Phantom Power and Condenser Microphones

Whether you are a seasoned pro audio expert or amateur home musician, at some point you will encounter phantom power. For many this occurs after purchasing a condenser microphone and wasting plenty of time trying to figure out why the thing isn’t working.

All condenser microphones (except electrets) require phantom power to operate. Phantom power is a DC current applied to the diaphragm of the mic. It is generated from pro audio equipment such as mixers and pre-amplifiers and supplied to the mic through a regular balanced microphone cable with 3pin XLR male and female connectors. Generally all audio mixer 3pin XLR inputs will output phantom power for condenser microphones. There may just be a switch on the rear of the mixer to turn the phantom power on and off.

If you have purchased a condenser microphone and want to connect it to your PC or MAC, some additional equipment will be required. Default PC and MAC sound cards do not output phantom power (unless you bought a USB condenser mic). A simple option is a standalone phantom power device. Though for not much more, these days you can get your hands on a small audio mixer. The mixer should have an XLR input outputting phantom power, plus other mixing options. It is then just a matter of grabbing audio cables with the correct jacks to connect the mixer to the PC or MAC sound card.

Another option is a USB audio mixer. These mixers feature a USB output for the main signal, which offers a simplified connection to the PC or MAC without needing a sound card or extra cabling. Advancements in technology and manufacturing mean small USB mixers can be found at quite low prices making them a good solution for the home recorder with a condenser microphone.

The other pro audio device you may encounter that requires phantom power is the Direct Injection Box or DI. (Note, only active DI boxes need phantom power, passive DI’s do not). An active DI uses phantom power for a different purpose to that of condenser mics. Active DI boxes often use the power to offer additional controls and functions to the DI box.

Phantom power is usually outputted at a voltage between 16V and 48V, with 48V being the most common. A microphone will draw as much current from this voltage as needed. Just check that your mixing desk outputs the common 48V, and you know all your mics are going to work with it.

Note that some dynamic microphones don’t like phantom power running to them (dynamic mics don’t need phantom power), so if your mixing desk allows, switch phantom power on for condenser microphones only. Ribbon microphones especially don’t like phantom power.