Audioden

31. B

Backlighting
A technique of illuminating the buttons and keys on a remote control so they can be identified in a dark room.

Balance
A control that changes the relative volume level in two or more channels

Balanced
When positive and negative signal wires have a separate earthed (grounded) shield around them to improve interference rejection. Unbalanced connections use a coaxial cable with a single core and the outer shield doubles as the signal return path. are less apt to pick up external noise.

Band-pass Filter
An electric circuit designed to pass only middle frequencies.

Bandpass
A two-part filter that cuts both higher and lower frequencies around a center band. A bandpass enclosure cuts high frequencies by acoustic cancellation and low frequencies by natural physical limitations on bass response.

Bandwidth
The total frequency range of any system.

Bass
The low end of the audio frequency spectrum, from approximately 20 Hz up to 400 Hz.

Bass Blocker
First order high-pass crossovers (non-polarized capacitors), generally used on midbass or dash speakers to keep them from reproducing deep bass frequencies.

Bass Drive Unit (Woofer)
A drive unit designed to produce bass frequencies only. In classic two-way speakers the bass drive units are more accurately described as bass/midrange units.

Bass-Reflex
A type of loudspeaker enclosure in which the sound emitted from the back of the woofer's diaphragm is used to augment low-frequency output by feeding it through a port of passive radiator.

Beaming
The tendency of a loudspeaker to concentrate the sound in a narrow path instead of spreading it out.

Bessel Crossover
A type of crossover design characterized by having a linear or maximally flat phase response. Linear phase response results in constant time-delay (all frequencies within the passband are delayed the same amount). Consequently the value of linear phase is it reproduces a near-perfect step response with no overshoot or ringing. The downside of the Bessel is a slow roll-off rate. The same circuit complexity in a Butterworth response rolls off much faster.

Bi-Amplification
The use of two amplifiers, one for the lows, one for the highs in a speaker system. Bi-amplification can be built into the speaker design or accomplished with the use of external amplifiers and electronic crossovers.

Bi-polar
1) The condition of possessing two pole sets. In a conventional (non-FET) transistor, one pole set exists between the base and collector, and the other pole set exists between the base and emitter. 2) Speakers that consist of two driver arrays facing opposite directions and wired in electrical phase with one another to create a more diffuse soundstage.

Bi-Wiring
The use of two pairs of speaker wire from the same amplifier to separate bass and treble inputs on the speaker.

Bit
Originally short for Binary Digit. In digital, the small unit of information. A bit represents either an on of off value represented by a 0 or 1.

Bit Stream
Refers to a stream of bits transmitted over a communications line between two devices.

Black Level
Light level of the darker portions of a video image. A black level control sets the light level of the darkest portion of the video signal to match that of the display's black level capability. Black is, of course, the absence of light. Many displays, however, have as much difficulty shutting off the light in the black portions of an image as they do creating light in the brighter portions. CRT-based displays usually have better black levels than DLP, plasma, and LCD, which rank, generally, in that order.

BNC
A type of 75 ohm connection often used in video and digital audio. The BNC format utilizes a locking adapter.

Boomy
The smearing of transients that makes bass reproduction sound muddled, usually because of improperly designed sealed (to small), ported (to small or tuned improperly), and bandpass enclosures.

Bridging
combining both left and right stereo channels on an automotive amplifier into one higher powered mono channel. When an amplifier is bridged, the impedance that the amplifier sees is calculated based upon the output of both stereo channels. Here is a simple formula to help define this:

Bridged Mono Impedance = (Y / X)/2

Y = impedance of driver(s) (both drivers should be identical)

X = # of drivers in circuit

Based on this formula, hooking up one 4 ohm sub bridged mono would be equal to hooking up two 2 ohm subs in stereo, one to each channel.

Brightness
For video, the overall light level of the entire image. A brightness control makes an image brighter; however, when it is combined with a contrast, or white level control, the brightness control is best used to define the black level of the image. For audio, something referred to as bright has too much treble or high-frequency sound. (See also Black Level)

Butterworth Crossover
A type of crossover circuit design having a maximally flat magnitude response, i.e., no amplitude ripple in the passband. This circuit is based upon Butterworth functions, also know as Butterworth polynomials.

32. C

Capacitor
A device made up of two metallic plates separated by a dielectric (insulating material). Used to store electrical energy in the electrostatic field between the plates. It produces an impedance to an AC current.

Casa
A multi-source/multi-room audio control system, that can be controlled from a hand held IR (infra red) remote, or through an in-wall keypad. It is designed to offer a high quality permanent audio installation, reliably and independently serving many rooms in one home through a simple yet powerful user-interface.

