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How to Choose an Amplifier for Car Speakers

How to Choose an Amplifier for Car Speakers

How to choose an amplifier for car speakers

Truth be told, the sound system fitted in an automobile serves no real purpose as far as its functions in transporting are concerned. But ask someone who travels often and they will tell you how important it is to have a decent set of speakers in a car.

Most car owners blame their car speakers for flat and distorted sounds. While it may be the case in some automobiles, in others the cause is usually a substandard inbuilt amplifier provided by the manufacturer.

External amplifiers have been designed to work around this problem. Whether you have an inbuilt amp or not, they can be hooked up to your existing sound system, thereby improving the vehicle’s audio quality.

If you are out on the market to buy an amplifier for car speakers, there are certain factors to consider – the types, amp specs, and the budget. This short guide will help you make a sound decision when it comes to your amp purchase.

Why add an amplifier?

An amplifier is not a necessity, but an option. If you have good speakers, you can do without them. The most logical reason for fitting an amplifier in your vehicle is to power up its audio system. Amplifiers enhance sound quality. This means louder, clearer, sharper sounds.

As a car owner, you might think of upgrading the speakers or adding a subwoofer in the future. The original amps may not meet the power requirements of these additional components, thereby affecting their performance. This is where installing an external amplifier helps.

Car Amplifier Purchase: What to consider

Here are a few factors you may want to think about when buying a car amplifier.

Number of channels

Car amplifier models are designed to have varying numbers of channels. Choosing the right number to meet your audio needs is key. A channel is a source of power to your speaker. A single channel powers a single speaker. Thus, if your audio system comprises multiple speaker units, a multichannel amplifier is your best bet.

Subwoofers with their high-power requirements demand a single channel amplifier. Less heat emission and low power consumption are the advantages of a mono amplifier. Added to these are features of tone control and sound filters that allow you to adjust the bass and quality. However, they are available only on high-end amp models.

Along with mono channel designs, amplifiers are made in 2, 3, 4, 5 and 6 channel formats. The 2 channel amplifiers can be used to power up to two speakers individually or bridged and connected to the subwoofer.

Designed in an A and AB class, the former is known for its clear sound quality, but has a lower energy efficiency rating. The AB variant consumes less power but falls short in its sound quality.

If you are short on space, the 3-channel amplifier is a suitable option for you. However, if you are looking for rich sound and full amp, you may want to consider other variants. A 3-channel amp gives you two amplifiers in one; two channels plug into the speakers and one supplies power to the subwoofer.

A 4-channel amp is a very versatile option. You can plug in four speakers into the four channels or choose to use two channels for two speakers and the bridge the remaining two for a subwoofer. They offer good audio quality at a reasonable price.

The 5-channel setup combines two amplifiers in one, with four channels to power four speakers and one channel reserved for the subwoofer. The 6-channel amplifier is designed to meet the power needs of a larger sound system fitted in bigger vehicles such as SUVs and trucks.

The number of speakers or subwoofer you intend to use in your vehicle will assist in choosing the right number of channels. Yet another option is to have more than one amplifier wired to your sound system. A multiple channel amplifier can be used for the speakers, while the mono-channel amplifier could be reserved for the woofer.


The purpose of getting an amplifier in your car is to supply more power to the speakers. Lack of enough power might damage your speakers. The Root Mean Square (RMS) value of the speakers is a good criterion to decide the power requirements of your audio system.

Experts recommend getting an amp with a power output of at least 75 to 150 percent of the RMS value. A subwoofer demands more power; therefore, audio systems that use a subwoofer together with factory speakers might need a multichannel amplifier (bridging two channels for the subwoofers) or an independent mono-channel unit to run the subwoofer.

The second option is the right choice if you are picky about sound quality. The bottom line is that you should always buy the speakers before you buy the amplifier.

System Compatibility

Prior to making a purchase, you also need to check the compatibility of the amplifier and audio system. For those unaware of how the components connect, the head unit connects to the amp which further plugs into your car speakers.

A common issue with preinstalled head units is that often they do not include preamp outputs. A preamp output amplifies low level signals. A head unit missing a preamp output will require an amplifier that incorporates speaker level inputs.

An amplifier with line level inputs is a suitable option for a head unit that has preamp outputs. In comparison, the latter is known to offer better sound quality.

Size and Space Constraints

Car owners mostly concentrate on amplifier specs when buying; they rarely consider the size of the vehicle or the availability of space. An amplifier with two small speakers fitted in an SUV will affect the surround quality of the sound. Similarly, a bulky amplifier will only eat up space in a smaller or mid-sized vehicle.

You should first decide a suitable location for the amplifier given that it will be an external attachment. Amplifiers are usually fitted in the trunk, below the seat or the firewall on the passenger side. Think about where you plan to install the amplifier and measure the space. There should also be sufficient place to wire the amplifier properly.

Amplifiers vary in their size and shape. One thing to remember is that the size of the amplifier is not directly related to its performance. Smaller amps do not mean poor quality sound. So, choose an amplifier keeping the car and amplifier dimensions in mind.

Amp Classes

Amplifiers are categorized into different classes depending on the electronic circuit. It is crucial because it determines the sound fidelity, energy efficiency, and heat generation. Amps are rated as A, B, AB, and D.

A-class amps provide superior sound quality but aren’t the often recommended option due to large amounts of wasted energy and high heat generation. Class B amps perform much better than class A amps in terms of being efficient. However, the cross-over distortion caused by the transistors switching on and off is a major drawback. Hence, they are not preferred.

Class A/B amps are by far the most popular option. They are class A and B amps combined minus their respective downsides namely low energy efficiency and crossover distortion. Class D amplifiers are the best in their class.

They offer more than 90% operational efficiency. With less energy wasted, less heat is generated. Small size and lower weight are plus points on the D class amplifiers. They are recommended for lower frequency applications.

Trusted Brands

Companies selling amplifiers on the market are dime a dozen. We advise buying amplifiers from reputed brands, even if that means spending a few extra dollars. It is both for the sake of quality and safety.

Where you buy the amplifier and wiring kits from is yet another important decision in this direction. Amplifiers can be purchased at local stores or online outlets. Getting them from a trusted brand, but from an unauthorized dealer could compromise the quality of the product.

Products bought from authorized dealers are usually backed by a manufacturer’s warranty, which further becomes a mark of credibility. The manufacturer’s website lists the names of authorized partners for customer convenience.

How Much are you Willing to Pay?

The budget is a decisive factor in every purchase. You can choose from high-end amplifiers costing thousands of dollars to budgeted options available for a few hundred dollars.

The price differs based on the brand you opt for or the amp specs you choose. Get the best value for your money by buying an amplifier that is both suited to your budget and system requirements. If you are lucky, you might even get a good deal on a second-hand purchase.

Choosing an amplifier need not become an overwhelming experience if you know how to go about it. Educate yourself on the types of available amplifiers and pay attention to the tips given above. The kind of music you listen to should also influence your purchase. Stronger bass sounds need base speakers along with a subwoofer.

So, make the right choice of an amplifier and enjoy sharp and clear music every time you hit the road.