Triad Audio Terms

DCL: Dispersion Control Lens: used in Triad LCR's & Centers. It limits vertical dispersion while maintaining a wide horizontal dispersion pattern so that all of the listening area becomes a sweet spot.

Engineered Sealed Enclosure: A design system used in all Triad inwall speakers, which employs a sealed, fully braced MDF enclosure to prevent sound bleed into adjoining walls.

Industry Audio & Video Terms

Amplifier: A component that increases the level of an audio signal from line level to speaker level.

Anamorphic: Process that condenses the image in the source material to be expanded by the display device. With DVD, the anamorphic recording preserves a vertical detail that would otherwise be lost on a widescreen film that is cropped, or letterboxed, to fit the 4:3 reading image space.

Aspect Ratio: The ratio of image width to height. The majority of motion pictures are 1.85 or 2.35 times the height, or 1.85:1 and 2.35:1. Television screens are usually 1.33:1, alsoknown as 4:3. In the '50s, 1.33:1 was also the Academy standard for films. 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.

To turn down, reduce, decrease the level of; the opposite of boost.

Attenuation: Reduction; the opposite of boosting.

A weighting: A method of changing a measurement based roughly on the uneven frequency sensitivity of the human ear. The influence of low and high frequencies are reduced in comparison to midrange frequencies because people are most sensitive to midrange sounds.

Balanced input:
An input circuit whose electrical midpoint is grounded.

A two-part filter that cuts both high and low frequencies to leave a band in the middle. A bandpass enclosure cuts high frequencies by acoustic cancellation and low frequencies by natural physical limitations on bass response.

Bandwidth: The range of frequencies covered by a driver or network.

Bass: Low frequencies; those below approximately 200 Hz.

Bi-wiring: Of or referring to a method of connecting the amplifier or receiver to the speaker in which separate wiring is run to the woofer and the tweeter, or in a three-way system, to the midrange driver.

Boost: To make louder (to increase the amplitude of); opposite of attenuation.

Bridging: Combining two channels of an amplifier to make one channel that's more powerful.

Capacitor bank: Any network of capacitors connected in combination, yielding a desired characteristic.

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: The color portion of a video signal. The chrominance channel carries the color signal that is laid on top of the luminance information when creating a picture.

Coaxial: 1) A speaker with one driver in front of (and on the same axis of) another driver. 2) An audio or video cable with a single center pin that acts as the lead and the outer shield that acts as a ground.

Coloration: Any change in the character of sound, such as the overemphasis on certain tones, that reduces naturalness.

Component Video: This signal is recorded or transmitted on three channels: one channel for luminance information, and two channels of color. Compared to S-Video signals, a component signal carries more color detail and eliminates rainbow patterns completely. DVD and DBS are component video sources.

Cone: A typical shape of a speaker driver.

Crossover: A component that divides an audio signal into two or more parts by frequency, sending, for example, low frequencies to one output and high frequencies to another. Crossovers are sometimes built into amplifiers or equalizers.

Crossover network: Following final amplification in a sound-reproduction system, an outboard circuit facilitates delivery of high- and low-frequency (AF) components to correct speakers. (Passes correct sounds to correct speakers.)

Crossover point:
The frequency that appears in two adjacent outputs of a crossover (such as high and mid) at the same level. For example, if a two-way crossover is set for a crossover point of 100 Hz, a 100 Hz signal will be at the same level in both the high-pass output and the low-pass output.

Cut: To reduce, lower, attenuate, make less loud; opposite of boost.

Damping: Of or pertaining to the control of vibration by electrical or mechanical means.

Damping material: Any material added to the interior of a speaker enclosure to absorb unwanted sound and reduce the out-of-phase reflection to the driver diaphragm.

Decibel (dB):
Not a unit like inches, but a ratio-like percent, the Bel and the decibel define power differences. (One decibel is one tenth of a Bel.) One dB is a difference of 27%. A 3-dB difference is a difference of two times, or 100%; that's why a 200-watt amplifier is only 3 dB more powerful than a 100-watt amp. A power difference of 1,000% is a 10-dB difference. A 60-dB difference is a difference of 1 million times, and so on. The decibel is used to compare power differences in voltage, current, watts, sound pressure, etc. One dB SPL is commonly accepted as the smallest difference that people can hear. The logarithmic nature of the decibel scale corresponds to the logarithmic nature of human hearing.

