Once signed to EMI's progressive imprint Harvest Records, Spectrum went into the studio to make their first official recordings under producer Howard Gable, who had worked with The Masters Apprentices. They had a #1 Australian hit with their first single, "I'll Be Gone", which has become one of the most enduring Australian rock songs of that era. The B-side, "Launching Place Part Two" was written to promote a music festival. They released their debut LP "Spectrum Part One" in March 1971 but Rudd would not allow their hit single to appear on the album. Drummer Kennedy left just after it was recorded and was replaced by Ray Arnott (ex-Cam-Pact, Company Caine).