Click on the letters below find words associated with that letter or fill in your search term in the supplied box:
AAD
Seen on CD cases, meaning the music was recorded and mastered in analogue form - the first two As - but stored digitally (on the CD)
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AC-3
See Dolby Digital
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ADD
Music recorded in analogue form (A), mastered or remastered digitally (D), and stored digitally on CD (the third D)
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Alignment
Adjustment of a record-player cartridge relative to the groove on the vinyl disc. Bad alignment causes distortion. Tape heads also need alignment, but it's best left to the experts.
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Amplifier (Power Amplifier)
A device used to increase the amplitude of the voltage, current, impedance or power of a signal. In audio, an amplifier boosts signals to drive speakers. Can be one-box (integrated) or have separate pre and power sections.
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Analogue
LPs/cassette tapes store audio in non-digital form directly related to the signal.
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Anti-skating
Applied to arms on turntables to prevent them from swerving towards the centre.†
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Balanced connections
Positive and negative wires are shielded (for better interference rejection) in balanced connections. Normal connections use the negative to shield the positive cable. Use a three-pin XLR type plug to connect from the amplifier - also used in the AES/EBU digital format.
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Banana Plug
An electrical connector designed to join audio wires, such as speaker wires, to binding posts.
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Bass
Portion of the audible frequency which encompasses lower pitches. Bass frequencies are generally considered to be between 30Hz and 200Hz.
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Bass Reflex
A speaker design using air-flow from a port in the cabinet to help distribute low frequencies.
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Biamping
Each drive unit of a speaker is driven by a separate amp channel, so a pair of two-way speakers needs two stereo amps, and two runs of cable to each speaker. See biwiring.
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Binding Post
A terminal which allows wires to be connected to the output of an amplifier. Binding posts are usually designed so they can accept alligator clips, banana plugs, as well as, bare wires.
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Bit
A single piece of digital information, basically an 'on/off' signal. Digital-to-analogue converters turn strings of bits into audio signals.
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Bitstream
One method of turning digital CD data into analogue signals. Bitstream digital-to-analogue converters process single bits of digital data much faster than multibit DACs, which work on chunks of digital data.
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Biwire
A wiring technique that employs two runs of wire from amplifier output terminals to speaker: one for the woofers; another for the midrange/tweeter drivers. The speaker must have two separate sets of terminals to use this wiring method. Compared to biamping, biwiring tends to be subtle in sonic difference, requiring listening sophistication to discern any qualitative change.
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Biwiring
Biwiring offers some of the benefits of biamping but at a lower cost. You need speakers with two sets of inputs and a split crossover, then send twin runs of cable from amp to each speaker.
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Bridging
Connecting two power amplifiers in such a way as to give one power amplifier double the output power. By inverting the polarity of one amplifier before sending it to another amplifier and connecting the load between hot terminals of the two amplifiers, the effective voltage swing is doubled. Note: amps must be designed to be bridged in the first place.
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Cable TV
Multi-channel TV down a wire to your home. You pay for different combinations of services. Stereo provision varies between companies.
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Cables
Copper conductors are mostly used with purity expressed as a number of 'nines'. So 'six nines' or '6N' purity might be 99.99997 per cent pure copper. Good speaker cables can have many strands (multistrand) or one or more thick wires (solid core). Look for arrows, which should point from the amp to the speaker, on directional cables. Directional interconnects have arrows that point from source to amp.
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Capacitance
The tendency to store an electrical charge. The quantitative measure of the electrical effect of a capacitor.
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Capacitor
A device which stores an electrical charge.
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Cartridge
The device which actually plays the record. It converts the wobbles in the record's groove into electrical signals for your amp. See moving magnet and moving coil.
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CD-R
CD-Recordable. Uses a special blank disc in a recording CD player. Once recorded it can't be erased, but plays in standard CD players when 'fixed up'. CD-R discs look green. Comes in two flavours, professional and consumer. Discs and machines are not interchangeable
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CD-ROM
Uses CD as a Read Only Memory for computers. Vast storage capacity - around 600MB - on single disc.
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CD-text
New system which allows CD players to display a limited amount of text such as track names or lyrics. Being introduced shortly by Sony
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Class
Amp in which positive and negative half cycles are amplified together. Runs hot, as the transistors in the power amp are on all the time, but has high sound quality.
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Class
Positive and negative halves of the signal dealt with by different parts of the circuit, the output devices switching continually. Runs cooler, but the sound is not as pure.
