Growing up in St. Louis, he studied music composition and theory. After moving to New York, Nelson worked as the house engineer in Harlem’s Apollo Theater. He began his recording career in 1959, his breakthrough being “The Blues And The Abstract Truth” (1961) that led to him working as an arranger on large ensemble artists for many important jazz artists of that era. After moving to Los Angeles in 1967, he became a successful film and television composer. Nelson died of a heart attack at age 43.