4:3
Standard "square" screen size ratio of an NTSC TV -- four arbitrary units wide by three arbitrary units high; often expressed as 4 x 3 or 4 by 3. Known as the Academy Ratio prior to 1954, when the wide screen aspect ratio was introduced; referred to in the film world as 1.33:1. (See 16:9)

16:9
Sometimes expressed as 16 x 9 or 16 by 9 (known as 1.78:1 in the film world), it is DTV's standard wide screen television screen size, or aspect ratio -- 16 arbitrary units wide by 9 arbitrary units high, as compared to a standard TV aspect ratio of 4:3. The phrase describes the shape of a TV, not an actual measurement. (See aspect ratio)

480p
(480 progressive) Form of standard-definition television (SDTV) that is comparable to VGA computer displays; not considered high-definition television (HDTV), though it is discernibly cleaner and slightly sharper than analogue television. The native resolution of DVD's is 480p, but that resolution can be seen only with a DVD player that outputs a progressive-scan signal and a TV with progressive scan or component video inputs

5.1-channel surround
Surround sound system with three front and two rear speakers (the ". 1" is the sub woofer).

720p
(720 progressive) One of two formats designated as high-definition television in the ATSC DTV standard; 720 vertical pixels (dotted picture elements) by 1280 horizontal pixels. The "p" stands for "progressive," as opposed to interlaced scanning, which is used in 1080i, the other accepted HDTV standard. Contrary to myth, 720p is not inferior to 1080i; while 720p does have fewer lines; it has the advantages of progressive scanning, as well as a constant 720 vertical lines, making it better able to handle motion. (See interlacing, progressive scanning)

Acoustic suspension
Type of loudspeaker that uses an airtight sealed enclosure. Typically has more disciplined bass than bass-reflex designs. (See bass reflex)

Active sub woofer
Speaker that produces nothing but bass and which has a built-in amplifier. (See passive sub woofer)

Anamorphic
Adopted from the film technique of shooting a wide screen image on a square 35mm frame, it's the process of compressing wide screen images to fit into the squarer 4:3 television signal. The images are then expanded for viewing in their original format on a wide screen display device. Not all wide screen DVD's are so compressed. To fill a wide screen TV, a non-anamorphic DVD must be blown up, resulting in loss of resolution and detail. Conversely, a DVD that is anamorphic, or "enhanced for 16:9," delivers 33 percent more resolution than regular letterboxed transfers and does not need to be blown up on a wide screen set. An anamorphic DVD also looks better letterboxed on a "square" TV because it does contain greater resolution.

Aspect ratio
Relationship between the width and the height of an image. DTV's standard wide screen ratio is 16:9 (1.78:1), as compared to NTSC's squarer ratio of 4:3 (1.33:1). (See 16:9, 4:3, anamorphic, wide screen)

Auto convergence
Feature in rear- and front-projection TVs that automatically aligns the red, green and blue CRT projectors to create a clear picture.

A/V receiver
Home theatre control center that performs surround decoding, audio/video switching, audio preamplification, audio amplification, volume control and other functions. It's also the device to which other audio and video components are connected. Sometimes called a surround receiver.

Bass reflex
Most common type of loudspeaker system. Uses a vented (ported) enclosure, with a hole or port in the speaker that allows bass energy to vent out from the speaker, thereby enhancing the speaker's bass response. Typically offers deeper bass response than an acoustic-suspension speaker of similar size and construction. (see acoustic suspension)

Bipolar
Type of loudspeaker with drivers mounted on opposite sides of the cabinet, or speaker enclosure. Drivers move in and out together so they remain "in-phase.” Used as rear-surround speakers; better when placed closer to the listener. (See dipolar)

Biwire
Separate connections (usually to the woofer and tweeter) between an amplifier and a loudspeaker. Almost identical electrically to a single-wire connection, but considered by many audiophiles to offer an improvement in sound quality.

Biwired or biwirable
Loudspeakers with four rather than two binding posts, enabling separate connections to the woofer and tweeter.