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. For example, using the crossover in a receiver's bass management setting and the one in a subwoofer simultaneously will create an exaggerated loss of signal.

CD
Also known as Compact Disc. An optical disc storage media that is designed to store audio, video, and computer data in a digital format. CD's have a capacity to store 700 Mb (megabytes) of data. The digital information in a standard audio CD is encoded in the PCM format. (See also PCM)

Center Channel
The center speaker in a home theater setup. 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 important, as voices and many effects in a multichannel mix 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.

Channel Balance
In a stereo system, the level balance between left and right channels. Properly balanced, the image should be centered between the left-right speakers. In a home-theater system, refers to achieving correct balance between all the channels of the system.

Chassis
Frame or basket that houses the midrange or bass driver components.

Chrominance (C)
The color portion of a video signal.

Circuit Breaker
An electrical switch that automatically breaks a circuit if the current through it is too high, then can be manually reset. Performs the same function as a fuse, without the need for replacement after it is activated.

Classes, Amplifier
Basically, amplifying the audio signal means using the wall-current (usually either 120 or 240 volts) to increase the amplitude of the audio signal from milliwatts(mW) to watts (W). Different classes of amplifiers accomplish this in different ways. Turning a vacuum tube on or off with current demand increases the efficiency of the amplifier but may add switching distortion. A Class A amplifier is relatively inefficient, converting much energy to heat, but has no switching distortion. (See also Amplifier Classes)

Clipping
Audible distortion occurring when the peaks of an amplifier's output are flattened (or clipped). When the input is too high, an amplifier has insufficient power to accurately reproduce the output waveform.

Cms
Mechanical suspension compliance of a driver, consisting of the spider and surround.

Coaxial
1) A speaker typically with one driver in the middle of, and on the same axis as, another driver. 2) 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.

Coaxial Driver
A speaker composed of two individual voice coils and cones; used for reproduction of sounds in two segments of the sound spectrum.

Codec
Mathematical algorithms used to compress large data signals into small spaces with minimal perceived loss of information.

Coloration
Any shift away from the natural rendition of music. Coloration is undesirable - boomy bass, a nasal midband or a splashy treble, for instance. All colorations tend to get in the way of the music.

Compliance
The relative stiffness of a speaker suspension, specified as Vas.

Component Video
A signal that's 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 nearly all consumer video devices. Chrominance is carried in a 3.58-mHz sideband and filtered out by the TV's notch or comb filter. Poor filtering can result in dot crawl, hanging dots, or other image artifacts.

Compression (Audio)
Compression is when the amplitude is squashed to reduce the level difference between the loud and soft parts of the music (the peaks and troughs on the wave form). This is often used by radio stations to improve the sound of cheap radios with limited output capability when played loud. It is usually avoided in Hi-Fi, because it restricts dynamics. However, with powered subwoofers, a form of compression called soft clipping can be useful to avoid the harsh sound of transistors clipping when the amplifier is used near its limit. It's similar to the way valves (tubes) limit their output.

Conductor
Materials along which electrons will flow, making them suitable for use as connecting links in electrical circuits.

Contrast
Relative difference between the brightest and darkest parts of an image. A contrast control adjusts the peak white level of a display device.

Conventional Current
The representation of current as flowing from positive to negative potential when describing the behaviour of electricity, despite the reality that the actual electrons constituting that flow move from negative to positive potentials.

Crossover
A frequency divider. Crossovers are used in speakers to route the various frequency ranges to the appropriate drivers. Additionally, many crossovers contain various filters to stabilize the impedance load of the speaker and or shape the frequency response. Some crossovers contain levels controls to attenuate various parts of the signal. A passive crossover uses capacitors, coils and resistors, usually at speaker level.A passive crossover is load dependent (the transition may not be very smooth or accurate if a different speaker is substituted for the one the crossover was designed for). An active crossover is based on integrated circuits (ICs), discreet transistors or tubes. An active crossover is impedance buffered and gives a consistent and accurate transition regardless of load.

Crossover Frequency
The frequency at which an audio signal is divided. 80 Hz is a typical subwoofer crossover point and is the recommended crossover point in theatrical and home THX systems. Frequencies below 80 Hz are sent to the subwoofer; signals above 80 Hz are sent to the main speakers.

