Spectrum released their debut studio album, "Spectrum Part One", in March 1971, although it did not include the hit single. Rudd had refused to add it as "It didn't fit with the innovative roaming style of the rest of the music." The album reached No. 10 in April. Kennedy had left in August of the previous year just after it was recorded, he had "lost patience" as the group "struggled for gigs (promoters found them 'too progressive')." He was replaced on drums and vocals by Ray Arnott (ex-Chelsea Set, Cam-Pact, Company Caine). Rudd praised Kennedy's musicianship: "Mark really carried us through the first year because people would say 'Wow, look at that drummer, they must be a good group'... He used to play things like drum solos!, but he was very good. By the same token, I was almost relieved to get away from that 'cause the emphasis swung back to the material and the band in general rather than one player." Kennedy later worked with Leo de Castro, Ayers Rock and then Marcia Hines.