Microphone Selection Guide
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One of the most important decisions you will make for your sound is choosing the right microphone. With so many different microphones available, this choice can be a chore unless you know what to look for. The basic information we've provided below will help.

Types of Microphones: Dynamic and Condenser
Dynamic microphones are the most popular and widely used as they are economical, hardwearing, and supply their own power. They are proven all-purpose microphones with exceptional performance.

Condenser (or Electret) microphones are well known for their high sensitivity to sound making them preferable for high quality studio recordings and special applications such as speech, music or overhead choir installations. These microphones also require power from an outside source such as batteries or a mixing console to operate-this power is known as phantom power. Unlike the dynamic microphone, a condenser mike does not make its own voltage and will not work without phantom power.

What is Phantom Power?
Phantom Power is a method of power for condenser microphone circuitry. This power adds a phantom voltage (usually +48V) generated from mixing consoles, mic preamplifiers, batteries, or in-line phantom power supplies. You may use any one of these depending on which one your condenser microphone requires.

Microphone Pickup Patterns
A Microphone Pickup Pattern identifies how your microphone picks up sound for amplification. The figure below illustrates some of the more popularly applied pickup patterns being used.

Microphone Frequency Response
A frequency response measures how well a microphone picks up different sound frequencies. Most provide a wide-ranging response that allows the microphone to respond well with most any application.

Wired Microphone Connectors (Cables)
There are two ways to connect a microphone to your equipment: either an unbalanced line (¼" jack or 3.5mm plug), or balanced line (usually XLR).

When connecting microphones and sound equipment together, make sure the inputs and outputs have a matching voltage level. There are two important voltage levels to remember; microphone level and line level.

Microphone level - This is the output voltage of microphones. It is a very small voltage of one millivolt (.001 volt). A microphone level output must be routed to a microphone level input.

Line level - This is the interconnecting voltage level of devices such as CD players, tape decks, audio mixers, and most all other non-microphone audio equipment. This voltage is one volt (1 volt). A device that is not a microphone uses a line level connection. Line level inputs and outputs are also called auxiliary inputs and outputs. A line level output MUST be routed to a line level input!

FYI - Speaker output should never be confused with mic or line level. Speaker output levels can be very high, so ONLY connect speaker inputs to a speaker output!

Microphone and Line Level Mixing
An audio mixer will usually have both microphone level and line level inputs. This is how Microphone level and line level devices may be combined into a single audio signal. A mixer allows the level of each input to be controlled individually.

Wireless Microphones
One of the most obvious advantages of integrating a wireless microphone system into your sound is that you have the freedom to move about without the distraction or limitation of a microphone cable. And as always, with new and ever-improving technology, there can be some challenges, such as whether to go UHF or VHF, and making sure your wireless systems won't interfere with one another.

A wireless microphone delivers audio to a sound system without using an interconnecting cable. This is done with a transmitter (handheld, lavalier, or headworn microphone) that sends a signal to a receiver. The transmitter and receiver are on the same frequency. Most wireless receivers will output either microphone or line level signals.

Wireless Range-Don't Be a Dropout
The more open the "line of sight" between your receiver and transmitter, the better. Obstacles such as walls or floors may produce a condition known as "drop out." A drop out is a momentary loss of signal at the receiver's antenna. The loss of a signal can also be caused by a reflected signal canceling the primary signal.

True Diversity Wireless Systems
True diversity systems use two antennas. A wireless microphone using a "true diversity" antenna system is less likely to have a signal drop out. This is because these antennas are constantly switching back and forth, looking for the strongest signal. If the signal is weak at one antenna, chances are it will be stronger at the other antenna. The receiver always uses the antenna with the stronger signal.

Wireless Frequencies
Wireless microphones are assigned (by the FCC) to use both VHF and UHF frequencies. Many of these frequencies are co-shared with television station frequencies. Therefore, if you have a local TV channel 8 station, you cannot use a frequency that would fall inside the channel 8 frequencies. You'd pick another frequency such as channel 12 or 7 frequency.

In some large public address situations, it is not unusual to have anywhere from five to ten wireless systems on at the same time. However, it is important to note that you cannot have two wireless microphones operating on the same frequency at the same time. They will only cancel each other out and send a distorted signal to the receiver.

If your receiver offers more than one wireless operating channel, such as a dual-channel or a four-channel receiver, each transmitter should be paired its own frequency within that receiver.

Good Wireless Sense
Below are some wireless "tricks of the trade" which will help optimize wireless performance as well as avoiding potential problems.

1. Make sure there are no transmitters (microphones) any closer than 10-15' from your receiver's antenna.
2. Make sure you have the correct distance between your receiver's antenna (check/read product literature).
3. Make sure your microphone or bodypack has good batteries -low batteries can cause the mic to produce interference.
4. If you have a combination system, (handheld and bodypack sharing the same frequency) make sure you only have one turned on at a time.

Boundary Microphones/Piano
When you set the stage for concerts or theater, you don't want microphones to get in the way of performance. Boundary microphones are designed for fixed-install mounting in a wall, ceiling, stage floor, tabletop or podiums. They lie flat and usually contain a more sensitive condenser transducer element.

Because of their high sensitivity, boundary microphones will pick up sound without having to be in close proximity. They are low-profile and made for a variety of sound reinforcement applications.

Pianos are percussive instruments. They provide the widest range of musical tones with a wide range of dynamic capability than any other acoustical instrument. To preserve and amplify that robust sound, usually only one boundary microphone is placed underneath the piano lid, two for stereo.

Podium Microphones
Although having a lectern almost guarantees all eyes will be in your direction, it doesn't guarantee all ears will hear and understand every word. The best way to provide clear, audible sound without having to raise your voice above normal levels is through amplification.

Choosing a lectern with a powered amplifier and mounted microphone is the easiest way to benefit without investing time and money putting together a whole sound system. Systems like these are complete, easy-to-use, and even give you the option to connect with existing sound systems for greater sound coverage.

"What if I already have a lectern without sound amplification?"
That's okay! There are many options available to help you equip your existing lectern with sound reinforcement. From mounting a podium microphone and powering it through an existing sound system, to providing an entire self-contained system.

Preventing Feedback
Feedback is an undesirable condition that occurs when amplified sound (usually from a speaker) is reintroduced into the microphone. The amplifier then tries to re-amplify the audio and it gets amplified over and over until all you hear is a loud squealing sound coming from the speakers. Careful placement of microphones and speakers can reduce feedback problems to a minimum.

First, always keep stage microphones behind the main house speakers, with the speakers directed out toward the audience. When a microphone moves in front of a speaker, it will pick up the sound being amplified and then "feed" that sound "back" through the amplifier, causing feedback.

Another feedback risk is placement and volume level of any on-stage floor monitors. Monitors help performers hear themselves, however, they are still speakers. Make any performer-requested level adjustments slowly and with caution while they are testing their microphone. With proper placement and level adjustment, you'll keep feedback to a minimum.

When feedback occurs, or begins to occur, NEVER place your hand over the top of the microphone. It's a natural reaction, however, this makes feedback worse. The fastest way to stop feedback once it starts is either turn the main level down, or better yet, turn down the level of the offending microphone. Then, you can gradually raise your levels and begin troubleshooting to find a suitable level adjustment.

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