There is more than one artist with this name: 1) Petra is a Christian Rock band formed in 1972 by Bob Hartman, Bill Glover, John DeGroff, and Greg Hough. "Petra" means "rock" in NT Greek, making the band name a triple pun. Rising from the jesus music movement, and initially signed to Myrrh Records, they fought to gain acceptance and recognition in a church culture that at the time believed rock music to be off-limits.
Bruce Cockburn, (pronounced "CO-burn"), has had a long and distinguished career with much success in his native Canada. His first albums were fairly straight ahead folk music spotlighting his brilliant guitar playing. In fact, there were a good number of instrumental guitar numbers on those early recordings. A Christian element came into his music around the time of the album Salt, Sun And Time, and over time his writing has taken on a stronger and stronger political orientation.
El Ten Eleven is a Los Angeles-based instrumental rock duo consisting of Kristian Dunn and Tim Fogarty. What separates El Ten Eleven from their musical peers is that they are only two musicians on stage creating pounding landscapes of sound with no laptops or sequencers. Dunn switches off (sometimes mid-song) between a double-neck bass/guitar and a fretless bass, while his feet dance on an extensive floorboard of looping devices and effects pedals. He plays everything live, loops himself and juggles all the layers of tracks on top of each other.