Relay noise in audio applications can be a persistent challenge that injects disruptive electrical noise into your sound signal. This noise typically occurs when mechanical relays change state, causing rapid current surges that induce noise in audio pathways. While relays are ideal for isolating high-voltage circuits, their physical switching mechanism makes them highly susceptible to voltage spikes.
To eliminate switching artifacts, start by selecting an appropriate relay technology. Solid state relays are often a preferred solution for audio because they have no moving parts and switch more smoothly, minimizing transient generation. If you must use a coil-driven relay, select one with a minimized coil inductance and consider using a RC snubber—a passive R-C filter—across the relay coil to dampen the back emf generated during switching.
Additionally, ensure robust ground plane design and shielding. Keep relay power and control lines away from low-level input circuits and use twisted pair or shielded cables where possible to limit induced noise. Place the relay as far as practical from high-gain audio circuits, and consider adding a ferrite choke on the relay power line to filter high frequency noise.
Power supply filtering is also critical. Use bypass capacitors near the relay’s power input and consider a dedicated clean power rail for the audio section. Finally, implement firmware-controlled switch scheduling if the relay is driven by a microcontroller, so that switching happens during periods of no audio activity.
By combining these techniques—choosing low-noise switching technology, filtering transients, physically separating noise sources, رله and synchronizing with audio silence—you can significantly reduce or eliminate relay noise and ensure studio-grade audio performance.
