Sonosax is a Swiss professional audio manufacturer based in Le Mont-sur-Lausanne, founded in 1977 by Jacques Sax. The company began as a small Lausanne hi-fi shop before Sax started designing his own mixing consoles to address gaps he encountered while working as a live-sound engineer. The first console bearing the Sonosax name, the SX-B, was released in 1980, followed in 1983 by the portable SX-S, which became a standard tool in location-sound work for film.

The company specializes in modular mixing consoles, portable multitrack recorders, and microphone preamplifiers aimed at film, broadcast, and live recording professionals. Its catalog includes the SX-R4+ 16-track production recorder, the compact MINIR82, the SX42 mixer, the SX-BD1 preamp, and the flagship SX-ST and SX-VT consoles. In 1993 Sonosax acquired the Stellavox recorder brand, later reissuing products such as the STELLADAT II under its own umbrella.

Sonosax received a Technical Achievement Award from the Academy of Motion Picture Arts and Sciences in 1995 for its contributions to portable mixing technology. The company continues to design and build its equipment in-house from its Le Mont-sur-Lausanne workshop, with a reputation among location-sound recordists for handcrafted Swiss engineering, transparent preamps, and modular, field-serviceable designs.

Sonosax has 1 product cataloged on Equipboard, including Preamps. Their gear is featured by 1 artist, with the strongest followings in Rock and Pop. Notable users include Mac DeMarco.