Jan. 19: Charlie Waller was one of the guys who invented urban bluegrass — music made with bluegrass instruments, arrangements, harmonies and timing, but that didn’t always hew to memories of the old homeplace. The band he helped start in the late ’50s, The Country Gentlemen, incorporated country music as well as folk and pop into its repertoire of song sources. The Gents had a great sound that appealed to people outside the South and outside the blue-collar experience. On what would have been Charlie Waller’s 75th birthday, let’s listen to an evocative number from the early ’70s, the beginning of the Gents’ second great period. Waller’s guitar kicks it off, followed by his distinctive voice.