Indy: Your music is eclectic. But I read that you feel sort of trapped, doing all these different genres, because you've been doing them for so long. Is that fair to say?
Harper: You know, that is fair to say. I feel simultaneously trapped and liberated, but the challenge is which direction to go in next. The good part is, I got my gospel record [the 2004 collaboration with the Blind Boys of Alabama, There Will be a Light] out of the way. So I guess at some point, I'm going to have to make a blues record and a rock record and a soul record and a reggae record, because I do want to do an entire body of work of specific sounds over time.
Indy: You're in a fairly high-profile marriage with actress Laura Dern. How much do you turn to your relationship for inspiration for songs?
Harper: I am greatly influenced by all of my relationships, but none as much as the relationship closest to me, being my wife. She is an incredible inspiration, and she's got great musical ideas and tastes. She's got her own musical side of the fence that she guards and introduced me to. So she loves music. She's passionate about music.
Indy: You play multiple instruments on a number of songs on your new double CD Both Sides of the Gun including drums and bass. Why did you take that approach?
Harper: For this record, I have a specific style, and when it comes to drum and bass, it's very visceral. It's unlearned. And you can't have great musicians play in an unlearned style, because they're too good. But a lot of these songs called for the nastiness and rawness of the style that I played them in, so I wanted to serve that.
At Red Rocks Amphitheatre, Wednesday, Aug. 23.