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Amplifier Essentials

What They Do and Who Needs Them



A good amp is essential if you want a car sound system that's both loud and free from distortion.

Image courtesy of JVC America
What Are Amplifiers For?

An amplifier is a device that takes weak audio signals and outputs signals that are powerful enough to drive speakers. This amplification process is a necessary part of every single home and car audio system, and the power of an amp dictates how loud and distortion-free that the sound will be.

Do I Really Need an Amp?

Most head units contain built-in amplifiers, but they’re usually not very powerful. Head units that do contain powerful amps tend to be prohibitively expensive, at which point it’s typically a better idea to just buy a separate amp anyway. There are a number of reasons to include an amplifier in your car audio system, and you definitely need one if you want:

If you don’t mind a little distortion, and you have no desire to crank your head unit to eleven, then you can probably skip the amp and focus on your head unit and speakers. Some head units have enough power to provide relatively distortion-free sound, and adding a high pass crossover can help clear things up.

Another factor to consider is whether your head unit has preamp outputs. If it doesn’t, you’ll need to find an amp that had speaker level inputs. That can lead to some distortion, though, so it’s typically a better idea to get a head unit that has preamp outputs before you invest in an amplifier.

Channels and Other Features

One of the main differentiating factors between amps is how many channels they have. They are available in multiple configurations, from mono to six channels, each of which is best suited to different speaker setups. At least one channel is needed for each speaker, but it’s also possible to use more than one amp in a single car audio system. For example, a 4-channel amp can power four coaxial speakers, and a separate mono amp can be used for a subwoofer.

There are also different channel configurations that will work best with component speakers, so each amp has to be matched to the system that it’s going to power. Some amps have low pass or high pass filters built right in, which make them perfectly suited to powering woofers or tweeters. Other amps have variable filters, bass boost, and other features.

The Importance of Power

The power of an amp refers to the wattage that it can send to the speakers. Since the whole point of an amplifier is to increase the audio signal strength, the power of an amp is one of its most vital statistics.

The key value here is the RMS, but there is no specific number to look for. The RMS of an amp should be matched to the power handling of the speakers, which is different in every car audio system. An optimum ratio to shoot for is an RMS that is somewhere between 75 and 150 percent of the power that the speakers can handle, and overpowering the speakers a little is better than severely underpowering them.

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