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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