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Microphone Primer Audio is just important in video as the picture is and acquiring good audio sometimes requires just as much creativity. Hopefully this article will fill in some of the blanks that you may have with acquiring audio for video. Types of microphones. There are two basic types of microphones, dynamic and condenser. Dynamic mics are not powered and pickup sound by vibrating a diaphragm that is attached to a coil of wire that moves through a magnetic field. These mics are designed for short range sound pickup and tend not to be as good with higher frequencies, but are less likely to 'overload' with high sound levels. Dynamic mics are also more wind-noise resistant right-out-of-the-box than condenser mics, with the use of external foam and other wind canceling devices. Condenser mic requires power, either from an internal battery or through external 'phantom' power. This class of mic is usually more sensitive and much better at picking up higher frequencies and at greater distances. This is accomplished by an internal amplifier called a preamp. With the increased pickup, this mic is also susceptible to overloads with very loud sound. Although some more expensive models can withstand 130dB and more ithout clipping or distortion (live rock bands could be as loud as 120dB at the distance of a few feet). Within each of these two types of mics, there are many variations that designed for specific applications. Dynamic mics can be omni-directional (all directions) or uni-directional (single direction). Uses for these types of mics; interviews, mic'ing speakers/sound systems, anywhere the sound source is less than a couple of feet from the mic. Condenser mics, because of its electronics and smaller sound pickup element, are configured in many different ways to pick up sound. Cardioid, hyper-cardioid, figure 8, super cardioid and line + gradient are some of the pickup patterns that are available. Super cardioid and line+gradient mics are also known as shotgun mics, deriving their name from the length of the microphone and its similarity in looks to a weapon. Additionally there are PMZ or boundary mics and lavaliere mics and are variations of the condenser mic. So how do you determine what microphone to use for what purpose? Here are some quick guidelines. For interviews, PA, mic'ing amplifiers or anywhere else that requires ambient sound rejection or exposed to high sound levels, then a dynamic microphone is your best choice. For pickup of distant sound or extreme directivity, a shotgun or line + gradient (condenser) microphone is the choice. Lavaliere or lapel mics are the choice for mic'ing individuals, when you need individual control over sound levels or the person may be moving around or not always facing the microphone. (these can be wired or wireless). PZM or boundary mics modification of a condenser mic) are used for area sound pickup. Their pickup pattern is hemispherical, which means that it picks up the sound in a 360 degree pattern. These are used as stage mics or for panels and meetings. Short-shotgun or cardioid or super-cardioid mics are general purpose mics that have varying degrees of pickup and are the real workhorses of mics. Through their internal electronics, their sound is tailored to have a flat response (equally sensitive at all frequencies), although they tend to attenuate the lower frequencies somewhat (due to their smaller diaphragms). These are
the basic types of microphones and within these groups there are
many variations. Pickup patterns, frequency response and diaphragm
size all modify how a microphone works and how it sounds. Most
better microphones will suggest what they are designed for and
their best uses. Use this information as a guideline and experiment
with mixing microphone types to get the best sound. And like the
saying goes, 'you get what you pay for'. |
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