Into the miraculous recording booth Big Dave McLEan and a steel-bodied guitar crammed. Two minutes and seven seconds later, "Pet Rabbit" popped out. Yet in that flash, the 1947 low-fi Voice-O-Graph----the closest thing this world has to a genuine time machine----stripped away decades, intentionally leaving behind a rumpled vestige of the 78-rpm era.  Or so the severely-backdated result sounds: Confirmation that Big Dave could've hung with Charley Patton as easily as with Johnny Shines. However, Better The Devil You Know 's 12 preceding rootsy rambles have not been pre-aged. Veteran producer Steve Dawson sees to it that McLean's bottleneck remains sharp; that his harmonica flickers in the present. Plus, aside from a band rustically equipped from fiddle to saloon piano, Dawson is always there himself to intensify the mood with just the right sort of string lick: the stroke of mandolin, a banjo's dead plunk, or, of course, every voicing of slide guitar. But McLean's commanding presence already fills the room with a boom that rumbles about love, homicide, and roadside specters. "Angeline" points the accusatory finger for Blind Willie Johnson's death. "Deep Down in Florida" is one of two nods to Muddy Waters, who counted the Canadian among his personal friends in the 1980's. (Having written "Muddy for President" certainly helped.) Yet the 65-year-old's throat doesn't always grind rock into gravel with big, bold gestures. Behind a sunny sing-along delivery, "Swingin' On Heaven's Gate" sweetly toys with its seriousness of purpose.