2 Why Isolation Helps

Whether in a commercial studio or a home audio set-up, non-ideal power supplies and electrical wiring can be a common cause for ground loop interference in audio. Eliminating the root cause may be time consuming or costly, and using a galvanic isolator can be an effective design to break a ground loop.

Most methods focus on limiting ground loop interference by attenuating the noise or making substantial system changes. The typical methods to solve ground loop interference consist of power conditioners, re-working AC power mains, audio transformers, or a ground loop break circuit. However due to time, money, and system constraints, these are not always options.

The left image in #FIG_UWZ_KPZ_DWB shows a large ground loop without isolation. Here, each device has two return paths. One is the device’s respective local ground and the other is the local grounds with respect to each other. Each ground has their own fixed impedance and have a voltage drop on the return path that can cause the grounds to be at different potentials. After isolation, we see that the two sides of the isolator are independent as shown in the right image of #FIG_UWZ_KPZ_DWB. The GPD is still there however, the two devices are on their own ground plane and are no longer affecting each other. The large ground loop is broken and each device has there own, independent return path.

Adding isolation to an application can be done several ways. One common method is to add isolation to use a 1:1 audio transformer. A transformer on the analog signal will decouple the system grounds and isolate the two sides of the system, however this process is not applicable to digital audio signal transfer. For digital signals, isolation is achieved through the use of digital isolators.