Gene Pitney was midway through his British tour and had shown no signs of being unwell.
Mark Howes of Gene Pitney's management company In Touch Music said his tour manager, who had been a friend of the singer's for over 30 years, found him dead in his bed. He added that everyone had been shocked by the death and there had been no signs that Pitney was ill.
"He did a good show last night at St David's Hall and it was wonderful," Howes said.
"I've seen him quite a few times on this tour and he was fit and well. He said it was the best tour he had done for quite a few years," he added.
Gene Pitney had continually toured for last 40 years and he received a standing ovation at what was to be his final gig in Cardiff on Tuesday night.
Pitney's songs have been recorded by some of the world's biggest stars, including Rick Nelson and Roy Orbison.
Gene Pitney is survived by wife Lynne and three sons who live in his native Connecticut.
