Stephan Mathieu (born 11 October 1967) is a German mastering engineer and former musician. He currently lives in Bonn, Germany where he runs Schwebung Mastering, an independent studio for audio mastering and restoration.

"(In 1997), I worked as an engineer and teacher in a classic electronic music studio in France, the former CERM (Centre européen de recherche musicale) Metz, where I had set up an experimental analog lab around their vintage devices by ARP, Crumar, EMS, Moog, New England Digital and Roland, as well as a digital production studio featuring the latest Pro Tools 24-Bit audio technology. There I started mastering in 1998 – without exactly knowing that’s what I did – by transferring countless DATs and reels with recordings made during their annual festival, cleaned, edited, and EQed them for archival purposes and as CD-R copies for the composers and performers. Around the same time, I began a long journey of learning more about listening critically, frequencies and dynamics while attending many mastering sessions for my material."

Mathieu founded Schwebung Mastering in 2014 and has "collaborated with producers running the gamut of modern recorded music." He has worked for labels such as Editions Mego, Important Records, Kranky, Mexican Summer, One Little Independent Records, Past Inside The Present, RVNG Intl., Sacred Bones, Saltern, Secretly Canadian, Sferic, Shelter Press, Unseen Worlds, and mastered music by Ákos Rózmann, Alessandro Cortini, Anton Webern, "Blue" Gene Tyranny, Catherine Christer Hennix, Celer, Charles Curtis, David Rosenboom, Éliane Radigue, Félicia Atkinson, Fennesz, Grouper, Jefre Cantu-Ledesma, John McGuire, Kali Malone, Morton Feldman, Richard Landry, Robert Ashley, Stephen O'Malley, Terry Jennings, The Caretaker, Yoshi Wada among many others.