By 1975 Cohen began working as a sound engineer under the guidance of Roger Savage. In April of the following year he was working as an assistant record producer, alongside Molly Meldrum, on Perth's glam rock group, Supernaut's lead single, "I Like It Both Ways" (May 1976). Cohen produced the group's associated self-titled album, which appeared in November of that year, and its follow-up single, "Too Hot to Touch" (September). In July 1976 Cohen and fellow engineer, Ian MacKenzie, met with Meldrum to organise the production of pop group, the Ferrets' debut album, Dreams of a Love: "It was all a bit of Elton John, a bit of the 'Real Thing', [Meldrum] called us in for a production meeting 9:00 in the morning at his place and he was still in bed [...] and putting the music on [...] very, very loud and then proceeds to shout at you over the top of it, and we were all sitting there sort of terrified thinking, what on earth is he saying?" After a year production was still incomplete so the Ferrets took over, together with Cohen and MacKenzie assisting. It was finalised in August 1977 and released in October with Meldrum credited as Willie Everfinish. In June 1978 Cohen started working with the Boys Next Door (later renamed the Birthday Party), as engineer at Richmond Recorders on their debut album, Door, Door (1979). He then engineered the Birthday Party's early extended play, Hee Haw (December 1979). Next he was the engineer and producer, on their second album, The Birthday Party (November 1980). He was engineer and producer for their third album, Junkyard (May 1982), which was listed in the book, 100 Best Australian Albums at number 17. Cohen told the authors that he was directed, "Forget all the bottom end and the rich, lush sounds. Make it sound like trash." He continued as engineer and/or producer for the group's leader, Nick Cave, in the related group, Nick Cave and the Bad Seeds. From From Her to Eternity (18 June 1984) to No More Shall We Part (2 April 2001). Cohen followed the group to London in mid-1986 and then on to Berlin in January 1987 to continue to work with Cave. He returned to Melbourne in January 1988 with his drug habit "spiraling out of control." Cohen reflected on his early work with Cave, in an interview with Richard Fidler in