A
Active
An active speaker includes an active crossover and built-in amplifier.
Amplifier
A component that increases the gain or level of an audio signal.
Aspect Ratio
The ratio of image width to image height. Television screens typically have a 4:3 aspect ratio. Widescreen televisions and HDTVs have an aspect ration of 16:9. When widescreen movies are displayed on 4:3 televisions, the image must be letterboxed to fit the space.
B
Bass
Low frequency audio signals (below approximately 200 Hz.).
Bipolar Speakers
Speakers that consist of two driver arrays facing opposite directions to create more sound diffusion.
C
Cathode Ray Tube (CRT)
This is the type of picture tube used in a traditional television. The image in a CRT television is created by an electron gun that generates the image on the screen.
CD-R
Recordable Compact Disc.
CD-RW
Rewritable Compact Disc.
Center Channel Speaker
This speaker in a home theater is typically used for the dialogue channel. It is usually placed directly above or below the television or display device so that the sound of dialogue appears to come from the screen.
Channel
In a home theater, channel refers to the separate signal paths created for various audio channels. In a typical 5.1 channel home theater, the audio for a movie is divided into 5 channels plus one channel for a subwoofer (this is the .1 channel).
Component Video
A video signal that separates luminance (brightness) and chrominance (color) for better quality and color detail.
Composite Video
A video signal in which the luminance (brightness) and chrominance (color) have been combined rather than kept separate as in component video.
Contrast
The difference between the brightest and darkest parts of an image.
Crossover
A component that divides an audio signal into two or more ranges by frequency.
D
Diaphragm
The part of a speaker that produces sound. It usually has the shape of a cone or dome.
Diffusion
In audio, the scattering or dispersion of sound waves.
Dipole
Speakers with drivers facing opposite directions to create a larger sound field to mimic the effect of a cinematic experience.
Direct-Stream Digital
A format for encoding high-resolution audio signals.
Dispersion
The spread of sound over a wide area.
Distortion
Any undesired change in an audio signal between input and the output.
DLP (Digital Light Processing)
A video processing system created by Texas Instruments. DLP projects images by using a light source to reflect off of an array of tens of thousands of microscopic mirrors. Each mirror represents a pixel. The reflected light is directed through a lens and onto a screen, creating the image. DLP is considered the leading projection technology.
Dolby Digital
An encoding system that digitally compresses up to 5.1 discrete channels of audio (left front, center, right front, left surround, right surround and subwoofer) into a single bitstream. Five channels are full-range; the .1 channel is typically used for a subwoofer. A Dolby Digital processor (found in most receivers, preamps, and DVD players) can decode this signal back into the 5.1 separate channels. Additional formats of Dolby Digital, such as Dolby EX, apply this same format to systems with more channels such as 6.1 or 7.1. Competing format is DTS (see below.)
Dome
A type of shape used to describe speaker drivers, typically the tweeters. Concave domes are usually referred to as "inverted domes."
Driver
The active element of a speaker system that creates air movement to create sound. The primary parts of a driver are the cone (or dome), which moves the air, voice coil and the magnet.
DTS (Digital Theater Systems)
A digital sound recording format that was originally developed for theatrical film soundtracks, starting with Jurassic Park. Digitally compresses up to 5.1 discrete channels of audio (left front, center, right front, left surround, right surround and subwoofer) into a single bitstream. Five channels are full-range; the .1 channel is typically used for a subwoofer. Competing format is Dolby Digital (see above).
DTV (Digital Television)
Umbrella term used for the system that will eventually replace our NTSC system in 2006. HDTV is a subset of the DTV system. While the FCC does not recognize specific scan rates in the adopted DTV system, typically accepted rates include 480i, 480p, 720p and 1080i.
D-VHS
A recorder that records digital signals onto magnetic tape and has greater capacity than a standard VHS.
DVD (Digital Video Disc)
Has 4.5 Gb (single layer, single-sided) to 17 Gb storage capacity and is currently the best and most common format for source material of movies.
