ABSORPTION
   The ability of a room to take up or absorb the acoustic energy radiated within it. There are many types of absorption, since it can be frequency dependent. There are certain materials such as acoustical ceilings that may absorb more high frequencies than lows, such as acoustical ceilings. Diaphragmatic absorptions (caused by loose wall panels or cavities behind the panels) that cause certain low frequencies to be absorbed.
AC MAINS
   110-120 Volts alternating current (60 Hz) (what you plug your power cord into.)
ACOUSTIC
   Relating to, containing, producing, arising from, actuated by, or carrying sound. Pertaining to the act or sense of hearing, the science of sound, or the sound heard.
ACOUSTICAL
  Sound or properties of sound; the acoustical response of a room has to do with the way that room responds to sound.
ACTIVE
  A type of electronic circuitry that can increase the gain or amplitude of a signal. Active gain controls. Active Equalization. Active Direct Boxes. Active Crossover.
AMPERE
   Named after Andre Ampere (1775-1836), French scientist. A unit of measurement of electrical current (I). One amp of current represents 6.28I8 x 10 electrons flowing past a given point in one second, and is equal to one coulomb.
AMPLIFIER (AMPL)
   A device capable of increasing the gain (magnitude) or power level of a voltage or current that is varying with time (frequency), without distorting the wave form of the signal. The amplifier is, just as the word implies, a signal amplifier. The incoming signal from any program material source is far too weak to power a speaker system. The role of the amplifier is to take that weak signal and strengthen it to the necessary power level to operate the loudspeakers with minimal distortion.
ANALOG
   A physical variable which remains similar to another variable in so far as the proportional relationships are the same over some specified range. The electrical signal produced by a microphone is an electrical analog of the acoustic sound that the microphone is reproducing. The continuous electrical signal that the microphone produces varies in voltage and frequency as a direct correlation to the nonelectrical acoustic information impressed on the transducer. The electrical signal is analogous to the acoustical sound that the microphone reproduces, i.e., the voltage that the microphone produces is the electrical analog of the acoustic sound source.
ANECHOIC
   Refers to a room in which all surfaces are lined with acoustic absorption material to such an extent that the room absorbs sound energy instead of reflecting it around the room (no echo). A room that offers nearly total absorption is called an Anechoic Chamber and must be quite large in order to accommodate low frequencies.
ATTENUATION
   The reduction in level of a signal.
AUDIO CHAIN 
   The order of sequence for connecting audio components, i.e., microphone, preamplifier (mixer), effects device, graphic equalizer, crossover, amplifier, and speaker.
AUDIO RANGE 
   20 Hz to 20,000 Hz. (Twenty cycles per second to twenty thousand cycles per second). The frequency response spectrum of human auditory perception.
AUX INPUT
   An auxiliary input that serves as a straight connection to a signal BUS (for instance: Monitor Aux input is an Aux input to the monitor BUS.)

BAFFLE
   The panel on which the speaker is mounted within the speaker enclosure. The term derives from its original use in preventing or baffling the speaker's rear sound waves from interfering with its front waves.
BALANCED CABLE
   A pair of wires surrounded by a braided shield.
BALANCED LINE
   A transmission line consisting of two conductors plus a braided shield, capable of being operated so that the voltages of the two conductors are equal in magnitude (voltage) and opposite in polarity with respect to ground. A balanced line offers common mode rejection or cancellation by attenuation, signals are electromagnetically induced into the signal lines.
BANDPASS
   Refers to a type of filter that passes a certain band of frequencies uniformly and attenuates, or reduces, the level of frequencies below and above the specified bandpass.
BANDWIDTH
   Response characteristic in which a definite band of frequencies, having a low frequency and high frequency limit, are transmitted or amplified uniformly.
BASS REFLEX
   A type of speaker enclosure in which the speaker's rear sound wave emerges from a critically dimensioned auxiliary opening or port to reinforce the bass tones.
BIAMP
   Separating the audio spectrum into two bands, i.e., high frequencies (high pass) and low frequencies (low pass) by means of an electronic crossover, using two separate amplifiers or channels of an amplifier; one amp or channel is used to amplify and project the high pass signals (high frequencies) from the high frequency component or horn of the speaker system and the other amp or channel amplifies the low pass signals (low frequencies) and projects them from the woofer or low frequency component of the speaker system, resulting in increased headroom and dynamic range.
BOOST
   A term used to indicate an increase in gain of a frequency, or band of frequencies, when equalizing an audio signal. Opposite of cut.
BRIDGE MODE(Mono)
   Operating a stereo amplifier in mono via the bridge mode switch, which then makes Channel A output the positive power rail and Channel B output the negative power rail. Since the signal swings between A and B Channels, the output of the amplifier is twice that of single channel operation.
BRIDGING
   Connecting one electrical circuit in parallel with another. Example: Paralleling power amplifier inputs.
BUS
   A conductor that serves as a common connector to several signal sources, most often associated with a mixer. A separate signal routing to a specified output.
CAPACITOR
   A device which consists essentially of two conductors (such as parallel metal plates) insulated from each other by a dielectric (a material in which an electric field can be sustained with a minimum dissipation in power) and which introduces capacitance into a circuit, stores electrical energy, blocks the flow of direct current (DC), and permits the flow of alternating current (AC), to a degree dependent on the capacitor's capacitance and the current frequency.
CARDIOID
   A type of microphone having a heart shape pickup pattern that picks up sound better from the front (on axis) than back (off axis).
CLIPPING
   Amplifier overload causing a squaring off or undesirable change in the wave form, resulting in distortion or perceptible mutilation of audio signals.

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