baffle The front surface of a loudspeaker, on which the drivers are mounted.

balanced cable A cable that carries a balanced signal on three conductors. Contrast with unbalanced (or “single-ended”) cable.

balanced output A connector on some A/V products that presents the audio signal on three conductors ,rather than the two conductors of an unbalanced output. Balanced outputs appear on XLR jacks. Found only on high-end products.

banana jack A small tubular connector found on A/V receivers and power amplifiers for connecting speaker cables terminated with banana plugs.

banana plug A common speaker-cable termination that fits into a banana jack.

bandwidth In audio, the range of frequencies that a device can processor pass; the human ear has a bandwidth of 20Hz–20kHz. In radio and television transmission, the range of frequencies occupied by one channel of information; a television broadcast channel occupies a band of frequencies 6MHz wide. In digital, the maximum bit rate a system is capable of conveying; the bandwidth of a FireWire 400 connection is 400Mbps.

bass Sounds in the low audio range, generally 20Hz–200Hz.

bass extension The lowest frequency an audio system can reproduce. A measure of how deeply an audio system or loudspeaker will reproduce bass. For example, a small subwoofer may have bass extension to 40Hz. A large subwoofer may have bass extension to 16Hz.

bass management A combination of controls and circuits in an A/V receiver or controller that determines how bass frequencies are distributed among the loudspeakers.

bass reflex A speaker with a hole or slot in the cabinet that allows sound inside the cabinet to emerge into the listening room. Bass-reflex speakers have deeper bass extension than similarly sized speakers with sealed cabinets, but that bass is generally less tightly controlled.

below black Information in a video signal that falls below the technical threshold of black, 7.5 IRE. Some DVD players pass signals that are below black; others do not.

bi-amping Using two power amplifiers to drive one loudspeaker. One amplifier typically drives the woofer, while the second drives the midrange and tweeter.

big screen A large-screen direct-view television or rear-projection set. Usually reserved for sets with diagonal dimensions greater than 40 inches.

binding post A connection on receivers and power amplifier for attaching loudspeaker cables.

bipolar speaker A speaker that produces sound equally from the front and the back. Unlike the dipolar speaker, the bipolar’s front and rear soundwaves are in phase with each other.

bit rate The number of bits per second transmitted by a digital audio or digital video signal. For example, the bit rate of Dolby Digital is 384kbs (384,000 bits per second) or 448kbs. MPEG-2 video encoding produces a digital video signal with a variable bit rate that averages about 3.5Mbs (3.5 million bits per second). Higher bit rates translate to better audio and/or video quality.

bi-wire Connecting a loudspeaker to a receiver or power amplifier with two runs of cable to each of the positive and negative terminals. Possible only with speakers featuring two pairs of input terminals. Bi-wiring results in better sound than single-wiring.

black drop The black masking area above and below a screen used with a front-projection system.

black level Technically, the video level that produces black in a video display. Commonly, “black level” refers to a video display’s ability to present the color black as truly black and not as dark gray.

Blu-ray Disc New optical disc for-mat that can store 50GB on a dual-layer disc the size of a DVD. Competing with HD DVD to be the high-definition replacement for DVD.

BNC jack A type of connector used in high-end consumer and professional A/V equipment. Used primarily for RGB and component-video signals.

bridging Amplifier-to-loudspeaker connection method that converts a stereo amplifier into a monoblock power amplifier. One amplifier channel amplifies the positive half of the waveform, the other channel amplifies the negative half. The loudspeaker is connected as the “bridge” between the two amplifier channels.

brightness In audio, an excessive amount of treble that adds a shrillness to the sound. In video, the amount of light generated by a video display device.

brightness signal More correctly called “luminance” and represented by the letter Y, the brightness component of a video signal contains all the black-and-white information. A complete color-video signal is a combination of luminance and chrominance (color information).

burn-in Technically called “differential phosphor aging.” Phenomenon that occurs in phosphor-based video displays (CRT and plasma) in which static images displayed on the screen for long periods cause that static image to be permanently superimposed on the screen.