Hi-Fi Corner Hi-Fi & Home Cinema Dictionary

The Hifi Corner dictionary is a bit different from most. Our version is in no-nonsense Scots-English. There will be some 'pure dead brilliant' or 'braw' remarks against some terms which we consider useful and worthwhile. There are also some 'yeuk' comments against advertising spiel.

AAD

On cds this means that the music was recorded and mastered in analogue form. However it is stored digitally on CD (on the CD) Analogue>Analogue>Digital.

AC-3

Pure dead brilliant. Also known as Dolby Digital, gives rear effects on home cinema systems in stereo.

ADD

On cds this music is recorded in analogue form but it is mastered stored digitally on CD: Analogue>Digital>Digital.

Alignment

Adjustment of a record-player cartridge relative to the groove on the disc. Bad alignment causes distortion and excessive wear. Tape heads which go out of alignment will cause poor recordings and playback.

Amplifier

Amplifiers the signal from whatever source. Sometimes known as pre-amps (switching box) and power amp (power but no switching). Integrated amplifiers have pre and power amps built in. Generally the more expensive options are:

• Integrated amplifier
• pre and power amp (stereo)
• pre and two mono amplifiers.

Analogue

Non digital format such as LPs and cassette tapes

Anti-skating -Anti-bias

Forces pull record tone arms towards the centre, a bias is required to corrects this. Sometimes known as anti-skating. Not a group against sports!

Bass

Low frequencies. The type of low notes one hears when a car full of teenagers goes by. Tuneful deep and tight bass is only available on the very best systems.

Bass reflex

A type of speaker design which cleverly uses the knowledge that speaker drive units produce sound to the rear and front and turns the sound around to increase bass output.

Biamping

Every drive unit of a speaker, is driven by a separate amplifier channel (which may be a mono or single channel from a stereo amp). If you have a pair of two way speakers you would require four mono amps or two stereo power amps. Great improvement on sound quality.

Biwiring

Bi-wiring offers an improvement on sound. Two set of cables are run from you amplifier to your speakers. The electronics in your speakers should be capable of being split (the terminal at the back which leads to the crossover should have four sets of sockets). On new speakers there are joining pins for those who don't wish to bi-wire. These are removed and you connect your cables one to the high frequency terminal and one to the low. A less expensive option than bi-amping (see bi-amping).

For those sober enough to want a semi technical theoretical explanation here it is.

When a current is pushed forward by the amplifier through the voice-coil in the magnetic field of a loudspeaker driver, the voice coil and attached cone move forward - the electric motor effect. However, the voice coil moving in the magnetic field generates a back voltage - the electric generator effect. In a perfect driver, the back voltage matches the forward voltage, giving rise to the driver's dynamic impedance. In the real world, the back emf is distorted by nonlinearities in the magnetic field etc giving rise to harmonic distortions and so does not exactly cancel the forward voltage. These harmonic products from one driver's terminals end up across other drivers in the loudspeaker if they have common terminals and can cause further muddling of the sound. By connecting each driver through separate leads back to the amplifier, the distorted harmonics generated by each driver can be short-circuited by the low impedance output of the amplifier.

Blu-Ray

Blue laser recording system agreed by the big nine electronics manufacturers. A single sided 12cm Blu-Ray disc stores 27GB of computer data,records 13 hours of broadcast tv or holds 2 hours of High Definition video. Not spelt blue ray.

Bridging

Adding up amplifiers (as in a bridge) to increase the power. The amplifiers must be designed to be bridged, otherwise damage can occur.

Cables

Cables or interconnects do make a difference to the sound. There are various different types but ultimately it depends on your system and ears which are best for you. Cables are directional and despite not believing this at Hifi corner we have demonstrated that even novices can hear the difference between the direction a cable is laid. For the paranoid, the manufacturers' suggestions are not always the best sounding.

Cartridge

Called a pick-up in days gone by as this 'picks-up' the sound from the stylus and fed it into the amplifier. There are several different types, Moving magnet, Moving Coil and Electret. The cartridge holds the stylus, or 'needle' in older parlance. (Those were the days)

CD-R

CD-Recordable- cd-r can be recorded using a cd-r recorder. The ones in computers are a not considered good enough for serious music reproduction. CD-Rs recorded on a hifi machine and "fixed" at the end of the recording (ie fixed once and for all) should then play back on any CD player. However CD-RW (read/ write)can normally only be played back on the machine which recorded them, although some modern cd players will play them. Check your specifications very carefully.

CD-ROM

A computer thingy (read only memory) and for this exercise a complete waste of time.

CD-text

CD Text offers limited a limited text message display. However your cd player must be cd-text compatible (ie have a display for it). Never really caught on except with the party animals.

Class A

Amplifier design in which positive and negative half cycles are amplified together. Class A is an expensive amplifier design option and is normally reserved for low output high quality amplifiers. As the amps run hot expensive heat sinking (a sink to soak the heat) is required. Not common in budget designs.

Class B

This refers to amplifier positive and negative halves of the signal dealt with by different parts of the circuit, the output devices switch continually. This is the most common form of amplifier design or Class A/B a mixture of the two.

