AC

Alternating Current - Voltage that alternates from positive to negative in regular or irregular cycles. This type of voltage flows back to its source

AC-3

Audio Coding 3 - Dolby's digital audio data compression algorithm adopted for HDTV transmission and used in DVDs, laserdiscs and CDs for 5.1 multichannel home theater use and automotive surround application.

Acoustical Energy

Energy consisting of fluctuation waves of pressure called sound waves.

Acoustics

A science dealing with the production, effects, and transmission of sound waves through various mediums.

Acoustic Coupling

The interaction between two or more speakers stacked together in a PA system which may produce a sound different to (and often better than) the sound produced by the individual speakers.

Acoustic Feedback

Howl or whistle caused by the recirculation of acoustic output of an amplifying system. In a hearing aid the sound emanating from the receiver may reach (or feed back into) the microphone and be reamplified until it builds up into a high-pitched whistle.

Acoustic Suspension-Enclosure

A speaker construction alternative in which a sealed enclosure traps air to serve as a spring-like return and damping mechanism.

Active Crossover

An analog or digital device performing high-pass, low-pass and bandpass functions ahead of power amplifiers driving the transducers in a loudspeaker.

Active Display

A step-up display feature that generates animated patterns for both segment and dot matrix LCDs that proceed the sequential display of information such as clock, Custom File titles and radio station frequencies.

Active Servo Control

Technology for CD and MD players. A circuit which monitors tracking and focus functions, among others, and actively adjusts those functions for optimal performance.

Adaptive Reception

A circuit that provides adjustable delay such that the time at which a sound wave from various signal channels can be changed. This allows synchronization for each channel of a multi-channel output device, so sound waves from multiple speakers will arrive at the same time to a single point in space.

ADS

Advanced Digital Servo — A combination of new RF amp and DSP designs—boosts the signal of the reflected light by about four times and makes CD-RW readable just like CD and CD-R.

Advanced MOSFET OFR

A high-performance, amplifier power supply design that can efficiently provide the power needed by the amplifier, while running cool. Advanced MOSFET OFR power supplies are used in JBL mobile audio amplifiers to allow maximum headroom and drive difficult loads.

AGC

Automatic Gain Control Provides optimal reproduction of CD's by tightly controlling the player's tracking of the audio data.

AGLR

"Anti-Glare, Low Reflection Coated Screen"

AIFF

Audio Interchange File Format - a common format for storing and transmitting sampled sound, developed by Apple Computer and the standard audio format for Macintosh computers. Files are 8-bit mono or stereo and generally end with a .AIF or .IEF extension. Normal AIFF does not support data compression so files tend to be large, but another format called AIIF-Compressed (AIFF-C or AIFC) does support compression.

Alternating Current

An electric current that periodically reverses its direction. The standard current used by utilities in the U.S. is 60 cycles per second; in Europe and other parts of the world it is 50 cycles per second.

Alternator-Whine

A siren-like high pitch sound that appears as the rpm of an engine increases. The noise is usually the result of a voltage differential created by more than one ground path or a poor ground path to the affected equipment.

Ambience Synthesizer

A unit that produces an artificial ambience pattern; one that is used to create the impression of the listener and/or performer being in a particular performance space.

Ammeter

An instrument used for measuring the amount of current flowing in a circuit

Amperage

A unit of electrical current. The force through which the energy is pushed through a conductor. Measured in amps; Ohm's Law symbol is I.

Ampere

The unit of measurement used to determine the quantity of electricity flowing through a circuit. One ampere flows through a 1 Ohm resistance when a potential 1 Volt is applied.

Amplification

An increase in signal level, amplitude, or magnitude.

Amplifier

A device that strengthens or enlarges an electrical signal.

Amplifier Classes

There are different classes of amplifiers, depending on how the biasing of the amplifier circuit is done. Audio power amplifiers are classified primarily by the design of the output stage. Classification is based on the amount of time the output devices operate during each cycle of signal swing. Also defined in terms of output bias current, (the amount of current flowing in the output devices with no signal).

Amplitude

The measure of how powerful sound waves are in terms of pressure.

Amplitude Modulation

A method of modulation in which the amplitude of the carrier voltage is varied in proportion to the changing frequency value of an applied (audio) voltage.

AMPS

(Advanced Mobile Phone Service - The cellular system used in the U.S., as well as a number of other countries.

AMS

Automatic Music Search - A feature that allows a CD or cassette mechanism to skip forward or backwards to another track.

Analog

An electrical signal in which the frequency and level vary continuously in direct relationship to the original acoustical sound waves. Analog may also refer to a control or circuit which continuously changes the level of a signal in a direct relationship to the control setting.

Analog Switch

A hardware-oriented switch that only passes signals that are faithful analogs of transducer parameters.

Anechoic Chamber

A special room that is constructed without acoustically reflective surfaces, such that it is without echoes, or an-echo-ic. This experimental setup enables engineers to more precisely measure the acoustical properties of many types of equipment. A real life anechoic situation is experienced by skydivers. However, they may be a bit distracted from the experience by the approaching ground.

Anode

The electrically positive pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and a negative pole; these are known as the anode and the cathode.

Antenna

A mechanical device, such as a rod or wire, which picks up a received signal or radiates a transmitted signal.

Apex Off-Axial Tweeter

Coaxial speaker design where the tweeter is located in the base of the woofer cone. Apex mounting equalizes signal path length differences of all frequencies handled by the speaker. This ensures all frequencies reach the listener's ear at the same time and improves stereo imaging.

Aquaplas

A water based compound high in particulates which is used to adjust the mass of, and to add damping to, a variety of loudspeaker diaphragm materials.

ASL

Automatic Sound Levelizer - Pioneer Technology, which uses a microphone to adjust receiver's volume automatically to compensate for changes in road noise levels.

Aspect Ratio

Aspect Ratio refers to the relationship between width and height on a TV or LCD Screen. E.g.. a 16:9 Aspect Ratio means that for every 16 inches of width there are 9 inches of height. This aspect ration is commonly called Widescreen.

ATA

Automatic Tuner Activation - A feature that allows the tuner to be accessed while a tape deck is rewinding or fast forwarding.

ATRAC

Adaptive Transform Acoustic Coding - The process used in MiniDisc that utilizes psychoacoustic principles to limit quantization noise and reduce the data quantity from 16 bits to 4 bits by using non-uniform frequency and time division.

Attenuate

To lessen the amount of force, magnitude, or value of something.

Audio

1. Of, or relating to, humanly audible sound, i.e., audio is all the sounds that humans hear. 2. a. Relating to the broadcasting or reception of sound.
b. Relating to high-fidelity sound reproduction.

Audio Frequency Spectrum

The band of frequencies extending roughly from 20 Hz to 20 kHz.

Audio Oscillator

A device that produces tones at specific frequencies for testing either equipment or entire systems.

Audio Signal

An electrical representation of a sound wave in the form of alternating current (AC) or voltage.

Auto EQ

Pioneer Technology. This system uses a microphone to automatically calibrate a flat frequency response for your vehicle. This can make a dramatic improvement in the sound quality of your system. Systems with Auto-EQ actually have TWO equalizers, the Auto-EQ sets the system to a flat response, then additional equalizer adjustments can be made using the built-in preset EQ button, or custom make your own setting.

Auto Memory

A tuner feature that automatically finds the strongest stations in the local area, and places them in preset memories.

AWG

American Wire Gauge - A standard for measuring the diameter of wire commonly used in electrical circuits. The higher the AWG number, the smaller the thickness of the conductor. For power carrying, choose lower numbers; for signal only wires, choose a higher number.