UltraMedia, Inc. - Glossary

Glossary

5.1 channels: The standard number of channels for encoding film soundtracks: left, center, right, surround left, and surround right.The .1 channel carries high-impact, low-frequency signals (bass).

AC3: Audio Codec 3: The original, and more technical, name for Dolby Digital. Replaced because Dolby's name was not in the title. Some RF modulated, 5.1-encoded laser discs were labeled as AC3. Later versions were labeled as Dolby Digital.
A/V: Short for audio/video.Identifies a component or system as one that processes video as well as audio signals.
A/V Input: An input on an A/V receiver or controller that includes audio and video jacks.
A/V loop: An A/V input and A/V output pair found on all A/V receivers and controllers.Used to connect a component that records as well as plays audio and video signals.
A/Vreceiver: The central component of most home theater systems that receives signals from the source components, selects which signal you watch and listen to, controls the playback volume, performs surround decoding, receives radio broadcast, and amplified signals to drive a home theater loudspeaker system.Also called a “surround receiver.”
acoustic suspension: A sealed speaker enclosure that uses air trapped in the cabinet as a reinforcing spring to help control the motion of the woofer(s).
active: Powered.An active cross-over is electrically powered, dividing the line-level signal prior to amplification.An active speaker includes an active crossover and built-in amplifier.
anamorphic: Process that horizontally condenses (squeezes) a 16:9 image into a 4:3 space, preserving 25% more vertical resolution than letterboxing into the 4:3 space. For the signal to appear with correct geometry, the display must either horizontally expand or vertically condense the image. Used on about two or three promotional laser discs and many DVDs. Also called Enhanced for Widescreen or Enhanced for 16:9.
aspect ratio: The ratio of image width to image height. Common motion-picture ratios are 1.85:1 and 2.35:1. Television screens are usually 1.33:1 (also known as 4:3.HDTV is 1.78:1, or 16:9. When widescreen movies (films with aspect ratios wider than 1.33:1) are displayed on 1.33:1 televisions, the image must be letterboxed, anamorphically squeezed, or panned-and-scanned to fit the screen.

balanced input: A connection with three conductors: two identical signal conductors that are 180 degrees out of phase with each other, and one ground. This connection is very resistant to line noise.
bandwidth: In audio, the range of frequencies a device operates within. In video, the range of frequencies passed from the input to the output.
bass: Low frequencies, below roughly 200 Hz.
base management: A combination of controls and circuits in an A/V receiver or controller that determines how bass frequencies are distributed among the speakers.
binding post: A connection on receivers and power amplifiers for attaching speaker cables.
bright: A term used to describe sound that has too much treble (high frequency), relative to the lower tones in the music.

calibration: The act of fine-tuning an audio or video component for correct performance.In an audio system, it includes setting of the individual channel levels.In video, it means setting a video display device to display the correct color, brightness, tint, contrast, and other parameters.
cascading crossovers: Two crossovers used in series on the same signal, in the same frequency range, causing greater attenuation of the out-of-band signal. (Using the crossover in a receiver's bass management setting and the one in a subwoofer simultaneously will create an exaggerated loss of signal.)
cathode ray tube (CRT): An analog display device that generates an image on a layer of phosphors driven by an electron gun.
center channel: The center speaker in a home theater. Ideally placed within one or two feet above or below the horizontal plane of the left and right speakers and above or below the display device (unless placed behind a perforated screen). Placement is importantÖ voices and many effects in a multichannel recording come from this speaker.
channel: In components and systems, a channel is a separate signal path. A four-channel amplifier has at least four separate inputs and four separate outputs.
chrominance (C): The color portion of a video signal.
channel balance: The relative levels or volumes of different channels in a home theater system.
clarity: The ability of a system to reproduce music without adding distortions or noise.
coaxial: A speaker with one driver in the middle of, and on the same axis as, another driver.Or, an audio or video cable with a single center pin that acts as the hot lead, and an outer shield that acts as a ground.
component video: A signal recorded or transmitted in its separate components. Typically refers to Y/Pb/Pr, which consists of three 75-ohm channels: one for luminance information, and two for color. Compared with an S-video signal, a Y/Pb/Pr signal carries more color detail. HDTV, DVD, and DBS are component video sources, though most DBS material is transcoded to component from composite signals.
composite video: A signal that contains both chrominance and luminance on the same 75-ohm cable. Used in almost all consumer-video devices. Chrominance is carried in a 3.58-mHz sideband and filtered by the TV's notch or comb filter. Poor filtering can result in dot crawl, hanging dots, or other image artifacts.
contrast: The relative difference between the brightest and darkest parts of an image. A contrast control adjusts the peak white level of a display device.
controller: Generic term that refers to a combination preamp/surround processor or receiver. Can also refer to a handheld wireless remote.
crossover: Circuit that splits up the frequency spectrum into two or more parts.Crossovers are found in virtually all loudspeakers, A/V receivers, and controllers.An active crossover is powered and divides the line-level audio signal prior to amplification. A passive crossover uses no external power supply and may be used either at line level or, more commonly, at speaker level to divide the signal after amplification and send the low frequencies to the woofer and the high frequencies to the tweeter.
crossover frequency: Frequency at which an audio signal is divided. 80 Hz is a normal subwoofer crossover point, and is the recommended point in theatrical and home THX systems. Frequencies below 80 Hz are sent to the subwooferÖsignals above 80 Hz are sent to the main speakers.
crossover slope: Rate of attenuation expressed in decibels of change for every octave away from the crossover frequency.

