Most bands/singers pre-1990's don't own the rights to their music, I think since the raise of internet and the whole dyi concept more acts own the rights to their music. I do know that one of the biggest bands Metallica owns the rights to their catalog.
The Original 7ven (previously known as The Time) is the result of a clause in Prince's contract at the time with Warner Bros. http://en.wikipedia.org/wiki/The_Original_7ven