Conversation so far:
When did Modern Sounds in Country and Western Music start recording?
The first two sessions were set on February 5 and 7 at Capitol Studios in New York.
When were the later sessions?
February 15 of that same year at United Recording Studios in Hollywood.
Why did he change studios?
CANNOTANSWER.
Who did he work with on the recording?
Charles enlisted premier jazz arrangers Gerald Wilson and Gil Fuller.

Question: Who produced it?
Self-contained rewrite: Who produced "Modern Sounds of the Country and Western Music?"