For experimental-music fans too elevated for country blues and country-blues fans too down-home to reckon pretentious gibberish, there’s John Fahey. An acoustic guitarist who mixed dissonance and drone into American roots music, Fahey formed an eerie, instrumental sound he explored for nearly 40 years. This set — six meticulously documented hours recorded before his first proper album — is a progress chart. In hour one, he bangs his guitar with a paintbrush; by hour six, he’s making ragas backwards before the Beatles set foot in India.