| 1-9 |
| 5.1-CHANNEL Six discrete channels, usually front left and right, centre, surround left and right, and a subwoofer. 6.1 and 7.1 are also available. |
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A |
| AAC Advanced Audio Coding. A successor to MP3, which allows lower bit rates whilst maintaining higher quality. Used by Apple for its popular iTunes music player. |
| AAD Seen on commercial music sleeves, AAD means the music has been recorded and mastered in analogue but is stored digitally on the disc. |
| ADD Seen on commercial music sleeves, ADD means the music has been recoded using analogue technology, but was mastered (or often remastered) and stored digitally. |
| AMPLIFIER An amplifier can either come in two parts (a pre-amp and power amp) or integrated as one unit. It is used to boost signals so as to power speakers. |
| ANALOGUE Legacy technologies such as tape and vinyl store music as a direct representation of the sound wave. This is described as 'analogue recording'. |
| ANAMORPHIC Anamorphic DVDs include picture optimised for widescreen (16:9) TV sets. This eliminates the letterbox effect. |
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| B |
| BALANCE Most speakers have a characteristic frequency balance resulting from emphasising or de-emphasising particular parts of the audio range. |
| BALANCED CABLES In cables which are said to be 'balanced', two cores carry the signal, plus and minus, while the screen simply carries out the job of screening. |
| BASS The lowest three octaves of the audio band. Low bass is the bottom octave (20-40Hz); mid-bass is the middle octave (40-80Hz); and upper bass is the 80-160Hz octave. |
| BASS REFLEX A speaker design whereby a port in the cabinet helps to deliver better bass reproduction |
| BINDING POST A speaker terminal designed for the connection of bare wires (and sometimes banana plugs). |
| BIT The smallest piece of digital data, either a '1' or a '0'. |
| BITSTREAM A fast method of converting digital data (from CD, DVD or MD) into analogue signals. |
| BI-AMP (sometimes tri-amp) Some speakers have separate access terminals to each drive unit allowing individual drive units to be driven by separate (matching) power amplifiers. |
| BI-WIRE (sometimes tri-wire) Loudspeakers with separate access terminals to each driver can be driven by separate cable runs between the amp and each driver. |
| BRIDGING Increasing output power by connecting two 'bridgeable' stereo amplifiers together, each working on a single channel. |
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| C |
| CARTRIDGE Converts the impressions left in the surface of a vinyl record into an electrical signal by passing through the grooves left in the disc's surface. |
| CD-R Recordable CD that cannot be erased or written on to after it has been 'finalised'. |
| CD-RW Re-writable or re-recordable CD. Often early CD players are unable to playback CD-Rs. |
| CLASS A Amplifier in which positive and negative are amplified together, offering superior quality, but generates considerable heat. |
| CLASS B In this amplifying process, positive and negative are dealt with separately, with the output alternating between the two. Class A generally offers lower distortion, Class B tends to generate less heat. |
| CLASS AB Most amps operate in Class A for the first fraction of a watt and Class B thereafter. |
| CLIPPING This form of distortion occurs when an amplifier's output waveform is advanced too far and no more 'volts' are available to sustain increasing power levels. |
| CLOCK Any electronic oscillator used to generate a timing reference signal. Its purpose is to synchronise the data being taken from a disc by a CD or DVD player. |
| (DIS)COLOURATION A move away, usually owing to unwanted interference or poor quality components, from the 'true' sound of a recording. |
| COMPRESSION 1. Describes a method used by radio stations to minimise the audible difference between soft and loud parts of a track. 2. Refers to a digital treatment of music to allow greater amounts to be stored or broadcast within restricted space or bandwidth, usually by the removal of certain frequencies that are deemed to be inaudible. |
| CROSSOVER A simple electrical network which divides the full bandwidth signal received from an amplifier, sending different parts of the audio spectrum to the various drive units in a speaker ie bass, mid and treble. Various speakers have their crossover points set at different frequencies. |
| C.R.T. Cathode Ray Tube, the conventional technology behind television sets and some high end projectors. Three different coloured tubes (red, green and blue) work together to create a colour image on the screen. |
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| D |
| DAB Digital Audio Broadcasting. Digital radio uses frequencies in the band 217.5-230MHz in the UK. Broadcasters use varying degrees of compression which can cause the audio quality to vary greatly. Many national stations are only available on DAB. |
| DAC Digital-to-Analogue Converter. The stage in a digital component where incoming digital data is used to reconstruct an analogue (music) waveform. |
| DATA COMPRESSION See compression. |
| DDD Seen on commercial music sleeves. DDD means the disc has been reordered, mastered and stored digitally. |
| DECIBEL (db) Measures strength of sound waves. A change of 1db marks an audible increase, where an increase of 10db effectively doubles the volume. |
| DIGITAL OUTPUT Allows an external DAC, in a mixer or recorder for example, to process or record the digital sound. |
| DIPOLE SPEAKERS Two speakers within a single cabinet which fire in different directions, out of phase with one another. By providing a less focused sound source, the dipole aims to replicate the ambient wash of sound in a large auditorium such as a cinema. This is deemed to more closely represent the cinema experience. |
| DISTORTION Changes or additions to the sound signal that are undesired. |
| DOLBY B, C and S Noise reduction systems used on the recording and playback of audiotapes. |
| DOLBY DIGITAL A popular compressed digital audio format which usually contains five or more discrete channels, e.g. 5.1 which includes side and rear channels, a centre speaker and a sub-woofer. |
| DOLBY DIGITAL SURROUND EX A development to Dolby Digital whereby the rear channel is matrixed, to offer a more enclosing surround sound experience. |
| DOLBY HX PRO A means of ensuring that high frequency recorded sounds are delivered to the tweeters, while lower ones remain with the woofer. |
| DOLBY PRO-LOGIC DPL is a forerunner to Dolby Digital that 'steers' sound from a stereo source to the front, centre and mono surround channels via an analogue matrix. |
| DRIVER/ DRIVE UNIT The business part of any loudspeaker is a transducer which converts electrical energy into acoustic energy, e.g. bass driver, tweeter. |
| DSD Direct Stream Digital is the coding format used for SACD and offers a frequency response of over 100kHz with a dynamic range over 120dB. It has over four times the data capacity of CD. |
| DSP Digital Signal Processor. An integrated circuit that decodes the digital audio streams. In 5.1 processors it separates the left from right and front from rear as well as managing the various bass options. |
| DTS Digital Theatre Sound. Competitor to Dolby Digital with a reduced compression ratio that can, in theory, produce higher quality audio. |
| DTS EX MATRIX The DTS equivalent to Dolby Digital EX. |
| DUAL DISC Technology which allows a DVD disc to have an additional CD layer, allowing DVD-Audio discs to be played in standard CD players. |
| DVD-AUDIO High-resolution DVD variant which offers up to 192kHz bandwidth and 24-bit dynamic range. DVD-A discs play in all standard DVD players. |
| DVD VIDEO Video recorded on a disc physically similar to a CD. Large capacity allows for high picture quality, as well as additional features, such as surround-sound audio for example. |
| DVD-R/-RW A recordable/rewriteable DVD format developed by Pioneer. |
| DVD+R/+RW An alternative DVD format developed by Phillips. |
| DVD-RAM The DVD format developed by Panasonic. The method of recording allows the user to watch the beginning of a program whilst the remainder is still being recorded. |
| DVI-D A digital connection allowing for the transmission of video and audio without the need to convert it to analogue. |
| DRIVER A transducer designed to convert electrical signals into sound waves, e.g. A woofer. |
| DYNAMIC RANGE The range between the smallest and largest audio signals in Hi-Fi sound. |
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