While not everyone is eager to return to their awkward youth, Cassius is obviously nostalgic for their long-gone teenage days. But whether this translates into good music on their new album — “15 Again” — is less clear.

“15 Again” is Cassius’ third album. Philippe Cerboneschi (alias Zdar) and Hubert Blanc-Francard (alias Boom Bass) worked as producers for a number of French artists — MC Solaar, Daft Punk and Cut Copy among them — before putting these projects aside to create their own house-music duo in 1999. These two dance-floor deities have clearly mastered the art of fine-tuning beats and rhythms but, stupidly enough, put their own talent aside on “15 Again” to make room for vocal collaborations which only falter, fizzle and fail entirely.

Cassius’ Web site (in French for the first half, English for the second) cites a range of American pop-music influences for their third album. Marvin Gaye, Britney Spears, Outkast, Prince: It’s an all-star line-up taken from 20th century airwaves. Pharrell Williams makes an appearance on “15 Again”; he wrote, produced and sang on the track “Eye Water.” This is the collaboration and influence Cassius is most proud of. But in a way, it exemplifies the entire first half of the album — it’s got star power, sure, but is disjointed, awkward and painful to listen to. Seriously. “Fear eye water / clear eye water / real eye water” in screeching tones over tacky electric crescendos does not a good song make.

The first six songs (Pharrell’s among them) have something in common: They borrow liberally from a range of genres and fail spectacularly in attempts to meld these genres into cohesive tracks. Cassius loves the ’80s and wears this love on its album sleeve. The title of the album is a reference to Zdar’s and Boom Bass’ ages 20 years ago — they were teens when synthesizers and cheesy hooks were the norm. These nods to nostalgia are not used with any degree of creativity or innovation, though; the tracks are formulaic and fall back on juxtaposing fast and slow beats and male and female vocals to feign complexity.

A noticeable shift arrives seven songs in — “See Me Now” is driven by a mellower, funkier beat which is a successful mix of ’70s influence and modern production. The low-key, smoky and sauntering vocals on “A Mile From Here” echo this effect: This is clearly the nod to Marvin Gaye. We have finally moved away from Pharrell shouting about depleted ozone layers and “Christians Muslims Jews” killing each other and on to more sophisticated and tightly crafted pieces. But the song “Jackrock” is when the album really comes into its own: Here is a track that is unabashedly house and blessedly free from any overwrought American references. The lyrics, simple to begin with (“rock / jack jack to the beat”), disappear almost entirely from the song and let the infectious beat lead the way for nine and a half minutes.

If the first half of “15 Again” fetishizes American culture, the last three songs pay a stylish homage to the European club landscape. The end of the album could be a record of its own; the songs are so radically different (and significantly better) that it’s hard to imagine Zdar and Boom Bass as the same duo behind both crap like “All I Want” and standouts like “La Notte.” There is certainly a market for the last three songs — hip kids in Paris and Ibiza have probably latched on to these trance-inducing rhythms and elegant transitions. But there shouldn’t be a market for the weird, spastic beginning songs anywhere. Not even in America. Not even on MySpace.

Unfortunately, Cassius caters to the MySpace generation in portions of “15 Again.” Their liner notes contain forced witticisms (lyrics spell out the second person as both “you” and “u”; they say to “all english speaking people and teachers, sorry for our grammatical mistakes”), which are European in aesthetic but American in content. Spelling you as “u” and feeling obliged to create songs in English? It’s disheartening to see such shining talents saddle themselves with the painful task of incorporating crappy culture from the other side of the Atlantic. This is what drags Cassius and “15 Again” down from a lofty position among the Gods of Techno.

Zdar and Boom Bass have what it takes to lay down successful beats and keep a synthesizer churning out long, wonderful loops of music. They are legends in their world and have worked with enough big-name talent to claim the right to put out their own albums as the duo Cassius. But they need to learn that repackaging electronica as a pop song isn’t going to make for a listenable track or a receptive audience. An overdose of self-awareness doesn’t do good for music best suited to the unconscious, ambient European house scene. Cassius can go ahead and pretend like they are 15 again in their world of dance music — they just need to avoid pretending to be 15 now in a world of Americanized pop culture.