Electromagnetic Compatibility (EMC)
Electromagnetic compatibility (EMC) is the interaction of electrical and electronic equipment with other equipment and the electromagnetic environment. This equipment includes microphones, preamps, sound mixers, and recording devices, as all electronic devices can potentially emit – and be influenced by – electromagnetic fields.

Controlling the EMC is done by limiting the unintentional generation, propagation, and reception of electromagnetic energy, which may cause unwanted effects such as electromagnetic interference (EMI) or even physical damage to the equipment. The goal of EMC is to obtain the correct functionality of equipment in a typical electromagnetic environment.

EMC encompasses three main areas or classes. 

The first class concerns emission. Emission is the generation and radiation of electromagnetic energy, whether deliberate or accidental, by a source. EMC studies unwanted emissions and how to reduce them.

The second class, susceptibility, is the tendency of electrical equipment to malfunction or break down in the presence of unwanted emissions, which are known as radio frequency interference (RFI). Immunity is the opposite of susceptibility, being the ability of equipment to function correctly in the presence of RFI.

The third class concerns coupling, which is the mechanism by which emitted interference reaches any piece of equipment in question.

The electromagnetic compatibility may be achieved by addressing any or all of the mentioned areas, i.e., reducing interference sources, inhibiting coupling paths, and protecting equipment from the electromagnetic fields.

Microphone signals are low voltage. The microphones are often surrounded by radio transmitters, light controllers, noisy powerlines, and other types of emitting equipment. Thus, designing for EMC is an essential discipline within the development of microphones and related equipment. Most microphone users love old microphones. However, they must realize that EMC was not considered to the same degree years ago as it is today. Typically, modern, high-quality microphones perform nicely regarding EMC.