DBS (Direct Broadcast Satellite): Term that replaced DSS, to describe small-dish, digital satellite systems such as DirecTV and Dish Network.
DTS (Digital Theater Systems): A discrete, digital surround-sound format used in movie theaters and home-theater systems.An alternative to Dolby Digital that uses a higher bit rate.
DTA-ES Discrete: A 6.1-channel surround-sound format that includes a rear surround channel in addition to the conventional 5.1 channels.Called “discrete” because the rear surround channel is completely separate from the left and right surround channels, unlike DTS ES Matrix, which matrix-encodes the third surround channel into the existing left and right surround channels of a 5.1-channel signal.
DTS-ES Matrix: A 5.1-channel surround-sound format that includes a rear surround channel that is matrix-encoded into the left and right surround channels of a 5.1-channel signal.
DTS-HD: Higher quality version of the D T S developed for HD DVD and Blu-ray disc.
DTS Neo:6 Cinema: A DTS decoding technology for playing back two-channel film-soundtrack sources through 5.1 or 7.1 loudspeakers.
DTS Neo:6 Music: A DTS decoding technology for playing back two-channel music sources through 5.1 or 7.1 loudspeakers.
DTV: Digital Television. Umbrella term used for the ATSC 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.
DVI: Digital Visual Interface. Connection standard developed by Intel for connecting computers to digital monitors such as flat panels and DLP projectors. A consumer electronics version, not necessarily compatible with the PC version, is used as a connection standard for HDTV tuners and displays. Transmits an uncompressed digital signal to the display. The latter version uses HDCP copy protection to prevent unauthorized copying. See also HDMI.
damping material: Material that absorbs sound waves, eliminating acoustic energy by converting it into a different form. Fibrous material, for example, turns acoustic energy into heat via friction.
decibel (dB):: Logarithmic measurement unit that describes a sound's relative loudness, though it can also be used to describe the relative difference between two power levels. A decibel is one tenth of a Bel. In sound, decibels generally measure a scale from 0 (the threshold of hearing) to 120-140 dB (the threshold of pain). A 3dB difference equates to a doubling of power. A 10dB difference is required to double the subjective volume. A 1dB difference over a broad frequency range is noticeable to most people, while a 0.2dB difference can affect the subjective impression of a sound.
delay: Time difference between a sonic event and its perception at the listening position (sound traveling through space is delayed according to the distance it travels). People perceive spaciousness by the delay between the arrival of direct and reflected sound (larger spaces cause longer delays).
diaphragm: The part of a dynamic speaker attached to the voice coil that produces sound. It usually has the shape of a cone or dome.
diffusion: In audio, the scattering of sound waves, reducing the sense of localization. In video, the scattering of light waves, reducing hot spotting, as in a diffusion screen.
diffusor: An acoustical treatment device preserving sound energy by reflecting it evenly in multiple directions, as opposed to a flat surface, which reflects a majority of the sound energy in one direction.
digital signal processing (DSP): The manipulation of audio or video signals by performing mathematical functions on the digitally encoded signal.
digital-to-analog converter (DAC, D/A): Device converting digital signals to analog signals.
discrete: These are codes that allow a remote control to have a button for every actionÖno toggles, absolute direct control.Think of a single power button: one press is on, one press is off. A discrete code from a manufacturer gives you a code for ñonî and a separate code for ñoff.î This prevents a user from turning the device off instead of on, or vice versa. The same thing happens with an input button. One button could toggle 6-8 inputs on a TV. If the manufacturer provides discrete codes, the remote can go directly to input 5, etc.
Dolby Digital: 5.1-channel discrete digital surround-sound format used in movie theaters and consumer formats.One of the surround formats used on DVD.
Dolby Digital EX: Surround-sound format that matrix-encodes a “back-surround” channel into the left and right surround channels of a 5.1-channel Dolby Digital signal.This back-surround channel is reproduced by one or two speakers located directly behind the listening position.
Dolby Digital Plus: Higher-quality version of Dolby Digital developed for HD DVD and Blu-ray disc.
Dolby Pro Logic II: Introduced in late 2001, Pro Logic II provides a superior decoding of two-channel music and film sources compared with Pro Logic.
Dolby True HD: Lossless audio-encoding system developed for HD DVD and Blu-ray disc. Dolby TrueHD can deliver high-resolution multi-channel audio with perfect bit-for-bit accuracy to the source.
dynamic range: The difference between the lowest and the highest levels; in audio, it's often expressed in decibels. In video, it's listed as the contrast ratio.

