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Attenuation – The decrease in amplitude of a signal.
Auxiliary channel (AUX) – A channel reserved for connecting an external audio and/or video device.
A/V – A/V is an abbreviation for Audio/Visual.
Balanced – A circuit having two sides (conductors) carrying voltages that are symmetrical around a common
reference point, typically ground.
CD+G – A specially formatted disc with additional sub-code (data) that is capable of displaying lyrics on video
screens for Karaoke systems. CD+G stands for Compact Disc + Graphics.
Clipping Refers to a type of distortion that occurs when an amplifier is driven into an overload condition.
Usually the "clipped" waveform contains an excess of high-frequency energy. The sound becomes hard and
edgy. Hard clipping is the most frequent cause of "burned out" tweeters. Even a low-powered amplifier or
receiver driven into clipping can damage tweeters which would otherwise last virtually forever.
Decibel (dB) Named after Alexander Graham Bell. We perceive differences in volume level in a logarithmic
manner. Our ears become less sensitive to sound as its intensity increases. Decibels are a logarithmic scale
of relative loudness. A difference of about 1 dB is the minimum perceptible change in volume, 3 dB is a
moderate change in volume, and about 10 dB is an apparent doubling of volume. 0 dB is the threshold of
hearing and 130 dB is the threshold of pain.
Delay Delay is a facet of the echo process. Delay refers to the amount of time that exists between echoes.
Digital Echo Digital echo is a synthetically processed sound effect that mimics natural echo. Echo in
general is the “bouncing” of waves back and forth between two surfaces. This effect gives a spacious or
ambient feeling that works great with vocals.
Enhancing Electronically adjusting the quality and sharpness of an audio signal.
Frequency The range of human hearing is commonly given as 20-20,000Hz (20Hz-20kHz). One hertz (Hz)
represents one cycle per second, 20Hz represents 20 cycles per second and so on. Lower numbers are lower
frequencies
Gain To increase in level. The function of a volume control.
Impedance The total of the resistive and reactive opposition, measured in ohms, that a circuit presents to
the flow of alternating current at a given frequency.
Input Selector A toggle switcher or auxiliary bus used to select through the available inputs of a given
device.
Line Level CD players, VCRs, Laserdisc Players etc., are connected in a system at line level, usually with
shielded RCA type interconnects. Line level is before power amplification. In a system with separate pre-amp
and power-amp the pre-amp output is line level. Many surround sound decoders and receivers have line level
outputs as well.
Line Voltage – The voltage level of the main power source to a device.
Midrange A speaker, (driver), used to reproduce the middle range of frequencies. A midrange is combined
with a woofer for low frequencies and a tweeter for high frequencies to form a complete, full-range system.
Glossary of Terms