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Car audio has moved a long way from the old standard AM/FM Radio/Tape Deck combo. Today, in-vehicle multimedia systems include DVD video, television and navigation systems with local hotspot news. Common to all systems is the sound quality.

The quality of sound in a car audio system depends upon a number of factors - the type and quality of the media player system, the type of speakers used, the acoustics of the vehicle and interference from other devices.

Type and Quality of Media Player System

Before we look at the different types of in-vehicle media players it pays to have a basic understanding of audio quality. When deciding what type of audio system to install, and also when comparing one make and model to another, there are two key specifications to consider:

Signal-to-noise ratio [SNR] - a measure of signal strength compared to background noise in the signal or equipment. Measured in decibels. The higher the dB, the better. A car CD player has an SNR of 90 or 100 dB.

Frequency response [FR] - a measure of how much of the audio spectrum, from bass to treble, gets reproduced. It's measured as a range in Hertz, and the wider the range, the better. Look for a CD player with a range of at least 10-20k Hz.

An FM radio, cassette player, and CD player all have different measurements for these specs. To help understand these two specifications, let's compare a car tape cassette player and a car CD player.

Cassette player has an SNR of 50-70 dB. This is much lower than a CD player, so the sound quality degrades at each end of the spectrum. The FR is around 30-18k Hz for a cassette player, so does not contribute as much to sound quality as the SNR.

That's why overall, a car CD player gives a much better sound than a cassette tape player.

Media players in vehicles today are either radio tuner, CD player/changer, or Digital Audio player.

CD Players & Changers

There are a number of options when it comes to playing CD's in a vehicle:

• An in-dash CD Player - often combined with radio tuner, WMA/MP3 player
• An in-dash CD Receiver - with a multiple CD cassette / changer located elsewhere in the vehicle
• Connect a portable CD player to an existing in-dash audio unit using either a cable and adapter or a bluetooth wireless connection.

When choosing a car CD player the first two things to consider are:

1. Will it physically fit into the vehicle?
2. Will it integrate cosmetically with the dash and other electronics?

Most decks have standardized form factors; so fit most cars, but there are exceptions, so make sure that the deck is suited for your car. You are usually pretty safe is the car stereo is made for the same market as the source of your car:

Cosmetic integration is a little more complex, but in many cases easily resolved through customisation features. For instance, many decks allow you to change the faceplates and color of the display.

Digital Audio Car Systems

With most home audio systems and portable players giving crisp quality sound using digital audio, we are no longer satisfied with the flat, bland analog sound from older car audio systems.

If you normally store your digital music files on CD, a compatible stereo or changer is a good option. Up to 10 hours of music [250 songs] can be stored on a single disc and allows use of random shuffling and repeat options. This disadvantage is ease of use, having to load and unload from cassettes located in the boot or under seats, and the limited file formats that your stereo can play back.

So now you have the media player selected, what about the speaker system.

Car Speaker System

The speaker system can be thought of in two parts: the channel amplifier and the physical speaker units.

Car amplifiers power the speakers in your car stereo system to provide crisp sound quality at high volumes. Each speaker requires one channel of amplification. This means a 4-channel amplifier, will support four speakers.

And choice of speakers is not limited either. With a range of options for your basic stereo speakers [2-channel], you can supplement the high note quality using a tweeter and the low bass notes with a sub-woofer. This gives you a standard 4-channel sound system that will rival your home audio system.

Adding to a basic car stereo option typically involves adding subwoofers, amplifiers and crossovers to tailor the output sound to personal tastes.

This does not mean the result is the boorish, obnoxious bass boom boxing that invades the entire neighbourhood. A subwoofer adds quality and purity to music.

For details of specifications on each part of your system, see Go-Reviews.com - Car Electronics Section

The main factors in selecting car speakers are:

• Design or Speaker Type
• Technical Specifications
• Fitting & Mounting

Speaker design is about the combination of sound drivers for midrange, subwoofer and tweeter. Depending upon the combination, the set is known as a two-way, three-way or four-way speaker system.

Car speaker specifications are similar to home audio speakers; the main difference in technical specification to compensate for the lower power outputs of car stereo receivers.

The speaker technical specifications include sensitivity, frequency response, signal to noise ratio, power handling and impedance. We will look at these specification in more detail in subsequent articles.

The fittings and mountings are selected depending upon where you choose to position the speakers. Car audio speakers are either: top mounted or bottom mounted. Clearance depth is most important when installing new speakers in a non-factory speaker location. So check all of your components carefully before purchase.

With such a range of combinations available the Internet provides a valuable resource in car electronics reviews. Sites like Go-Reviews.com seek out reviews and consolidate the recommendations to give you a quick reference buying guide.

Nicola is the product reviewer for Go-Reviews.com. For reviews on consumer and business technology, the latest technology news, product releases and recalls and useful hints on getting the best from your technology. With such a range of combinations available the Internet provides a valuable resource in car electronics reviews

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