Car Audio A to Z
What does it all mean?
Head Units:
Auto Blank Skip - Usually accompanies track search and allows the user to skip from the end of one track to the beginning of the next missing out any blank or unrecorded passages.
Automatic Volume Control - Head unit’s volume automatically increases along with car’s speed.
Autostore - Benefits the long distance driver by scanning the waveband in the area of travel and automatically storing five or six strongest stations in order of signal strength.
CT - Clock Time. See ‘RDS’
DAC - Digital-to-Analogue Convertor
DNR - Dynamic Noise Reduction. Similar to Dolby but not as effective.
EON - Enhanced Other Networks. Allows interruption of RDS bulletins from other local stations.
Fader - Control which balances sound from front to rear in a four speaker set-up
Intro Scan - Plays approximately the first 10 seconds of every track on a tape/CD
Local/DX - Two levels of sensitivity for tuner searching, local and distant.
Loudness - Boosts low frequencies. Useful at low volumes but most loudness circuits can cut off an unacceptable amount of treble.
Multipathing - Annoying ‘chopping’ interference on FM caused by reception of a signal that’s been reflected (ie. off tall buildings)
Oversampling - Method used in a CD player to reproduce digital information as faithfully as possible in analogue form, a part of the digital to analogue conversion process.
PI - Programme Identification.
PLL - Phase Locked Loop keeps FM signals locked on station.
Power Fader - Controls volume relation between front and rear speakers connected to built-in amplifier.
Power Loading - System loads and ejects CD or tape automatically.
Pre-Amp - Holds controls for volume, bass and treble but has no on-board amplification.
Presets - Stations which can be held in a tuners memory for instant recall.
PS - Programme Service
PTY - Programme Type
QRB - Quick Release Bracket, denotes extractable unit.
Radio Monitor - Radio reception when tape is set for fast forward or rewind
RDS - RADIO DATA SYSTEM. Traffic information system on FM. RDS shows station name display (PI/PS) and delivers traffic bulletins (TP/TA) Also locks onto best possible frequency for a station in a particular part of the country (AF) Can display time and date on the receiver (CT) Sets with PTY (Programme Type) will automatically tune into a station broadcasting Pop, Classical, News etc.
SDK - German traffic information system.
TP/TA - Traffic Programme/Traffic Announcement. See ‘RDS’
Amplifiers and Crossovers:
Bandpass Filter - A combination of high and low pass filters connected in series with an overlap between the lower and upper freqencies, usually used for the mid-range in a 3-way component system.
Bridgeable to Mono - Where the two separate outputs of some stereo amplifiers can be conbined to give a mono signal.
Crossover - A selective filter which splits signals into different frequency bands that can be fed independently to separate speakers. A passive crossover filters signals after they have been amplified. An active crossover (more effective and flexible) filters signals before amplification, sending different signals to different amps.
Crosstalk - The level of stereo separation ie. the isolation of the two channels of a system.
Gain - Degree of signal amplification, achieved by an amp, tuner or pre-amp circuit. Expressed in decibels (dB)
Mosfet - Amplifier power supply switching device designed for optimum performance.
Pre-Amp Fader - Adjusts front/rear balance at pre-amp level, used in combination with pre-outs and external amplifiers.
PRE-AMP OUTPUT - A pre-amp output (pre-out) on a head unit allows the addition of an amp or other peripherals when system building.
RMS - Root Mean Square, a realistic measurement of the maximum output of an amplifier. The higher the figure the more powerful the unit.
Signal to Noise Ratio - Indicates how much irritating background hiss is produced as a proportion of the full output power. Numbers higher than 90dB are acceptable. A good indicator of the quality of the amp.
THD - Total Harmonic Distortion
Speakers:
Bass - The lower end of the frequency spectrum, sometimes also known as mid-bass.
Bass Reflex - See ‘Port’
Coaxial - Speakers which have two separate drive units (normally a small woofer and tweeter) moving independently. Essentially this gives better high frequency response and hence greater range and clarity.
Components - Separate speakers, usually a tweeter and mid-range with appropriate crossover.
Dual Cone - Speakers which have two cones; the second cone is usually much smaller and glued directly to the centre of the main cone although it has just one voice coil.
Free-Air - Term relating to subwoofers which are designed to work most efficiently in free air using the boot for example, as an enclosure. Also known as ‘infinite baffle’
Full Range - Speakers designed to give a wide frequency response.
High Pass Filter - (Capacitor) Essentially allows more signal to pass through the higher the signal gets, typically used and supplied with tweeters.
Infinite Baffle - See ‘Free-Air’
Low Pass Filter - (Inductor or Choke) Allows more signal to pass through the lower the signal gets - ideal for a sub.
Midrange - As the name suggests, frequencies in the middle of the frequency range.
Ported - If the port length and diameter is correctly matched to the box volume and subwoofer’s characteristics it will greatly increase efficiency and a good ported box offers lower distortion.
Roll Off - The point at which the frequency level/performance of a speaker decreases.
3-Way - A speaker system made up of three different types of drivers.
Tweeters - Reproduce the higher frequencies (treble), they are generally fairly small.
2-Way - A speaker system with two types of drivers (see also ‘Coaxial’)
Sub Bass - The ‘thumping rumble’ in a system.
Subwoofers - Large speakers designed to produce the low frequencies, designed to be used in a cabinet, tube or free-air application.
Miscellaneous:
Attenuate - To turn down or reduce.
DAT - Digital Audio Tape. Medium used in the pro sector for reproducing pre-recorded material in digital format on tape.
DIN - DIN E is the German standard of measurement for most in-dash players to enable sets to be fitted in standard slots.
DSP - Digital Sound (Signal) Processor. Lets you programme a listening environment pattern and change the sound to suit the music. A type of super equaliser.
Hertz - Unit of measurement for frequency, often written as Hz or kHz
MDF - Medium Density Fibreboard. Used for building bass enclosures, door panels etc.
OHM - A measurement used of how much the flow of electricity is restricted or impeded. The higher the measurement the higher the resistance.
RTA - Real Time Analyser. Piece of equipment which measures frequency response and SPL level.
SPL - Sound Pressure Level. Monitored using pro kit and measured in decibels - basically the amount of volume produced.
Staging - Where the listening perceives the origin of the music to be coming from.
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