American mastering and lacquer cutting engineer, born circa 1945 in Savannah, Georgia, USA. Started his career at A&R Studios and later worked at Sterling Sound and Masterdisk, becoming vice-president at both. In 1992 founded [l265594] in Portland, Maine. In July 2023, he announced his retirement and the closure of Gateway Mastering.

As a rule of thumb he is generally credited as Bob Ludwig on pop/rock/mainstream releases and as Robert C. Ludwig or Robert Ludwig on classical releases. His cuts can be recognized by his initials RL or block-lettered rL (sometimes misread as ΓL) etched in the runouts