At 8 p.m. on Friday, April 7, 1967, Tom Donahue cracked open the microphone in the KMPX studio at 50 Green Street in San Francisco, firing a figurative shot that would echo across the radio landscape forever. 120-126x300 Tom Donahue, immortalized in 1968 by the revered rock photographer Jim Marshall. Having left Top 40 KYA a year earlier, Donahue had spent the months in between searching for something different, something better. No longer interested in fitting into the tightly-formatted world of Top 40 — which was being rubber stamped across the country with the assistance of Bill Drake, who had worked with Donahue five years earlier at KYA — the gargantuan “Big Daddy” had taken to playing his favorite songs from rock albums for friends visiting his North Beach apartment, often playing cuts buried deep in those LPs, which had rendered them largely invisible to the radio programmers who sought out only the hits. Donahue (born Thomas Coman) had even gone so far as to call on his former employers at KYA, seeking an opportunity to try this new, seat-of-your-pants style of choosing what to play, but was initially turned down. He was, however, offered jobs at the Bay Area’s two dominant soul stations, KSOL/1450 and KDIA/1310, but chose to decline them rather than take a job from a deserving black announcer. Taking a friend’s advice to look at stations on the FM dial,...