Audio System Grounding & Interfacing—An Overview

Although the subject has a black art reputation, this tutorial replaces myth and hype with insight and knowledge, revealing the true causes of system noise and ground loops. Although safety must be the top priority, some widely used cures are both illegal and deadly. Both balanced and unbalanced interfaces are vulnerable to noise coupling, but the unbalanced interface is exquisitely so due to an intrinsic problem. Because balanced interfaces are widely misunderstood, their theoretically perfect noise rejection is severely degraded in most real-world systems. Some equipment, because of an innocent design error, has a built-in noise problem. A simple, no-test-equipment, troubleshooting method can pinpoint the location and cause of system noise. Ground isolators in the signal path solve the fundamental noise coupling problems. Also discussed are unbalanced to balanced connections, RF interference, and power line treatments such as technical power, balanced power, isolation transformers, and surge suppressors.