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Phantom power, in the context of professional audio equipment, is DC electric power equally applied to both signal wires in balanced microphone cables, forming a phantom circuit, to operate microphones that contain active electronic circuitry.
It is best known as a convenient power source for condenser microphones, though many active direct boxes also use it. The technique is also used in other applications where power supply and signal communication take place over the same wires.
Phantom power supplies are often built into mixing consoles, microphone preamplifiers and similar equipment. In addition to powering the circuitry of a microphone, traditional condenser microphones also use phantom power for polarizing the microphone's transducer element.

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