Crossover Slope
High and low pass filters used for speakers do not cut-off frequencies like brick walls. The rolloff occurs over a number of octaves. Common filter slopes for speakers are 1st through 4th order corresponding to 6db/oct to 24db/oct. For example, a 1st. order, 6db/oct high pass filter at 100hz will pass 6db less energy at 50Hz and 12db less energy at 25Hz. Within the common 1st through 4th filters there is an endless variety of types including Butterworth, Linkwitz-Riley, Bessel, Chebychev, etc. Salesmen and product literature will sometimes make claims of clear superiority for the filter used in the product they are trying to sell. Since the subject fills books, suffice it to say that there is no one best filter, it depends on application and intended outcome. Good designers use the filters required to get the optimum performance from the system.

Crosstalk
Unwanted breakthrough of one channel into another. Also refers to the distortion that occurs when some signal from a music source that you are not listening to leaks into the circuit of the source that you are listening to.

CRT
Cathode Ray Tube. Analog display device that generates an image on a layer of phosphors that are driven by an electron gun.

Current
The flow of electrons along a conductor.

Current (I)
The flow of electrical charge measured in amperes

Cycles Per Second
The unit of measure denoting frequency. (See also Hertz - Hz) (See also Frequency)

33. D

D-ILA
Direct Drive Image Light Amplifier. This Hughes/JVC technology uses a reflective LCD to create an image. A light source is then reflected off the reflective LCD and is directed through a lens to a screen.

DAC
A Digital to Audio Converter. Converts a digital bitstream to an analog signal. Can be a separate unit or an internal chip set.

DC
Direct Current. Current that moves in only one direction.

DDD
An acronym found on CD cases to indicate that the music was recorded (D) and mastered (D) and stored (D) digitally. (See also ADD) (See also AAD)

De-coupling
In a loud speaker - the separating of each drive unit from its enclosure, and also each enclosure from the others, such that no vibration is transmitted from one to another.

Decibel (dB)
Named after Alexander Graham Bell. A 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.

- 0 dB is the threshold of hearing
- 130 dB is the threshold of pain.
- Whisper: 15-25 dB
- Quiet background: about 35 dB
- Normal home or office background: 40-60 dB
- Normal speaking voice: 65-70 dB
- Orchestral climax: 105 dB
- Live Rock music: 120 dB+
- Jet aircraft: 140-180 dB


Delay
The 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 loudspeaker attached to the voice coil that moves and produces the sound. It usually has the shape of a cone or dome.

Dielectric
Insulating materials exposed to electric fields are called dielectrics. Dielectrics are necessary parts in the construction of any cable because they prevent oxidation and keep the conductors from touching one another. In audio cables, relatively low voltage and current levels mean that dielectric strength is not the most important factor. Far more significant in its effect on the sound is a material's dielectric absorption. This characteristic describes the way a dielectric may discharge a secondary signal into the conductor out of phase with the audio signal.

As a current is passed through a conductor, an electromagnetic field is created which interacts with the dielectric material and temporarily displaces the molecular structure. If the dielectric material has good elasticity and can return quickly to its normal state, then the material is said to have low dielectric hysteresis or loss and will have little audible effect on the signal.

Diffraction
The re-radiation of sound waves at discontinuities such as cabinet edges. The time-delayed wave interferes with the original sound output, causing peaks and dips in the frequency response and smearing the transient response.

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
Acoustical treatment device that preserves 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
Represented by a numerical code. For sound, the conversion of an analogue waveform to a series of numbers representing the instantaneous amplitude for each sample taken, the storage of those numbers, and the eventual conversion back to analog format for replay.

Digital Dolby
An encoding system that digitally compresses up to 5.1 discrete channels of audio (left front, center, right front, left surround, right surround, and LFE) into a single bitstream, which can be recorded onto a DVD, HDTV broadcast, or other form of digital media. When RF-modulated, it was included on some laser discs, which requires an RF-demodulator before the signal can be decoded. Five channels are full-range; the .1 channel is a band-limited LFE track. A Dolby Digital processor (found in most new receivers, preamps, and some DVD players) can decode this signal back into the 5.1 separate channels. Most films since 1992's Batman Returns have been recorded in a 5.1 digital format, though a number of films before that had 6-channel analog tracks that have been remastered into 5.1.
(Dolby Digital and Pro-Logic are registered trademarks of Dolby Laboratories Inc.) (See also AC3)

Dipole
Speakers with drivers on opposite faces that are wired electrically out of phase, creating an area of cancellation to the sides. Recommended by THX for use as surround speakers, with null directed at the listener to create a more ambient and non-localizable effect.

Direct View Television
Display whose image is created on the surface from which it is viewed.

Dispersion
The spreading of sound waves as they leave a source. The spreading of sound waves as they leave a source.

