Some of this can probably be chalked up to hip-hop's revolving-door approach to studiocraft: Eight different producers, each with an established sound, contributed to 3D, so if Lopes only shows up on a handful of tracks via work completed prior to her death and outtakes from her U.K.-only solo album, Supernova, it's not exactly like Paul, George and Ringo cobbling together new Beatles songs out of John's scratch vocals. (Oh, wait . . .) But that reality (and the persistence of long-running breakup rumors) overlooks the real chemistry TLC displayed during its decade as a group together, as the members matured from bravely dressed around-the-way girls to bravely dressed future-shock robo-babes, an infectious esprit de corps that's still palpable on 3D, even when Lopes isn't actually in the mix. More than that, though, there's an unexpected gravitas to the music here, a glimmer of sadness that acknowledges a loved one's absence in a way a hasty show at the Hollywood Bowl never could. These kids aren't all right, but they will be.