Compression

Yeuk, radio stations use this to make all of their music sound "loud" in the car. Flattens out the quiet pieces from the noisy. The high the compression the flatter the sound. The hifi person's arch enemy.

Crossover

An electronic circuit inside loudspeakers which splits high frequencies in to low and high.

DAB

Digital Audio Broadcasting - a method of broadcasting which will eventually replace FM and AM as the main quality radio medium in the UK and Europe. The advantages are, no mulit-path distortion (reflected sound from buildings), more stations and no hiss. Possible advantages are less compression, and data text/computer information broadcasts.

DAC

Digital-to-analogue converter- a device for changing analogue (all normal sound) into a digital format. DACs are normally built into cd players, unless it is a CD transport (ie the moving part without the electronics) If you have an old cd player consider upgrading the DAC by adding an external one.

DAT

Digital Audio Tape - now used in the main by radio stations and professionals on the move. Dat uses a revolving drum head like a video. More moving parts than a mini disc and a bit bigger but if you need to make serious recordings sing a microphone, use this rather than mini-disc.

Data reduction

Yeuk, this lowers the amount of data needed to store music. ATRAC (Adaptive Transform Acoustic Coding) is the Sony system,

DCC

Digital Compact Cassette - Philips digital recording format to compete with mini-disc. Unfortunately not taken up by the public. DCC recorders could playback ordinary cassettes but could only record on DCC tapes. Record quality was better than mini-disc at launch.

DDD

On CDs Digital > digital > digital - music that was recorded, mastered and stored in the digital domain.

Decibel #(dB)

Measures changes in sound pressure. A logarithmic measurement so that engineers and really clever show offs can talk about it.

Digital

Method of storing data. Put crudely, the crunching up of an analogue sound into bits of information. Analogue lovers claim it is never put back well enough.

Digital Read-out

On a tuner, a digital read-out is a digital tuner. Don't be conned into buying a digital tuner from a spotty youth who mainly sells washing machines. Digital tuners must be DAB tuners if you want hiss free digital reception.

Digital output

Normally found on the back of a digital machine such as a cd player. This will allow you to connect to a DAC (a digital to analogue converter). Sometimes the sockets are coaxial and digital fibre optic. The purists prefer the coaxial sockets from the sound point of view.

Dolby B, C + S

Noise reduction systems which work on the basis of increasing certain parts of the signal and on replay flattening it out again. As it's a pre and de emphasis system you need to do both parts otherwise it will sound wrong. If you think your system sounds better with the Dolby switched out (and the tape has been recorded using Dolby) you have a problem. Maybe your high frequency drive units in your speakers are faulty.

Dolby Digital

Pure dead brilliant. Also known as AC-3, a home cinema sound system from Dolby, using five discrete channels of digital sound plus a separate channel for a low frequency drive unit (called a sub-woofer)

Dolby HX Pro

Pure dead brilliant. Not a noise reduction system. Dolby HX pro work on the recording of a tape (not its playback). It is a bias signal applied to the record heads and gives extra "headroom". Ultimately it improves the sound quality and is recommended if you are buying a tape deck.

Dolby Surround

The predecessor to Dolby prologic and Dolby AC3. this was two front speakers and two rear speakers encoded into a stereo source (such as tv or video)

Dolby Pro-Logic

Braw. The successor to Dolby Surround and uses an extra centre speaker at the front which is mainly used for dialogue. 5.1 means five speaker plus an output for a low frequency unit (subwoofer)

Drop-out

Term used when information momentarily is lost. Normally applies to playback of tapes when the magnetic information has been damaged but can apply to CDs

DVD

Pure dead brilliant. Digital Versatile Disc - if you don't know what this is you have been living on another planet or Taransay for the several years. Contains video as well as sound. Playback only - although DVD-Rss are now available (at a price). A successor to CD-V (cd-video)

DVD A

DVD-Audio is a higher quality sound standard to DVD. DVD-A players sound better than DVDs but you require DVD-A players to play DVD-Audio discs.

Dynamic range

This is the range in sound (measured by those pesky engineers in DB) between the quietest passages of sound and the loudest. It is vital that good hifi has a wide dynamic range capability.

Electrostatic

Loudspeakers that use the force of high voltages to push and pull a thin light diaphragm, which produces the sound. Most famous design is Quad.

Flutter

Rapid speed instability on tape or vinyl leading to fluctuations in pitch. Caused by a variety of problems eg. transport, poor tape housing, uneven platters.

Frequency

High-pitched sounds have a high frequency, low-pitched ones a low frequency (bass notes). It is considered that normal audible sounds range from around 16Hz to 20kHz. This varies with age. There are many long scientific papers debating why one needs super tweeters which extend sounds and harmonics above and below the normal audible frequency range.

HDCD

High Definition Compatible Digital - a coding system for CD which aims to get better sound. Needs a decoder to hear proper playback. Some of the new Arcam Cd players have this as standard.