Dispersion Modifier
Center bullet in a midrange driver in place of a conventional dust cap. It improves dispersion in the mid-frequencies, and helps to maintain the high frequency response of midrange units.

Dither
The method used in digital systems to smooth out the transitions from one bit to another at low levels. Dither makes a digital recording sound and behave more like analog. The better a recording is dithered, the higher its apparent resolution.

DLP
Digital Light Processing. A Texas Instruments process of projecting video images using a light source reflecting off of an array of tens of thousands of microscopic mirrors. Each mirror represents a pixel and reflects light toward the lens for white and away from it for black, modulating in between for various shades of gray. Three-chip versions use separate arrays for the red, green, and blue colors. Single-chip arrays use a color-filter wheel that alternates each filter color in front of the mirror array at appropriate intervals. (See also DMD)

DMD
Digital Micromirror Device. Texas Instruments engine that powers DLP projectors. Uses an array with tens of thousands of microscopic mirrors that reflect a light source toward or away from the lens, creating an image. Each mirror represents a pixel. (See also DLP)

DNR
Dynamic Noise Reduction. A signal-processing circuit that attempts to reduce the level of high-frequency noise. Unlike Dolby NR, DNR doesn't require preprocessing during recording.

Dolby Digital EX Surround
An enhancement to the Dolby Digital 5.1 where a rear center channel has been added creating a 6.1 format. The Dolby Digital Surround EX format does not add an additional discreet recorded channel. The new rear center channel is matrix-encoded in the Dolby Digital left and right surround signals. The recorded Dolby Digital audio consists of five discrete main channels and a sixth, low-frequency-effects (LFE) channel. The two rear surround channels carry the signal for the rear center channel. The Dolby Digital Surround EX format made is debut in the 1999 movie Star Wars Episode I - The Phantom Menace.

Dolby Pro Logic
An earlier form of surround sound. Four separate signals are encoded in a 2-channel recording and re-separated by the processor into left, centre, right and surround channels. The surround channel is usually fed to 2 speakers at the rear. (Dolby and Pro-Logic are registered trademarks of Dolby Laboratories Inc.) (See also Dolby Surround)

Dolby Stereo
Developed by Dolby in the early 70s, Dolby Stereo produces 4 channel sound with three channels of sound in the front (left and right for music and effects and centre for dialogue) and a surround channel for effects and atmospheres.

Dolby Surround
Encodes sound for rear effects channels into the stereo tracks. Needs to be replayed through a decoder to produce surround. (Dolby is a registered trademark of Dolby Laboratories Inc.) (See also Dolby Stereo)

Dome Tweeter
A high frequency speaker with a dome-shaped diaphragm.A high frequency speaker with a dome-shaped diaphragm.

Driver
A speaker without an enclosure; also refers to the active element of a speaker system that creates compressions and rarefactions in the air.

DSD
Direct Stream Digital. A digital encoding format proposed by Sony and Philips used to record SACD albums. DSD samples an audio signal at a fixed rate (frequency) just as in the PCM method. However, instead of recording the volume or amplitude as an absolute number, as in PCM, the DSD method measures and records how much the volume has changed since the last measurement. If the signal is sampled fast enough, the amount of change since the previous sample would be very small. The proposal for DSD is for a sampling rate that's over 2 MHz (2 million times per second). At this high speed the changes in signal strength can be represented with one bit. DSD also compresses the data resulting in a 2:1 reduction. DSD will be able to provide a frequency response from DC to 100 kHz with a dynamic range of 120 dB.

DSP
Digital Signal Processing. DSP can be used to create equalization, compression, etc. of a digital signal.

DTS
Digital Theater Systems. Multi-channel digital surround system that encodes and decodes audio signals enhancing the fidelity of the signal to produce high quality sound. It is used in some movie theatres and is also available in some home theatre digital processors. (See also 5.1 Surround Sound)

DTS ES
An enhanced version of the 5.1 DTS system. Like Dolby's Surround EX, a sixth channel is added. In some cases (DTS ES Discrete), the sixth channel is discrete. Software is backwards-compatible with 5.1 systems, but requires an ES or 6.1 processor to obtain additional benefit. Neo:6 is a subset of DTS ES that creates 6.1 from material with fewer original channels.

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.

Dual / Double Voice Coil (DVC)
A voice coil with two windings, generally used in woofers. Each voice coil can be connected to a stereo channel, or both voice coils can be wired in parallel or series to a single channel.

