The car audio amplifier... its soul purpose is to take a low level signal from the source unit and transform it into a high level signal for activating the loudspeakers.

Amplifiers range in power from about twenty watts per channel to over one thousand watts per channel. Would you believe that the prices range anywhere from fifty dollars to several thousand dollars depending on features, power output and quality! Amplifiers range from one channel of output to as many as eight channels. The most common amplifiers are currently two and four channel models.

Amplifier Power Ratings Power amplifiers also have "optional equipment". These features include built-in active crossovers, equalizers, signal processing and speaker level inputs. When shopping for an amplifier consider that all power ratings are not created equal. The only true measure of an amplifier's power is its continuous power rating or R.M.S. rating ( or root mean square) and refers to the average power output of the amplifiers. Some of the low-quality brands will exaggerate or even outright lie about the power output of their amplifiers which is a good reason to stick with the well known manufacturers.

Car Amplifier Quality: Also keep in mind the quality of the amplifier. A generally good indication of quality build and the power output is the size and the weight of the amplifier itself. Better quality amplifiers will usually have a heavier and larger heatsink versus a low quality amplifier of the same power rating.

However there are many top quality amplifiers that do not follow this rule.

Blaupunkt makes a line of amplifiers that have a plastic shell. Because of the high efficiency design of those amplifiers a heavy heatsink is not required. Also a good indication of an amplifier's true output is the size of the fuse used.

Use your head when buying and keep in mind the brand's reputation for quality.

If you find yourself on a budget or lack space for many components then the economical thing to do is buy a multi-channel amplifier with the built in features and processors that you desire. By minimizing the number of components the chance of noise entering into the system is lessened.

Some features and aspects of amplifiers to consider are:

Bridgeable: This feature allows a pair of amplifier power channels to be combined into one channel of greater power. This is usually used for driving a subwoofer although it will work with any other type of speaker as well

Channels: The more channels an amplifier has the greater the installation flexibility it will have. Especially in terms of options, future add-ons and upgrades.

Class: This refers to the way the amplifier operates. The three types that are most likely to be encountered are A, A/B, and D. Class A amplifiers are the least efficient in terms of power consumption, staying on continually, but also have better sound in general than A/B amplifiers. They are very rare in car audio. Class A/B amplifiers are more efficient than the class A design and are the most common type. Almost all amplifiers in the car audio market are of the A/B design. Class D amplifiers are usually reserved for high power subwoofer amplifiers and can reach efficiencies in the 80%+ range. This design can therefore be smaller, uses less current and produces less heat than the other classes.

Connectors: This is the method of attachment used for wires that are connected to the amplifier, including speaker and power wires. The most common kind is the screw terminal strip. This is a series of screw connectors that can be removed and replaced without compromising the amplifier. The other main type of attachment is the "Molex" type connector. This method involves a wire harness that plugs into the amplifier after the power and speaker connections have been made with a crimp or solder connection. If the amplifier is installed in more than one system these wires can get pretty short over time and become more difficult and even dangerous to work with. A variation on the two is a harness that the power and speaker wires screw into. Then the harness plugs into the amplifier. This is probably the most convenient of all connections.

There are so many car stereo head units on the market. How do you know what to choose? Let's take a look at some of the things you should look for when buying a head unit.

1. How user friendly is the head unit?

Your head unit must be user friendly. This is the part of your car stereo you will interact with the most so you must feel comfortable using it. Before buying one be sure to play around with it and see how easy and quick it is to change tracks on a CD, switch radio stations, and so on. Are the buttons too small? You need to be able to enjoy using your head unit.

2. How is the unit's power measured?

Pay close attention to power. Look out for models where the manufacturers exaggerate the unit's power. This malpractice is common among most manufacturers. Ensure that power is measures in RMS. Be very wary of terms like "music power" and "peak power". These terms mean nothing when it comes to measuring power.

3. Choosing between a cassette player and a CD player.

It's all about your personal preference. Do you use more cassettes than CDs? In that case you should probably go with a cassette player. Many of them give you the option of hooking up a CD changer. Your CD changer can be operated from your head unit.

The only problem with some CD changers is the fact that you may have to get to your trunk or under your seat to change CDs. With in-dash CD players everything is in reach and can be operated easily.

More and more people are using CDs these days. CDs have several advantages including better sound quality. Many of them can be hooked up to a CD changer as well.

4. Does the head unit include pre-amp outputs?

If you're serious about sound you wouldn't buy a head unit that doesn't come with pre-amp outputs. With these outputs, you can run an amplifier directly without any need for conversion. This output is the cleanest. Higher volt outputs are better as long as your amplifier or crossover can handle the voltage. For less noise choose 4 volts over 1-2 volts.

5. Is there a theft prevention scheme?

If theft protection is important to you buy a head unit that includes a theft prevention scheme. You can choose between a partially detachable and fully detachable face. Detaching the face of your head unit renders it useless. So this is obviously a great deterrent for thieves.

Kenwood has some models where the face flips around so the thief can't see the head unit.

Some head units like Eclipse's ESN system, require a reference CD when you first apply power to them. If it is stolen it is useless. You must have the reference CD for it to work. The only problem with this is that if the thief has no clue about this feature, your head unit would be stolen anyway. Your only hope would be if he foolishly takes it to Eclipse for repair. Eclipse would be able to verify that it was stolen.

Ordering your car stereo head unit online is quick and easy. Before buying your head unit be sure to check out some online reviews. Find out what customers like yourself think of the unit you want to buy. You can order one online today.

For those who dare to dream and devilishly desire their acoustic car audio destinies they must also watch out for those disastrous and devastating dead batteries. But there is an answer and that is to go with the toughest batteries and best technologies to ensure rapid recharging and maximum life.

Your batteries in your car audio system can make or break you and you must have batteries, which can deliver maximum peak amps as fast as possible. The life of your batteries is also a serious concern because you will be draining and completely re-charging them back up more often with a super sound system.

To protect your expensive equipment you need a battery, which can deliver more consistent voltage across the discharge curve and he would be surprised the difference in battery performances. The larger the batteries the more the chance is that they will create fumes as they vibrate in your car and no one wants to three then H2S04 fumes.

Another thing you might consider is that you need a battery, which can be mounted in any position on your vehicle and will not spill no matter what angle you are parked at. Remember you are asking these batteries to do a lot when they are running super car audio acoustics and high output sound.