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Coaxial
A cable design commonly used in low voltage applications interconnects for audio, digital and video signal transfer. In these designs braided shields are used to enhance high frequency noise cancellation , however, the design can attract low frequency noise.
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Coloration
A shift away from the natural rendition of music. Coloration is undesirable - 'boomy' bass, a 'nasal' midband or a splashy treble, for instance. All colorations get in the way of the music.
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Compact Disc
Standard 12cm (4.73 in) disc, which stores information digitally, read by laser optical system. Originally designed for music storage, the CD is now used for many applications.
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Compression
Used by radio stations to reduce level differences between loud and soft parts of music. Helps in-car and transistor sound, but can be awful through a hi-fi tuner.
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Copper
(OCC, PCOFC, OFC, TPC)
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Crossover
Circuit inside speakers which splits high frequencies to the tweeter and low to the woofer.
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DAB
Digital Audio Broad-casting: digital stereo on both FM and AM. Currently broadcast by the BBC to a limited area, it banishes hiss and interference. No tuners yet out.
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DAC
Digital-to-analogue converter, turning on/off pulses into analogue sound. Most CD players have DACs built in. Separate DACs can upgrade a CDplayer or other digital player/ recorder, or can be used with dedicated CD transports.
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DAT
Digital Audio Tape. A digital recording system now used mainly professionally. Uses a revolving recording head similar to that used in a VCR.
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Data reduction
Lowers the amount of data needed to store music. Sony's MiniDisc uses an in-house system called ATRAC (Adaptive Transform Acoustic Coding) while the PASC (Precision Adaptive Sub-band Coding) used in Philips' DCCformat serves a similar function, removing signals its designers think you can't hear.
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DCC
Digital Compact Cassette - Philips' home digital tape system.
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DDD
On CD cases - music recorded and mastered digitally and stored digitally on CD.
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Decibel(dB)
The most common unit of measurement in audio delineating changes in sound pressure. A change of 1dB is just about audible, while +10dB sounds like the level has been doubled.
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Dielectric
An electrical insulating material as opposed to an electrical conductor ie: the outer insulation on a cable.
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Digital
Method of storing data used by CD players, DAT, DCC, MiniDisc etc. The sound or picture is converted to a stream of digits - effectively 1s and 0s representing on/off pulses.
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Digital output
Allows the digital signal to be recorded or processed by an offboard DAC. Electrical or optical (fibre optic) outputs are provided.
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Distortion
Unwanted signals or signal changes added by equipment.
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Divx
Recently announced by US company Circuit City, this is a low-price DVD format that allows only a 48 hour viewing period. It's an alternative to rental, but you keep the disc - if you rewatch, your DVD player ring DIVX headquarters by phone and charges your account. Also, these discs won't play on non-DIVX DVD players.
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Dolby 3 Stereo
In cinema sound amps, delivers the surround channel information through the front left and right speakers, while providing centre channel information.
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Dolby B, C + S
Noise-reduction to boost quiet signals when recording and reduce them on playback, cutting hiss.
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Dolby Digital
Also known as AC-3, this is the latest home cinema sound system from Dolby, using five discrete channels of digital sound plus a separate subwoofer channel
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Dolby HX Pro
Not noise reduction, but a way to record more high frequency information without distortion (often called 'increasing headroom').
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Dolby Labs
Developed noise-reduction and cinema surround systems.
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Dolby Pro-Logic
Uses an extra centre speaker at the front, which locks dialogue to the screen.
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Dolby Surround
Encodes sound for rear effects channels into the stereo tracks. Needs to be replayed through a decoder to produce surround.
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Drop-out
Momentary loss of signal during tape recording or playback from a defect in the magnetic coating or from the tape briefly losing head contact. Drop-outs can also occur on CDs, but it takes fairly serious disc damage.
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DTS
Discrete-channel home cinema digital sound system - rival to Dolb Digital
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Dual Mono
Some amplifiers are designed to keep the left and right signals separate throughout the amp - this helps avoid possible interference between the two channels.
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DVD
Video Designed for home entertainment, they play on consumer DVD players that plug into TV sets, or on desktop PCs equipped with a DVD-ROM drive and the requisite hardware/software.
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DVD Audio
The specification for DVD Audio (version 0.9) is still being finalised as we go to press. It is thought the standard will be based around 24 bit/96kHz sampling. Some audio-only discs have already been produced using the DVD Video standard.
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DVD-R
This is a type of DVD that allows once-only recording of data. DVD-R discs will store 3.95GB on a single-sided disc, and 7.9GB on a double-sided disc.
