A 48-volt DC current sent through an XLR cable by a mixer or interface to power condenser microphones.
Phantom power is a 48-volt DC current that a mixer, audio interface, or preamp sends through the same XLR cable that carries the audio signal, supplying operating voltage to condenser microphones and certain active DI boxes that have no internal power source. It is called phantom because the voltage rides invisibly on the signal lines without requiring a separate power cable.
Why it matters
Condenser microphones require an external power source to polarize their capsule; without phantom power they produce no usable output. Knowing which mics need it, and which do not, prevents silent inputs and avoids potentially damaging passive ribbon microphones that are sensitive to unexpected voltage.
In practice
Enable phantom power on the specific channel or globally only after connecting the microphone cable, and mute or lower the channel fader before switching it on to avoid a loud thump through the speakers.
