When grunge music up and killed hair metal in the early ’90s, Sacramento-based Tesla felt that shift deeply. Things got so awful the hair band went on hiatus for six years. But in 2000, they staged a comeback so successful they haven’t had to quit since. Nor should they. Frontman Jeff Keith still has those scene-stealing scratchy pipes, and Frank Hannon’s fingers shred as quickly as ever. Tesla was always more innovative than those other ’80s hair metal bands — they implemented elements of blues in their music and weren’t afraid to go acoustic. More than 30 years after the band’s inception, they still have the long-ish hair and the blues. Proving they’re not content just playing the hits (“Modern Day Cowboy,” “Love Song”), they plan to release a new album, Simplicity, this summer.