Integral component of the power supply that pulls power from the wall outlet and transforms it or makes it into power that can be used by the electronic device (with special importance being its use in amplifiers). ransformers’ power output is measured in watts and should be several times higher than the peak output of the amplifier (or other device, but this discussion will focus on amplifiers, which are the most critical power supply users). Amplifiers running in a class AB operation do not need as large a transformer as those running in pure class A. However, the transformer must still be large and capable of large power output. he transformer outputs its power as alternating current as it receives power from the wall outlet. This output is sent to the rectifiers in a power supply that change the alternating current to direct current. The direct current power is then sent to the capacitors. The capacitors store the energy for later use by the amplifier (or other electronic device). igh quality amplifiers should possess large transformers of the toroidal (doughnut shaped) variety. Large transformers are heavy, weighing potentially tens or hundreds of pounds. For this reason, a general litmus test to the quality of an amplifier’s power supply is how much it weighs. The more it weighs typically the larger its transformer and more robust its power supply (of course, this is not a tried a true method of amplifier testing and any amplifier should be judged on its total merits not merely its weight). Good quality amplifiers need strong, well-designed power supplies in order to perform well.