How to Buy a Car Amplifier on eBay

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How to Buy a Car Amplifier on eBay

An amplifier uses an external energy source to increase the power of a signal. External car amplifiers are used to boost the incoming signal from the stereo, and to direct the new, more powerful signal to the speakers. Generally speaking, amplifiers increase the volume and quality of a person's already installed sound system. The quality of amplifiers can vary greatly amongst manufacturers, as can their power. An amplifier's power is directly related to sound, with increased power providing a cleaner sound. Amplifiers are grouped by different class ratings and are categorised by the number of channels that they provide. When it comes to purchasing a car amplifier there are many things that one should look out for such as the classes of amplifiers, the different channels involved as well as the installation process. When purchasing car amplifiers on eBay all of these factors are extremely important and one should know exactly what they are looking for prior to their purchase.

Amplifier Classes

An amplifier's circuit design, or the way in which the amplifier is constructed, determines its class of operation. Although all amps ultimately increase a musical signal, each type has a different design and a different method of achieving this result. Amplifiers are classified by different class ratings and can be searched as such on eBay.

Class of Operation


Class A

Class A amplifiers are known for their high quality of sound, but their design is often not used when it comes to car installation because of their inefficiency and high heat production. This high heat production is a result of the large amount of power that is generated by the amp.

Class B

Class B amplifiers produce good sound quality, are moderately efficient, and use a great deal of power, half of which is lost in the form of heat.

Class AB

Class A/B car amplifiers are the most commonly used car amplifiers because they are efficient, provide lower distortion than class A amps, and are reliable. At low volumes, the class A portion of the amp is utilised and at higher volumes, the class B portion of the amp is employed.

Class D

Class D amplifiers boast a higher efficiency, produce less heat because they are using minimal power, and draw less current than the class AB design does. However, they do tend to have more distortion. This distortion is usually filtered out by the low-pass filter and is inaudible to the human ear, and therefore produces decent sound quality.

Class T

Class T amplifiers are a combination of the design of class AB and class D amplifiers. This class is known for its high power, its compact size, and its low heat production.

Amplifier Channels

The number of amplifier channels that a person needs is directly related to the number of speakers to which they are connecting the amplifier. The number of channels on an amp does not limit it to the number of speakers that are connected, but the frequency being sent to the speakers does. This means that a person can put as many speakers on an amplifier channel as desired provided that the electrical resistance does not fall below what the amp is capable of handling and that the power handling has not been exceeded. Some of the common types of amplifiers with regard to channels include mono amplifiers, 2-channel amplifiers, 4-channel amplifiers, 5-channel amplifiers, and 6-channel amplifiers.

Mono Amplifiers

Mono amplifiers have one output channel. They are usually used to power subwoofers since subwoofers cannot handle high frequencies and must be driven by a separate amp. Most systems have higher-powered amps for the subs than for the other speakers. Depending on the amp and on the impedance of the subwoofers buyers can connect one, two, or even more subs to just one mono amp. These amps generally produce more power than multi-channel car amplifiers do.


2-channel amplifiers offer increased versatility. They allow buyers to power a pair of speakers or to combine the output of the two channels by bridging the amplifier to create a single channel. Bridging is a great way to power a subwoofer. 2-channel amps are commonly used in single cab trucks or in two door coupes that do not have rear speakers. These amps use class AB circuitry, which is often unstable at lower impedances.


4-channel amplifiers can power four speakers. This provides a buyer with the most options of any amp that has been discussed here and is perfect for powering component speaker systems. These amps also allow buyers to use two of the amp's channels to power a pair of full-range speakers in the front of the car, while bridging the output of the other two channels to drive a sub. Bridging down to a 3-channel or to a 2-channel amp creates more power, but it also decreases stability.