efficiency rating: The level of sound output measured at a prescribed distance with the standard input power. Efficiency rating standard is 1 watt (2.83V at 8 ohms) at 1 meter over a specific frequency range and is measured in decibels.
electrostatic: One of the oldest speaker design principles; electrostatic speakers are generally comprised of two fixed perforated panels with a constant high-voltage charge applied to them. Between these two panels is an extremely low-mass diaphragm to which the audio signal is applied, causing it to move. There are variations to this construction, but all electrostatic speakers are free from the magnets and voice coils used in conventional speakers.
enclosure: Container of air that surrounds the rear of a speaker driver.
equalization: Generally, any type of relative frequency adjustment. Specifically, the process of changing the frequency balance of an electrical signal altering the acoustical output.
equalizer: A component designed to alter the frequency balance of an audio signal. Equalizers may be graphic, parametric, or a combination of both.

feedback: The transmission of current or voltage from the output of a device back to the input, where it interacts with the input signal to modify operation of the device. Feedback is positive when it's in phase with the input, and negative when it's out of phase.
fiber optic cable: Glass, plastic, or hybrid fiber cable that transmits digital signals as light pulses.
frequency: The number of cycles (vibrations) per second. In audio, audible frequencies commonly range from 20 to 20,000 cycles per second (Hz). In video, frequency is used to define the image resolution. Low-frequency video images depict large objects or images. Higher frequencies depict smaller objects (finer details).
frequency response: A measure of which frequencies can be reproduced and how accurately they are reproduced. A measurement of 20 to 20,000 Hz ± 3dB means those frequencies between 20 and 20,000 Hz can be reproduced no more than 3 dB above or below a reference frequency level.
full-range: A speaker designed to reproduce the full range (20 Hz to 20 kHz) of audio frequencies.

gain: An increase in level or amplitude.
graphic equalizer: An equalizer with sliding controls that create a pattern representing a graph of the frequency-response changes. Raising sliders boosts the affected frequencies; lowering sliders cuts the affected frequencies.
gray scale: The ability for a video display to reproduce a neutral image color with a given input at various levels of intensity.

HDCP: High-Bandwidth Digital Content Protection. Created by Intel, HDCP is used with HDTV signals over DVI and HDMI connections and on D-Theater D-VHS recordings to prevent unauthorized duplication of copyright material.
HDR: Hard-Drive Recorder. Device that uses a computer hard drive to store compressed digital audio and video signals.
HDMI: HDTV connection format using a DVI interface that transfers uncompressed digital video with HDCP copy protection and multi-channel audio.
HDTV: High-Definition Television. The high-resolution subset of our DTV system. The FCC has no official definition for HDTV. The ATSC defines HDTV as a 16:9 image with twice the horizontal and vertical resolution of our existing system, accompanied by 5.1 channels of Dolby Digital audio. The CEA defines HDTV as an image with 720 progressive or 1080 interlaced active (top to bottom) scan lines. 1280:720p and 1920:1080i are typically accepted as high-definition scan rates.
hanging dots: Artifact of composite video signals that appears as a stationary, zipper-like, horizontal border between colors.
high gain screen: Material that reflects more light than a reference material. Increases a projector's light output at the expense of uniformity.
high pass: Filter that passes high frequencies, and attenuates low frequencies. Same as low cut.
home THX: A set of patents, technologies, and playback standards for reproducing film sound tracks in the home as the producer intended.
horn: Type of speaker that looks like a horn. They have small drivers and very large mouths; the horn shape serves to transform the small radiating area of the driver into the much larger radiating area of the mouth of the horn.

