In early 1975, just a year after cementing their lineup with the addition of singer Bon Scott, AC/DC released their debut album, High Voltage. On Dec. 1, they delivered their second, T.N.T., and, as if their debut left any doubt, these boys meant business.

Both albums were initially released only in their native Australia. They would later be chopped up and combined to make up their U.S. and U.K. debut under the name High Voltage, but several tracks would remain unreleased in the U.S. for years.

Still, T.N.T. kicks off with an anthem for the ages, "It's a Long Way to the Top (If You Wanna Rock 'n' Roll)." From the signature pile-driving riff onward, this is the sound of a young and hungry band poised to take on the world. Loud guitars? Check! Nasty vocals? Check! Kick-ass rhythm section? Check! Bagpipes? Huh?! Yes indeed, bagpipes made the cut and in many ways, make the song.

George Young, brother of Angus and Malcolm, producer and former member of the great Easybeats, was responsible for bringing bagpipes into a full-on rock assault. "He just said, there's a big break in there, can you play bagpipes?" recalled Bon Scott in an interview shortly after the album's release. "Why he thought of bagpipes, I'll never know. I'd played a bit of recorder before, so I played 'em."

Many songs that would later become AC/DC classics make up their sophomore LP, including "Rock and Roll Singer," "Live Wire" and the title cut. "The Jack," is another, with its mean and dirty blues groove all awash in double-entendre. It's the kind of raunchy blues that most who ride this rail can only dream of producing. "Her deuce was wild, but my ace was high," indeed. Meanwhile, "Rocker" is one of the most intense blasts of super charged rock and roll you are likely to ever come across. Clocking in at just under three minutes, it's like Status Quo on amphetamines, a pure blast of pure adrenaline.

"Can I Sit Next to You Girl?" was the band's debut single back in 1974, which featured the vocals of original singer Dave Evans. That version had a bit of glam swagger and stomp and, while fine in its own right, lacks the conviction and oomph of the revamped take on T.N.T. Scott's vocal is perfect for the tune and the whole band are more in command of the song. The album closes with a storming take on the Chuck Berry staple "School Days," which shows off one of the band's key influences. Faithful to the original while injecting it with their unmistakable style, they transform the song from '50's nostalgia to '70's urgency.

T.N.T. was a huge hit in Australia, checking into the charts there at No. 2. The revamped U.S. and U.K. release under the name High Voltage would be released the following April, helping to present the band to an international audience.

AC/DC were able to take the basic formula of rock 'n' roll, and turn it into something all their own -- something they have continued to do since day one. "We've always been a rock 'n' roll band," Angus profoundly stated back in 1975. "That's always what we played, and that's what we always want to keep playing, rock 'n' roll."

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