NSO Trombonist Milton Stevens

Milton Stevens taught extensively and enjoyed performing for children. (By Carol Pratt)

Milton Stevens, 64, the principal trombonist of the National Symphony Orchestra and a co-founder of the Washington Symphonic Brass chamber group, died July 30 of a heart ailment at a hotel in Denver, where he was attending a music conference. He had been hospitalized the previous week after a mild heart attack.

Dr. Stevens held the NSO's principal trombone chair for the past 29 years and was regarded as one of the finest orchestral trombonists in the world. Since 1993, he had been the music director and conductor of the Washington Symphonic Brass group, a 17-member ensemble that performs in Washington and Annapolis.

In addition to maintaining a crowded performing schedule, Dr. Stevens taught at Catholic University, had many private students and was an artist in residence at the University of Maryland. He directed clinics and master classes throughout the country and led seminars on musical intonation.

"Milt was one of the NSO's treasures," Music Director Leonard Slatkin said in an e-mail. "His unflagging enthusiasm and artistry will be sorely missed. Not only as a performer but in his role as a teacher, Milt made a lasting impression on all those he touched."

Dr. Stevens played most of the trombone solos in the NSO's symphonic repertoire and was occasionally featured with other orchestras. Whenever the NSO performed Modest Mussorgsky's "Pictures at an Exhibition," Dr. Stevens played the lumbering but haunting "Bydlo" theme on euphonium, which has the same tonal range as the trombone.

He toured the United States and Europe with the orchestra and often appeared in chamber concerts with its Brass Principals Quintet, Gabriel's Brass and other groups.

He was in Denver this week to perform and record with Summit Brass, a group of 16 of the country's leading brass instrumentalists.

At his audition for the National Symphony in 1978, he performed the long solo passage of Maurice Ravel's "Bolero" and was named principal trombonist by then-Music Director Mstislav Rostropovich.

Dr. Stevens, who was previously the principal trombonist of orchestras in Columbus, Ohio, and Denver, became one of the NSO's most respected members and a mentor to younger musicians.

"It was more than a job to him," said Dave Bragunier, who played tuba with the NSO for 43 years and was its personnel manager. "He was an expert coach for taking auditions. He knew exactly what was required to get through a symphony audition.

"He would do anything to help the National Symphony."

Milton Lewis Stevens Jr. was born in Great Barrington, Mass., and began playing trombone when he was 12. (He also played piano and clarinet.) He graduated from the music conservatory of Oberlin College in Ohio, received a master's degree in music from the University of Illinois in 1966 and a doctorate in music from Boston University in 1976. He did advanced work in Salzburg, Austria, where he also studied conducting.

Through the years, Dr. Stevens taught at dozens of trombone and brass workshops and was on the faculty of the Rafael Mendez Brass Institute in Denver. He gave master classes at many of the nation's foremost conservatories, including the Juilliard School of Music in New York, Eastman School of Music in Rochester, N.Y., Manhattan School of Music and his alma mater, Oberlin.

In 1999 and 2002, he was named principal trombonist of the Super World Orchestra, an international all-star symphony that has performed in Japan.

Dr. Stevens enjoyed presenting music to children and sometimes attached his trombone mouthpiece to a rubber hose with a funnel on the end. He and other brass musicians often delighted young audiences by opening concerts with the theme from "The Flintstones," performed on conch shells.

In Washington, he was a featured soloist with the Army and Navy bands. His chamber group, the Washington Symphonic Brass, has made four recordings, and its major-label debut, "Burana in Brass," will be released next month by Warner Classics. On Oct. 14, Slatkin will take Dr. Stevens's place on the podium when the Symphonic Brass appears at the Kennedy Center.

His first wife, Elizabeth M. Stevens, died in 1984.

Survivors include his wife of 21 years, Priscilla Stevens of Falls Church; two sisters; and one brother.