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DC Mains Supply
One common issue is ‘DC on the mains’ – a problem well known to affect the performance of audio equipment, especially amplifiers. In theory, the mains electricity we obtain from the sockets in our homes should be pure AC, with a perfectly symmetrical sine wave alternating between positive and negative phases. However, the presence of ‘asymmetrical loads’ – myriad household devices that use the AC energy available in the mains cycle unevenly, from dimmer switches to kitchen appliances to computer power supplies – causes the waveform to become offset, resulting in the presence of DC voltage on the AC supply.