Delay: The time effect of distance (sound traveling through space is delayed according to the distance it travels). People perceive spaciousness by the delay between the arrival of direct sound and reflected sound (larger spaces cause longer delays).

Diaphragm: The part of a dynamic loudspeaker, attached to the voice coil, that produces sound. It usually has the shape of a cone or dome.

Dipole: Dipole speakers are a popular choice for surround speaker application and a THX requirement. Each speaker enclosure consists of two speaker arrays facing opposite each other and wire out of phase from one another to create a more ambient or nondirectional soundfield.

The degree of sound that is spread over the listening area.

Nonlinear and unwanted changes in an audio signal, often not including the addition of noise, but including harmonic, intermodulation, transient intermodulation, phase, and frequency distortion.

DNR: Dynamic Noise Reduction; a signal-processing circuit that reduces the level of high frequencies. Unlike Dolby NR, DNR doesn't require processing during recording; it works on any signal.

Dolby B: A noise-reduction system that increases the level of high frequencies during recording and decreases them during playback.

Dolby C:
An improvement on Dolby B that provides about twice as much noise reduction.

Dome: A type of speaker-driver shape usually used for tweeters (convex, not concave).

Driver: A speaker without an enclosure; also used to refer to the part of the speaker that compresses and rarefies the air (the diaphragm).

DSP: Abbreviation of digital signal processing.

DVD: Abbreviation for Digital Video Disc. Dynamic range: The difference between the smallest possible signal and the largest; expressed in decibels.

Efficiency rating: The loudspeaker parameter that shows the level of sound output when measured at a prescribed distance with a standard amount of energy fed into the speaker.
Efficiency rating standard is 1 watt at 1 meter and is measured in decibels.

Enclosure: The container of air that is pressurized by the backward motion of a speaker driver.

: Equalization or equalizer.

Equalization: Loosely any type of relative frequency adjustment. Specifically, the process of changing the frequency balance of a signal so acoustical energy is proportional to the electrical input.

Equalizer: A component designed to alter the frequency balance of an audio signal. Equalizers may be standard, graphic, parametric, or a combination of these types.

Feedback: The transmission of current or voltage from the output of a socket or 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.

Flat response: The reproduction of sound without altering the intensity of any part of the frequency range.

How often something happens. Audio frequencies are commonly defined as ranging from 20 to 20,000 cycles per second (Hz), assuming that sound waves that change the air pressure 20 or 20,000 times each second can be heard.

Frequency response: A measure of what frequencies can be reproduced and how accurately they are reproduced. A measurement of 20 to 20,000 Hz ±3 dB means that frequencies between 20 Hz and 20,000 Hz can be reproduced no more than 3 dB too loud (twice as loud) or 3 dB too soft (half as loud).

Fs: The frequency resonance of a driver in free-air.

Full range: A speaker designed to reproduce the full range of audio frequencies. Most full-range speakers can't reproduce very low or very high frequencies loud enough, but reproduce mostly midrange frequencies.


Graphic: A type of 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 (attenuates) the affected frequencies.

Gray scale: A reference scale for use in black-and-white television and video-display images, consisting of several defined levels of brightness with natural color.

Harmonic distortion:
The generation of harmonics by the circuit or device by which the signal is processed.

HDTV: Abbreviation of High Definition Television.

High (frequencies): Treble frequencies; those over approximately 3,150 Hz.

High pass: A filter that lets high frequencies go through, and attenuates low frequencies. Same as low cut.

Horn: A type of speaker that often looks like a horn. These speakers have very small drivers and very large mouths; the horn shape serves to gradually match the high impedance of the driver to the low impedance of the air.

Hz: Short for hertz; cycles per second. Something that repeats a cycle once each second is moving at a rate of 1 Hz.

Also called RCA plug and phono plug. A plug designed especially for the quick connection and disconnection of coaxial cables used with audio and other low frequency devices.

Interlace: In CRT displays, every second field/frame is scanned between the first field/frame. Usually, this process divides and presents each video frame as two fields, as if the field was raked by a comb. The first field presents 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 HDTV 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 makes the fields noticeable. Interlaced images have motion artifacts when two fields don't match to create the right frame, often the case with film-based material.

Imaging: The ability to reproduce sound so accurately that listeners can imagine the sound sources (such as musicians) sharply, clearly, accurately, and in their correct sizes.

