Amplifier
Hi-Fi component (or any electrical circuit) that boosts signals. See Pre-amplifier and Power amplifier.
Analogue
A signal that’s an exact replica of the original sound’s waveform. See Digital.
Bass
Low frequency signal(s).
Bi-wired
A speaker with separate terminals to connect its woofer and tweeter to the amplifier.
Bit
The smallest component of a digitised musical signal. See Digital.
Blu-Ray
A new type of high definition disc is one of the formats that aim to replace conventional DVD. It will store up to 10 times the information that DVD does.
Component
The highest quality analogue video connection available. Uses three RCA plugs and splits the picture signal into various components of video. Note – does not carry an audio signal.
Crossover
Electrical filter network that ensures a loudspeaker’s drive units only receive the frequencies they’re designed to handle.
DAB
Digital Audio Broadcasting. Digital radio which gives a clearer signal, immune from interference and a greater selection of radio stations
DAC
Digital to Analogue Converter. Used in CD players and other digital components to change digitised information back into an analogue waveform that the amplifier and speakers can process.
Digital
Any system that represents analogue signals as streams of numerically encoded data.
DiVX
A way of compressing video signal down without losing masses of quality. Usually used for sending video files over the Internet.
Dolby B, C, S & HX PRO
Noise reduction systems used in cassette decks. Dolby HX Pro isn’t noise reduction but serves to improve the high frequency performance of some tapes.
Dolby Digital
The accepted standard for DVD, offers superior sound and separation. Again uses 5 speakers but offers a separate sub woofer channel.
Dolby Digital EX
The newest surround sound system. Works as Dolby Digital above but with an extra channel in the rear (6.1), or 2 extra speakers at the side (7.1)
Dolby Pro Logic
The basic surround sound system takes a properly encoded stereo signal and converts it to 4 channel surround sound. Compatible with most sources, the quality is limited, most notably by a mono, reduced bandwidth signal to the rear effects speakers.
Dolby Pro Logic II
Like Pro Logic (above), Pro-Logic II turns a properly encoded 2 channel source into a full blown 5 channel signal. Improvements over the original Pro-Logic include better channel separation and a full bandwidth, stereo signal to the rear speakers.
DTS
Higher specification than Dolby Digital but not as widely available.
DTS ES
Rivalling Dolby Digital EX, ES offers an extra rear centre channel for improved image placement and definition.
DVD-A
Digital Versatile Disc-Audio. Very high definition music disc using the DVD format. Like SACD, it uses 24-bit resolution at up to 192 kHz sampling.
DVD-RAM
A re-recordable DVD recording format that allows for time-slip recording.
DVD – R
DVD (minus R) A write-once only DVD recording format.
DVD + R
DVD (plus R) A write-once only DVD recording format.
DVD – RW
DVD (minus RW) A re-writable DVD recording format.
DVD + RW
DVD (plus RW) A re-writable DVD recording format.
DVD-V
Digital Versatile Disc-Video. The popular DVD film format.
DVI
Available in A (Analogue), D (Digital) and I (Integrated – both A and D) versions. High quality, picture only, sockets used between a DVD player and TV set. DVI-D or DVI-I sockets can be part of the requirement for High Definition TV.
Dynamics
The dynamic range of a system is the difference between the quietest and loudest signals it can reproduce.
EPG
Electronic Programme Guides. These are found on Freeview units, and simply list programmes on all the TV channels – usually for 7 days.
Freeview
Digital TV that gives a greater choice of Digital channels. Available built-in to TV sets, DVD recorders, or as a separate box.
Frequency
The pitch of a signal. A bass guitar produces mostly low frequencies while a flute or whistle produces high frequencies. Measured in Hertz (Hz) or cycles per second (CPS).
Hard drive/disk
An internal disc, like a computer, that can store large amounts of picture, video and audio information. Mostly used in MP3 players, digital audio recorders, DVD recorders and some Freeview boxes.
HD DVD
The other format that seeks to take over from DVD. Again, storage will be 10 times greater than it is at the moment, and HD DVD also has the advantage of being backwards compatible with DVD.
HDCP
High-bandwidth Digital Content Protection. A copy protection circuit that’s featured in TV sets and is crucial for full compatibility with High Definition signals.
HDMI
Fully digital socket that carries both sound and vision between home cinema components. It is an important part of a High Definition system.
