Three-Stage EMI Filter Board 20A

This EMI filter board is designed specifically for high-fidelity audio amplifiers. It measures as a standard PCB module with terminal block connectors: input uses a 3-wire 7.62 mm terminal block (including L/N/PE), output uses a 2-wire 7.62 mm terminal block (L/N). Rated for single-phase AC 110–250 V input and output, with a continuous load current capacity of 10 A (peak handling up to 20 A). Constructed using FR-4 PCB and industrial-grade electronic components including differential inductors, common mode chokes, and X2 safety capacitors. The housing-free design allows direct integration into amplifier chassis or power supply enclosures. The circuit implements a three-stage common mode filtering architecture combined with first-level differential mode filtering — one differential mode stage plus two cascaded common mode stages — delivering robust suppression of electromagnetic interference across a broad frequency range. It effectively attenuates rapid transient burst noise up to several kilohertz, mid-to-high frequency AC line noise, and switching power supply harmonics. Ideal for use with tube amplifiers, solid-state power amplifiers, or DAC/preamp power supplies. When installed, it reduces transformer-induced hum, minimises high-frequency power supply noise, and enhances audio performance — resulting in improved clarity, finer resolution, and deeper background silence. Grounding requires connection of input GND to the mains earth wire; chassis grounding is optional and installation-dependent.