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Explanation of terms in the car audio business
In the business of car audio sales and instalation there are many terms which need to be understood in certain areas of the business. I am going to share with you definitions for the terms that I know:
Active - Any electrical componant that is used to either modify or split the head-unit's output before it reaches the amplifier is called active. Typically an EQ or active crossover.
Amp Rack - A platform used to support amplifiers, often thick MDF, it saves damage to the boot or floor.
Amps - Short for Amperes, the measure of current. In basic terms the current is the flowing power of electricity.
Baffle Board - A baffle board is a sheet of material into which a sub-woofer can be mounted in order to insulate the front of the speaker from the back.
Bass reflex - Another name for a ported box.
Bridging - Most modern amplifiers are bridgeable, this means two channels outputs can be used together to power one speaker with twice the power.
Channels - A channel is an output from a device such as an amplifier, comprising of positive and negative terminals to which a speaker is wired.
Coaxail - Meaning shared centre axis: used to describe a speaker that has two drivers, e.g. a small woofer and a tweeter. Saves installing a seperate tweeter.
Components - Seperate speekers, usually a tweeter and a mid-range with an appropriate crossover.
Cone - The cone is the tough membrane between the speaker surround and the voice coil of a speaker.
Crossover - A selective filter that limits sound signals from above or below certain values or when combined between a pair of frequencies from reaching a specific speaker.
DAC - A digital-to-analogue convertor.
DIN E - (Apart from being Scottish for didn't or don't know) A German standard that has been adopted through the automotive history as the standard slot size for a car radio.
DSP - Digital Signal Processor, similar to an equaliser, but more technically advanced, a DSP can add a reverb or effect to an audio system. e.g. Hall, Club or Live.
EON - Enhanced other networks. Allows interuption for RDS bulletins.
EQ - Short for equaliser.
Equaliser - This is used to make sure that the right amount of each level of sound is being put out to make a powerfull and quality sound.
Excursion - The distance that a voice coil moves during sound production. The larger this is the higher the maximum volume before distortion will be.
Free Air - A sub-woofer that has been designed to work without a box. Also called infinate baffle.
Frequency Range - The range of frequency that a speaker can produce sound from. Using a set of speakers that between them can produce every sound frequency known to man you can produce a full soundstage.
Gain - The input signal to an amplifier can be boosted to create a more powerfull sound.
Loudness - Boosts lower frequencies. Useful at low volumes but can be harsh when played at high volumes.
Mosfet - Amplifier power supply switching device common to most modern amplifiers. Not a brand name.
OFC - Oxygen Free copper, OFC cable is manufactured without trapping any air in the coating or between the strands of a wire. This prevents oxidisation, which in turn leads to signal loss over time.
Over sampling - Method used to stop CD's skipping. CD is played into a 10 or so second memory then is played from the memory rather than the CD, when you go over a large bump the CD stops but the memory doesn't.
PI - Programme Identification.
Power CAP - Fitted in the power line, a power CAP stores some of the batterys energy so that if the amplifier needs to draw more out it can take it without touching the supply to the car's lights or any other important electrical features. Can be very dangerous if wired incorrectly.
Pre out - This is the output from the head unit to the amplifier.
RCA Cable - At the heart of any hi-fi system is the RCA cable this carries all the signals from the head unit to its various components. e.g. Amplifier
RMS - Root Mean Squared. Basically the most realistic the amplifier power rating.
Sound deadening - Bitumen based matting used to absorb vibration in panels and provides a barrier between sources of noise.
SPL - Sound Pressure Level. Measured in Decibel (dB)
Sub woofers - Large speakers designed to produce low frequencies. Can be used in a box, tube or free air application.
THD - Total Harmonic Distortion. A measure of the percentage of distortion from the original input signal. The lower the better. Typically between 0.2% and 0.6%. If above 1% your amp is not one of the best!
Three way - A speaker with three drivers. Also known as Triaxail.
Tweeters - Speakers that specialise in producing higher frequencies, they are usually the smallest speakers of the system.
Voice Coil - The section of the speaker that generates the cone movement from electrical input. If you ever buy a second hand speaker check that there isn't a grinding noise when you press the cone. If a grinding noise is preasent the speaker is knackerd!
Watts - A unit of power. Max and RMS power are given in Watts.