Impedance: A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance. Measured in ohms.


Keystoning: A form of video image distortion in which the top of the picture is wider than the bottom, or vice versa. The image is shaped like a trapezoid, rather than a rectangle.

kHz: One thousand Hz; 1 kHz equals 1,000 Hz and 20 kHz is 20,000 Hz.

Kintoscope: A motion picture projector.

LCD: Liquid Crystal Displays are a transmissive device. Light isn't created by the liquid crystals, but transmitted through it. The display consists of two polarizing transparent panels and a liquid crystal surface sandwiched in between. Voltage is applied to certain areas, causing the crystal to turn dark. A light source behind the panel is transmitted through transparent crystals and is partially blocked by dark crystals. Because the light is only partially blocked in dark areas, LCDs aren't able to create deep blacks; therefore, it can't generally create a considerable contrast. Resolution is limited by the panel array. LCDs are capable of substantial light output.

LCR: A term that designates the three channels at the front of a theater...Left, Center & Right.

Letterbox: Format used widely on, laserdisc and some DVDs to fit widescreen movies (1.85:1 and 2.35:1) on the average, 1.33:1 TV screen. The image is shrunk 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 pressure too low to make speakers move sufficiently (from 25 millivolts up to about 4 or even 5 volts). Amplifiers receive line-level signals and amplify them to speaker level.

Loop: An electrical circuit consisting of elements connected in series.

Low (frequencies): Bass frequencies; those below approximately 200 Hz.

Low pass: A filter that lets low frequencies go through, but doesn't let high frequencies go through. Same as high cut.

L-pad: A variable-resistance control that puts one element of resistance in series with the load and another element in parallel. This permits the L-pad to vary the signal to a driver while maintaining constant impedance at its input.

The black and white portion of a video signal. The luminance channel carries the detail. 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.

MHz: Short for megahertz, which is 1 million Hz.

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 used for drivers designed to reproduce both bass and midrange frequencies.

The middle of the audio frequency range, from approximately 200 to 3,150 Hz.

Monophonic sound. A method of recording or reproducing sound in which sound from all directions is blended into a single channel.

Noise: An unwanted signal such as hiss, hum, whine, static, buzzing, etc.

The difference between two frequencies where one is twice the other. For example, 200 Hz is an octave higher than 100 Hz.

Ohm: A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.

Passive radiator:
An undriven loudspeaker cone that is mounted in a bass-reflex (sealed) enclosure with other speakers.

Parametric: A type of equalizer with adjustable parameters, such as center frequency and bandwidth (Q), as well as amplitude.

Phase: Time.

Piezo: A type of speaker driver that creates sound when a quartz crystal receives electrical energy.

Pixel: Contraction of a picture element. The smallest bit of data in a video image. The smaller the size of the pixels in an image, the greater the resolution.

Polarity: The 180-degree difference in the phase of audio signals that must be observed when wiring speakers.

Port: An aperture in a loudspeaker enclosure used to help tune output. A ported enclosure is also called vented or bass reflex.

Power output: A measure, usually in watts, of how much energy is produced by a component.

Preamplifier: A control and switching component that may include equalization functions. The preamp comes in the signal chain before the amplifiers.

Presets: Memory locations in a tuner where radio-station frequencies are stored.

: The ability to play tracks in a specified order.

Progressive scan: Each frame of a video image is 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 interlace images.

the magnification of resonance factor of any resonant device or circuit. A driver with a high Q is more resonant than a driver with a low Q.

Qes: The electrical Q of the driver.

Qms: The mechanical Q of the driver.

Qts: The total Q of the driver at fs.

Quasiparametric: A type of equalizer with adjustable center frequency or bandwidth as well as amplitude.

RCA jacks
: Receptacles for RCA cables carrying line-level audio signals.

Raw speakers:
Speakers that are separate, not part of a multidriver set, combined with other drivers (like coaxials), or mounted on a connecting surface (like plates).

Any component that receives broadcast signals.

Resonance 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.

The stretching of time a sound is audible by reflections of the, sound within a closed space.

Ribbon speaker: A loudspeaker 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.

RMS: Abbreviation for ROOT MEAN SQUARE; the square root of the arithmetic mean (average) of the square's set of values.

A type of speaker enclosure that doesn't allow the pressure generated by the back of the diaphragm to leave the enclosure.

