EMI interference suppression in symmetrical non-regulated power supply for high immunity audio power amplifier

Different non-regulated symmetrical power supplies for audio power amplifier are presented in this work, where the conducted interference to the ac power grid, measured by a LISN, has been suppressed to the minimum. EMI measurements in different topologies have been compared in this paper. Also, several conventional EMI suppression components have been tested in these topologies in order to reduce EMI interference. As a result several rectifier circuits for main power supply with very low emissions are presented in this paper based on fast rectifier diodes.