 Hetfield and Ulrich fired Mustaine on the morning of April 11 , after a gig in New York , because of his drug and alcohol problems , overly aggressive behavior , and clashes with bandmates . On Whitaker 's recommendation , Metallica recruited Kirk Hammett , who played in Exodus and was a one @-@ time student of Joe Satriani . Hammett learned the songs on his flight to New York , and started recording the album with Metallica barely a month later . Metallica met producer Paul Curcio at Music America studios in Rochester , New York , and recorded the album in two weeks . Unable to afford a hotel during the recording sessions , the band members lived in people 's houses in Rochester and at the Music Factory in Jamaica , Queens , where Anthrax held rehearsals . Curcio had set the studio equipment as if he were recording an ordinary rock band . He thought the initial tapes sounded very distorted and tried to compensate by turning down the knobs . Metallica resented Curcio 's involvement because he seemed uninterested and had little impact on the sound . Although Zazula wanted Hammett to replicate Mustaine 's solos , Hammett 's guitar solos on the album were partially based on Mustaine 's original solos , with the first four bars of most solos written by Mustaine before his departure . Despite their differences , Mustaine 's contributions to the early years of Metallica were still acknowledged and he received four co @-@ writing credits on Kill ' Em All . Zazula was not satisfied with the initial mix because he thought the drums were too loud and the guitars were too low in the mix . The remix was done by sound engineer Chris Bubacz , according to Zazula 's instructions . 