Chrominance
Fancy name for the TV signal that carries the colour information -- red, green, and blue -- that's needed to produce a colour picture; often called chroma.

Component video
Elements that make up a video signal: luminance, which represents brightness in the image, and separate red and blue signals (expressed as either Y R-Y B-Y or Y Pb Pr). Component video is superior to both composite video and S-video because it provides improved colour purity, superior colour detail, and a reduction in colour noise and NTSC artifacts. ** Three-jack video output of a video device (such as a DTV set-top box or a DVD player), or the input of a DTV receiver or monitor to send/receive the luminance (Y) and two colour difference signals, each on a separate coloured RCA cable. Toshiba calls its component video ColorStream. (See composite video, S-video)

Composite video
Video signal combining luminance and chrominance, the burst signal and sync data (horizontal and vertical). Also, a direct video connection using an RCA-type plug and jack; it's superior to the RF type of connection but inferior to S-video and component video. (See component video, S-video)

Convergence
TV circuits that align the red, green, and blue electron beams to produce a colour picture. Misaligned beams degrade quality, causing colours to bleed. ** User-defined adjustments, usually on rear or CRT front projectors, of the red, green, and blue electron beams; often called digital convergence. It's unnecessary on DLP or LCD projectors. ** Term used to describe melding of disparate technologies into single product concepts, such as the "convergence" of the TV and the personal computer. (See DLP, LCD)

D-ILA
(Digital-Image Light Amplifier) High output digital projection TV technology that's used for front- and rear-projection TV systems in both a home and a theatre. (See DLP)

Dipolar
Loudspeaker with drivers mounted on opposite sides of the cabinet or speaker enclosure; the drivers are wired out of phase (usually above about 500 Hz) so that they that move in and out in opposite directions. This design is used in many rear-surround speakers to create a completely non-directional sound field. Electrostatic and ribbon loudspeakers are also considered to be dipolar, because they radiate sound to the rear that is out of phase with the sound radiating to the front. (See bipolar)

DAC
(digital-to-analogue converter)Built-in or external device that converts the digital signal from a CD or other digital source into an analogue signal, which can then be reproduced by an analogue audio system.

DLP
(Digital Light Processing) Type of high-resolution front- and rear-projection TV system invented by Texas Instruments in the mid-1990s.A DLP projection system consists of a light source, up to three tiny Digital Micromirror Devices (DMD), a projection lens, and a cooling system, and is capable of projecting bright, movie-theatre-sized images. DM (digital mono) Single channel of digitally recorded audio usually on remastered movies on laserdisc.

Dolby Digital
Formerly known as AC-3, a digital multichannel surround sound technology developed by Dolby Laboratories to encode films for theatres and home video; it uses lossy compression technology to compact the digital audio soundtrack. Dolby Digital is the standard sound format on all DVDs and in DTV broadcasting. In typical home theatre settings, Dolby Digital is a 5.1-channel system with three speakers in front and two speakers in the rear (the ".1" is the subwoofer). Dolby Digital decoders are built into most A/V receivers, A/V preamps and surround processors. Unlike its analogue 4-channel predecessor, Dolby Pro-Logic, Dolby Digital provides full separation in the two rear-surround speakers.

Dolby Digital Surround EX
(DDS-EX) Variation of Dolby Digital surround sound in which the basic 5.1 discrete speakers are augmented with a sixth speaker in the rear-surround center. The signal feeding this additional speaker is derived (or "matrixed") from the rear-surround left and right channels, so the number of channels remains at 5.1.Originally intended for movie theatres, DDS-EX is a controversial "feature" of Dolby Digital. (See Dolby Digital)

DTS
(Digital Theatre Systems) Film and video surround system that incorporates 5.1 channels. Its proponents say it has a warmer, more natural sound than its main rival, Dolby Digital. It can be built into an A/V receiver or A/V preamp, or purchased as a separate surround processor. DTS is well supported by hardware makers but not by software labels, and it's available on only a few DVD and CD titles. (See Dolby Digital)

Dual-tuner picture-in-picture (PIP)
TV with a second channel selector allowing the display of a separate signal in an inset window; standard PIP requires the connection of a second tuner, normally from a VCR.

