Like the Punch Brothers, Steep Canyon Rangers and other so-called newgrass groups, Hackensaw Boys tweak tradition just enough to still be branded as bluegrass, even with their individual imprint. Their reverence is obvious, from the mournful Appalachian balladry of “Content Not Seeking Thrills (Ain’t You?)” to the down-home delivery that marks “By and By” and “Limousin Lady.” However, even the easy pluck, steady strum and ready stride can’t mask the fact the band’s earnest intents aren’t always as sunny as they seem. “Ol’ Nick” becomes a cautionary tale about a character as duplicitous as the devil, while “Wolves Howling” is a chilling treatise about bad omens that are hard to avoid. Despite those occasional darker designs, producer Larry Campbell ensures that the proceedings shuffle along at a spirited clip, with an amiable attitude and a deft delivery. There’s no lack of sentiment—”Don’t Bet Against Me,” “You Want Me to Change” and “Worlds Upside Down” make a plea for affirmation and indulgence (“Out with the old/ And in with the old/ It’s good to be true/ Better to be gold”), but the rough-hewn melodies and stripped-down delivery demonstrate an undeterred confidence. Hey, kids, it’s cool to stay old-school.