Throughout his career, he has mastered recordings on all the major recording formats for all the major record labels, and on projects for more than 1,300 artists including Led Zeppelin, Rush, Jimi Hendrix, The Police, Paul McCartney, Eric Clapton, Rolling Stones, Def Leppard, Nirvana, The Who and Dire Straits.
As an 8-year-old child in South Salem, New York, Ludwig was so fascinated with his first tape recorder he used to make recordings of whatever was on the radio. Ludwig is a classical musician by training, having obtained his bachelor's and master's degrees from the Eastman School of Music of the University of Rochester, New York, where he was also involved in the sound department and played Principal Trumpet with the Utica Symphony Orchestra. Inspired by Phil Ramone when he came to the school to teach a summer recording workshop, he ended up working as his assistant. Afterward, he was contacted again and offered work with Ramone at A&R Recording. Together, they did sessions on projects with The Band, Peter, Paul & Mary, Neil Diamond, and Frank Sinatra.
After a few years at A&R, Ludwig received an offer from Sterling Sound, where he eventually rose to become a Vice-President. After seven years at Sterling, he moved to its larger direct competitor, Masterdisk, where he was Vice President and Chief Engineer. In 1993, Ludwig decided to take control over his career by starting his own record-mastering facility in Portland, Maine named Gateway Mastering.
His mastering credits are extensive, and include albums for many major classic artists, such as the Kronos Quartet, and rock acts, including Jimi Hendrix, Phish, Megadeth, Metallica, Gloria Estefan, Nirvana, The Strokes, Queen, U2, Guns N' Roses, Richie Sambora, Tool, Simple Minds, Bryan Ferry, Tori Amos, Bonnie Raitt, Paul McCartney, Bruce Springsteen, the Bee Gees, Madonna, Supertramp, Will Ackerman, Pet Shop Boys and Radiohead.
He has occasionally undertaken long projects, such as remastering the entire back catalogues of Rush, Dire Straits, Creedence Clearwater Revival and the Rolling Stones, Ludwig cites his most musically satisfying projects as: the CD reissue of Music From Big Pink (The Band), There's a Riot Goin' On (Sly and the Family Stone), Led Zeppelin II, Painted from Memory (Bacharach & Costello), Spirit (Jewel), Loreena McKennitt, and Ancient Voices of Children (George Crumb). Ludwig still actively influences the music industry. As a judge for the 8th and 10th annual Independent Music Awards, his contributions helped assist the careers of upcoming independent artists. 
Ludwig is active in the Audio Engineering Society and was a past Chairman of the NY section. He is on the advisory board of the Producers and Engineer’s section of National Academy of Recording Arts and Sciences.
Awards and recognition
- First winner of the Les Paul Award 1991 from the Mix Foundation created to honor individuals or institutions that have set the highest standards of excellence in the creative application of recording technology.
- 1986, 1987,1989, 1990, 1994, 1995, 1996, 1998, 2000 TEC Award OUTSTANDING CREATIVE ACHIEVEMENT - Mastering Engineer
- 1994, 1995, 1996, 1998, 1999 OUTSTANDING INSTITUTIONAL ACHIEVEMENT - Mastering Facility
Since the inception of Gateway, Ludwig/Gateway have been regular winners of TEC Award for "Best Mastering Engineer" and "Best Mastering Facility", namely the following:
- 2001 TEC Award OUTSTANDING CREATIVE ACHIEVEMENT Record Production/Album: - Riding With the King, B.B. King & Eric Clapton
- 2002 TEC Award OUTSTANDING CREATIVE ACHIEVEMENT Record Production/Single or Track: - The Space Between • Everyday, Dave Matthews Band
- 2004 TEC Award OUTSTANDING CREATIVE ACHIEVEMENT Record Production/Album - Hail to the Thief, Radiohead
- 2006 TEC Award: OUTSTANDING CREATIVE ACHIEVEMENT Surround Sound Recording - Brothers in Arms-20th Anniversary Edition, Dire Straits
- 2009 TEC Award: OUTSTANDING CREATIVE ACHIEVEMENT Record Production/Single or Track - "Viva La Vida", Coldplay
- 2009 TEC Award: OUTSTANDING CREATIVE ACHIEVEMENT Record Production/Album - Viva La Vida, Coldplay
2006: Best Surround Sound Album: - Brothers In Arms - 20th Anniversary Edition, Dire Straits.
2012: Best Surround Sound Album: - Layla and Other Assorted Love Songs (Super Deluxe Edition), Derek and the Dominos
2013: Album of the Year: - Babel, Mumford & Sons
Latin Grammy Awards
2004: Album of the Year - "No Es Lo Mismo", Alejandro Sanz
Cinema Audio Society
2005: Outstanding Achievement in Sound Mixing for Television Non-Fiction, Variery or Music-Series or Specials: - Hammersmith Odeon London 1975, Bruce Springsteen and the E Street Band
2012: The Association of Professional Recording Services Sound Fellowship - received 27 October 2012
Quotes about Ludwig
"No mastering engineer has mastered more music that has been enjoyed by more people ever than Bob. I can't think of anyone else that might be true of. So there's a start. Simple fact" - Mark Parsons.
- Brown, Mark (2006-08-24). "Fogerty's CCR classics in 'respectful' hands". Rock Mountain News. Retrieved 2006-09-09.[dead link]
- "Bob Ludwig - Worked with 1307 Artists". Album Credits. Retrieved 2010-12-28.
- "Bob Ludwig". Gateway Mastering. Retrieved 2013-05-27.
- Anderman, Joan (2001-11-08). "Sound judgment - Music stars find a master's touch in Maine". Boston Globe. pp. D1. Retrieved 2006-09-09.
- Murphy, Steve. "Remastering the Rolling Stones". Pro Audio Review. Retrieved 2006-09-09.[dead link]
- Independent Music Awards - 8th Annual IMA Judges
- Audio Engineering Society. "Recent Activities". McGill University. Archived from the original on 2006-08-23. Retrieved 2006-09-09.
- "The TEC Awards". The Mix Foundation. Retrieved 2006-09-09.
- "The Grammy Awards". The Recording Academy. Retrieved 2006-09-09.
- Parsons, Mark. "An interview with Bob Ludwig (from Expo98)". Parsons Audio. Retrieved 2006-09-09.