His daughter, Lisa Grossman of Babylon, gave the cause as kidney failure.
"He knew everybody, he worked with everybody," she said. "He was sort of a connective tissue among an incredibly broad and deep number of parts of the musical world."
Herbert Daniel Grossman was born Sept. 30, 1926, in New York City, and graduated in 1947 from Queens College. In 1951, he married the writer and opera translator Anne Chotzinoff, a niece of violinist Jascha Heifetz. Widowed in 2002, he later married former opera singer Sylvia B. Davis, who survives him, as does his younger brother, Ronald, of Florida.
With help from Grossman, Peter Herman Adler and Samuel Chotzinoff, Grossman's future father-in-law, persuaded NBC founder David Sarnoff to let them create the network's in-house opera company, which debuted in 1949. Grossman conducted numerous TV productions.
He assisted the legendary conductor Toscanini of the NBC Symphony Orchestra, who called Grossman "Young Maestro," said his daughter.
As music director, he was nominated for a 1965 Emmy award for Outstanding Individual Achievements in Entertainment, for the Hallmark Hall of Fame production of "The Fantasticks."
He went on to conduct for the New York City Opera, as well as operas in San Francisco; New Orleans; Baltimore; Pittsburgh; Munich, Germany, and elsewhere. In 1966, he founded San Francisco's Western Opera Theatre, and two years later became music director of the Babylon-based Orchestra da Camera of New York. He continued with that touring company through 1984, while serving as music director of the Great Neck Symphony from 1970 to 1985. He was a music director or choral arranger for six Broadway shows in the 1960s and 1970s.
There are no immediate plans for a memorial service.