Rockford Fosgate, MOBILE AUDIO FOR FANATICS. Manufacturers and specialists in 12 Volt audio products for cars, motorcycles, marine and all terrain vehicles, which are made available through a network of RTTI Trained authorized dealers who specialize in custom audio installations. Fosgate was invented in 1973 by Jim Fosgate USA. Rockford Corp formed in 1980 creating Rockford Fosgate which holds numerous patents making the brand a unique and technological leader in the mobile audio industry.