I haven't heard it done quite this way before. Without either stale reiteration or radical revisionism, Sinner Friends -- a duo consisting of Grace van't Hof & Conner Vlietstra -- transport themselves into an earlier period in the history of America's vernacular music.

What they're doing is hillbilly duet music of a kind popular among rural Southerners in the early days of country music, or so it would be called eventually; "country" as a genre identification did not take hold until the middle of the last century. This kind of duet sound survives, though mostly in rural settings and on field recordings but definitely not on present-day commercial releases. So it's rather startling to encounter Bad News Gospel, so unexpectedly to me that when the disc started playing I first thought this was just an intro, that the sound would soon change character in a way that the occasional album starts retro and flips progressive soon enough. Hof & Vlietstra's thrilling, unvarnished harmonies are backed by their own banjos, guitar and mandolin and by assorted guest artists' accordion, lap steel, drums, piano and bass, spinning a cozy aural cocoon.

Make no mistake about it, this is a bunch of old songs, the likes of which usually get to our modern ears via oldtime string outfits, bluegrass bands and archival reissues. This is none of those. It's recently recorded, isn't done bluegrass style and isn't exactly the traditional Appalachian music oldtime bands preserved (and still preserve). Rather, most of the 12 cuts are heart songs and gospel numbers, most obscure even to someone who likes to think he knows old Southern tunes fairly well. Like me, say. In short, the Sinners know their stuff.

The closer and best-known is "Nearer, My Good, To Thee," which legend though not history asserts the Titanic orchestra played as that great ship went down. The secular numbers most probably recognizable, at least by informed listeners, are "Lord, I'm Free from the Chain Gang Now" (cut decades apart by both Jimmie Rodgers and Johnny Cash, if not among their most famous records) and "Signed, Sealed, & Delivered." The latter, a hit in 1948 for Cowboy Copas, feels uncannily like a 19th-century parlor ballad and in no way seems out of place. The Sinners' music-verse, incidentally, is wide enough to encompass a blues about lesbianism ("Mister Mary Blues").

Hof & Vlietstra, from Michigan and Tennessee respectively, have resumes in bluegrass and oldtime, not necessarily together in the same company, in Della Mae, Chris Jones & the Night Drivers, and Bill & the Belles. What they're doing with Sinner Friends is not what one would call a market category in the 21st century, but they do it in style, in a fashion that opens up the past and renders the present open to intriguing possibilities.