(1948?-) Co-founder, along with Scott Wedge, of E-mu Systems. Rossum grew up in the San Francisco Bay area in the USA, and attended college at the California Institute of Technology, graduating in 1970 with a degree in biology. During that time, he was asked to help set up a Moog modular synthesizer, which got him interested in electronic music. After graduating, he went to the University of California - Santa Cruz for graduate school. While there, he met up with Wedge, whom he had known from high school, and they formed E-mu Systems in 1972.
Rossum became the company's expert in analog circuit design. Under his leadership, E-mu collaborated with SSM, Oberheim and Sequential Circuits, as well as a number of non-music customers, on circuit design. As the company grew, the business aspects became more demanding. In 1979, Rossum and Wedge decided that they needed to incorporate the company and divide themselves between engineering and management. As Rossum tells it, Wedge lost a coin flip and took the job of president, leaving the chief engineer job to Rossum. After the duo designed the Emulator, Wedge moved away from engineering, leaving Rossum to direct the development of the bevy of follow-on products -- the Proteus line and the software libraries that were the company's bread and butter products in the 1980s and '90s.
Rossum became the chief technologist of Creative Labs when the company acquired E-mu in 1993. He held that position (working reduced hours after 1999) until Creative shut down E-mu in 2011. At that point, he went to work for Audience Inc., a company that specializes in voice processing for mobile phones and voice communications. However, a desire to get back into the music business led Rossum to leave that company in 2015. In July 2015 he announced the formation of Rossum Electro-Music. The company announced its first product -- a re-creation of the "Z-Plane" filter from the E-mu Morpheus -- in 2016.