DVD-A (DVD Audio)
Digital Versatile Disc-Audio. Enhanced audio format with up to six channels of high-resolution audio encoded onto a DVD.
DVD-R
One-time only recordable DVD format.
DVD-RW
Recordable/re-recordable DVD format.
DVD-RAM
A recordable DVD format that is capable of being written and erased more than 100,000 times.
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G
Graphic Equalizer
Sliding controls on a Graphic Equalizer create a pattern representing a graph of the frequency-response changes.
H
HDTV (High-Definition Television)
A television capable of producing high-resolution, digital images (at least twice the resolution of the existing TV standard). HDTVs are widescreen (16:9) in format and produce an image with 720 progressive or 1080 interlaced active (top to bottom) scan lines.
Home Theater
Home Theater recreates the cinematic movie theater experience within the home. Home theaters, like those developed by members of HTSA, are professionally designed and installed in the home and come complete with electronics, video, audio, furniture and often lighting and custom accessories such as drapery and theater seats.
Home Theater in a Box
A very poor substitute for the real thing. See Home Theater above.
I
Integrated Amplifier
A combination preamp and amplifier.
Interconnects
Any cable or wire running between two pieces of electronic equipment.
Interlace
A television image technology referring to the process of alternating scan lines to create a complete image. In CRT televisions, every second field/frame is scanned between the first field/frame. The fields are aligned and timed so that the human eye views them as one image. Interlace scanning does not generate a comparable image quality as progressive scanning.
Inverted Dome
A type of speaker-driver shape (usually used for tweeters).
K
Keystone
A form of video image distortion in which the image is shaped like a trapezoid rather than a rectangle.
kHz
Kilohertz or one thousand Hz.
L
LCD (Liquid Crystal Display)
A television monitor technology that sandwiches a layer of liquid crystal between two transparent displays. A light source behind the panel transmits the image through the crystals. Each crystal, controlled individually, acts like a shutter.
Letterbox
A conversion format to fit wide-aspect-ratio movies. When an image is shrunk to fit the screen without distorting the original widescreen (16:9) format, black horizontal bars are used to fill in the missing area, leaving blank space on the top and bottom.
Luminance
The black and white (Y) portion of a video signal. The luminance channel carries the detail of a video signal.
K
Keystone
A form of video image distortion in which the image is shaped like a trapezoid rather than a rectangle.
kHz
Kilohertz or one thousand Hz.
L
LCD (Liquid Crystal Display)
A television monitor technology that sandwiches a layer of liquid crystal between two transparent displays. A light source behind the panel transmits the image through the crystals. Each crystal, controlled individually, acts like a shutter.
Letterbox
A conversion format to fit wide-aspect-ratio movies. When an image is shrunk to fit the screen without distorting the original widescreen (16:9) format, black horizontal bars are used to fill in the missing area, leaving blank space on the top and bottom.
Luminance
The black and white (Y) portion of a video signal. The luminance channel carries the detail of a video signal.
M
Megachanger
CD or DVD player with massive disc storage capacity, holding 50 or more discs.
MHz
Megahertz, or 1 million Hz.
Midbass
The middle of the bass part of the frequency range, from approximately 50 to 100 Hz.
Midrange
The middle of the audio frequency range.
Mono
One channel or monophonic/monochannel sound.
Multi-Room/Multi-Zone
An electronic component, system or feature capable of producing multiple source material in different rooms of a home, often simultaneously. For example, the same movie can be displayed in the kitchen, home theater and a bedroom at the same time.
E
EDTV (Extended Definition Television)
The term used to describe any Digital Television (DTV) capable of displaying image quality of 480p or higher.
Equalization
The process of changing the frequency of an electrical signal to alter the acoustical output.
Equalizer
An electronic component that alters the frequency balance of an audio signal.
F
Feedback
Some or all of the output of the device (such as an amplifier) taken back to the input. This may be accidental (such as feedback from a speaker) or intentional, to reduce distortion.
