Five albums into their career, Roxy Music finally nailed it. Not that their records leading up to Siren were short on inspiration, creativity and excellence. Indeed, they were one of the era's most innovative and exciting groups, merging art-rock aesthetics with a sort of winking soft-pop overbite.

But Siren, which was released in October 1975, was something different for the London-based sextet: an album of nervy art-rock swathed in what would be the start of the lush landscapes that would dominate their later work. Self-aware, clever and maybe a bit too arch for its own good at times, Siren is the sound of a band claiming a faraway corner of mid-'70s music as its very own.

On earlier albums like For Your Pleasure, Stranded and Country Life, Roxy Music developed a reputation as one of rock's most adventurous groups, with Brian Eno's oddball synth squalls colliding with Bryan Ferry's hotel-lounge-ready vocals. Eno was gone by the time of Siren, which gave Ferry even more room to play the oily crooner.

But that winking persona gives way to something more romantic, and even more genuine, on Siren. It's there in the tracks "Sentimental Fool" and "Nightingale," covered in sheets of artsy adornment, and it's there in the opening "Love Is a Drug," the band's first U.S. chart hit. Ferry lets down his guard, relatively speaking, here, giving the emotionally detached robot of past Roxy Music albums a heart for once. Though that may be part of the act too.

It doesn't really matter. Roxy Music were never stronger or more focused than they are on Siren. They recorded it in London during the summer of 1975, seven months after Country Life was released as their fourth album in a brief two-and-a-half-year period. And unlike those earlier records, which seemed to force the band's nutcase appeal at times (during Eno's two-album stay, for instance, synthesizer bombs would fall out of nowhere, often taking entire songs out of their grooves), Siren stays on course, leaving few gaping holes in the arrangements.

It wasn't necessarily a breakthrough moment for the group in its native U.K., where the album made it to No. 4 -- Stranded had hit No. 1 there in 1973, and predecessor Country Life reached No. 3. And in the U.S., Country Life climbed to No. 37 while Siren stopped at No. 50. But thanks to "Love Is the Drug," Roxy Music were reaching a whole new batch of fans. The song made it to No. 2 in the U.K., their highest showing at that point. In the U.S., it made it to No. 30, their only Top 40 appearance.

But on another level, Siren was a breakthrough moment. Freed from some of their past shackles (at least the ones that kept them from reaching a wider audience, particularly those music fans who might have been frightened away by some of their earlier, more experimental material), Roxy Music steered their art-rock into a brave new territory, one that infused some warmth into their inherent coolness. After this, they never looked back.

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