If you look at the characteristics of some audio interfaces or mixing consoles, you can see the Phantom Power + 48V parameter. Empirically, it is established that without the Phantom Power button, for some reason, the microphones connected to the XLR connector do not work. We recommend understanding in more detail what is phantom power 48V and how it works, which microphones are needed, and which ones can damage.
Phantom power is a direct current transmitted through microphone cables to power microphones that contain active electronic circuitry. Phantom power supplies are often built into mixing consoles, mic preamps, and audio interfaces. Most microphones require it to work properly!
Plug the mic into the mixer’s input, and then turn on phantom power (press the 48V button usually located on the top of the mixer). The cable must have XLR* connectors to carry phantom power. Important tip: Make sure the gain or fader is down on the mixer when turning phantom power on or off.
For example, Phantom power is a 12 to 48 V DC voltage (typically 48 V) that is used to power the active components of a condenser microphone. It is also necessary to set the microphone capsule in motion. The voltage is carried along the microphone cable along with the audio signal, so no additional wires are required. Hence the name “phantom” arose – the power is not supplied by a separate cable.
If you have a condenser microphone and you connect it to your audio interface or mixer you will find that the signal is very low. By activating the phantom power or 48v, the signal will be amplified, giving you a greater volume to record.
Also in this way, by receiving more signal, you can avoid the noise that is generated due to having to increase the volume due to the low signal. Therefore, having a good source of phantom power is essential, for example when recording vocals with a condenser microphone. Most audio interfaces or mixers already have built-in phantom power.
When You Need It
Condenser microphones have active electronic parts inside that include a diaphragm and a backplate. Both elements must be electrically charged to work properly. But the condenser microphone itself is not able to provide it, and therefore it needs to be powered from an external source.
And phantom power was invented to power microphones without the large external power supplies that are still used for tube models. When phantom power is on, the balanced XLR cable carries DC current to provide voltage. Unlike dynamic microphones, condenser microphones require voltage to polarize the microphone’s transducer element.
The transducer element of a dynamic microphone has a diaphragm, a voice coil, and a magnet. The voice coil is connected to the diaphragm and passes through the magnet. As the diaphragm moves up and down, the voice coil generates different levels of current.
That is why a dynamic microphone does not require phantom power. They are less sensitive than condensers and can handle higher sound pressure levels without distortion.
Also, passive ribbon microphones do not need phantom power. Moreover, it can damage them: prolonged exposure to stress can stretch or render the tape element unusable. This does not apply to active ribbon microphones.
Separately, there are USB microphones. They are usually condensers and require phantom power. But their design allows you to receive it via USB.
Phantom power requires a balanced connection to work properly. If phantom power is supplied through an unbalanced or damaged cable, it may overload the microphone and damage it.
In order to amplify the signal to a dynamic microphone, you need special compact microphone preamps-boosters. They are able to significantly amplify the signal (25 dB or more) while maintaining a low level of self-noise.
After reviewing what phantom power is, we understood that it is essential for recording condenser microphones with a good signal. The good thing is that in most cases, you do not need to buy additional phantom power, as it is built into 99% of today’s audio interfaces and mixers.