DVD
(digital video disc) Video disc format that provides at least 135 minutes of compressed digital video and hi-fi/surround sound audio on each layer of a 4.5-inch, CD-sized disc. (See DVD-Audio)

DVD-Audio
Format for high-resolution audio-only version of DVD that's capable of 96 kHz/24-bit sound reproduction, compared to standard 44.1 kHz/16-bit CD. Includes Meridian Lossless Packing to achieve greater storage capacity. Pre-2000 DVD players and discs with stereo 96/24 capability are not necessarily fully compatible with DVD-Audio. (See SACD)

Field
Half of a TV picture. In analogue television, an interlaced scanning system produces a full frame (still image) from two fields. First all the odd-numbered scanning lines fill the screen from top to bottom, constituting a single field. Then the even-numbered scanning lines fill in the gaps, adding a second field to complete the frame. There are 60 fields (and 30 full frames) per second in U.S. analogue (NTSC-standard) television.

Front-projection
Type of TV in which the picture is projected like a movie onto a reflective screen. Some front-projection sets often are capable of producing an image measuring more than 12 feet diagonal. The larger the picture, the more visible the pixels or scan lines, and the darker the image. CRT-type uses three tubes (red, blue and green); LCD and DLP types use a single projection lens. (See D-ILA, DLP)

Flat-panel TV
Video display, usually a DTV monitor (with no tuner or channel selector), typically using gas plasma or LCD technology to produce a picture with dotted vertical and horizontal pixels, or picture elements.

Flat square tube
Television picture tube that is flatter (though not perfectly flat) than conventional tubes. It is less convex and appears flatter than a standard TV screen; it's also squarer than conventional tubes and its sides are less likely to be curved.

HDTV
(high-definition television) High-resolution digital television broadcast and playback system composed of roughly a million or more pixels (picture elements), 16:9 screens and digital audio. (See DTV, SDTV, 480p, 480i, 720p)

infrared
Thermal radiation of wavelengths that are longer than those of visible light. Portion of the light spectrum that can be broadcast in pulses. Used in remote controls to transmit function-specific codes to equipment.

LCD
(liquid crystal display) Display system used on many electronic products including clocks, answering machines, handheld organizers, camcorders and personal computers. Liquid crystals are sandwiched between two glass plates. Minor temperature variations are introduced to particular points in the display using pinpoint electric charges, illuminating the crystals or causing them to change colours in predetermined patterns.

LCD TV
Television that employs a liquid crystal display screen rather than a cathode ray tube; used primarily in portable video equipment, small, personal TVs and front projectors; but being developed for larger, direct-view displays. An LCD projector uses a lamp to shine light through liquid crystal panels, then through mirrors and lenses to the screen. (See LCD)

LCR
(left/center/right) Abbreviation/acronym for the front three speakers in a home theatre sound system.

Learning remote
Type of universal remote control that can "learn" IR codes from other remote controls, usually one button at a time. (See pre-programmed remote)

Letterboxed
A movie on DVD, laserdisc or videotape that is presented in its original theatrical widescreen aspect ratio. The film is shown with black bars above and below the picture area to create the wider theatrical image. (See anamorphic, aspect ratio)

Lines of resolution
Method of comparing the relative amount of detail in a television picture, usually measured by counting the number of horizontal lines that can be reproduced from top to bottom. Not the same as the scanning lines that form the picture -- lines of resolution are produced by the scanning lines -- although the two may be the identical number. DVD has 480 lines of resolution (this is one case in which lines of resolution and scanning lines are the same number). In analogue television, which has 525 scanning lines, lines of resolution vary: S-VHS and Hi8 have between 380 and 400 lines. Analogue broadcast television has about 330 lines of resolution, cable about 300. VHS and 8mm have 240 lines.

