To describe the recording process for Def Leppard's 1983 powerhouse album,, as a labor of love would be an understatement.

When you've done so many takes that the tape is falling apart, it's best described as a labor of hate.

But for the man behind the board on that amazing record, producer Robert John "Mutt" Lange, it's all par for the course as he set out to make an album the likes of which had never been heard before.

Mutt Lange is a perfectionist who knows what he wants a band to sound like, and basically stops at nothing until he gets it. And even though the members of Def Leppard (drummer Rick Allen, guitarists Steve Clark and Pete Willis, singer Joe Elliott and bassist Rick Savage) had all worked with Lange previously on the fantastic High N Dry record, they'd never been through the ringer like they did working on Pyromania from January-November 1982.

Just ask Leppard frontman Joe Elliott, who endured take after take - for months on end - to lay down the vocals for Pyromania.

"He's saying 'look, you can do it better'," recalled Elliott, who actually took vocal lessons from Lange's ex-wife at the time. "All you're wanting to do is go 'no, I bloody well can't. This is as good as it gets'. And (Lange) says 'Well it ain't good enough then'."

And those excessive vocal takes are the tip of the iceberg as Lange added layer upon layer of guitar, drums, bass and background vocals. In fact the recording tape had actually begun to break down by the time the album was ready for final mixes.

"It became clear from the intensity of working on a record like that, going over and over and over, blocking out backgrounds, changing arrangements, and all that. I'm surprised we ever got it finished, because the tape literally fell to pieces," said the late Mike Shipley, who engineered the record.

There were so many overdubs, so much rewinding of tape, that the oxide started coming off the tape to the point where Lange could actually see through it. In the end, all that rewinding meant a major loss of high end in the final mixes.

Leppard Loses a Member

The intense recording process certainly took a toll on the band as guitarist Pete Willis was fired in July after he showed up in the studio severely hung over from partying the previous night. Leppard were working on the "Stagefright" solo and he simply couldn't play guitar that day, so Lange told him to go home and dry out. He was fired shortly thereafter and Phil Collen was quickly recruited as Willis' replacement.

Willis still left a big mark on the record, though. He played rhythm guitar on all 10 tracks (and helped co-write "Photograph", "Too Late for Love" "Comin' Under Fire" and "Billy's Got a Gun").

It was a tough process for drummer Rick Allen as well, who was ostensibly replaced by a Fairlight instrument sampler (drum machine). The only thing Allen actually played on Pyromania were the cymbals.

In terms of the songs themselves, the band went into the studio with only a bunch of riffs. The idea was to work directly with Lange to put the songs together, and the band ended up giving him songwriting credit on every track.

Two old Leppard song ideas resurfaced on the album. The first was the main riff and intro section of "Rock! Rock! (Till You Drop)" which were taken from the 1980 track "Medicine Man' – a song they performed live during much of the 1980 'On Through The Night' tour. The second was "Too Late For Love" which was a reworking of the live song "This Ship Sails Tonight" which the band had debuted on the December 1980 club tour of England. Die Hard The Hunter's main riff was written in 1980 during the band's debut US tour.

When working on "Rock of Ages", the song didn't have any lyrics, so Elliott would just hum along with the riff. But then the band let a choir use the studio and Elliott found a hymn book they'd left behind on an organ. It was opened to the old hymn "Rock of Ages", so Elliott tried that as the chorus and Lange loved it.

All the pain Def Leppard endured was well worth it in the end. Pyromania, released on January 20, 1983, would reach No.2 on the Billboard charts and No. 4 in Canada. Heck, if it wasn't for an album called Thriller by an artist named Michael Jackson, Pyromania would have gone to No. 1 in the US. It set the standard for mainstream metal in the 1980s and has now sold more than 10 million copies.

Read about how important guitarist Steve Clark was to Def Leppard before his untimely death