What is Phantom power?
Phantom power is a DC power source that feeds a microphone power through a standard microphone cable. It originates at the mixer, active splitter or an outboard phantom power supply. Microphones that don’t need phantom power should ignore it.

What is a Dynamic microphone?
Dynamic microphones use a diaphragm/voice coil/magnet assembly to generate the electrical signal. Sound waves strike the diaphragm which makes it vibrate along with the voice coil that is attached to the back of it. The voice coil is surrounded by a magnetic field that is created by a small magnet. When the voice coil moves in the magnetic field it generates the electrical signal corresponding to the sound picked up by the microphone.

What is a Condenser microphone?
Condenser microphones use a electrically-charged diaphragm/backplate assembly that creates a sound-sensitive capacitor. Sound waves strike the diaphragm which makes it vibrate. The diaphragm is mounted just in front of a rigid backplate. This assembly creates a capacitor which stores an electrical charge. When the space between the diaphragm and the backplate changes by the diaphragm vibrating it generates the electrical signal corresponding to the sound picked up by the microphone.

What is microphone directionality?
The directionality of a microphone is defined as the variation of its output when it is oriented at different angles to the direction of the sound. The two most common directional types are omnidirectional and unidirectional.

Omnidirectional microphones exhibits the same output regardless of its orientation to the sound source. This means the microphone is equally sensitive to sound coming from all directions. An omindirectional microphone can be used to pick up sound from a wide area, but cannot be “aimed” to favor one sound over another.

Unidirectional microphones is most sensitive to sound coming from only one direction. The most common type of unidirectional microphone is called a cardioid, because of its heart-shaped polar pattern. Cardioid microphones are most sensitive to sound coming from in front of the microphone.

What is STI?
STI (Speech Transmission Index) is a measure of how well you are able to understand the spoken word. STI values range from 0 = completely unintelligible to 1 = perfect intelligibility. On this scale, an STI of at least .5 is desirable for most applications.

STI	0 – 0.30	0.30 – 0.45	0.45 – 0.60	0.60 – 0.75	0.75 – 1
Intelligibility	unintelligible	poor	fair	good	excellent

What is reverberation?
Reverberation is the persistence of sound in a particular space after the original sound is removed. Reverberation is usually measured with an RT60 time. RT60 is the amount of time required for reflections of a direct sound to decay by 60 dB below the level of the direct sound. The RT60 value will vary based on the frequency of the sound.

What is the difference between LCD and DLP projectors?
LCD (Liquid Crystal Display) projectors usually contain three separate LCD glass panels, one each for red, green, and blue. When light passes through the LCD panels, individual pixels can be opened to allow light to pass or close to block the light. This activity is what creates the image that is projected onto the screen.

DLP (Digital Light Processing) is a proprietary technology developed by Texas Instruments. Instead of having glass LCD panels that light passes through it uses a DLP chip that has thousands of tiny mirrors on it. Each mirror represents a single pixel. The light from the projectors lamp is directed onto the surface of the DLP chip. The mirrors will move back and forth directing light either into the lens path to turn the pixel on, or away from the lens path to turn it off. There are typically two types of DLP projectors, single chip and three chip. Single chip projectors use a color wheel that contains red, green, blue, and sometimes clear. The color wheel spins between the lamp and the DLP chip to change what color the mirrors reflect. In three chip DLP projectors there is one DLP chip each for red, green, and blue.