- Phantom Power

WARNING:  NEVER APPLY PHANTOM POWER FROM A MIXER OR PREAMP, UP TO ANYTHING OTHER THAN A MICROPHONE THAT REQUIRES IT. For example, never apply phantom power from a mixer or preamplifier up to a sound board, a wireless microphone receiver, an unbalanced microphone, a microphone which is being powered by battery power, a dynamic microphone, etc. Improper application of phantom power can effectively short 48 volts to ground, and damage your equipment. 

Condenser microphones need to have a voltage applied to it for power. This can come from a battery plugged into the microphone itself. Or, it can be provided by what is known as "phantom power".

Phantom power means that the microphone is going to expect the voltage to be sourced by a what ever the microphone is plugged into (mixer, preamplifier, sound board, etc). The mixer or preamplifier will generate their required voltage, and transmit that voltage up the microphone cable to the microphone, which then powers the microphones condenser element.

Different microphones may require different voltages. Older style microphones will require 48 volts. Many modern microphones will work down to 12 volts. If you are using a microphone that will operate down to 12 volts and a preamplifier which also supplies down to 12 volts, then that will help extend the battery life of the preamplifier (as it will take much more of the batteries to generate the higher 48 volts).

An advantage of using a microphone that will work from phantom power only (and does not have facilities for inserting a battery), is that the microphone can then be much smaller, lighter, and easier for the boom operator to manipulate.