Complex sentence: In legend, Clarke was said to have been discovered while playing bongos on the beach by Byrds founder David Crosby, but in fact he was discovered by singer-songwriter Ivan Ulz and not "on the beach" but in San Francisco's North Beach.
Split into simpler sentences: In legend, Clarke was said to have been discovered by Byrds founder David Crosby while playing bongos on the beach, but in fact he was discovered by singer-songwriter Ivan Ulz. And, he was not discovered on the beach "per se", but in San Francisco's North Beach.