Phantom power is a power delivery system in which one piece of equipment draws power from a piece of equipment to which it is connected, rather than drawing from its own power supply. In audio, this means of power delivery is useful because it enables a higher degree of sensitivity and also reduces the need for batteries or separate power supplies. Microphones are typically phantom powered, drawing +48V power from the amplifier or interface to which they are connected via an XLR cable.
Things you need
Connect the audio interface to the computer. Although you can power a phantom power microphone with a preamplifier, this is most commonly used in professional studios or in the live environment. Due to audio interfaces being cheaper and being specifically designed to work with computers, it is preferable to use a dedicated audio interface in this situation. The means of connection varies according to the type of interface you use, but you typically use either a USB or Firewire cable to hook up the audio interface.
Connect the microphone to the audio interface. First, connect the male end of the XLR cable to the three-pin connector on the bottom of the microphone. Then connect the female end of the XLR to the XLR input jack on the audio interface
Enable the phantom power setting on the microphone. Look for a small switch marked either “Phantom Power” or “+48.” Turn this switch on. This configures the audio interface to send power to the microphone.
Turn the monitor level of the audio interface to zero. This prevents any loud feedback or other noise emanating if there is a connection problem.
Launch your preferred audio recording software, for example GarageBand or Audacity.
Create an audio channel. Microphones send an audio signal, so its important to configure the audio recording software to accept audio, as opposed to MIDI. Channel creation methods vary, but you typically need to click “File,” “Create,” and then select “Audio channel.” Some programmes have shortcuts. For example, in Logic you simply click the “+” symbol then select “New Audio Channel.”
Talk into the microphone to check that the computer is receiving a signal. Gradually turn up the output level until the volume metre on the audio recording software begins to move. Try to get this signal as high possible before the metre flashes red. This gives a nice, loud signal without distortion.
Things you need
- audio interface
- XLR cable