Specifications

14
PHANTOM POWER
A little earlier, we talked about the fact that condenser microphones
require electrical power to operate (usually between 11 and 48 volts DC).
Phantom powering
is a method of supplying that power through the
microphone cable from a remote supply. This supply can be a stand-alone
unit or may be incorporated in the audio mixer, or, in some cases, the video
recorder. It is called "phantom" power because it comes from somewhere
outside the microphone and is not supplied by a battery.
While it’s a popular myth, plugging a dynamic microphone (which doesn’t
need any power to work) into a mixer that is supplying phantom power will
not damage the microphone. As long as you are using a balanced
microphone, phantom power cannot possibly cause it to burn out, or harm it
in any way. If you connect an unbalanced microphone to an input that is
supplying phantom power, you may hear a steady hum or buzz. To get rid of
it, just turn off the phantom power supply. (We’ll discuss the concept of
“balanced” and “unbalanced” in the Cables and Connectors section.)
Phantom power is occasionally referred to as simplex power; the two are
one and the same electrically. You may also encounter some European
microphones which require a different type of power called A-B power
or
T power
. These are electrically incompatible with phantom power.
Microphones which operate on phantom power will not operate on A-B
power, and vice-versa. Some mixers can provide phantom power and A-B
power to different mic inputs simultaneously.
WHAT ABOUT WIRELESS?
Wireless microphones (occasionally referred to as “RF mics” or “radio mics”)
have become increasingly popular in the last few years, especially in situations
where the presence of a conventional mic cable puts constraints on the user’s
actions. In essence, a wireless microphone is a miniature radio station. A
microphone cartridge (which may be a dynamic or condenser type) converts
incoming sound waves to an electrical signal. The signal is sent out by a low-
power transmitter, and then picked up by a receiver located nearby, which
converts the radio-frequency signal back into audio. The transmitter can be
contained in the handle of the microphone or in a small pack designed to be worn
on the body. The combination of the microphone, transmitter, and receiver is
known as a wireless system
. A cable then connects the audio output of the
receiver to the input of the audio mixer or videotape recorder.
Just like radio stations, wireless microphones operate on specific frequencies
in sections of the frequency band which are regulated by the Federal
Communications Commission (FCC). These frequencies are measured in
megahertz (abbreviated “MHz”), which describes the number of times that the
signal oscillates or vibrates in one second. Wireless microphone systems are
available in different sections of the frequency band: