Blyth started in professional audio equipment manufacturing in the early 1970s by joining with Paul Dobson and Phil Dudderidge to form RSD, a company that built custom public address systems for bands such as Roy Wood's Wizzard, and Steve Harley & Cockney Rebel.
Blyth started in professional audio equipment manufacturing in the early 1970s with Kelsey Morris, a company designing and making mixing consoles for T. Rex, Ten Years After and King Crimson. He joined with Paul Dobson and Phil Dudderidge to form RSD, a company that built custom public address systems for bands such as Roy Wood's Wizzard, and Steve Harley & Cockney Rebel.