Hertz (Hz)

Unit of frequency. One Hz means a signal has one cycle per second. And no, 2 hertz is not a bicycle.

Home Cinema

Pure dead brilliant. In American it's called home theatre (or theater). Surround sound for the home, best from hifi separates rather than a built in television.

Impedance

Electrical property. A low impedance draws a high current flow from the source, while a high impedance draws a little. This tends to mean that loudspeakers with a low impedance (lower than 6-8ohms) are more difficult for an amplifier to drive. Those of you who took higher physics will know impedance varies with frequency. This means the 4ohms or 8ohmns are not fixed values. Both values can go up and down. Amps have different power ratings depending on impedance values.

Moving coil

Pure dead brilliant. A turntable pick-up cartridge with a stylus connected to coils which move in relation to fixed magnets thereby creating electrical signals. Lower output than moving magnet. Will not work into a moving magnet input so be careful. Needs a high quality pick-up arm for best performance and a high quality designed input. Can sound really amazing in right set up.

Moving magnet

A turntable pick-up cartridge with a stylus connected to small magnet which moves relative to a fixed coil in the body thereby generating the signal.

Nicam

Near Instantaneous Compressed Audio Modulation - big long words meaning "stereo". Normally used in association with television stereo.

Ohm

Unit of resistance to current. The impedance of a speaker is measured in Ohms. Ohm sweet Ohm, don't get too hung up on the power of the Ohm.

Oversampling

Used in Digital to Analogue Converter systems(DAC). Increases signal frequency thus it makes it easier for conversion electronic systems to filter out unwanted signals.

Passive

Used normally to describe a component which does not amplify the signal. Introduces very little distortion or effect of the sound. The sound however can be effected by the quality of the product itself.

Phono stage or phono pre-pre amplifier

Turntable pick-up cartridges output signals at much lower levels than other sources. The phono stage amplifier the sound within the pre-amplifier (or externally if a separate phono pre-amp) to a higher level. There are Moving Magnet and Moving Coil pre-amps. Records are encoded and need to be decoded. This pre and de-alteration of the signal is to a standard called the RIAA (record industry association of America) curve.

PMPO

Peak Music Power - used by advertisers to boost the real RMS power rating of their equipment. Forget this specification!!!

Power amplifier

Supplies audio signals to the loudspeakers. You require a source or pre-amplifier for sound. If the pre-amplifier is built into the box with the power amplifier then it's called an "integrated" amplifier. Single mono power amps are called "monoblocs".

Power handling

A notional power handling for loudspeakers. This will vary with frequency. In our experience most speakers are damaged by too low an output rather than too high. If you "overdrive" your amplifier you send out a signal which burns the coils within the speaker. Be warned that's not under guarantee!!

Preamplifier

The control part of an "integrated amplifier" or a separate control box. Higher quality amplifiers tend to be split into pre and power amplifiers.

RDS

Radio Data System: data broadcast on FM radio allowing RDS tuners to display the names of stations. Also allows a range of station-seek and switching functions.

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. The sampling rate determines the highest frequency recordable a digital system can carry.

Shielding

Sometimes known as magnetic shielding. Prevents magnetic or electrical interference. For example, it is vital that your centre (or any speaker) is kept away from your television if the speaker s not shielded otherwise the bright blues may turn green and a lot of football supporters in Glasgow would be unhappy.

Signal-to-noise ratio

Describes the difference between the level of the audio signal and the level of unwanted noise, such as tape hiss, fm hiss, record noise. The larger the figure the lower the noise will be. Measured in DBs (decibels)

Subwoofer

A separate low frequency bass box to produce deep low frequency notes. Woofer is an American word meaning low frequency driver. Sub-woofers can be obtrusive in music if not of high enough quality. Ideal for home cinema. Comes in two types: passive (not common) and active (ie having a self contained built in amplifier)

Tape Circuit

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 sometimes known as a tape loop.

THX

Developed by LucasFilm, this is basically a set of standards for Dolby Pro-Logic gear. Needs electronics and speakers made to specific specifications in order to obtain the THX logo. Not proved exceptionally popular in the UK.

Tonearm

A turntable arm which holds the cartridge. In previous times when the summers were dry and the winters had real snow it would have been called the "pick-up arm".

Transients

Short and sudden events in music. Transients tell the men from boys when it comes to hifi equipment. Transients demand the "best" from the whole hifi chain.

Treble

High frequencies.

Triamping - triwiring

Basically 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, and makes you very unpopular with the misses or mister.

Tweeter

The speaker driver unit handling the treble or high frequencies.

Watt

Unit of power. How many watts for a room? This depends on speaker impedance, sensitivity, soft furnishings, type of music, etc. Plus it is better to have a low power higher quality amplifier from the sound point of view than a big beast with no subtlety.

Wavelength

The length of a wave, not unsurprisingly. Sound at 50Hz in air has a wavelength around 6.9m.

Woofer

An American word for the low frequency drive unit in a loudspeaker.

Wow

Slow variations in speed of a tape deck or turntable, making sustained notes sound unsteady and shaky like my singing. My singing has often been described as "wow".

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