Glossary Terms for Beginners


Dolby Digital has six discrete digital audio chan­nels: 5 full-bandwidth (for front left/right, center, and surround left/right) and 1 “low frequency effects” subwoofer channel. These six channels are sometimes referred to as “5.1-channel.”

Acoustic suspension

Speaker design that uses a sealed, airtight enclosure.


An anamorphic video image is one filmed in true 16:9 aspect ratio. If it is watched on a screen with 4:3 aspect ratio, it gets “squeezed” — everything appears taller and thinner, and actors have pointed heads! An anamorphic image needs to be viewed on a true 16:9 screen to look normal.

Aspect ratio

The ratio of width to height for an image or screen. The North American NTSC television broadcast standard is 4:3 (1.33:1). The new HDTV (High Definition digital television) standard calls for a wider screen with a 16:9 (1.78:1) ratio.

A/V inputs

They allow direct connection of your video components.

Rear A/V inputs are located on your gear’s rear connector panel, for components you normally leave connected.

Front-panel A/V inputs allow for quick and easy hook-up of a camcorder, second VCR, video game, etc.


Refers to the range of frequencies a component can reproduce. For audio components, like receivers, “frill bandwidth” is generally considered to be the entire frequency range of human hearing (20-20,000 Hz).

Bass reflex

Speaker enclosure design that uses a port (a hole in the box timed to a specific frequency) or a bass radiator (“drone cone”) to produce more bass output in the “tuned” frequency range.


A speaker design which generates equal amounts of sound both forward and backward, with the two sounds being in phase. See also Dipole, and the surround speaker illustrations on pg. 20.

Center channel speaker

In a home theater system, a video-shielded speaker placed above or below your TV dedicat­ed to reproducing on-screen sound and dialogue.


The portion of the video signal that carries the color information.

Component video

A video signal which has been split up into its component parts. TVs with three-jack component video inputs are designed to be compatible with the component video outputs found on some DVD players. If you think of S-video as a type of component video signal (separate brightness and color portions), the three-jack component video connection carries the concept a step further by splitting the color signal into two parts for even greater accuracy and less color bleeding.

Direct Broadcast Satellite (DBS)

A method of receiving over 200 channels of programming via satellite signals beamed to a small (18-24″) dish and passed through a receiv­er. DBS systems include Sony’s DIRECTV and JVC’s DISH networks. These networks also supply SDTV-fonnat and limited HDTV-format programming, and a few high-end DBS receivers can pass the Dolby Digital audio signals accompanying some programs to your Dolby Digital receiver.

Digital comb filter

A filter for picture sharpness which reduces “jitter” and “dot crawl.” Standard digital comb filters are “2-line” — they compare consecutive scan lines within a field. 3-line digital comb filters compare three consecutive scan lines within a field, for still better clarity. The most effective comb filter, the 3D digital comb filter, compares a scan line to adjacent lines in the same field, as well as the corresponding lines in the preceding and following fields.

Digital Signal Processing (DSP)

Some receivers use Digital Signal Processing for creating soundfields (simulated acoustic environments) and time delays, and for precise steering of multichannel surround information. When an audio signal is processed and routed in the digital domain (instead of the analog), it is less susceptible to signal loss and distortion.

Digital Television (DTV)

The new American digital broadcast TV stan­dard, it falls into two general categories: HDTV and SDTV. HDTV includes a number of formats, which share the same basic characteris­tics: resolution from 720 to 1080 lines, Dolby Digital audio, and an approximately 16:9 widescreen format. The formats in the SDTV category are far more common, and include resolution starting at 480 lines, and aspect ratios from standard 4:3 to, in a few cases, 16:9. Only digital televisions and analog televisions with digital set-top converter boxes are able to receive the signal. Digital TV is being broadcast in over 30 major markets across the country already, and by 2006, every broadcaster (whether local, national, cable, or satellite) is required to comply with digital broadcasting standards.

Digital Theater Systems (DTS)

A multichannel digital audio format first introduced in commercial movie theaters in 1993. See pg. 8 for more info.


A speaker design which generates equal amounts of sound both forward and backward, with the two sounds being out of phase. Dipoles are often used as surround speakers. See also Bipole, and the surround speaker illustrations on pg. 20.

Dolby® Digital

A form of encoding audio information digitally. 5.1-channel Dolby Digital contains an advanced decoding matrix for a bitstream of digital data consisting of six channels (front left, center, front right, left surround, right surround, and a subwoofer channel). Five main channels are full-bandwidth and the “low frequency effects” subwoofer channel has a frequency range of 3-120 Hz. Although it is often used in reference to 5.1-channel surround sound, Dolby Digital can also take the form of Dolby Pro Logic surround sound, stereo, or even mono audio. See the diagrams on pg. 6 for more information on a Dolby Digital surround setup, and the Dolby Digital encoding/decoding process.

Dolby Digital “ready”

AN receivers that do not have Dolby Digital decoders built in, but feature 5.1-channel inputs for hooking up an external Dolby Digital decoder. Increasingly, these receivers are called “5.1-ready.”


Audio in a two-channel, left and right format.

Years ago, stereo sound replaced mono sound as the standard music-listening format.

Dolby® Surround

The term used with consumer equipment and for the identification of Dolby-encoded video software released for use at home. Dolby Pro Logic and Dolby Digital are the two current formats of Dolby Surround.

Dolby® Pro LogicTM

An audio format consisting of four channels of matrixed sound (front left, center, right, and surround). Dolby Pro Logic delivers distinct channel separation, precise localization of on-screen sounds and dialogue, plus realistic special effects and theater ambience. See the diagrams on pg. 7 for more information on a Dolby Pro Logic surround setup, and the Dolby Pro Logic encoding/decoding process.