HD Ready
High Definition Ready. Denotes that a TV will accept High Definition television broadcasts. For this the TV must have a high resolution screen, HDCP and have either a DVI-I/D or HDMI socket.
High Resolution
Relates to the picture on a TV set. A high resolution screen features a higher number of pixels and is a crucial part of a TV being HD Ready.
Impedance
The resistance, measured in Ohms, offered to AC (alternating current) signals by a component. In loudspeaker specifications 8-ohms is the norm, 6-ohms is becoming more popular, but be careful with low-impedance 4-ohm speakers because not all power amplifiers are happy driving them.
Integrated
Any component that’s self-contained – a CD player with an on-board DAC, or a one-box amplifier, for example.
LCD
Flat screen displays that use Liquid Crystal Displays to create the pictures. Commonly available in sizes from 14″ – 42″. Also known as TFTs (Thin Film Technology).
Line-level
Literally, a component operating at ‘line’ voltage – a maximum of 2V. Often used to describe a pre-amplifier or integrated amplifier that doesn’t have a phono stage.
Memory Card
An SD or PC type card input that allows for cards from PCs and digital cameras to be plugged into a TV or DVD recorder.
Midrange
The most vital band of the musical spectrum, it’s the bit between the bass and treble. The midrange driver in a three-way loudspeaker handles most instruments and the human voice; in a two-way it also handles bass signals.
Moving coil, moving magnet
The most common types of phono cartridges. Moving coils generally require a special phono stage. See Phono.
Multi-region
Sometimes referred to as ‘Region free’, this applies to DVD players which have been modified to play discs from anywhere in the world.
NTSC
The American system of TV broadcasting. Not compatible with our system (Pal), so if you are buying DVDs from America, you will need to check that your DVD player/recorder or your TV has a NTSC to Pal converter.
Ohm
See Impedance.
Oversampling
Technique used in DACs to improve their resolution of low-level (quiet) signals.
Passive, Active
Passive crossover networks, using components that aren’t powered, are the norm in loudspeakers. Some sophisticated speakers use active (powered) crossovers, which divide the signal into the different frequency bands required by the speaker before it reaches the power amplifiers. Also refers to the types of volume controls used in some amplifiers.
Phono (-stage, -input, -amplifier)
Phono cartridges work at very low voltages and require additional amplification before reaching the line-level parts of a pre/integrated amplifier.
Pixel
An individual dot of a TV pictures image. The more pixels, the more detailed a picture is likely to be.
Plasma
Flat screen displays that use heated phosphors to create the pictures. Screens most commonly come in sizes between 32″ – 60″.
Power amplifier
Either a separate component or the part of an integrated amplifier that boosts the signals from line-level to the required voltage to drive loudspeakers.
Pre-amplifier
Either a separate component or part of an integrated amplifier that controls and routes signals coming from your CD player, cassette deck, etc.
Progressive Scan
Gives a higher quality image than the more common interlacing. Picture has more depth and is more stable in appearance. Most commonly used in conjunction with a component output.
RDS
Radio Data System. This is fitted to some hi-fi tuners and car radios (where it’s genuinely useful) and supplies additional information and controls signals to the tuner.
Receiver
An amplifier (see above) with a built-in radio.
RMS
Root Mean Square. Found in component specifications, usually amplifier power ratings. Other types of rating, such as music power and DIN, are less meaningful.
SACD
The highest quality digital audio format. Uses 24-bits of information and up to 192 kHz sampling and can be decoded into either stereo or multi-channel. Sometimes found in “universal” DVD players.
Screen (shield)
Used in cables and components to provide a barrier to electrical interference.
Sensitivity (efficiency)
When quoted in loudspeaker specifications, this tells you how easy a job the amplifier will have driving the speaker. Measured in dB (decibels), 88dB is average, 84dB is low (so get a big amp!), and 90dB or above is very high (so a little amp will do).
Soundstage (image)
The illusion a system creates of musicians being in different positions between the loudspeakers.
THX
THX certified gear conforms to the exacting standards laid out by Lucasfilm. These have recently been separated into various standards the premium being THX Ultra.
Transient
A fast, short signal such as a rim-shot that’s a good test of a system’s responsiveness.
Tweeter
A loudspeaker’s high frequency drive unit.
Watts
Used to specify amplifier or loudspeaker power handling.
Wi-Fi
A wireless connection that can be used for connecting hi-fi and TV components around an entire house.
Woofer
A loudspeaker’s low frequency drive unit.
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