Netzbrummen

Netzbrummen is a term used in German-language electronics to describe an audible or measurable hum and related noise that originates from the electrical power network (Netzspannung) and propagates into devices connected to it. The phenomenon is common in consumer audio, home theater, and laboratory equipment, where it can degrade signal integrity and user experience.

Causes include ground loops created when multiple devices are connected to different outlets or grounding paths, impedance differences between devices, and coupling via transformers or switched‑mode power supplies. Long cable runs, inadequate shielding, and electromagnetic interference from nearby equipment or radio signals can also contribute.

Effects vary from a subtle hum in speakers and headphones to measurable noise in measurement instruments and data systems. In audio engineering, Netzbrummen is often addressed by identifying and eliminating ground loops, using balanced connections, and ensuring devices share a common earth reference.

Remedies include using a single power outlet for devices sharing a signal path, installing isolation transformers or audio isolators, employing star grounding, applying shielding and proper cable management, and using power conditioning or line filters. In design, manufacturers can reduce Netzbrummen by robust grounding schemes and EMI filtering.

Etymology: Netz (network or mains) and brummen (to hum). Historically, the term has been used in German electronics literature to describe mains‑related hum problems that affect both audio and measurement systems.