No one will ever accuse Billy Corgan, the Smashing Pumpkins' lead singer, guitarist, songwriter, keyboard player, arranger, auteur, and probably studio-floor sweeper, of thinking small. In the world of alternative rock, where magnitude of any kind (be it production values or popularity) is viewed warily, Corgan wants the world and wants it now. Five years ago, the Pumpkins signed with an independent label to establish their hipster credibility; once that was accomplished, they quickly leaped to a major. (And they say journalists are cynical.) Siamese Dream, their sleeper 1993 sophomore album, retained the wayward melodies and emotional distance of the genre, but bundled them in fussily produced sonics a world removed from standard grunge.
Naturally, Corgan did not take the task of following up Siamese Dream lightly. By the time he and his three band mates switched off the studio control board after 10 months of work, they had recorded enough material for several albums. And instead of whittling it down, they've released it all a two-CD set spanning more than two hours. (Guns N' Roses and Bruce Springsteen took the same route, but released their double discs separately.) For extra weightiness, Corgan has saddled it with a groaner of a title that would humble old-school progressive rockers: Mellon Collie and the Infinite Sadness (Virgin). The separate discs even have Yes-style subtitles ''Dawn to Dusk'' and ''Twilight to Starlight.'' Who would have imagined the anti-pomp world of alterna-rock would someday upchuck something like this?
Mellon Collie, though, is the furthest thing from a compendium of indie-rock cliches. A sprawling sonic carpet that never stops unfurling, its 28 songs careen from ravaged, apocalypse-now metal assaults to glucose-coated ballads. Corgan has stripped away the lacquered sheen of Siamese Dream and replaced it with wild-eyed eclecticism that works, once you get a handle on it. ''Tonight, Tonight'' is whipped into a frenzy by hurricane-like strings; the burbling, nine-minute ''Porcelina of the Vast Oceans'' conjures up an underwater playground it's the closest the Pumpkins have come to becoming Yes. And that's not to mention the forlorn piano instrumental, the haunted-house romp of ''We Only Come Out at Night,'' or the campfire lullaby that brings the album to a gentle close.
Mellon Collie is occasionally belabored, but never fatally so. In a typical example of overthink, ''Cupid De Locke'' piles on a shimmery harp, a spoken-word reading, and strings. (Also, no rock song should ever use the words hath and ye.) Their hard rock still sounds a little too fastidious, too marshmallow-gooey, to scare anyone. But the two discs are, at the very least, inordinately diverse and entertaining. The music has such vivid hills and valleys that you never know where it's going next, and that's part of the fun of absorbing it.