Since his promising debut with “Get Lifted” (2004) as a new kind of old-school soul man, singer and songwriter John Legend has been busy moving to the toothless center, content to churn out ever more generic and lightweight easy-listening fluff. Apparently, some time after performing “If You’re Out There” at the 2008 Democratic National Convention and watching Barack Obama move into the White House, he decided it was time to get heavy again, working with one of the best live bands in hip-hop or R&B, and covering a set of socially conscious protest songs from the ’60s and ’70s, with one new original (the disc-closing “Shine”) thrown in for good measure.

On his last two albums, “Once Again” (2006) and “Evolver” (2008), the problems were Legend’s increasingly featherweight material and uninspired productions. Yet while a number of the tracks here are associated with some of the all-time R&B greats — Nina Simone, Donny Hathaway, Harold Melvin and the Blue Notes, and Bill Withers among them — Legend manages to declaw these, too, over-emphasizing the more dated sunshine utopianism (especially in the cover of Hathaway’s “Little Ghetto Boy” and the reggae-inflected “Love the Way It Should Be”), playing light with other songs that call for the opposite approach (“Hang On In There” by Johnny Bristol), and generally coming off as much more Bobby McFerrin than Curtis Mayfield — by no means a good thing.

It doesn’t help that the Roots sound as if they’re phoning it in, showing no hint of the inspired intensity on their extraordinary recent release, “How I Got Over.” But it’s doubtful that even Questlove and company could have saved this soggy, self-important mess, or sparked a fire that Legend doesn’t seem capable of stoking.

John Legend and the Roots, “Wake Up!” (Columbia) Rating:1/4