Langevin began in the early 1940s in New York, creating designs for major clients such as Western Union and early aerospace firms like Hughes Aircraft. The company expanded significantly during World War II as it served as a second-source manufacturer for Western Electric. By the early 1950s, Langevin had relocated to Santa Ana, California, where it became known for producing respected tube and solid-state recording and sound-reinforcement equipment. Although the Langevin trademark is now owned by Manley, which continues to produce gear under the name, support for earlier Langevin products is provided by Quad Eight.

From the 1950s through the late 1960s, Langevin shared a Santa Ana facility with Electrodyne, and the two companies often produced electronically similar products packaged differently, even using each other’s components. At one stage, Electrodyne’s production demands were so high that they acquired Langevin to secure essential parts—particularly faders—needed to keep their console manufacturing on schedule.