Buyers Guides > Audio

Audio Terms Explained

AMPLIFIER
Hi-Fi component (or any electrical circuit) that boosts signals. See Pre-amplifier and Power amplifier.

ANALOGUE
A signal that is 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.

BITSTREAM
One type of Digital to Analogue conversion. Also called low-bit, one-bit or single-bit.

CLASS A, CLASS B and CLASS AB
Different power amplifier topologies. Class AB is the most common.

COLOURATION
A distortion that alters the character or tonal quality of a musical signal.

CROSSOVER
Electrical filter network that ensures a loudspeaker's drive units only receive the frequencies they're designed to handle.

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.

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 seperation. Again uses 5 speakers but offers a seperate sub woofer channel.

DOLBY DIGITAL EX
The newest surround sound system. Works as Dolby Digital above but with an extra channel in the rear.

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 seperation 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.

DYNAMICS
The dynamic range of a system is the difference between the quietest and loudest signals it can reproduce.

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).

IMPEDENCE
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 15" - 36". 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.

MID-RANGE
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.

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.

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.

RCE
Region Code Enhancement - designed to prevent multi-region machines (see above) from playing these discs.

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.

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 seperated 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.

WOOFER
A loudspeaker's low frequency drive unit.

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