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DVD-ROM
Like CD-ROMs but better. Read by DVD-ROM drives installed in PCs. DVD-ROM discs exist in various capacities from one-sided single-layer (4.7GB) to dual-layer, dual side (17GB).
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DVD-RW
A 3GB erasable and rewritable format under development by Sony, Philips and Hewlett-Packard as an alternative to the DVD RAM storage format (see below). Sony is also developing a 12GB DVD-RW disc that will give five hours of TV recording, and predicts this will be available in two years. DVD RAM This is a version of computer DVD that is erasable and can be rewritten. The specification for DVD RAM enables users to store 2.6Gb on a single-sided disc and 5.2Gb on a double-sided disc. DVD RAM drives are expected to be released in the US in 1998.
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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.
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Dynamic Range
The range, in dB, between the largest and smallest signals reproduced by hi-fi.
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Electrostatic
Speakers that use the force of high voltages to push and pull a thin light diaphragm, which produces the sound.
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Firewire
Apple's trademark name for the IEEE 1394 standard. FireWire is a fast and versatile interface used to connect DV cameras to computers. FireWire is well suited to applications that move large amounts of data, and can also be used to connect hard disks, scanners, and other kinds of computer peripherals.
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Flutter
Rapid speed instability on tape or vinyl leading to fluctuations in pitch. This is caused by transport problems.
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Frequency
The number of wave cycles that pass a given point during a one second interval. With respect to soundwaves, frequency corresponds to pitch; high-pitched sounds have a high frequencies, low-pitched sounds low frequencies. Audible sounds range from around 16Hz to 20kHz.
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Front end
The signal source in a system, eg LP or CD. Also the stage in a tuner which handles signals from the aerial.
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Gamma Geometry
Ixos cable design where the positive and negative are woven in a non(c)aligned waveform and held together by a third Inductance Control Core (ICC) of pure dielectric resulting in lower inductance.
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HDCD
High Definition Compatible Digital - a coding system for CD which aims to get better sound. Needs a decoder to hear the full effects.
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HDMI
A high-speed serial interface, capable of transmitting standard, enhanced, or high-definition video. The standard supports tranmissions of up to 2.2 gigabits per second and resolutions up to 1920x1080p at 30Hz. All data is sent uncompressed, to minimize additional artifacts from recompression. Audio signals may also be included, and up to eight channels of 192KHz audio is supported.
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Hertz (Hz)
Unit of frequency. One Hz means a signal has one cycle per second.
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Impedance
Electrical property. A low impedance draws a high current flow from the source, while a high impedance draws a little. This means that speakers with a low impedance (lower than 6-8ohms) are more difficult for an amplifier to drive.
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Inductance
The tendency to allow a constant electric current to exist, yet resists any change in current.
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Inductor
A device which allows constant electric current to exist through it, but resists any change in current.
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Line level
Describes inputs to amplifiers which don't need amplifying before the amp can use them.
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Mid(c)Range
The frequency span of the middle of the audio range. It is in this frequency range where most of the instruments and voices are heard. Mid(c)range frequencies are considered to be between 200Hz and 2kHz.
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MiniDisc
Sony's 64mm disc that can record up to 74 minutes of sound. Looks like a mini computer disc but works optically, like CD, on prerecorded discs, or magneto-optically in the case of blank software.
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Monobloc
An independent mono power amp, so two are required for a stereo system. Advantage is a lack of interaction between channels.
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Moving coil
Cartridges with a stylus connected to coils which move in relation to fixed magnets, creating electrical signals. Lower output than moving magnet
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Moving magnet
Record-playing cartridge (pickup) design in which a tiny magnet connected to the stylus moves relative to a fixed coil in the body, thus generating the signal.
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Nicam
CD-quality digital stereo television sound transmitted alongside the picture.
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Ohm
Unit of resistance to current. Impedance of a speaker is measured in ohms - generally the lower the figure the harder it is to drive.
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Oversampling
Used in DAC systems. Increases signal frequency, making it easier for conversion circuitry and ancillary systems to filter out unwanted
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Parallel Pairs
Cable design most commonly used for speaker cables because they offer low resistance and low signal attenuation. The design often suffers from low poor noise rejection properties but cable manufacturers attempt to improve noise cancellation by keeping the positive and negative conductors close to each other signals.
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Passive
A circuit or component which does not amplify the signal. Introduces very little distortion.
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Phase
The position of two sound waves relative to each other. The effect of one wave has on another is relative to their respective phase relationship.