Luminance
Black signal portion of a television transmission that controls brightness of the red, green, and blue proportions in a television picture. The standard luminance setting in a picture is 30 percent red, 60 percent green, and 10 percent blue. These percentages are adjusted to produce varying colours, grays, whites, and blacks.

Magnetically shielded
A type of loudspeaker in which the electromagnetic field created by the driver magnets -- which can discolour a TV picture and potentially ruin a tube -- is contained. The field can be contained with a metal can around the magnet, with a "bucking" magnet that counteracts the driver magnet's field, or with both. Any speakers used in a home theatre system, especially those placed near a TV, should be shielded. Rear-projection TVs are less susceptible to electromagnetic interference from an unshielded speaker because the RPTV picture tubes are positioned deep inside the set, near the bottom.

Monitor/receiver
Video monitor with a built-in TV tuner and at least one speaker; high-end synonym for a TV set.

NTSC (National Television Standards Committee)
FCC engineering committee formed in 1940 to develop technical standards for black and white television (NTSC broadcasting began July 1, 1941), colour television (1953); video transmission standard used in the western hemisphere, Japan, and other Asian countries. NTSC standards are 525-lines of resolution transmitted within a 6 MHz channel at 30 frames per second.

Outboard D/A converter
A separate component that performs digital-to-analogue conversion, often higher quality than a digital-to-analogue converter built into a digital audio device. (See DAC.)

Oversampling
Process in many CD players and other digital reproduction devices or systems of sampling the digital waveform at two, four, or eight times the standard rate to filter out distortion.

Pan and scan
Technique used to view a widescreen film on a standard TV set. During film-to-video transfer, the widescreen frame is adjusted slightly to the left or right depending on where the action is taking place in the widescreen image, with the rest of the widescreen frame cropped off, resulting in a loss of image or action (i.e., losing one person when two are talking to each other from opposite sides of the widescreen image)

Passive radiator
A diaphragm (either a cone or a flat material) fitted to a speaker cabinet, which reinforces the bass output of the speaker. Acoustically similar to a port (See bass reflex).

Passive subwoofer
A subwoofer with no internal powered amplifier. May or may not have passive filtering inside to reject midrange and treble. (See subwoofer)

Picture-in-picture
(PIP) Advanced TV feature that displays pictures from two sources on a TV screen simultaneously. The second picture appears in a small window overlaid on the primary picture; requires two tuners

Power-line conditioner
High-end power outlet strip with added internal components that filter out interference from other electronic products co-existing on the same power line (such as lamp dimmer switches) or within the same neighbourhood power grid (such as your neighbour’s air conditioner) that could affect audio or video quality. Also provides surge protection. (See surge protector/suppressor, power strip)

Pre-programmed remote
Type of universal remote control that allows a user to select from and activate IR codes stored in the remote to control equipment from other manufacturers. (See learning remote)

Progressive scanning
Also called sequential scanning and the antithesis of interlaced scanning used in broadcast television, the process by which all 525 odd and even scanning lines are "painted" by an electron beam every 1/60th of a second. This method reduces flicker and increases vertical resolution. Used by computer monitors and several DTV formats (the "p" in 480p and 720p) and the native scanning format of DVD. (See interlacing)

Progressive scan output
Video output (from a computer, line processor, DVD player, or set-top box) that carries a video signal in which each horizontal line follows the next -- unlike an interlaced output, which presents the odd-numbered horizontal lines, then the even-numbered horizontal lines, and so on. Progressive-scan video has less flicker and fewer motion artifacts than interlaced-scan video. (See progressive scanning)

Rear-projection
Projection TV system where the picture is projected onto the rear of a translucent screen via a series of mirrors and viewed like an average television; may be a self-contained unit or a two-piece system. (See CRT, D-ILA)

Rear-surround effects
Background noises reproduced by the rear-surround speakers in a surround sound system, ranging from low-level ambient sounds (crickets in a nighttime scene) to dramatic loud noises (explosions, whooshing spaceships). (See Dolby Digital)

Rear-surround speakers
Also called "surround" speakers, the two speakers in the rear of a room in a 5.1-channel or a Dolby Pro-Logic surround sound system; used more for effects than dialog. (See Dolby Digital)

Receiver
In telecom, an electronic device that can read and translate incoming wireless transmissions. ** Another name for a telephone's handset. ** The combination of an audio amplifier, preamp, and tuner in one housing that shares a single power supply.

