I’m slightly confused by his “there were two guitarists already so I bought a bass” story
in The Unforgettable Fire, by Eamon dunphy it says that Adam was at boarding school and begged his parents to buy him a bass so he could play homemade “dirges” with a school friend
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Wikipedia has the story the same way I recall it from that book. See “early life” on his Wikipedia page - he got one at 14, so perhaps his memory is failing him