Welcome to our Blog
(800) 267-5486

Tuesday, June 26, 2012

Microphone Instructions (Wireless, Handheld, Lavalier, Headset, Condenser)

All public address systems (PA systems) have three basic components.
1. Microphones
2. Speakers and 
3. Amplifiers
Download entire Wireless Sound System Setup Guide Here.

The microphone converts a sound source into electrical energy. In a presentation, that sound source happens to be you, the presenter! Microphones are relatively simple devices; however, there are a few factors to consider.

Handheld – Handheld mics are easy to pick up and use, they can be put down when you are done and they are easy to pack up at the end of your event. Unfortunately, they also keep you from using both hands and they are subject to some handling noise. People trained in microphone dynamics can be very effective with handhelds since the gain can be controlled and even the tonal quality of the sound varied by using the microphone in different ways.

Many directional microphones exhibit a phenomenon known as the proximity effect. When the mic is held very close to the mouth, the bass response dramatically increases. While this is good for singers and comedians, proximity effects can work against the presenter. Even so, the handheld mic is a popular choice for many presenters.

Wireless Handheld Microphone
Lavalier – This is a commonly used type of microphone. It clips on to the collar and is very small and very sensitive. They come in a wide array of styles and shapes. The lavalier mic leaves the presenters hands free and can be easily hidden under a lapel, if necessary. This makes these microphones popular with public speakers, motion picture production, television production, and church systems.

Headset – This type of mic is popular with auctioneers, aerobic instructors and broadcast announcers. The headset mic uses a boom to place the microphone very close to the lips.

By doing this, the user can get more gain from the microphone and the background noise is lower. This mic is the best bet for hands free public address usage such as auctioneering, coaching, announcing or aerobic instruction.

Around the neck mics – Many people will purchase a headset mic and wear it around their neck for comfort, while this may be more comfortable, there is a trade-off. Very few people keep their heads in one position while they speak, causing the mouth to constantly change distance from the microphone. Because the mouth is 1-2 inches from the mic in the closest position and several inches away when the head is turned to one side, the volume level rises and falls more dramatically. This can distract from the presentation. This is why you never see broadcast professionals use a headset mic in this way. If the comfort factor is important then careful attention to how you move may make the trade off worth it.

After deciding whether to hold or wear the microphone, the next step is selecting the pickup system.

Directional vs. Omni-Directional
All microphones have what is known as a pickup pattern. The pickup pattern is how the microphone “hears” sound. The pickup pattern can have a dramatic effect on the PA system, affected both intelligibility, (how understandable the speech is to the listener) and gain (how much amplification you can get from the system).

Omni-Directional Microphones
Omni-directional microphones pick up sound from all directions. Sounds coming from almost any direction will be picked up by the microphone. Generally speaking, omnidirectional microphones have a “flat” frequency response – they sound very normal, and they are resistant to wind and handling noise. However, they can add feedback problems to indoor settings, something we’ll discuss later in this manual. Most headset microphones are omnidirectional since they are so close to the mouth they have enough gain to avoid the feedback problems an omni-directional handheld would exhibit.

The Cardioid microphone picks up the sound more from the front than the sides and back of the mic. The pattern is heart shaped, hence the name “cardioid.” The microphone picks up sound from all directions.

Directional Microphones
Also called cardioid microphones, these mics tend to pick up sound from only one general direction. They help avoid feedback and interfering noises that many come from the rear and sides of the microphone. For example, at a livestock auction, a directional mic may help prevent the animals from “mooing” over the PA. Cardioid mics tend to sound higher pitched and need bigger windscreens to prevent wind noise.

Microphones are built with different sensing components called elements. The three most common are the dynamic, condenser and electret.

Dynamic Microphones
The dynamic mic is the simplest of all. In effect, it is very much like a speaker. Because of their simplified construction, they are durable, reliable and inexpensive. However, they are generally not as sensitive as the other types of elements.

Condenser Microphones
Condenser mics use a different construction involving a charged diaphragm vibrating near a
charged plate. They are much more sensitive because their internal parts are lighter in weight.
Since these pats are lighter, they can be moved around by sound more easily. The charged
parts require power, however, so the amplifier must provide “phantom” power. Phantom
power is provided by applying voltage to the microphone through the cable. Most condenser
Headset Microphone with Transmitter
mics require anywhere from 9V to 48V. This can restrict usage to wired operation only on some models. Their other drawback is lower durability. The higher sensitive of these mics makes it much easier to get more amplification from a lower sound level source.

Electret Microphones
Electret mics are a modified version of condenser mics. Instead of charging the diaphragm, they have a permanently charged plastic film diaphragm. Now only the other surface requires phantom power. Many require only 1.5V of power to work. Since the film is extremely light, these can be very sensitive. Advantages include good durability, very high sensitivity, extremely compact size and low power requirements, for example lavalier (tie-clip) microphones are electrets.

Wireless Microphones
Around the Neck Mic
Wireless mics are available in all of the variations discussed above. Basically, two additional components are added to the microphone, a transmitter and receiver. The transmitter translates the signal from the microphone into a radio signal. That signal is picked up by the receiver, translated back into an audio signal and sent into the amplifier. Eliminating the wire also eliminates the restrictions a microphone cable places on your ability to move about during the presentation.

[ Blog Posts: Presentation Tips ]