imaging: The ability to localize the individual sound sources in three-dimensional space.For example, in a stereo recording, the image of the main instrument or singer will often sound like it is centered between the two speakers.
impedance: Resistance to the flow of an alternating electrical current.
integrated amplifier: Combination of a preamp and an amplifier.
interconnects: Any cable or wire running between two pieces of A/V equipment. For example, RCA terminated cables connecting pre/pros and amps.
interlace: Process of alternating scan lines to create a complete image. In CRT displays, every second field/frame is scanned between the first field/frame. The first field represents the odd lines; the second field represents the even lines. The fields are aligned and timed so that, with a still image, the human eye blurs the two fields together and sees them as one. Interlace scanning allows only half the lines to be transmitted and presented at any given moment. A 1080i HD signal transmits and displays only 540 lines per 60th of a second. 480i NTSC transmits and displays only 240 lines per 60th of a second. Motion in the image can make the fields noticeable. Interlaced images have motion artifacts when two fields don't match to create the complete frame, often most noticeable in film-based material.
inverted dome: A type of speaker-driver shape; usually used for tweeters (concave).

keystone: Form of video image distortion in which the top of the picture is wider than the bottom, or the left is taller than the right, or vice versa. The image is shaped like a trapezoid rather than a rectangle.

LCD: Liquid Crystal Display. A display that consists of two polarizing transparent panels and a liquid crystal surface sandwiched between. Voltage is applied to certain areas, causing the crystal to turn dark. A light source behind the panel transmits through transparent crystals and is mostly blocked by dark crystals.
LCOS: Liquid Crystal on Silicon
LNB: Low-Noise Blocker. The receiving end of a satellite dish.
letterbox: Format used widely on laser disc and many DVDs to fit wide-aspect-ratio movies (1.85:1 and 2.35:1, for example) into a smaller frame, such as the 1.78:1 area of an anamorphic DVD or the 1.33:1 area of a laser disc or video tape. The image is reduced to fit the screen, leaving blank space on the top and bottom. This process sacrifices some vertical detail that must be used to record the black bars.
line-level (low-level): A level of electrical signals too low to make the average speaker move sufficiently. Amplifiers receive line-level signals and amplify them to speaker level.
low frequency effects (LFE): A separate channel in the Dolby Digital format reserved for low-bass effects, such as explosions.The LFE channel is the “.1” channel in a 5.1-channel format.
low pass: A filter that lets low frequencies go through but doesn't let high frequencies go through. Same as high cut.
luminance: The black and white (Y) portion of a composite, Y/C, or Y/Pb/Pr video signal. The luminance channel carries the detail of a video signal. The color channel is laid on top of the luminance signal when creating a picture. Having a separate luminance channel ensures compatibility with black-and-white televisions.

Malpha: MPEG-1 Audio Layer-3. Compression scheme used to transfer audio files via the Internet and store in portable players and digital audio servers.
midbass: The middle of the bass part of the frequency range, from approximately 50 to 100 Hz (upper bass would be from 100 to 200 Hz). Also a term for loudspeaker drivers designed to reproduce both bass and midrange frequencies.
midrange: The middle of the audio frequency or human hearing range. Also used as a term for loudspeaker drivers designed to reproduce this range.
muddy: Bass or midrange that is distorted or noisy, leaving a sound that is not clear.
multizone/multisource: A feature on some A/V products that lets you listen to multiple sources in multiple rooms simultaneously.

NTSC: National Television Standards Committee. Government-directed committee that established the U.S. color TV standard in 1953. Also known, sarcastically, as Never Twice the Same Color or Never The Same Color due to the inherent difficulty in achieving proper color calibration.
negative gain screen: Material that reflects less light than a reference material. Often used for DLP and LCD projection systems.
noise: An unwanted portion of a signal such as hiss, hum, whine, static, or buzz.