If you don’t have a Dolby Digital system, you can still enjoy excellent Pro Logic or stereo sound from your DVDs. All DVD players have the ability to take a “5.1-channel” Dolby Digital soundtrack and “downmix” it to two channels, which can then be sent to a stereo receiver, a TV, or an AN receiver with Dolby Pro Logic decoding.


A 12 cm optical disc format for video and audio, which is rapidly superseding VHS in popularity. There are already thousands of movies available on DVD, and hundreds more are released each month.

Frequency response

Expressed in cycles per second, or Hertz (Hz), it tells you how wide a range of music an amplifier or speaker is reproducing.

High Definition Television (HDTV)

A high-quality DTV categoiy which refers to several different formats, all of which have the following attributes: resolution of 720 lines or higher, a 16:9 aspect ratio, and Dolby Digital audio.


Videos that show the entire picture as seen in a movie theater. The resulting image width is much greater than its height. On a TV screen with standard 4:3 aspect ratio, letterboxed videos appear with horizontal black bars above and below the image.

Line doubler

Technology found in television sets which, by doubling the amount of information per line, offers a clearer, more defined picture. Other variations on this theme include Sony’s Digital Reality Creation, which is more efficient and more precise than standard line doublers because it enhances each pixel.


The brightness or black-and-white component of a color video signal. Determines the level of picture detail.


The process of transferring a movie or other source material to videocassette or broadcast so that it fits the 4:3 aspect ratio of the NTSC (National Television System Committee) system, as well as nearly all current TVs. This results in some lost picture information, particularly in the width of the image.

Remote control

The capabilities of receiver remotes can vary a lot from brand to brand, and model to model.

A/V remote controls can operate several A/V components from the same manufacturer. Multibrand remote controls have pre-programmed commands for components made by popular brands. Programmable, or learning, remotes can be programmed by the user to oper­ate A/V equipment from other manufacturers.


The sharpness of a video display in the horizon­tal direction; the number of vertical lines that can be resolved from one side of the screen to anoth­er. The detail you see depends on your signal source. All NTSC TVs offer resolution that surpasses standard signals such as TV broadcasts (330 lines) and VHS VCRs (240 lines). New technology enhances built-in NTSC resolution still further. However, future hybrid TVs (a mix­ture of NTSC and ATSC capability) and digital TVs should have noticeably better resolution.

Satellite/subwoofer system

Speaker system that uses between two and five small satellite speakers for tweeter and midrange drivers, and a separate box specially designed to house the woofer(s).

Signal-to-noise ratio (S/N)

Expressed in decibels (dB), it compares the level of an audio or video signal to the level of internally generated noise (such as audio hum).

Speaker efficiency

Measures in decibels (dB) how well a speaker system turns input power into sound.

Standard Definition Television (SDTV)

The category, containing multiple specific formats, for standard DTV broadcasts. This format will be more common than HDTV, and entails a minimum of 480 lines of resolution. It will offer both 4:3 and 16:9 aspect ratios, and a wide range of sound encoding (from stereo to Dolby Digital 5.1).


A speaker designed specifically for bass output. Subwoofers are usually powered (with a built-in amplifier). Subwoofers offer deep, resounding bass, and are an important part of Dolby Digital surround sound.

Super VHS

An improved VHS format which offers better picture quality than standard VHS 240-line resolution. SATIS VCRs record at 400+ lines of resolution, and can even improve the picture quality of standard VHS tapes during playback. Some also use SATIS ET to record at S-VHS quality on standard VHS tapes. Although S-VHS players will play standard tapes, most standard players will not play SATIS tapes (however, some brands offer Quasi S-VHS to let you do just that!).

Surround speakers

In a home theater surround sound system, this pair of speakers is positioned to the sides or behind your listening seat, creating ambience and providing directionality to off-screen sound effects.

S-video inputs/outputs

Special four-pin connectors that cany the chrominance (color) and luminance (brightness) portions of the video signal separately, for improved color accuracy and reduced distortion.


A division of Lucasfilm Ltd. devoted to accurate sound reproduction in theaters and on home systems. See FAQ on pg. 24 for more info.

Total harmonic distortion (THD)

A measurement of amplifier accuracy, it indicates the presence and amount of internally generated noise.


Brief bursts of musical energy.

VCR Plus+ with cable box & DBS control

Easy videotaping for cable, DBS, and over-tile- air broadcasts! Simply enter the show’s “PlusCode” (found beside its title in most TV listings) and the VCR is automatically set for the channel, date and times. Cable box control means the VCR is able to switch most cable boxes to the appropriate channel at the appropri­ate time, automatically. Some VCRs also include infrared transmitters which let them control of DBS receivers, so you can make timed record­ings of satellite programs.

Video shielding

A way of containing a speaker’s magnetic energy inside its enclosure. This is usually achieved by placing another speaker magnet back-to-back with the existing one so that the two magnetic fields cancel each other. Shielding may also be achieved by lining the inside of the speaker cabinet with metal. Video shielding is important in home theater — especially with the center channel speaker. If an unshielded speaker is placed too close to your TV, the magnetic energy can cause picture distortion and even permanently damage the TV’s picture tube.


Refers to speakers with a similar timbre or tonal quality. Voice-matched speakers will result in more seamless, consistent, and convincing wraparound sound in your home theater.


The aspect ratio associated with movie theaters from around the 1950s on. Widescreen usually means movies filmed in a 16:9 aspect ratio (although theaters do not use 16:9 as their standard, it is a close approximation of the wide screen size of theaters). When transferred to video for home viewing, widescreen films are released in a pan-and-scan, “modified to fit your screen” format, a letterbox format, or both. With the onset of HDTV, we will see more films available in a true, non-letterboxed widescreen, or anamorphic, format.