When you need to provide power to a condenser microphone, your device — a camera, audio mixer, etc. — must deliver Direct Current (DC) voltage through a balanced audio cable (XLR) carrying the audio signal. That method of providing power to microphones is called phantom power, and it is a power source supplied by microphone preamplifiers, mixing consoles, audio interphases and camcorders. Standard phantom power is +48 Volts DC, and when activated, it passes through to the balanced audio cables to the connected microphone.
How does phantom power work?
Phantom power consists of a phantom circuit where direct current is applied equally to the two signal lines of a balanced audio connector. For simplicity, look at a balanced XLR cable. You will see three pins:
- Ground wire
- Positive audio signal
- Negative audio signal
The audio signal from your microphone travels via pins 2 and 3. At the same time, phantom power applies +48V DC on both pins.
Most important, since the power goes to a balanced cable, it does not affect the sound of the audio and does not add noise to the signal. Nearly all modern mixing consoles have a switch for turning phantom power on and off. Some high-end equipment can add phantom power to individual channels while other smaller mixers deliver the power to all channels.
Different scenarios to power up your microphone with phantom power
Now that you understand what phantom power is and how it works, let’s demonstrate how you can use it to turn on a microphone. For these examples, we are using a condenser XLR shotgun microphone. For the power source, we will give you three different scenarios.
Scenario 1: camcorder + condenser XLR microphone
In this scenario, we connect the condenser microphone with an XLR cable into the Sony AX2000’s built-in XLR input — input 1 in this case. Once everything is connected, we need to toggle phantom power ON, which, in this camcorder model, is done by pushing the input 1 switch to “MIC +48V.”
Then we need to let the camera know that we want to use input one as a source of audio by toggling from “INT MIC” to “INPUT 1.”
After that, check the audio monitors to test whether the microphone picks up any audio. Please note that the method for activating phantom power varies from camera to camera, so consult the manual to find your options.
Scenario 2: portable audio recorder + condenser XLR microphone
We connect the condenser microphone to a portable audio recorder’s — the ZOOM H4n — XLR input in this scenario. The phantom power options are inside the menu for this specific device.
When turned on, it will apply +48V phantom power to the two XLR channels simultaneously — compared to scenario one, where we have options to apply it per individual channel. First, we connect the microphone to XLR channel one and go to Menu > Input > Phantom Power > +48V.
After connecting the microphone and activating phantom power, test by looking at the audio monitors and using good quality headphones. Note you can select +24V on this audio recorder, which is usable for specific microphones. Please consult your microphone manual for more info, but most microphones generally use +48V.
Scenario 3: mirrorless camera + condenser XLR microphone
In this scenario, we have a mirrorless camera with no built-in XLR inputs. Here you have three options:
- Use an XLR audio adapter — something like Sony XLR-K3M: With the recommended equipment, you will be doing similar steps as in our first scenario.
- Connect the audio recorder with a line-to-mic attenuator cable: You are doing the same thing as in the second scenario, but now you are connecting the camera and audio recorder to record audio and video simultaneously.
- Use an audio recorder, the camera’s built-in microphone and a clapper to later sync everything in post-production: You are doing the same thing as scenario 2 but adding a clapper sound at the beginning of each shot. You will later need to sync all that audio in post-production. If you want to speed the post-production process, plugins such as Plural Eyes will batch sync your video and audio.
In all three options, you will be able to use phantom power and condenser microphones with no issue.
Types of microphones that use it
To understand which microphones need phantom power, we must compare dynamic microphones and condenser microphones. Dynamic microphones use permanently charged magnets and require no additional power. The conductive voice coil movement inside the magnet structure field generates a current. On the other hand, the condenser microphone requires extra power, usually +48V of DC. Basically, dynamic microphones are passive while condensers microphones are active electronics. For a more detailed explanation, check out our article about condenser microphones.
Some microphones that use phantom power can be small-diaphragm condensers such as the Neuman KM184MT or the Sennheiser MKE 600. Then there are large-diaphragm condensers such as the Bluebird SL or the AKG C414 XLII.
Is it dangerous?
Phantom power isn’t dangerous and will not cause you bodily harm. However, it can damage your microphone. To protect your microphone, make sure it can handle phantom power and don’t connect it to active phantom power input. Remember, dynamic microphones don’t require phantom power, but condenser microphones do.
Does it reduce noise?
Phantom power supplies a condenser microphone with voltage. It does not reduce noise, but if you use a condenser microphone without phantom power, significant noise could be present in the audio signal. This noise could be because of a faulty XLR cable or the device itself. Also, turning phantom power on could be masking the presence of noise. That is why it’s good to test the device first by connecting headphones and then the XLR cables before activating it. In most cases, it will be silenced, but there could be an electric hum making it to the output.
Should you turn off phantom power before plugging in a microphone?
Always turn off phantom power before connecting your microphone to prevent damage to your equipment. If you don’t, you may hear a loud pop that could damage the microphones and possibly your speakers as well.
New audio possibilities
To summarize, phantom power is +48 Volts DC voltage generated by a device and used to power condenser microphones. It does not affect the sound of the audio. Additionally, it doesn’t add noise to the signal, and you can turn it on and off. Professional camcorders have built-in phantom power options that can be toggled per individual input channel. Then there are portable audio recording devices with phantom power capabilities. They can be connected to a camera without XLR connections using specialized cables to record video and audio simultaneously.
As for which microphones to use, you’ll need phantom power to use condenser microphones. It will not bring you bodily harm, but be aware that it could damage specific microphones that don’t require phantom power. Always check your specific equipment manuals if you aren’t sure.
Overall, phantom power is an excellent technology that allows you to use high-end microphones to capture better audio. Keep an eye for equipment and devices that will enable you to use it, and in no time, you will become a master at it.