There's no doubt which decade Goldfrapp would like to relive. From the dark disco of its 2006 album, "Supernature," to the sleepier, psychedelic strums of 2008's "Seventh Tree," fashionista frontwoman Alison Goldfrapp and producer Will Gregory are firmly ensconced in the turbulent '70s. On Goldfrapp's fourth full-length, "Head First," the act returns to poppier form while trying to channel ABBA. The song "Alive" sounds like a more muted "Waterloo," with a guitar punch on the verse and Goldfrapp harmonizing with herself, and the title track uses a grand piano vamp and a side-to-side melodic shuffle. Overall, however, the set is uneven. Basic songs like "Rocket" and "Believer" sound as if Goldfrapp is consciously trying to replicate the synch success of "Supernature" (from which every cut was licensed), while the more nuanced "Dreaming" and "Hunt" pile on the breathy, electronic drama of its most distinctive work. Lovely moments abound, but the overall effect is less intoxicating.