Ohm: A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.
optical digital cable: Fiber optic cable that transfers digital audio signals as light pulses.

PVR: Personal video recorder. Marketing term for Video HDRs.
passive: Not active. A passive crossover uses no external power and results in insertion loss. A passive speaker has no internal amplification.
passive radiator: A radiating surface (usually similar to a conventional speaker cone) that is not electrically driven but shares the same air space in a sealed cabinet with an electrically driven loudspeaker. This arrangement is functionally similar to a loudspeaker with a vented (ported) cabinet, with the passive radiator serving the duties of the air in the port.
pixel: The smallest element of data in a video image.
plasma: Flat-panel display technology that ignites small pockets of gas to light phosphors.
port: An aperture in a loudspeaker enclosure that helps extend the usable low-frequency output. A ported enclosure is also called vented or bass reflex.
power output: A measure of a power amplifier's ability, in watts, to deliver the electrical voltage and current to a speaker.
power output: The measure, usually in watts, of how much energy is modulated by a component.
preamplifier: A control and switching component that may include equalization functions. The preamp comes in the signal chain before the amplifiers.
pre outs: Connectors that provide a line-level output of the internal preamp or surround processor.
pre outs/main ins: Connectors on a receiver that provide an interruptible signal loop between the output of the internal preamp or surround processor portion of the receiver and the input of the amplifier portion of the receiver.
pre/pro: A combination preamp and surround processor.
processors: Anything that processes an incoming signal in some way. Surround processors, for example, can decode a Dolby Digital signal to send to an amp so you can hear it.
progressive scanning: Each frame of a video image is scanned complete, from top to bottom, not interlaced. For example, 480p means that each image frame is made of 480 horizontal lines drawn vertically. Computer images are all progressively scanned. Requires more bandwidth (twice as much vertical information) and a faster horizontal scan frequency than interlaced images of the same resolution.
projection system: Display that projects image onto a screen.
pulse code modulation (PCM): A way to convert sound or analog information to binary information (0s and 1s) by taking samples of the sound and record the resulting number as binary information. Used on all CDs, DVD-Audio, and just about every other digital audio format. It can sometimes be found on DVD-Video.

RF: Radio Frequency. Television signals are modulated onto RF signals and are then demodulated by your television's tuner. VCRs and DBS receivers often include channel 3 or 4 modulators, allowing the output signal to be tuned by the television on those channels. Also, laser discs used an RF signal for modulating Dolby Digital 5.1 soundtracks on some movies. This requires an RF demodulator (usually referred to as an AC3-RF demodulator) before or in the surround processor to decode the signal.
RGB: Red, green, blue. Sometimes refers to an unprocessed video signal or the color points of a display device. Together these colors make up every color seen on a display device.
RMS: Root Mean Square or the square root of the arithmetic mean (average) of the square's set of values. A reasonably accurate method of describing an amplifier's power output.
RPTV: Rear-Projection Television
re-EQ: Short for re-equalization. A feature found on THX-certified receivers and pre/pros. Movie soundtracks are mixed for theaters or far-field monitors with an expected high-frequency roll-off otherwise known as an X-curve. If these soundtracks are not re-mixed for home use, they will sound too bright when played back through home speakers or near-field monitors. Re-EQ inserts an X-curve response into the signal to compensate for this, which takes out some of the soundtrack's excess edginess or brightness.
rear-projection television: Display that projects an image on the backside of a screen material, usually after having been reflected off of a mirror.
receiver: A component that receives, or tunes, broadcast signals, be it NTSC, HDTV, DBS, or AM/FM radio. Typically refers to the single component that includes a preamp, surround processor, multi-channel amplifier, and AM/FM tuner.
resonant frequency: The frequency at which any system vibrates naturally when excited by a stimulus. A tuning fork, for example, resonates at a specific frequency when struck.
reverberation: Reflection of sound within a closed space.
reverberation time: The amount of time it takes the reverberation to decay 60 dB from the level of the original sound.
ribbon speaker: A speaker that consists of a thin, corrugated, metallic ribbon suspended in a magnetic field. The ribbon acts electrically like a low-impedance voice coil and mechanically as a diaphragm.

