What Is a Car Amplifier and What’s Its Use?

What Is a Car Amplifier and What’s Its Use?

If you’re new to the car audio world and want to learn what a car amplifier is and does so you can feel confident choosing the best one for your system, read on.

I am an audiophile and I have true passion for car audio, and my aim is to help anyone who’s interested in souping up their car stereo system. And whether you’re just updating the car amp or overhauling your entire system, soundrating.com should be your first stop.

This article is an introduction to car amplifiers. Once you’ve read it, you’ll know exactly what one is, why it’s an important part in any car audio stereo system, what type of amps there are to get, and which car amp to get for your wheels, and for your taste in music.

So, without further ado, let’s get into it and discuss the intricacies of car amplifiers.

What is a Car Amplifier?

Basically, an amplifier, whether it’s for the car or home, is a device that amplifies sound. That might sound obvious, but the way it works is it takes a low voltage signal from the unit and amplifies it to a much greater sound.

Every speaker in your car needs an amp to work, and most cars have some kind of preinstalled amp. But of course, these aren’t the best for someone who demands the best sound quality and they won’t be sufficient for any loudspeaker upgrade.

Any car audio update means you really have to get a new amp. Without a new one, your aftermarket speakers will sound better than your factory speakers, but the difference won’t blow your mind.

That said, even if you don’t upgrade your speakers, getting a better car amp will improve the sound quality of your factory car stereo system, so really it’s a no brainer if you want better sound quality.

Different Types of Car Amplifiers

There are many different car amplifiers on the market, and depending on its size will determine the output of the sound it amplifies.

The amplifier will take the low voltage signal and amplify it to power your speakers. Some speakers can run off low power and your factory car stereo amp, but if you really want that loud, clear sound you’re better getting a good car amp.

The size of the amp you should get all depends on the sound you want. Most people are happy with 100-150 watts. This will give excellent sound, but if you’re a basshead and want a subwoofer then you’ll need something bigger, like a 1000W amplifier.

The benefits of having the right amp is that it will give you the power you need to crank up the volume for a clean and crisp sound without any distortion.

Choosing the right car audio amplifier

How many channels for your amplifier you want is determined again by the system you intend to set up. The most common amplifiers are 2, 4 and 5 channel amps, and monoblock amplifiers.

Monoblocks, also known as subwoofer amplifiers, are a single channel amplifier. And yes, you’ve guessed it, they are used to run one speaker or a subwoofer, whereas a 4 channel amp might be used to connect 4 speakers, and a 5 channel amp will do the same as well as a subwoofer.

Although you can bridge channels, if you get a bridgeable amplifier. For example, this allows you to convert a 4-channel amp into a 3-channel amp and the two channels converted into one, will allow you to run a more powerful sub or high performance speakers.

Car amplifiers are also classified on the amplification type. The 2 most common types of amps are Class-AB and Class-D amps, and both classes have their pros and cons..

Class-D is used for monoblock for their efficiency, lower operating temperatures, and good bass reproduction, but Class D is becoming more common tech in multi-channel amps.

Class-AB amps deliver a much better midrange and treble reproduction and these are more expensive but you can run pretty much any system you like on them.

So, it’s important to know the type of sound you’re after before you go shopping for a car amp. Once you do, you need to match it up with the speakers and subwoofer to make sure it can handle everything you’re intending to install.

Choosing The Right Car Amp

There are lots of different amps of all shapes and sizes, with a varied amount of power and cost. The most common are single channel amps, 2, 3, 4, 5 and 6-channel amps, so which car amp should you get?

As stated, it’s all down to personal preference. Are you a deep basshead? Or are you just after a crisp, clear midrange sound quality without any distortion?

Whether you get a new car stereo or keep the factory system, getting a new amp will ensure you have much better and louder sounds.

Newer amplifiers are compact too, so getting one, even if it’s to boost your factory speakers, won’t take much space and today’s amps are easier to install than those of yesteryear.