Sensitivity (with input of 1 watt at 1 meter): A measure (in decibels of sound-pressure level) of how much sound comes out when 1 watt of power is put in. The measuring microphone is placed one meter away from the speaker.

Signal: A variation in an electrical current that represents pressure changes (sound). Most audio signals are alternating currents, reversing direction according to how often the signal crosses zero level.

Signal-to-noise ratio: A measure of how much louder the signal (such as music) is, in comparison to the noise (such as hiss). Larger numbers are better.

Skip: A CD feature that finds the start of a desired track.

Slope: The rate of boost or attenuation expressed in decibels per octave. Steeper slopes (larger numbers) are usually better.

Soft dome tweeter:
A tweeter that uses a fabric dome as the radiating diaphragm.

Sound: Changing pressure. Pressure that changes too slowly to be heard is infrasonic; pressure that changes too quickly to be heard is ultrasonic.

Soundfield: The total acoustical characteristics of a space, such as ambiance; number, timing, and relative level of reflections; ratio of direct to reflected sound; RT-60 time; etc.

Soundstage: The area that seems to be occupied by sonic images. Like a real stage, a soundstage should have width, depth, and height.

Speaker: A component that turns electrical energy into acoustical energy.

Speaker level: Signal strength sufficient to drive speakers (greater than line level).

Spider: The part of the loudspeaker that holds the diaphragm in place, and allows it to move when activated. Also called suspension.

SPL: Sound-pressure level, measured in dB. More is louder. May be weighted or unweighted.

Standard equalizer: An equalizer that doesn't have sliders, whose positions represent boost or cut and doesn't have variable parameters (such as center frequency or bandwidth), but fixed center frequencies and fixed bandwidth; relative amplitude is usually controlled by knobs.

Subwoofer: A speaker driver designed to reproduce very low frequencies, usually those under about 100 Hz. Often larger than 6.5 inches in diameter. However, since this is a relative term, even a 15-inch driver in a two-way system is really a woofer, not a subwoofer.

Suspension: See spider.


THD: Total harmonic distortion
Toroidal coil: A coil wound in a form that is shaped like a donut. The form is made of powered iron or ferrite. Toroidal coils have certain advantages over solenoidal coils: greater inductance for given physical size, better isolation properties, and higher Q factor.

Transducer: Any device that converts one quantity into another quantity, specifically when one of the quantities is electrical. Thus, a loudspeaker converts electrical impulses into sound, a microphone converts sound into electrical impulses, a photocell converts light into electricity, etc.

Treble: The higher part of the audio signal range, approximately 3,150 Hz on up.

Triad: Triad: A rapidly growing, well known speaker manufacturer providing high quality, custom speakers, designed to integrate within a home's decor.

Tuner: A component (or section of one) that receives radio signals and tunes in one from many.

Tweaking: Of or referring to any refinement that an audio professional or enthusiast can make to improve the naturalness of sound reproduction from a system no matter how great the effort nor how small the improvement.

Tweeter: A speaker driver designed to reproduce very high frequencies, those over approximately 5,000 to 10,000 Hz.

When the crossover point is more than 3 dB below the unattenuated level.

The volume of air that offers the same degree of restoring force on the cone as that of the cone's suspension.

Volt: The unit of electrical potential, or difference in electrical pressure, expressing the difference between two electrical charges. Voltage is the force that makes electrons move from where they are overcrowded to where they are scarce. It isn't a measure of how many electrons are moving. (that's electrical current, which is measured in amperes).

A unit of power or energy. One horsepower is equal to 745.7 watts.

Woofer: A speaker driver designed to reproduce low frequencies.

Wow-and-flutter: A measurement of speed instability usually applied to cassette transports. Wow is slow-speed variations, and flutter is fast-speed variations. Lower percentages are better.

Length of voice coil winding; thickness of top/bottom plate.

Z meter:
A device used for measuring impedances. Instruments of this kind take four principal forms: 1) a direct-reading meter resembling an ohmmeter; 2) an adjustable circuit manipulated somewhat like a bridge that compares an unknown impedance with a standard resistance; 3) an impedance bridge for evaluating reactive and resistive components of an unknown impedance; 4) a section of transmission line used with a signal source and voltmeter for measuring impedance in terms of a standard resistor and/or standing waves.