A shielded, low-noise, high-voltage power supply having a plurality of voltage multipliers, each having a toroidal transformer, and collectively producing a high DC output voltage from an AC voltage. A main conductor carries the AC voltage, and is positioned proximate each toroidal transformer of the plurality of voltage multipliers. A conductive shell is conductively connected to the main conductor, and substantially encloses the plurality of voltage multipliers and the main conductor, the conductive shell providing a return path for the AC voltage in the main conductor and providing EMI shielding of the voltage multipliers and the main conductor. Other features are provided, including an intermediate transformer for conditioning/isolating the AC voltages.