Most car amps have speaker level input so that you can connect speaker wires directly. Once fit the amp will adjust the signal so it can then amplify the sound to your speakers.

If you try this way, you might not have the cleanest sound, so a good line output converter might be necessary. This is a special box designed to take the speaker wire and convert the signal to a level that your amplifier can work with.

How To Install A Car Amplifier

If you want to install an amp yourself, it’s not as difficult as it seems. And as long as you follow directions to a tee, you can’t really go wrong. As long as you have all the right tools, including a good amp wiring kit and go about your job with patience, you will be fine. Anyone wanting to install more than one amplifier, it’s a similar process, but with a few extra things to do. Check out this article for advice on installing multiple amps.

Read the instructions in my amp installation article and watch this video for visual understanding.

How Many Channels Should You Get?

One of the first things to consider is how many channels you need from your amp. The easiest way to look at it is the number of channels should equal the number of speakers and other components you’re using.

If you want to replace your 4 factory speakers with new ones and get an amplifier, you should probably get a 4-channel amp. But if you’re a basshead and want a subwoofer you should go for more than 4 channels.

Bridging amps

Most subwoofers use a mono subwoofer amplifier, which is a 1 channel amplifier made specifically to drive your sub.

If you get a flexible amplifier, which allows you to bridge channels, you’ll have more channels and power configurations, so you don’t have to match channel for component.

For example, if you have a 4-channel amplifier that produces 75 watts per channel, you can run two 75W speakers from two channels, and bridge the other two to make room for 150W subwoofer.

And you can always drive more than one speaker out of each channel, which I will get to later. Let’s take a closer look at the most common amplifiers you can get for your vehicle.

Monoblock Amplifiers, also known as single-channel amps, boosts a single input signal through a single output channel.

Monoblock amplifiers lack left-right separation, and therefore, can’t reproduce stereo signals, so in the car audio industry, they’re used almost exclusively to power subwoofers.

If you only run a subwoofer and no other high-powered speakers, you only need a single-channel amp, but most people getting a subwoofer want high-powered speakers so choosing this method means you’ll need to install more than one amplifier in the car.

And remember, more amps means using more power, so if you go with a single channel amp, go for a class D amp as it will consume less power and emit less heat.

Rockford Fosgate R500X1D A not so cheap, but great single-channel Class D car amplifier that drives 50oW x 1 @ 2 ohms RMS. Amazon customer reviews 4.8/5.

Orion Cobalt Monoblock Amplifier A well priced mono block Class D car amp that pushes 1000W RMS @ an impressive 1 ohm. Amazon customer reviews 4.9/5, but there aren’t many reviews.

2-channel amps are basically 2 amps built into one. They are great if you’re just wanting to power two loudspeakers. If you get the right 2 channel amplifier, it will boost the overall sound quality no end, and this is more than good enough for many audiophiles.

Of course, you can power more speakers to a 2-channel amp, as you can with any sized amps, but you’re always limited by the RMS of the amp.

Never overdo it. Each channel can drive an unlimited number of speakers as long as the combined impedance is within the limits of the amplifier, but never overdo it.

Pioneer GM-A3702 A great 2-channel 500W Peak Power car amplifier that pushes 170W x2 @ 4 ohms or 250W x2 @ 2 ohms. Can bridge it and should smoothly run 1200-1800w subwoofers, no problem. Amazon customer reviews 4.1/5.

Rockville RVT-1 Not the best car amp on the market but for under $100 you can’t go wrong. 2 Ohms: 125 Watts x 2 Channel, 4 Ohms: 95 Watts x 2 Channel. Can be bridged to power 4 Ohms, 250W 1 channel. Amazon customer reviews 4.3/5.

3-channel amps aren’t that common as most people tend to go for 4-5 channels or a 2-channel and monoblock. But of course, they’re useful and one will allow you to run a set of speakers and a subwoofer without the need for any bridging.

