How voltage from a phantom power supply is applied to a microphone.
Phantom power is a method for supplying voltage to a device, using its signal cable. It is often used to supply condenser microphones with the required polarizing voltage and power for any built-in preamplifiers. Phantom powering consists of a voltage being applied equally through the hot and cold signals lines of a balanced microphone connector. The supply voltage (12–48V) is with reference to the ground pin or shield of the connector. Phantom power supplies are often built into mixing desks, amplifiers, or other equipment that takes a signal direct from a microphone. The term "phantom" refers to the fact that there's no visible power cord and the voltage is not perceptible in the audio path.