Chilton died at a hospital in New Orleans after experiencing what appeared to be heart problems, said his longtime friend John Fry. Fry said Chilton's wife, Laura, was very distressed by the unexpected death.
"Alex was an amazingly talented person, not just as a musician and vocalist and a songwriter, but he was intelligent and well read and interested in a wide number of music genres," said Fry, the owner of Memphis-based Ardent Studios.
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As the teenage singer for the pop-soul outfit the Box Tops, Chilton topped the charts with the band's song "The Letter" in 1967. Their other hits were "Soul Deep" and "Cry Like a Baby." Chilton grew up in Memphis, Tenn., and formed the band with friends from school.
His short run with Big Star brought less mainstream success but made him a cult hero to other rock musicians, as evidenced by the title of the 1987 Replacements song, "Alex Chilton." Big Star's three 1970s albums all earned spots on Rolling Stone magazine's list of the 500 greatest.
Chilton said in a 1987 interview with The Associated Press that he didn't mind flying under the radar with Big Star and later as a solo artist.
"What would be ideal would be to make a ton of money and have nobody know about you," he said. "Fame has a lot of baggage to carry around. I wouldn't want to be like Bruce Springsteen. I don't need that much money and wouldn't want to have 20 bodyguards following me."
"If I did become really popular, the critics probably wouldn't like me all that much," he said. "They like to root for the underdog."
Chilton had been scheduled to perform with Big Star on Saturday at the South by Southwest music festival in Austin, Texas.
"Alex Chilton always messed with your head, charming and amazing you while doing so. His gift for melody was second to none, yet he frequently seemed in disdain of that gift," the festival's creative director, Brent Gulke, said in an e-mail.