When you’re running a subwoofer from your amplifier, you need an amp that can match the impedance of your subwoofer. If this is 2 ohms, your amp must match this or the sound quality will be distorted. Of course this is the case for amps of all channels.

Also, a 3-channel amplifier will use less power and take up less space than an equivalent 2-channel and mono amps.

Taramp’s TL 1500 3 A sweet little Class D car amplifier that should fit under your seat, and it won’t break the bank. Can power 2 channels (L/R) of 95 Watts RMS each,  and 1 channel for a subwoofer of 200 Watt RMS, maximum power of 190 Watts RMS at 2 ohms. Amazon customer reviews 4.5/5.

Soundstream ST3.1000D Stealth Series Another Class D car amp that will definitely fit under your seat. Don’t let its micro size fool you though, @ 4 ohms it can power 2 x 65W + 1 200W, or bridged it will deliver RMS 1 x 200W and 1 x 300W for your sub.  @ 2 ohms you’ll get 100W x 2 and 300W x 1 channel. Amazon customer reviews 3.9/5.

4-channel amps are the most common types of amplifiers in the car audio industry. With these you can run 4 speakers for amazing clarity and crisp volume. The difference will be huge.

Or, as already stated, you can bridge 2 channels to run a powerful subwoofer along with 2 speakers, among other configurations. Doing this with a 4-channel amplifier takes a bit of wiring knowledge, but nothing you can’t learn online.

Blaupunkt 1500W Blaupunkt don’t have the best of reputations after some misleading marketing, but this relatively cheap Class A/B 4 channel car amplifier packs a punch. 1500W Peak Power and 4 Ohms RMS Power drives 150W x 4, or 2 Ohms will give you RMS Power: 300W x 4. A good piece of equipment for a very good price. Amazon customer reviews 4.3/5.

Kicker 46CXA360.4T CX Series Not cheap but a very impressive Class A/B 4 channel car amp. The amp features a variable bass boost with Kicker’s KickEQ™, which gives you as much as a 6dB of extra bump. At 4 Ohms it drives 65W RMS x 4 speakers, or 90W RMS x 4 @ 2 Ohms. Or 180W RMS x 2 speakers bridged at 4 Ohms. Amazon customer reviews 5/5 but only 3 reviews.

A 5-channel amp is like a combination of 4 channel and a monoblock amplifier. If you intend to get a subwoofer and run 4 speakers, they’re easier to work with as you don’t have to bridge any channels.

5-channel amplifiers offer a complete system amplification without the troubles of having to bridge channels if using one with less channels.

For the inexperienced audiophile, a 5-channel amp isa popular choice if you want the full works. It will make life much easier, and it will give you an amazing listening experience.

Kicker 46CXA6605 This Kicker CX car amplifier uses powerful Class A/B technology to power four mid/high-range channels and a Class D power plant for the bass channel. Can drive many powered variations, including 90W x 4 @ 2 Ohm Stereo RMS and 300 Watts x 1 @ 2 Ohm RMS for your sub. It’s an absolute beast and the price isn’t cheap by any means but, you’ll be hard pressed to beat this amp. Amazon customer reviews 4.5/5.

BOSS Audio Systems PV3700 A Class A/B Full Range 5-Channel car amp with 3700 Peak Power. RMS 413W x 4 speakers + 1125W x 1 RMS @ 2 Ohms for your bass channel. As with most amps the power rating is questionable, but for a relatively decent price, its good value. Amazon customer reviews 4.3/5.

A 6-channel amplifier is as it says on the tin. It has 4 channels for your 4 component speakers plus two channels, that are usually used for your subwoofer.

Depending on your full set up, a 6-channel amp gives most people the capability of bridging two channels to run a more powerful subwoofer than you could with a 5-channel amp. These are more pricey of course, but for many people the clarity and power makes it worth it.

