General:
|
The closer the microphone is to the sound source the better it picks up
that particular sound or voice. Walls and other surfaces can reflect sound into the
microphone. |
Omni-directional Microphone:
|
Picks up sound about equally from every direction. Often preferred
in a good acoustic environment due to their ease of use and normally better at
resisting wind noise and handling noise. Also less prone to "popping" caused by
consonants "t", "p", and "b". |
Directional (Cardioid) Microphones:
|
Picks up sound best from the front, while tending to lessen sound pickup
from other directions. Can suppress unwanted noise and reduce the effects of
reverberation |
- XLR output connector
- Balanced Microphone Line.
-
- 1/4" phone plug
- Unbalanced Microphone Line.
|
Balanced lines are much less susceptible to RFI
(Radio Frequency Interference) and the pickup of the other electrical noise and hum.
The shield of the cable is connected to ground, and the audio signal appears across
the two inner wires which are not connected to ground. It is possible to wire a low impedance microphone directly to an
unbalanced low-impedance input with short cable runs, but if longer cables are used, the
noise-cancelling benefit can be lost and a balanced input is preferred.
If high-level sound is creating distortion, before blaming the microphone, try
inserting an attenuator between the microphone and its input. |
Feedback:
|
Sound is picked up by the microphone, amplified then re-amplified
again. Eventually the system starts howling until the volume is reduced. The
directional microphone can be aimed to minimize pickup of extra sound or when sound comes
from a single direction.
Distance is also a factor. Moving the microphone to lengthen the acoustic path to the
loudspeaker can often reduce feedback. Bringing the microphone closer to the intended
sound source will also help.
The microphone should always be located behind the speakers.
|
Multiple Microphone Interference:
|
When the same sound arrives at two different microphones at
different times causes destructive wave interferences results in not only poor audio
quality, but often feedback problems as well. Minimum distance between the two
microphones should be at least a 3:1 ratio.
|
- Single Microphone
- Interference:
|
Sound is reflected off a nearby surface and arrives at the microphone
slightly after the direct sound. First, try putting the microphone closer to the sound
source. Second, move the microphone farther from the reflective surface. Third, use a
microphone specially configured to be placed extremely close to the reflective surface
(table). |
Dynamic microphones:
|
Rugged and reliable. No batteries or external power needed. Output
level is high enough to work directly into most microphone inputs with an excellent
signal-to-noise ratio. They need little or no regular maintenance, and with reasonable
care will maintain their performance for many years.
|
Condenser microphones:
|
Preferred for their uniform frequency response and ability to respond with
clarity to transient sounds. The low mass of the membrane diaphragm permits extended
high-frequency response, while the nature of the design also ensures outstanding
low-frequency pickup. The resulting sound is natural, clean and clear. |
