of style and the maintenance of its stature in international chamber music circles.”

He had cheerfully forsaken a promising solo career for a life in chamber music and — because that life entails as much — diplomacy. (A string quartet is nothing short of a quadrilateral marriage in which the spouses rarely see eye to eye on interpretive matters.)

It was a decidedly unexpected calling for a boy who had wanted only to be a forest ranger.

Robert Nathaniel Mann was born in Portland, Oregon, on July 19, 1920, into what he later described as a “very poor” family. Both of his parents were immigrants: His father, Charles, a tailor, had come from England; his mother, Anna Schnitzer, from Poland.

“My father knew nothing about music, but he used sense in going to the concertmaster of the Portland Symphony for advice,” Mann told The Toronto Star in 1995. “It was the greatest break of my life. He told my father, ‘Your son is no wunderkind, but if he practices hard, he can make a living.’”

When he was 9, Robert began lessons, at $1.50 each, with a teacher he recalled as an alcoholic. Two years later, the teacher was shot and killed — an actuarially unorthodox end for a classical musician.

Robert was 13 before another teacher could be found, but the new teacher proved transformative.

“Up to then, I was going to be a forest ranger, hopefully in a national park,” Mann, recalling a boyhood lesson, said in “Speak the Music Robert Mann and the Mysteries of Chamber Music,” a 2013 documentary. “But that day, I thought, ‘You know, music is very interesting.’”

At 18, the young Mann took up a scholarship at the Institute of Musical Art, a forerunner of the Juilliard School, in New York. The next year, he transferred to the Juilliard Graduate School (likewise a forebear of today’s Juilliard School). There, he studied composition with Stefan Wolpe and violin with Édouard Dethier, a passionate lover of chamber music.

In 1941, Mann won the violin competition of the Naumburg Foundation, which carried as its prize a debut recital at Town Hall in New York. As things fell out, the recital could scarcely have been booked for a more inopportune date: Dec. 9, 1941, two days after the Japanese attack on Pearl Harbor.

“Just before the concert the city’s emergency alarm went off,” Mann told The New York Post in 2001. Concertgoers fled, he said, “but we still drew about half the hall.”

The critics stayed, and commended the debut.

In 1946, after Army service, Mann joined the Juilliard faculty. At the time, the country had few homegrown quartets of stature. American concertgoers were inclined to prefer the sonic grandeur of symphony orchestras; the handful of quartets booked regularly in United States concert halls tended to be imports like the Budapest String Quartet.

By this time, Mann had resolved to abandon his solo career and devote himself to chamber music.

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“I could not conceive of myself playing those old chestnuts and getting pleasure from them again and again,” he told The Times in 1981. “I had not been a wunderkind. I could not play Paganini before I could read Shakespeare and I wasn’t interested in developing a virtuoso technique. The virtuoso looks for two things: those vehicles that allow him or her to display absolute wizardry on the instrument, and capturing that psychology of communication that knocks an audience dead.”

He added, “Those things were not as meaningful to me as the social phenomenon of making music among equals and the fact that, in chamber music, the composer was not interested in knocking anybody dead but in giving expression to his most subtle and complicated thoughts.”

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And so Mann began to dream of creating a resident quartet at Juilliard, American to its core, whose members would both perform and teach. Providentially, the composer William Schuman, who had become Juilliard’s president in 1945, was dreaming the same thing.

Schuman appointed Mann first violinist and deputized him to select the remaining players.

“He said, ‘Is yours going to be the best quartet in the world?’” Mann recalled on “CBS Sunday Morning” in 1996.

“I can’t guarantee that,” Mann said he replied, “but I can guarantee it will be one of the best.”

The Juilliard String Quartet made its formal debut at Town Hall on Dec. 23, 1947, in a program of Haydn, Beethoven and Alban Berg.

Reviewing the concert, The Times called it “a debut of unusual distinction,” going on to praise the group’s “ensemble playing of the highest order.”

In the quartet’s early years, however, its bookings were so scarce, and its coffers so correspondingly shallow, that when it traveled out of town by train, the players slept sitting up in coach to avoid paying for berths in the Pullman car.

Its fortunes had changed considerably by the 1960s, when Schuman conceived the Chamber Music Society of Lincoln Center and asked Mann to be its inaugural director. Already laden with quartet engagements, he declined.

Over the years, the Juilliard’s muscular style ran afoul of some critics.

“We didn’t want to have smooth chamber music,” Mann replied, in a 1997 interview with The Los Angeles Times. “If Bartok wrote ‘ruvido’ — ‘rough’ — we wanted to sound ruvido.”

But far more often the quartet drew praise. The groundswell of interest in chamber music in late-20th-century America, it is widely agreed, is in no small part traceable to the Juilliard.

The group has also seeded the world with other distinguished quartets that it helped train, among them the Tokyo, Emerson, Concord, Brentano and LaSalle.

Mann occasionally slipped the quartet’s confines to play with others. In 1980, with pianist Emanuel Ax, he gave a highly regarded series of performances of the complete Beethoven sonatas at the 92nd Street Y in New York. With pianist Stephen Hough, he recorded the sonatas of Beethoven and Brahms.

Mann played his last concert with the Juilliard, a Beethoven program at Tanglewood, on July 2, 1997. He was succeeded by the quartet’s second violinist, Joel Smirnoff; Smirnoff’s old chair was filled by Ronald Copes.

Today, the Juilliard String Quartet comprises first violinist Joseph Lin, second violinist Copes, violist Roger Tapping and cellist Astrid Schween.

Mann is survived by his wife, Lucy Rowan Mann; a son, Nicholas, a violinist on the Manhattan School of Music and Juilliard faculties; a daughter, Lisa Mann Marotta; a sister, Rosalind Mann Koff, a pianist who married the Juilliard Quartet’s original second violinist; and five grandchildren. Mann’s younger brother, Alfred E. Mann, a well-known scientist, industrialist and philanthropist, died in 2016.

As a composer, Mann was known for his Fantasy for Orchestra, given its premiere in 1957 by the New York Philharmonic under Dimitri Mitropoulos. He was also known for his settings of Hans Christian Andersen fairy tales for chamber ensemble and narrator.

As a teacher, he was not one to mince words. “You call that an accent,” he might say. “I call it dropping a pile of rocks on the downbeat.”

But his comments were leavened by his puckish sense of humor, a virtue that also helped ease the rigors of touring.

On one occasion in the 1960s, for instance, an airline barred Mann from bringing his Stradivarius aboard as carry-on luggage. Capitulating, he bought a seat for the instrument and belted it in.

At mealtime, Mann tucked a napkin under the seat belt and insisted that the flight attendant serve Stradivari his dinner.

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