The Tennessee-based VW Boys -- bluegrass veterans Tim White, Dave Vaught and Albert Blackburn -- are joined on Retroactive by various musicians whom fans of the genre will recognize. If not quite a novelty album, Retrospective feels cheerfully eccentric, or at least atypical, on multiple levels. Not the least is its open-throated, extroverted singing and vocal harmonies.

"Earl's Breakdown," "Brown Mountain Light" and "Keep on the Sunny Side" are familiar tunes -- one might even say groaners -- but till now I hadn't heard a bluegrass version of Jimmy Driftwood's "Battle of New Orleans" (for those with long memories, a megahit for Johnny Horton in 1959). Not at least that I can recall; if there is another, it's an obscure one. Even so, the traditional melody on which it's based -- the fiddle tune "Eighth of January," celebrating Andrew Jackson's victory on that date in 1815 -- shows up now and then.

I don't know why the presence of "Battle" should seem more noteworthy to me more than the appearance of the Everly Brothers' "All I Have to Do is Dream" or the Beatles' "I Feel Fine." Possibly it's because pop songs like these are hardly unheard on bluegrass stages. While "Dream" as a song appeals to me more than does "Fine," the latter translates with less effort into bluegrass treatment. "Dream" (by the late Boudleaux Bryant, who furnished Don and Phil with many of their most commercially successful songs) is, let's face it, kind of dumb -- it rhymes "is" and "gee whiz," after all -- but the Everlys' delicate, nearly androgynous harmonies cause "Dream" to transcend its limitations and long ago turned it into a country-pop evergreen.

The one excruciating misfire, though, is "Ugly Girl Blues," which is pretty much as advertised. It's a traditional song, apparently of Caribbean origin, and a variant of it under another title was a radio hit in the mid-1960s. It's supposed to be funny. It isn't. One need not be a fetishist about such things to think of it as sexist or at least, owing to its cruel premise, cringe-inducing. If lookism ever gains traction, the VW Boys will surely have to head for their home state's highest hills.

That aside, Retroactive is likable enough. As sunny-natured as bluegrass -- often deeply gloomy stuff -- comes, it takes an approach at once showy (one suspects the boys do a lot of playing for audiences not ordinarily attracted to the genre) and accomplished. With the above-noted exceptions, the songs are surprises of the pleasant sort. "Fire on the Mountain" is not the Appalachian tune but the Marshall Tucker Band rock warhorse, which feels fine decked out in bluegrass duds, as do the rockabilly "Hot Rod Lincoln" and the Western swing "Rag Mop." I'm sure the VW Boys, if as far as I know the first, won't be the last bluegrass outfit to pick up on "Wagon Wheel," from the neo-oldtimey Old Crow Medicine Show. This unlikely collaboration between OCMS's Ketch Secor and Bob Dylan rewrites an old folk-blues, "Rock Me, Mama," with maybe a hint of a Child ballad, "Oh the Wind & Rain."

What they lack in profundity, the VW Boys make up for in amiability and accessibility. If you're looking for something out of the ordinary in your bluegrass, Retroactive is certainly that.