Rachelle Spector said the note was given to her husband by a corrections officer at Corcoran State Prison, KTLA-TV, Los Angeles, reported.
"A guard brought Philip a note from Manson, who said he wanted him to come over," she said. "He said he considers Philip the greatest producer who ever lived. It was creepy. Philip didn't respond."
Manson and members of his "family" were convicted of several 1969 murders, including that of Sharon Tate, the pregnant wife of director Roman Polanski. At the time, Manson, who had ambitions to be a rock star, lived with his followers on a ranch that had been used as a film set.
Spector, 68, was sentenced to 15 years to life for killing Lana Clarkson, a B-movie actress.
Hal Lifson, Spector's publicist, said his client was "alarmed and scared" by the note.
"Phil mentioned that he used to get phone calls from John Lennon and Tina Turner and now it's Charles Manson calling, so he said, 'Go figure,' " Lifson told KTLA.
A prison spokeswoman said the note may have been a prank.