What Is Phantom Power?

What Is Phantom Power?

26th May 2020 @ 12:01 | Joe Dempsey

Clue: nothing to do with ghosts

The question, ‘what is phantom power?’ gets asked a lot by those new to music tech- here’s a simple explanation. You’ll often see it on mixing desks, microphone pre-amps and audio interfaces, but phantom power remains as mysterious as it sounds to many music tech ‘newbies’. Although it might sound as though you might be able to summon the musical powers of the ancients through flicking this switch, the truth is slightly more mundane but no less useful. What is phantom power, then? Read on for a simple explanation...


More power… It’s alive!

Phantom power is used in connection with microphones (although there are some other devices that also use phantom power). To understand how it works, you need to understand a little bit about the mechanics of how a microphone works. The majority of microphones can be divided into two categories: dynamic microphones, and condenser microphones.


Dynamic microphones are the simplest type of microphone. Put simply, when the air around a dynamic microphone vibrates due to sound, it causes a diaphragm mounted at the end of the microphone to vibrate, too. This is attached to a coil of wire, which is attached to a transducer. This converts the vibrations into an electrical signal, which is transmitted down the cable to the microphone pre-amp, where it will eventually be converted back to sound via another transducer. Dynamic microphones are not the most sensitive microphones around. Condenser microphones, however, are far more sensitive. Here, the diaphragm is a far thinner, lighter design, which is gold plated. As a result, it vibrates far more easily with lower levels of sound.


The diaphragm is suspended in front of an electrically charged plate, connected. As the diaphragm vibrates, the charge on the plate varies. This electrical signal is transmitted down a cable to the mixer etc. To charge this plate, the microphone needs power (unlike the dynamic microphone). Phantom power sends the correct power (+48V) to a condenser microphone via an XLR socket and cable. Plug in your condenser microphone, and switch on phantom power on the correct channel, and bingo- your microphone will spring to life. Sometimes, phantom power will just be labelled ‘phantom’, and occasionally '+48v'). Also, back electret type condensers can sometimes use batteries for power instead of phantom power. Many of this type of microphone will also accept phantom power too, however.


In summary, Phantom power sends the correct power (+48V) to a condenser microphone via an XLR socket and cable. Simply plug-in your condenser microphone and switch on phantom power on the correct channel.

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