There are two types of microphones
They are used for two different applications. A dynamic microphone, the
larger type with the ball windscreen, uses a diaphragm attached to
moving coil of wire suspended around a magnet to produce a small
In a condenser or electret microphone, an electrical signal is
generated by a capacitor in the element of the microphone. As you speak
into a condenser mic the sound wave pressure hits one side of the
capacitor and causes it to move closer to the other side of the
capacitor, compressing the dielectric (insulator) in between, causing
a bias electrical signal to vary. A transistor circuit, in
the mic handle or in an inline module,
amplifies the signal variations so the mixer can use it. Both types of
microphones have their advantages and disadvantages.
Dynamic microphones are very rugged.
They are designed to be used by solo vocalists and musical instruments
where high sound pressure levels occur.
Dynamic microphones work best when
they are used close to the sound source - within about six inches. They
are less sensitive and much larger than most condenser type
microphones. They are often well shock mounted to stop rustling noise
from hand movement. Neodymium and rare earth magnet structures have
made possible dynamic mics that approach the sensitivity of some
Condenser microphones are used where
it is not possible or desirable for the microphone to be close to the
sound source. We use condenser microphones on pulpits, suspended over
choirs, and on altars. These microphones have the advantage of being
much more sensitive than dynamic microphones and as such the source can
be farther away from the mic and still be picked up quite well. This
helps when you have inexperienced people using the microphones.
Condenser mics also work well as clip-on, or lavaliere type
microphones. Used in this manner, the microphone does not have to be
right up at the person's chin, it can be placed lower down on the
user's clothing. Also becoming popular are headset or even earset
microphones such as the nearly invisible Countryman E6, Audio
Technica AT892 or Galaxy AS-HSA. With the element right at the
performers' or pastors'
mouth, feedback is almost non-existent, the voice sounds clearer and
more natural, and the level never changes with head movement. If
you wear a robe and a collar, call us to try one. No
more trying to figure out where to clip the mic. After the
first five minutes the Janet Jackson/Garth Brooks- look-alike
comments end and most users say they will never go back to a clip-on
mic. If you get a chance to see one of the PBS Celtic Lady specials you
will see that all they use are miniature earset mics (granted, DPA
4066, almost $700/earset without the $8000 wireless system). They are
nearly unnoticeable and the sound is spectacular. All
professional grade belt-pack wireless transmitters can be outfitted
with head/earset mics
capacitor element and the
interface circuit built into the mic requires electricity to function.
This is usually supplied by your mixer power supply and is called
phantom power. Phantom power is DC (direct current) 'battery' power
that flows back to your mic through the microphone cable. Sound is an
AC (alternating current) electricity phenomenon. At the mic
at the mixer phantom power is filtered out of the audio signal. Most
audio mixers today have phantom power built into them as a standard
feature. Look for a phantom power switch on your mixer if your electret
mics are not working. Some have a switch on each channel. In cases
where a mixer used in a sound system does not have phantom power,
microphones can be powered from an external phantom power supply or
from batteries. Most electrets you will encounter will work with as
little as 9 volts. Some studio style mics often called "true
condensers" require as much as 52 volts, but most work with the 48
volts modern mixers supply.
Microphones are either directional or
omni-directional (all directions). Directional microphones (also called
cardioid for the rounded heart shaped pickup pattern) pick up sound
well from one direction and reject it from all other directions. The
standard pattern is about 120 degrees wide in front of the microphone.
A super- or hypercardioid mic will have a 90 to 100 degree pattern. The
"shotgun" mics used most often in news gathering have even tighter
patterns. Contrary to common belief, shotguns do not pick up sound from
farther away, they just block more of the off axis noise around the
mic. For the most part, directional mics are used in sound
reinforcement systems to reduce the possibility of feedback. Directional
microphones exhibit what is called proximity effect. The closer you get
to the head of the mic, the bassier and gutsier the sound becomes*.
Some singers and
rockin' preachers really like the effect and have come to count on it
to project "their" sound. The only exception are the ElectroVoice RE15
and RE20 "single-D" designed microphones.
Omni-directional microphones pick up
sound evenly from all around the mic element.Omni-directional
microphones are best suited for sound recording
systems where they are useful for picking up both the direct sound and
the effect of the room. They make lousy stereo mics because they pick
up everything and don't develop the audible directional cues that
create a stereo image. The tonal sound of an omni is usually more
natural. Because they pick up equally as well from the behind and in
front of the element, they are more susceptible to feedback and
discouraged in reinforcement systems. The only place we use
omnidirectional microphones are clip-on or earset wireless microphones.
Feedback is less of a concern because they are much closer to
mouth, lack of proximity effect makes them sound more natural, they
exhibit much less cable rubbing noise and head turning causes
much less level variation.
knows it those are words. They ought to be.