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Sunday, November 20, 2011

Types Of Microphone

Condenser Microphone

The condenser microphone is a very simple mechanical system, with almost no moving parts compared with other microphone designs. It is also one of the oldest microphone types, dating back to the early 1900's. It is simply a thin stretched conductive diaphragm held close to a metal disk called a backplate. This arrangement basically produces a capacitor, and is given its electric charge by an external voltage source. This source is often phantom power, but in many cases condenser mics have dedicated power supply units. When sound pressure acts on the diaphragm it vibrates slightly in response to the waveform. This causes the capacitance to vary in a like manner, which causes a variance in its output voltage. This voltage variation is the signal output of the microphone. There are many different types of condenser microphones, but they are all based on these basic principles. The condenser mic generally has a flatter frequency response than the dynamic one. That is why you should choose a condenser mic when high accuracy and clarity of the recording is needed. For example vocals of almost any type, the acoustic guitar or any other acoustic instrument will be most accurately recorded with a condenser mic. Because of its construction the condenser mic is more sensitive to sound and also more physically fragile than a dynamic one, so it should be handled with care. Too hard handling ( a drop to the floor), too high sound pressure (screaming into it close up) can cause this type of microphone to stop functioning.

IMPORTANT!! If you choose a condenser mic you will need a preamp or a mixer that will provide phantom power or "phantom feed" of usually 48 volts. This is because the condenser mic needs electricity to operate. Most of the new preamps and mixers provide this, but if you're going to use a condenser mic be sure to check just in case.

Dynamic Microphone

A dynamic mic is one in which audio signal is generated by the motion of a conductor within a magnetic field. In most dynamic mics, a very thin, light, diaphragm moves in response to sound pressure. The diaphragm's motion causes a voice coil that is suspended in a magnetic field to move, generating a small electric current. Generally less expensive than condenser mics (although very high quality dynamics can be quite expensive), dynamics feature quite robust construction, can often handle very high SPLs (Sound Pressure Levels), and do not require an external power source to operate. Because of the mechanical nature of their operation, dynamic mics are commonly less sensitive to transients, and may not reproduce quite the high frequency "detail" other types of mics can produce. Dynamic mics are very common in live applications. In the studio, dynamics are often used to record electric guitars, drums and more. One example of a highly popular dynamic microphone is Shure’s hand held SM58.

The dynamic mic is usually more rugged . It can handle more rough handling, moisture and high sound pressure levels than the condenser. This is why live performers on stage and outdoors preferably use dynamic mics. It can also be used in your recording studio, but it's not well suited for recording soft vocals or acoustic instruments since its frequency response is much narrower than the condenser's. For rough and loud vocals like heavy metal vocals though, a dynamic mic might even be the only way to go since a condenser would only distort under the high sound pressure. This type of mic does not need any phantom power.

Ribbon Microphone

A type of velocity microphone. A velocity microphone responds to the velocity of air molecules passing it rather than the Sound Pressure Level, which is what most other microphones respond to. In many cases this functional difference isn't important, but it can certainly be an issue on a windy day. Very old ribbon mics could be destroyed from the air velocity created just by carrying them across a room; today’s ribbon mics can handle the rigors of daily studio use. A ribbon mic works by loosely suspending a small element (usually a corrugated strip of metal) in a strong magnetic field. This "ribbon" is moved by the action of air molecules and when it moves it cuts across the magnetic lines of flux causing a signal to be generated. Naturally ribbon mics have a figure 8 pick up pattern. You can think of it like a window blind; it is easily moved by wind blowing at it, but usually doesn't move when wind blows across it from left to right. Ribbon mics were the first commercially successful directional microphones.

USB Microphone

Probably one of the hottest developments in recent microphone technology has been the USB mic. Yet it's actually a fairly simple item to describe. A USB mic contains all the elements of a traditional microphone: capsule, diaphragm, etc. Where it differs from other microphones is its inclusion of two additional circuits: an onboard preamp and an analog-to-digital (A/D) converter. The preamp makes it unnecessary for the USB mic to be connected to a mixer or external mic preamp. The A/D converter changes the mic's output from analog (voltage) to digital (data), so it can be plugged directly into a computer and read by recording software.

Electret Condenser Microphone

type of capacitor microphone invented at Bell laboratories in 1962 by Gerhard Sessler and Jim West. The externally applied charge described above under condenser microphones is replaced by a permanent charge in an electret material. An electret is a ferroelectric material that has been permanently electrically charged or polarized. The name comes from electrostatic and magnet; a static charge is embedded in an electret by alignment of the static charges in the material, much the way a magnet is made by aligning the magnetic domains in a piece of iron. Due to their good performance and ease of manufacture, hence low cost, the vast majority of microphones made today are electret microphones; a semiconductor manufacturer estimates annual production at over one billion units. Nearly all cell-phone, computer, PDA and headset microphones are electret types. They are used in many applications, from high-quality recording and lavalier use to built-in microphones in small sound recording devices and telephones.

Though electret microphones were once considered low quality, the best ones can now rival traditional condenser microphones in every respect and can even offer the long-term stability and ultra-flat response needed for a measurement microphone. Unlike other capacitor microphones, they require no polarizing voltage, but often contain an integrated preamplifier that does require power (often incorrectly called polarizing power or bias). This preamplifier is frequently phantom powered in sound reinforcement and studio applications. Monophonic microphones designed for personal computer (PC) use, sometimes called multimedia microphones, use a 3.5 mm plug as usually used, without power, for stereo; the ring, instead of carrying the signal for a second channel, carries power via a resistor from (normally) a 5 V supply in the computer. Stereophonic microphones use the same connector; there is no obvious way to determine which standard is used by equipment and microphones. Only the best electret microphones rival good DC-polarized units in terms of noise level and quality; electret microphones lend themselves to inexpensive mass-production, while inherently expensive non-electret condenser microphones are made to higher quality.

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