During 1967 and 1968, the Bee Gees became an international phenomenon with three albums and many more singles of folky balladry, most of them smashes. That stopped when their lavish 1969 double LP, Odessa, produced zero hits; guitarist Vince Melouney left, and Robin Gibb temporarily followed suit. The stereo and mono mixes included in the three-disc reissue of this disruptive opus present the Gibb brothers’ arrangements at their most opulent: The string-laden instrumentals and soulful baroque pop evoke the splendor of the Moody Blues. And a third disc with demos suggests the unpolished sprawl of the Beatles’ White Album. Stripped of window dressing, baubles like “Melody Fair” prove the Gibbs’ effusive melodies and aching harmonies are ends in themselves.