Just now pushing fifty, Jay Farrar, the creative force behind Son Volt, is still not as old as his voice. Not nearly. His singing voice, an ageless gift which sounds something like old timber looks, like the unpainted walls framing Walker Evans’ best portraits from Let Us Now Praise Famous Men: simple, durable, weathered and grooved and unplanned. Notes of Blue will be the twentieth album — including a couple live releases and two movie soundtracks — to which Farrar has lent his voice and songwriting. He is not quite a famous man, which is probably a comfort except when bills need paying. Plenty praised, though, from the moment his first band, the influential Uncle Tupelo, recorded a punked-up version of the topical Carter Family song “No Depression,” and named their debut album after it. Photographed for magazine covers, including the inaugural edition of No Depression magazine, which argued for the arrival of something called alt-country back in 1995, when Son Volt’s first album, Trace, came out.