Conversation so far:
When did Rudy Van Gelder begin recording?
From 1946, Rudy Van Gelder recorded in his parents' house in Hackensack, New Jersey.
Who did Rudy Van Gelder work with during his early career?
In the 1950s, Rudy Van Gelder performed engineering and mastering for the classical label Vox Records.
How did Rudy Van Gelder become interested in music?
Rudy Van Gelder's interest in microphones and electronics can be traced to a youthful enthusiasm for amateur radio. He was also a longtime jazz fan.
What else is interesting about Rudy Van Gelder's early career in addition to when he began recording and who he worked with?
Rudy Van Gelder became a full-time recording engineer in 1959.

Question: What labels did he work for?
Self-contained rewrite: What labels did Rudy Van Gelder work for?