Robert Carl Ludwig (born December 11, 1944) is a retired American mastering engineer. He mastered recordings on all the major recording formats for all the major record labels, and on projects by more than 1,300 artists, including Led Zeppelin, Lou Reed, Metallica, Queen, Jimi Hendrix, Bryan Ferry, Paul McCartney, Nirvana, Bruce Springsteen, Tool and Daft Punk, with more than 3,000 credits. He is the recipient of thirteen Grammy and other awards. In 1992, Ludwig founded his own mastering facility, Gateway Mastering Studios, in Portland, Maine. He retired in 2023.
