Robb Flynn is an American musician. He is the lead vocalist and rhythm guitarist for heavy metal band Machine Head. Machine Head is an American heavy metal band from Oakland, California. The band was formed in 1991 by vocalist/guitarist Robb Flynn and bassist Adam Duce. The band’s aggressive musicianship made it one of the pioneering bands in the new wave of American heavy metal, and it is also considered to be part of the second wave of thrash metal bands from the 1990s.