There tend to be two different eras when discussing the classic Metallica period. Although the thrash metal legends had been known as one of the most in-demand acts of the underground scene, they didn’t truly hit their commercial peak until they released The Black Album, working alongside producer Bob Rock. While Rock knew precisely how to get the most out of every band member during the sessions, he considered one of their earlier albums a complete disaster.

Then again, most of Metallica’s early albums were never meant to have a pristine recording value. Even in the band’s early days, they had complained about using any kind of reverb on their songs, thinking that it would make them sound like they were playing from far away rather than their in-your-face approach.

Once they got used to their studio surroundings, though, the band started to understand what made a great record sound incredible, eventually incorporating subtle touches like the single piano note at the beginning of ‘Welcome Home (Sanitarium)’ or bassist Cliff Burton using various echoing effects at the beginning of the song ‘Damage Inc’.

While the band had a bonafide metal classic on their hands with Master of Puppets, it would prove to be bittersweet when Burton was killed in a bus accident while on tour. As the group licked their wounds and returned home to California, the hunt was on for a new bass player so they could make up the dates they had missed.

Drafting in a new member of the Metallica family would not be easy, with the band auditioning legends like Les Claypool from Primus before landing on Jason Newsted from the band Flotsam and Jetsam. Although Newsted was ready to show his skills on the following record, And Justice For All, the band wouldn’t be so kind, turning down his bass in the mix where it can barely be heard.

While the songs may have benefited from that signature dry sound and James Hetfield’s fantastic guitar tone, Rock was less than impressed when listening to the album for the first time. Before he got the call to produce the band for their next record, Rock had no qualms about airing his opinion on what they had just released.

During an interview with Gibson, Rock recalled how lacklustre the album sounded compared to what the band could do live, saying, “I listened to the record, and there was just no bottom end. I’m going, ‘OK… This is kind of interesting…. [Later] I went to see The Cult, and I stayed for Metallica, and what I saw in Metallica was not the sound of Justice. I heard this big band that had weight and size. The record didn’t make sense to me. And I know it’s a standard for a lot of people, but I’m just being honest here”.

Looking to turn the band into a sonic juggernaut, Rock refined the band’s sound in the studio, helping them turn songs like ‘The Unforgiven’ and ‘Enter Sandman’ into sweeping epics while also letting the bottom end shine on tracks like ‘Wherever I May Roam’. Rock may have gotten the tag for helping produce the band’s first mainstream album, but if not for his sense of direction, there’s a good chance that Metallica’s next project would have spelt the end of their career.