Blame rap’s influence for making the best contemporary blues-rock (e.g., Jon Spencer Blues Explosion) so derivative and full of itself; what makes Railroad Jerk something more than an art-damaged version of the Yardbirds, though, is the band’s practice of picking grooves out of the ether instead of the earth. Jerk’s music is disjointed because the borrowed riffs, which float in and out like objects on a radar screen, are so disposable. As openers Skeleton Key should help confirm, the burden of the modern white bluesman isn’t having to overcome a lack of soul. It’s data overload. With Spoon at 8:30 p.m. at the Black Cat, 1831 14th St. NW. $6. (202) 667-7960. (Brett Anderson)