Neodymium A material used in some speaker magnets. Neodymium magnets are smaller and more powerful than conventional speaker magnets.
Octave The difference between two frequencies where one is twice the other. For example, 200 Hz is an octave higher than 100 Hz. 400 Hz is one octave higher than 200 hz.
Ohm A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.
Passive Not active. A passive crossover uses no external power and results in insertion loss. A passive speaker is one without 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
Piezo A type of speaker driver that creates sound when a quartz crystal receives electrical energy.
Pixel Contraction of picture element. The smallest element of data in a video image.
Phase Refers to the timing relationship of two or more signals or sound waves. It's especially important to be sure that your stereo speakers are playing "in phase." This means that the drivers (woofers and tweeters) of your right and left speakers are moving in and out at the same time. If your stereo speakers are "out of phase" — that is, with one set of positive and negative leads reversed — you'll hear significantly less bass, and instead of producing a strong center image, the sound tends to stay localized at the speakers.
Phase control A 2-position switch found on some powered subwoofers that lets you delay the subwoofer's output slightly so that it is in phase with the output from your main speakers.
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 handling A measure of how much amplifier power, in watts, a speaker can take before it is damaged.
Receiver: Any 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, multichannel amplifier, and AM/FM tuner.
Resonance When a component or system vibrates more at a certain frequency than at any other frequency. In a speaker system, resonance with the speaker enclosure or any of the components can lead to colorations in the sound.
RMS A term used to indicate the average level of power that a receiver or amplifier can sustain over a given period of time. Average power ratings (ex: 100 watts RMS) provide a more realistic assessment of your amp's performance than peak power (ex: 400 watts peak/dynamic power) since an amp can only sustain peak power for a short period of time. (RMS stands for "root mean square," which is one of the mathematical methods used to calculate an amp's average power output, and is commonly used throughout the industry to represent the average power rating.)
Satellite speaker A small speaker with limited bass response that's often designed to be used with a matching subwoofer.
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.Essentially, the higher the rating, the louder your speakers will play with a given amount of amplifier power. For Example: If a speaker has a sensitivity rating of 85 dB it will require 100 watts to produce a given volume, at that same volume, if you have a speaker that has a greater dB such as, 88 dB it will only require 50 watts ofpower.Further, if you have a speaker that has a 91 dB sensitivity rating, to achieve the same level of volume it would only require 25 watts of power. A higher dB is ideal when considering multiple speakers off one receiver.
Soft-Dome Tweeter A tweeter that uses a soft fabric or plastic dome as the radiating diaphragm.
Soundstaging A stereo or home theater system's ability to present music, dialogue, and other sounds as taking place within a physical space with definite width, height, and depth. The individual vocal and instrumental "images" are part of the "soundstage."
Spider Part of a loudspeaker driver's suspension that helps center the diaphragm and returns it to rest after being moved by an energized voice coil.
SPL (sound pressure level) The intensity or volume level of sound (measured on the dB scale).
Subwoofer A speaker designed to reproduce very low bass frequencies, usually those below about 80 Hz.A "powered subwoofer" includes a built-in amplifier to drive the speaker.
Surround Connects a driver's diaphragm to its basket. The two most common surround materials are rubber and foam. Rubber typically lasts longer than foam, especially in warm, moist climates, but tends to cost more.
Surround speakers In a home theater system, the speakers located beside or behind the listening/viewing position. These speakers can be mounted on the walls, in the wall or placed on stands, or set on bookshelves. They help create an enveloping three-dimensional soundstage by reproducing the surround information on video soundtracks and music recordings encoded with surround sound.
Terminals You probably don't think about the connectors on the back of your speakers until you go to hook them up. There are two basic types: spring clips and binding posts. Spring clip terminals Usually found on lower-priced speakers, and low- to medium-priced receivers. They work best with bare wire connections with small-gauge speaker wire, or pin-type connectors
Binding post terminals Sturdier, more versatile type of speaker jack, often found on higher-quality speakers and receivers, and on most amplifiers. They're threaded, so you can tighten them down against the wire or connector for an extra-snug connection.
THX Certification program for home theater equipment. Uses some proprietary features, but mostly assures a base quality level for a given room size. (See THX Select or Ultra.) Is compatible with any and all soundtrack formats. Stands for either Tom Holman's eXperiment, after the engineer who drafted the original standard, or is named after the company's founder George Lucas' first movie, THX 1138. Nobody agrees on which.
Timbre Pronounced "tam-burr." The quality of a sound related to its harmonic structure. Timbre is what gives a voice or instrument its sonic signature — for instance, why a trumpet and a saxophone sound different when they play the same note.
Transducer Any device that converts one form of energy into another form of energy, specifically when one of the quantities is electrical. Thus, a loudspeaker converts electrical impulses into sound (mechanical impulses), a microphone converts sound into electrical impulses, a solar cell converts light into electricity, etc.
Transient A short-lived aspect of a signal, such as the attack and decay of musical tones. A speaker that can react quickly to rapid changes in the music is said to have good "transient response."
Tweeter A speaker driver designed to reproduce high frequencies; usually those over approximately 5,000 to 10,000 Hz. Usually small and lightweight reproducing the highest musical frequencies, like violins, cymbals, female vocals, etc..
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 for home theater speakers — especially the center channel speaker — because 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.
Voice coil The cylindrical coil of wire that moves in the magnetic field of a dynamic driver. The voice coil is bonded to the diaphragm, which actually produces the sound.
Voice-matching When speakers possess a similar timbre or tonal quality. Voice-matched (or timbre-matched) speakers in a home theater system will result in more seamless, consistent, convincing wraparound sound. A good way to get voice-matched speakers is to stay within a family or series of speakers from a single manufacturer, or to get a pre-matched multi-speaker system.
Watt A unit of power or energy. One horsepower is equal to 745.7 watts.
Woofer A type of driver that features a cone-shaped diaphragm, commonly used for producing the mid- and low-frequency portions of the music signal.
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.
Home Audio Glossary of Terms has been created to inform and educate individuals interested in building a home theater environment. These home audio terms relate to all words beginning with the letters N through Z, such as Neodymium, Octave, OHm, passive, piezo, pixel, phase, phase control, port, power handling, receiver, RMS, satellite speaker, sensitivity, soft-dome tweeter, soundstaging, spider, SPL (sound pressure level), subwoofer, surround, surround sound, terminals, Spring clip terminals, bindig post terminal, THX, Timbre, transducer, transient, tweeter, video shielding, voice coil, voice matching, watt, woofer, and zone.