Robert Slack joined Pacific Symphony's percussion section in 1990, and became the principal percussionist in 1992. In addition to his work with Pacific Symphony, he has performed with the Los Angeles Philharmonic, the San Diego Symphony, the Long Beach Symphony, and in the orchestra of countless ballet companies and Broadway shows, including "Evita," "Fosse," and others. Previous to his position with Pacific Symphony, Slack held positions as timpanist with the Nassau Symphony on Long Island and Assistant Principal Timpanist/Percussionist with the Naples, Florida Philharmonic.

Slack received a Bachelor of Music Degree from the Curtis Institute of Music in Philadelphia, the nation's premier music conservatory. While at Curtis, Slack studied with Gerald Carlyss, principal timpanist of the Philadelphia Orchestra, and Michael Bookspan, principal percussionist of the Philadelphia Orchestra. Slack received an orchestral fellowship at the Tanglewood Music Center, summer home of the Boston Symphony Orchestra, in 1989. He also performed and studied with Roland Kohlof, former Principal Timpanist of the New York Philharmonic, at the Waterloo Festival in New Jersey. During high school, Slack attended the Juilliard School of Music Pre-College Division, and studied extensively with New York Philharmonic Principal Percussionist Christopher Lamb at the SUNY, Purchase.

Highly sought after as a teacher, Slack has had many of his students placed in major music conservatories and universities such as the Juilliard School, Indiana University, University of California, Los Angeles, the University of Southern California School of Music, and others. Several of his students have earned positions in professional orchestras. He has held teaching positions at Fullerton College, California State University, Fullerton, and Chapman University. Currently, Slack maintains a private teaching studio in Orange County.