Malcolm Young AC/DC had moved to Melbourne. In early 1977 they returned to Britain and began a European tour with Black Sabbath. While Bon Scott and Ozzy Osbourne quickly became friends, relations were less than cordial between the other members of the respective bands. In one incident, Geezer Butler pulled a knife on Malcolm Young. Towards the end of 1977, bassist Mark Evans was fired; purportedly to find someone who could sing backup vocals. Evans described disagreement with Angus and Malcolm as a contributing factor. He was replaced by Cliff Williams. In 1988, Young missed the majority of AC/DC's Blow Up Your
Angus Young he would begin using in 1977, was also used as a compressor and a booster in his signal to "fatten up" his tone. Ever since adding it to his rig, it was used on several albums in the studio for chosen rhythm guitar tracks and all lead guitar tracks. Beginning with "Rock or Bust", due to the discontinuation of the Schaffer system, Young began using a replica of the unit's preamp with a commercial wireless unit. Contrary to popular belief, Angus and Malcolm have both stated in guitar enthusiast magazine interviews that very little pre-gain, if any, is used on