- Audio Research
 - Minnetonka - Manufacturer of hi-fi equipment including preamplifiers, power amplifiers, compact disc players and more. - Timewave Technology Inc.
- Saint Paul - Manufacturers DSP based audio filters for use in communications.
- Atma-Sphere Music Systems
- Saint Paul - Designs and creates preampliers and amplifiers, using balanced differential design.
- Great River Electronics
- Inver Grove Heights - Designs and makes professional audio equipment, including preamps and mixers; industrial control systems; and DSP-based signal conditioning equipment.
- Radio Mall
- Minneapolis - Market sound effects, production effects, commercial music beds and oldies libraries to radio stations and help others market their products to radio stations.
- Luxman Electronics Corporation
- Minneapolis - Manufactures high-end audio equipment including power amplifiers, preamps, integrated amps, CD players, vacuum tube amplifiers & Surround Sound receivers.
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