The Necks have developed a near-mythic status. For a quarter century, they’ve been building hour-long piano/drums/bass pieces that overflow with the tension of contrasts—beauty versus bedlam, melody versus discord, momentum versus inertia. Live, the Sydney trio do it off the cuff, shaping tiny themes with familiar tools into improvised monoliths. Though the Necks draft more concrete plans for their records, they wield that same sense of wonder when they’re composing. At their best, the group’s albums sound meticulous but feel extemporaneous, like synchronized exhalations from a group whose chemistry suggests rock’n’roll’s best songwriting tandems. Made by just three musicians of ostensibly modest avant-garde-scene means, the Necks’ sets and records possess the same gripping power as a sitcom or documentary that might have cost millions of dollars and dozens of people to craft. The largely acoustic answer to New Zealand’s electric the Dead C, the Necks make miracles of efficiency and magnetism.Vertigo is the Necks’ 18th album and second for the New York label Northern Spy, the group’s first stable American home. Like many of its predecessors, Vertigo runs as one uninterrupted track, with 44 minutes roughly split between two interwoven movements.