FireWire
Also known as IEEE 1394. This is a high quality two-way connection between electronics.
Frequency Response
A measure of what frequencies can be reproduced by a given component and how accurately they are reproduced.
Full-Range Speaker
A speaker designed to reproduce the full range (20 Hz to 20 kHz) of audio frequencies.
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P
Passive Speaker
A speaker that does not have an internal or built-in amplifier.
Pixel
The smallest element of data in a video image.
Plasma
Flat-panel display technology that ignites small pockets of plasma gas to light phosphors. The illumination of the gas creates the image viewed on screen.
Preamplifier
A control and switching component that may include equalization functions.
Progressive Scanning
A format for displaying a video image in which each frame of a video is scanned complete, from top to bottom, not interlaced. Because the entire frame is displayed at one time (as opposed to Interlaced Scanning), better image quality is displayed and no content is lost.
Projection System
A system in which an electronic device (projector) projects an image onto a screen. See also DLP.
R
Rear-Projection Television (RPTV)
A television in which an image is reflected off a mirror then projected on the back side of a screen material.
Receiver
Typically a tuner combined with an amplifier and/or loudspeaker. Audio/Video receivers also combine additional functionality and typically have a digital sound processor built in such as Dolby Digital or DTS.
RGB (Red, Green, Blue)
These three colors combine together to make every color viewed on a display device.
Ribbon Speaker
A loudspeaker that consists of a thin, corrugated, metallic ribbon suspended in a magnetic field.
S
SACD (Super Audio CD)
An enhanced, high-resolution format of CD. SACDs are specially encoded and require an SACD player and six channels of digital audio for full playback performance.
Scan Lines
The lines drawn by an electron gun in a CRT television to make up the picture.
SDTV (Standard Definition Television)
A format of Digital Television (DTV). SDTVs have a lower resolution signal than High Definition TV (HDTV). Generally, 480i (interlaced) is considered the accepted quality for SDTV.
Soft-Dome Tweeter
A tweeter that uses a fabric or plastic dome.
Soundstage
The listening area between speakers. Correct speaker placement will create the appropriate width, depth and height of the soundstage.
Subwoofer
A speaker designed to reproduce low bass frequencies, usually those below about 80 Hz. Subwoofers are used for both music systems and home theater systems.
Surround Sound
A specific set of speakers designed to surround a listening area in fully dimensional, life-like sound. A typical 5.1-channel surround sound system will consist of five speakers plus a subwoofer (the .1 channel). The five speakers are: front left and right speakers, center channel speaker and rear left and right speakers.
S-VHS (Super VHS)
An enhancement to regular VHS that offers improved resolution.
S-Video (Separated Video)
An encoded video signal which separates the luminance (brightness) and chrominance (color) signals into a television from a video source such as a DVD player. The quality of S-Video is significantly better than composite video since it does not require a comb filter to separate the signals.
T
3:2 Pulldown
This line-doubling technology is used to improve the picture quality of an incoming signal to a video source by transferring the individual 24 frames per second (film) to 30 frames per second (video). This technology creates a smooth, even motion and reduces artifacts.
THX
Certification program for home theater equipment licensed by Lucasfilm Ltd. (the company of George Lucas, creator of Star Wars). Equipment meeting these specifications upholds the company's standards, which are intended to represent the highest quality home theater experience. Additional levels of THX certification include THX Select, Ultra and Ultra 2.
Tweeter
A speaker driver designed to reproduce high frequencies.
U
Universal Remote
A single remote that can control several different devices simultaneously.
W
Wall Mount
A bracket used to affix a flat panel television to a vertical wall.
Watt
A unit of power or energy.
Woofer
A speaker driver designed to reproduce low frequencies.
Wow
The verbal response typically generated by customers of HTSA upon seeing their new home theaters.
Z
Zone
An area in a house designated for an entertainment usage (such as music or movie distribution). A home can be divided into multiple zones, all of which can access the same source simultaneously.
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