Let's say you've invested in a new set of upgraded speakers and a sleek new stereo receiver unit. You're on your way to hearing your music in superior ways. However, your car may not be doing your custom audio system justice -- and your radio's built-in amplifier might not supply enough power to the new components.
This is why you might need an external amplifier, or amp, as your audio setup becomes more and more elaborate. Amplifiers take a signal from the stereo and use an independent power source to change it into a more powerful signal for the speakers. The more power the amplifier delivers, the cleaner the sound from the speakers. Granted, most aftermarket stereo units have at least twice the power of a stock radio, but in many cases, it's simply not enough [source: Consumer Guide]. If you're going to have a bunch of subwoofers and component speakers in your vehicle, an amp is probably a good idea.
In most cases, you'll want one amp for all the speakers in the car, which means you'll need multiple channels on the amp -- each channel drives one speaker. Since most cars have four speakers, four-channel amps are the most popular. Five- or six-channel amps will give you even more options. If you only have one subwoofer and no other high-powered speakers, you only need a one-channel amp. Otherwise, the subwoofer will probably require its own amp.
It is important to match up your stereo and speakers with the right amp. You'll see two power ratings when shopping for a car amplifier: root mean square (RMS) power, and peak power. Here's what they mean:
- RMS: The amount of continuous power that an amplifier produces, measured in watts. The RMS power on your amp should always match the RMS power rating on your subwoofer and speakers. The higher the RMS rating, the louder and cleaner your music sounds.
- Peak power: The wattage a car amplifier has available for brief sound increases. This number is always higher than the RMS power.
It's important to make sure the RMS number on your amp matches the rating on your speakers. If the numbers don't match, your speakers could be underpowered, or even overpowered. If they're overpowered, they have the potential to overheat and become damaged.
So now that you've bought all this great equipment, should you have a professional install it or do it yourself? In the next section, we'll weigh your options.