SACD: Super Audio CD. Enhanced audio format with up to six channels of high-resolution audio encoded using DSD. Requires an SACD player. Multi-channel also requires a controller with six-channel analog or proprietary digital inputs for full playback.
SDTV: Standard Definition Television. Lower resolution subset of the ATSC's DTV system. 480i is typically accepted as an SD signal. Digital broadcasters can offer multiple sub-programs at SDTV quality, as opposed to one or two HD programs. Digital satellite and digital cable often refer to the majority of their programs as SDTV, somewhat erroneously, as neither system has anything to do with DTV, though both, technically, consist of a digital 480i signal.
SPL: Sound-Pressure Level. Measured in dB.
subwoofer: A speaker designed to reproduce very low bass frequencies, usually those below about 80 Hz.
sampling frequency: How often a digital sample is taken of an analog wave. The more samples taken, the more accurate the recording will be. You need to sample at a minimum of twice the highest frequency you want to capture. For example, the 44.1-kilohertz sampling rate of a CD cannot record sounds higher than 22.05 kilohertz.
scan lines: The lines drawn by an electron gun in a CRT system to make a picture. Drawn horizontally, from left to right, starting at the top left and working to the bottom right.
sensitivity: A measurement (in dB) of the sound-pressure level over a specified frequency range created by a speaker driven by 1 watt (2.83V at 8 ohms) of power with a microphone placed 1 meter away.
signal-to-noise ratio: A comparison of the signal level relative to the noise level. Larger numbers are better.
soft-dome tweeter: Tweeter that uses a soft fabric or plastic dome as the radiating diaphragm.
soundfield: Total acoustical characteristics of a space, such as ambience; number, timing, and relative level of reflections; ratio of direct to reflected sound; RT-60 time; etc.
soundstage: The area between two speakers that appears to be occupied by sonic images. Like a real stage, a soundstage should have width, depth, and height.
source: A component from which the system's signals originate. DVD player, AM/FM tuners, and VCRs are sources.
speaker: A component that converts electrical energy into acoustical energy.
spider: Part of a speaker driver's suspension that helps center the diaphragm and returns it to rest after being moved by an energized voice coil.
surround mode: A setting on A/V receivers and A/V controllers that determines what surround decoding or signal processing is performed on the audio signal.
suspension: The elements that hold a speaker driver's moving parts together, allows them to move, and helps return them to rest. Most commonly, these include the flexible surround around the outer rim of the driver and the spider on the underside of the diaphragm.\

THX-certified: An A/V product that correctly implements the THX technologies and meets stringent technical performance criteria for film-sound reproduction.
THX Ultra: Certification program for speakers, receivers, and amplifiers that assures a base level of quality and performance when played in a room that's greater than 3,000 cubic feet.
tactile transducer: A device that turns electrical energy into mechanical energy, usually used to vibrate the seating in a theater. Effective in providing visceral impact without increasing the system's actual SPL level.
transducer: Any device that converts one form of energy into another form of energy, specifically when one of the quantities is electrical. Thus, a speaker converts electrical impulses into sound (mechanical impulses), a microphone converts sound into electrical impulses, a solar cell converts light into electricity, etc.
treble: The higher or upper frequencies that the human ear can hear.
tweeter: A speaker driver designed to reproduce high frequencies; usually those over approximately 5,000 to 10,000 Hz.

uniformity: Even distribution across a given space. In video, uniformity often refers to the distribution of light (hot spotting) or color.
unity gain: Output that equals the input. Unity gain screen material reflects as much light as the reference material. Has an even dispersion of light.
universal remote: Remote that has the commands of numerous brands stored into memory and can control several different devices simultaneously.
user interface: The “look and feel” of the controls and displays on a home theater product.

watt: Unit of electrical power, defined as the power dissipated by one ampere of current flowing through one ohm of resistance.
woofer: A speaker driver designed to reproduce low frequencies.
wow-and-flutter: A measurement of speed instability in analog equipment usually applied to cassette transports and turntables. Wow is slow-speed variations, and flutter is fast-speed variations. Lower percentages are better.

zone: One or more rooms powered by one or more amplifiers, which are all fed by one source. A home can be divided into multiple zones, which can play multiple sources, even though several rooms (say, the kitchen, dining room, and living room) all play the same source.