An AC voltage conditioner to be connected between a source of AC line voltage or non-linear voltage and one or more AC-powered devices (e.g., audio/video, medical and scientific equipment) to improve the performance of the devices by reducing the effects of interference and distortion often caused by an AC electromagnetic field or radio frequency interference in the vicinity of the devices. A pair of AC current conducting plates are respectively electrically connected between positive and negative output terminals of the AC line voltage source and positive and negative input terminals of each AC-powered device. The pair of AC current conducting plates are interposed between and separated from three DC current carrying plates. The DC current carrying plates are connected in electrical parallel with one another between positive and negative output terminals of a DC voltage generator. DC currents flowing through the DC current carrying plates from the DC voltage generator cause respective DC electromagnetic fields to surround the AC current carrying plates. Therefore, the AC currents flowing through the AC current carrying plates of the AC voltage conditioner will pass through the DC electromagnetic fields ahead of each AC-powered device.