5-channel amplifiers allow users to power their entire system with a single amplifier. This style of amplifier acts like two amps in one, providing users with a 4-channel amp and a monoblock amp to produce a higher power output for a subwoofer. This is usually accomplished by using four channels to power the front and the rear speakers and by using the fifth for powering the subwoofers. A 5-channel amp also takes up less space than having two separate amps does.


6-channel amplifiers are sometimes used in large SUVs and feature six low power speaker outputs that power three sets of speakers.

Installing a Car Amplifier

Car amplifiers can be installed in many locations, but they work best when mounted in the trunk or under a seat. They should always be kept at least two feet away from the radio receiver to avoid any interference. It is also important to install the amp where there is adequate ventilation to avoid overheating and to eliminate power shortages since amplifiers produce a lot of heat. The amp's cooling fins need an additional few inches of space to properly disperse any heat.

Buyers should also make sure to never mount the amp upside down. This can cause heat to emit back up into the amplifier. If an individual is using an amplifier to power subwoofers, it is best to put the amp in the trunk next to or attached to the subwoofer enclosure. If powering the main car speakers, buyers should consider mounting the amp under the passenger seat. Both locations work well to conceal the amp from plain view.

Under the Front Seat

Mounting an amplifier under the front seat of the car is both safe and secure. This also allows the installer to run shorter patch cables to the amp. During installation, the front seat of the car needs to be removed. Installers should also make certain that the amplifier is compact enough to fit into the provided space.

In the Trunk

The trunk of a vehicle is the ideal place for larger amps that are unable to fit under the seat of a car. The trunk is also closer in location to the sub and rear speakers. When installing the amplifier in the trunk, the installer needs to run longer RCA cables and power wires than when it is being installed underneath a seat.

What to Look for When Buying a Car Amplifier

When purchasing a car amplifier, consumers should consider all of the available amplifier channels and types. Buyers need to decide which type of amp to buy based on how many output channels and how much power they need. Once a buyer has determined what their amplifier is going to be used for, they can match their individual needs with a specific amplifier's features, including size, power, cost, and ease of installation.

Buying a Car Amplifier on eBay

While car amplifiers are available at electronics and stereo equipment stores, buying them online is made easy with sites like eBay because they offer a secure and convenient shopping experience. There are many used amplifiers available for purchase on eBay. Buyers can search from the eBay homepage where they can find many listings that they can browse through. To find used car amplifiers, type in "used car amplifiers" into the search box. This offers a variety of listings. If you are looking for a particular brand like Kenwood, then type in "Kenwood used car amplifiers". You can also take advantage of the filters on the results page to further narrow down results. This can save the buyer time, as there are fewer results, making the used car amplifier that they require easier to find. Purchasing a car amplifier on eBay gives the buyer the ease of shopping from home, and getting exactly what they are looking for in the process.


Car amplifiers improve the sound quality of a car's audio system by making sure that all the car's speakers are powered sufficiently. These speakers may include full-range speakers, component speakers, or subwoofers. Failure to power speakers adequately can distort sound frequencies at the low, mid, and high levels. Car speakers that are not powered properly can also be damaged or wear out prematurely, so be sure that all the speakers in a car, truck, or sport utility vehicle are powered adequately. Remember to carefully review the common terms used to describe car amplifiers and what makes them important.

Understanding the classes of amplifier that are available and what features they may include is very important to picking the right car amplifier. Class AB amplifiers are great all-around performers, and Class D amplifiers are ideal for powering subwoofers. Special features like bass boost, filters, and speaker-level outputs improve performance or ease installation. Matching the amount of configured amplifier channels to the number of speakers that require power and choosing an amplifier that produces RMS power equal to or greater than the RMS power rating of the most powerful speaker are two other aspects to consider before purchasing car amplifiers. Be careful to avoid car amplifiers that look attractive but contain inferior hardware.

Pay close attention to configurations and specifications while shopping for a car amplifier. Choosing the right car amplifier for your vehicle is key to making sure that your speakers sound their best and last a long time. Best of all, it is easy to make this selection yourself with a bit of time and patience.

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