DVD
Officially known as the Digital Video Disc, though marketers unofficially refer to it as the Digital Versatile Disc. DVD uses a 5-inch disc with anywhere from 4.5 Gb (single layer, single-sided) to 17 Gb storage capacity (double-layer, double sided). It uses MPEG2 compression to encode 720:480p resolution, full-motion video and Dolby Digital to encode 5.1 channels of discrete audio. The disc can also contain PCM, DTS, and MPEG audio soundtracks and numerous other features. An audio-only version, DVD-A uses MLP to encode six channels of 24-bit/96-kHz audio.

- DVD-Audio
- DVD-R
- DVD-ROM
- DVD-RW
- DVD-Video
- DVD+RW


DVD Audio (DVD-A)
An audio standard for high quality audio recorded on DVD's that exceed the capacity and quality of CD's. An DVD-Audio disk is capable of recording audio with frequencies up to 96Khz (compared to CD's at 20kHz) and with a dynamic range of up to 144dB (compared to CD's 96dB). DVD-Audio supports multi-channel recordings.

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)

Dynamic Headroom
The ability of an audio device to respond to musical peaks. For example, an amplifier may only be capable of a sustained 100 watts, but may be able to achieve peaks of 200 watts for the fraction of a second required for an intense, quick sound. In this example the dynamic headroom would equal 3 db.

Dynamic Range
The range between the loudest and the softest sounds that are in a piece of music, or that can be reproduced by a piece of audio equipment without distortion (a ratio expressed in decibels). In speech, the range rarely exceeds 40 dB; in music, it is greatest in orchestral works, where the range may be as much as 75 dB.

D\'Appolito
Vertically symmetrical driver array. Typically consists of a tweeter mounted between two woofers. Creates a more-vertically directional sound with evenly spaced lobes in the off-axis response when compared with asymmetrical driver arrays.

34. E

EBP
Efficiency Bandwidth Product. A guide that helps a designer determine whether a driver is more suitable for a sealed or ported enclosure. EBP of less than 50 indicates the driver should be used in a sealed, 50 - 90 indicates flexible design options, over 90 indicates best for a ported enclosure. EBP = Fs / Qes

EDTV
Enhanced Digital Television
EDTV refers to a complete product/system with the following minimum performance attributes:

 

• Receiver: Receives ATSC terrestrial digital transmissions and decodes all ATSC Table 3 video formats
• Display Scanning Format: Has active vertical scanning lines of 480 progressive (480p) or higher
• Aspect Ratio: None Specified
• Audio: Receives and reproduces, and/or outputs Dolby Digital audio

Enhanced Definition Television (EDTV) Monitor:
EDTV Monitor refers to a monitor or display with the following minimum performance attributes:

• Display Scanning Format: Has active vertical scanning lines of 480 progressive (480p) or higher
• Aspect Ratio: None specified

Enhanced Definition Television (EDTV) Tuner:
EDTV Tuner refers to a RF receiver with the following minimum performance attributes:

• Receiver: Receives ATSC terrestrial digital transmissions and decodes all ATSC Table 3 video formats
• Outputs: Outputs the ATSC Table 3 720p and 1080i/p and 480p formats with minimum active vertical scanning lines of 480p. Alternatively, the output can be a digital bitstream output capable of transporting 480p, except the ATSC Table 3 480i format can be output at 480i.
• Audio: Receives and reproduces, and/or outputs Dolby Digital audio

Efficiency Rating
Level of sound output measured at a prescribed distance with a standard input power. Efficiency rating standard is 1 watt (2.83V at 8 ohms) at 1 meter over a specified frequency range and is measured in decibels.

Electronic Crossover
Uses active circuitry to send signals to appropriate drivers. More efficient than passive crossovers. This is also known as an active crossover. (See also Crossover)

Electrostatic Speaker
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. In between these two panels is an extremely low-mass diaphragm to which the audio signal is applied, causing it to move. There are variations on this construction, but all electrostatic speakers are free from the magnets and voice coils used in conventional speakers.

Equalizer (EQ)
Electronic set of filters used to boost or attenuate certain frequencies.

Equilization
Loosely, any type of relative frequency adjustment. Specifically, the process of changing the frequency balance of an electrical signal to alter the acoustical output.

Euphonic
Pleasing. As a descriptive audio term, usually refers to a coloration or inaccuracy that non-the-less may be sonically pleasing.

Extension
How extended a range of frequencies the device can reproduce accurately. Bass extension refers to how low of a frequency tone the system will reproduce; high-frequency extension refers to how high in frequency the system will play.

35. F

36. G

37. H

38. J

39. K

40. L

41. M

42. N

43. O

44. P

45. Q