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Phono stage
Cartridges output signals at much lower levels than CD players and tape decks. Many amps have the extra amplification built-in, but increasing numbers don't, and require an add-on phono amplifier.
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PMPO
Stands for peak music power. This is the maximum instantaneous excursion from zero of an audio waveform. This is often used to make audio gear appear more powerful than it really is.
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Power handling
The maximum safe power for speakers. But be aware that it's easier to damage speakers with an amp of too low power driven hard, than with too much power.
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Preamplifier
In an audio system, the first amplifier to accept the signal from the transducer. Preamps must accept very low level signals and amplify them to a line level signal without adding any appreciable noise.
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Pro-Logic
- see Dolby
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Proximity Effect
The tendency of high frequencies to be conducted through the portions of a cable conductors which are closest to the opposite polarity conductors.
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RCA Plug
The most common type of audio connector. The RCA plug (sometimes called a Phono plug) is a coaxial connector used for the interconnection of audio and video devices.
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RDS
Radio Data System: data piggybacked on FM radio allowing RDS tuners to display the names of stations, and perform a range of station-seek and switching functions.
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Resistance
The amount of opposition a conducting material exerts on the flow of current. The unit measurement of resistance is the ohm.
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Sampling rate
How fast a digital recorder or player samples a signal. CD, DCC and MiniDisc use a rate of 44.1kHz - ie 44,100 samples per second - while DATrecorders offer a choice of 48kHz or 44.1kHz, and Digital Audio Broadcasting will work on 32kHz. A digital-to-analogue converter needs to work on all three rates. The sampling rate determines the highest frequency recordable a digital system can carry - hence the development of higher-sampling formats, such as Pioneer's 96kHz system, for better treble extension.
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Shield
An enclosure or covering which protects wires or cables carrying signals against the influence of magnetic fields, electrostatic fields or both. Double, Triple
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Signal-to-noise ratio
Describes the difference between the level of the audio signal and the level of unwanted noise. The larger the figure, measured in dB, the lower the noise will be.
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Skin Effect
The tendency of a high frequency current to travel near the outside of an electrical conductor rather than all through the cross section.
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Subwoofer
A separate woofer box to produce the deepest lows smaller speakers can't reach.
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Tape loop
A pair of sockets on an amp letting the signal out for recording on a tape deck and another pair to let the signal back in for replay.
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THX
Developed by LucasFilm, this is basically a set of standards for Dolby Pro-Logic gear, which should guarantee a certain quality of home cinema sound. Needs electronics and speakers made to exacting specs, which tend to be pricey.
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Tonearm
The device on a turntable which holds the cartridge. Toroidal transformer Transformers bring mains voltages down to the levels required. Toroidal transformers (doughnut-shaped) get better stability and less flux leakage (magnetic radiation that can interfere with other circuits).
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Transients
Short and sudden events in music (eg a cymbal crash). Difficult to reproduce. Treble Portion of the audible frequency which encompasses higher pitches. Treble frequencies are generally considered to be between 2kHz and 20kHz.
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Triamping/triwiring
Like biamping and biwiring, but for three-way speakers. Needs three runs of cable in the case of triwiring and three stereo amps if you want to triamp the speakers.
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Tube
Short for vacuum tube also known as a valve, tubes are used for the amplification of audio signals. Generally, tube equipment produces a warmer or softer sound, whereas transistor gear is noted for louder or brassy tones.
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Tweeter
In a multi(c)way loudspeaker system, the small speaker which reproduces the high frequencies.
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Twisted Pairs
A cable design whereby the conductors are repeatedly twisted together along their length and encased in an outer jacket. The continual twisting of the conductors attempts to ensure they cross in opposite phase to each other resulting in noise cancellation.
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USB
Universal Serial Bus. This is a standard for connecting peripherals to computers including low-bandwidth digital still and video cameras. USB supports low and medium-bandwidth peripherals. There are at least two versions of the USB standard: USB 1.0 and USB 2.0. USB is managed by the Universal Serial Bus Implementers Forum, Inc. (USB-IF), a non-profit corporation founded by the group of corporations that developed the USB specification. http://www.usb.org/
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Watt
Unit of power. More watts mean more power, but how loud a system sounds also depends on speaker sensitivity and room size. See PMPO.
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Wavelength
The length of a wave. Sound at 50Hz in air has a wavelength of around 6.9 metres (18.9 feet).
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Woofer
The low frequency loudspeaker or driver of a multi(c)way loudspeaker system designed to reproduce bass frequencies.
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Wow
Slow variations in speed of a record or tape deck, making sustained notes sound unsteady.
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