SACD - Super Audio Compact Disc
Enhanced compact disc format using a dual-layer disc, supported primarily by Sony. One layer is compatible with conventional CD players while the other provides the identical program material with resolution vastly higher than normal 44.1 kHz, 16-bit CDs; uses Direct Stream Digital process with an astronomical sampling rate of more than 2.8 MHz. Will compete directly with DVD-Audio, though it has less record-company support. (See DVD-Audio)

Satellite/subwoofer set
Speaker system consisting of a subwoofer and two to five smaller "satellite" speakers that reproduce midrange and higher frequencies; designed to fit more easily into interior decors or smaller rooms.

Sensitivity
Input signal level required by a VCR, TV, tuner, or amplifier to produce a stated output. The lower the necessary input stated in microvolts, the higher the sensitivity. ** Ability of a camcorder to capture a minimal acceptable image, measured in lux. The lower the lux number, the higher the sensitivity. ** Measure of the output of a loudspeaker at 1 meter when fed a 1-watt signal. The more sensitive the speaker is, the louder it will sound with a given amount of power.

SPL
(sound pressure level) Loudness of any sound source, expressed in decibels. SPL of 1 dB is the quietest sound a typical human can hear. Normal conversation is at about 70 dB SPL. High-end home theatre systems are designed to produce at least 113 dB SPL.

Surge protector/suppressor
Device that protects electronic products from sudden fluctuations in power, often caused by other electronic products co-existing within the same power line, or sudden power surges, spikes or fluctuations from the local power grid. (See power-line conditioner)

S-video
(Y/C) Higher quality video input and output that segregates chrominance and luminance signals for optimum reproduction from high-quality video sources such as S-VHS, Hi8 and DVD players. Replaces composite video (RCA) input cable with a delicate and difficult to fit multi-pin cable. Better than a composite video connection, not as good as component video but more common. (See component video, composite video)

THX- Tomlinson Holman Experiment
Proprietary surround-sound technology created by Lucasfilm and named for its developer, now called THX Ultra. Used first for enhanced movie-theatre sound reproduction, then for recreating cinema sound in a home-theatre system for rooms of more than 3000 cubic feet. The technology is licensed to a variety of home-theatre component manufacturers and multimedia speaker systems. (See THX Select, THX Ultra)

THX-certified
Designation given to a product that officially meets the specifications of the THX program. (See THX, THX Select)

THX Select
THX certification designed for optimal performance in smaller listening environments and at lower volume levels; conceived for rooms of less than 2000 cubic feet. (See THX)

THX Ultra
THX certification designated for ultra high-end A/V gear, as opposed to THX Select, which is aimed at more moderately priced equipment; conceived for rooms of more than 2000 cubic feet. (See THX)

Tweeter
High-frequency loudspeaker driver designed to reproduce treble frequencies.

Universal remote
General term describing all remote controls that can learn and/or are pre-programmed to operate audio and video components from various manufacturers. (See learning remote, pre-programmed remote)

Widescreen
Image with an aspect ratio greater than 1.33:1 or a picture wider and narrower than a standard television image. (See 16:9, 4:3, anamorphic, aspect ratio)

Woofer
Audio loudspeaker driver that reproduces low-frequency (bass) signals.

Y Pb Pr
(yellow, blue, red) (See component video)

Y R-Y B-Y
(yellow, red, blue) (See component video)

Y/C
(luminance [Y] and chrominance [C]) (See S-video)