Kenwood Excelon P-XR600-6DSP This 6-channel Class D car amplifier is an absolute beast. It has a controlling app that allows you to run it from your smartphone. Power rating offers many variations including 75W RMS x 6 @ 4 Ohms; 100W RMS x 6 @ 2 Ohms; and being a bridgeable amplifier you can drive 200W RMS x 3 @ 4 Ohms. Amazon customer reviews 3.8/5.

Lanzar Amplifier Car Audio This 4000W 6 Channel Mosfet Amplifier drives some power into your car audio system. Power rating allows for 6 X 250W RMS @ 4 Ohms; 6 X 350W RMS @ 2 Ohms; 3 X 1,000W Max @ 4 Ohms Bridged; 6 X 500W Max @ 4 Ohms etc. As always, question the Power Rating, but this amp is impressive and quite a bit cheaper than the Kenwood Excelon P-XR600-6DSP. Amazon customer reviews 4.1/5.

*The recommended car amplifiers are just a small selection of what is available. There are better and worse amps on the market, but I wanted to offer a wide selection from budget to someone with no cost issues. Always do some extra research before buying, starting here for the Best 4-Channel Car Amplifiers.

What Power Settings Should I Be Aware Of?

Peak Power And RMS

If you know how many channels you need, your next step should be to determine how much power you want from your amplifier. The more power the amplifier delivers, the cleaner the sound you’ll get from the speakers.

You should match up your stereo and speakers with the right amp, and even getting a more powerful amp is a good idea. Each amplifier has two power ratings: Root Mean Square (RMS) and Peak Power.

When buying a car amp, should i look for RMS or peak power?

RMS is the amount of continuous power that an amplifier produces. It’s measured in watts, and the higher the RMS rating, the louder and cleaner your music sounds.

Peak Power is the absolute highest power an amp can briefly generate on any given channel before failing. This is always higher than RMS power, but when you’re shopping for an amplifier go by the RMS.

When shopping for one, make sure the RMS power on your car amp matches that of your speakers and subwoofer.

If you don’t match them your speakers could be underpowered, or even overpowered, which could potentially overheat and damage your audio system.

45 watts per channel RMS should make a noticeable improvement to your speakers. If you want a louder and more powerful system, I’d look at 4 channel amps putting out 75+ per channel RMS.

Class AB amps tend to sound better than Class D amps, but class D amps are easier on power consumption, so again you should really consider this, too.

Personally, I don’t think you need anything more than 75 watts per channel, for a 4 channel amp for an average sized car. With this amount of power, you should be able to fill any vehicle with some crisp, loud sounds.


Impedance, measured in ohms (Ω) is more concern for your speakers, but something thing you should consider before buying a car amplifier. Impedance is basically the measurement of resistance that the speaker adds to the circuit.

In car audio, full-range mid-range speakers, and tweeters are nearly always rated at 4Ωs, whereas subwoofers are usually 2 Ωs.

Most multi-channel amplifiers are configured for 4-8 ohms, so if you’re only running speakers from your amp, you will have more options.

If you’re running a subwoofer, however, you have to make sure your amplifier impedance matches the impedance of your system configuration, so if your subwoofer is 2Ωs, make sure to get an amp that can power that.

If you have a 2 ohm amp, it can power speakers with 4 ohm impedance, but the other way round will bring you problems. Any speaker with 4-8 ohms shouldn’t be used with a lower impedance amp.

For 2 and 4 channel amps, the power is usually listed as 4 ohms, because most car speakers are 4 ohm speakers. Whereas, a mono subwoofer amp will likely be 2 ohms, because subs don’t usually require 4 Ω.

2-ohm impedance for a subwoofer will kick your sub into gear and ensure you get great sounding bass. That’s not to say you can’t get 4-ohm subwoofers. Of course you can, but a 2-ohm sub will demand less power from your amp and will deliver louder bass than a 4 ohm equivalent.

That said, a 4-ohm sub will demand more power from your amp and although the bass won’t be as loud it will likely be of a higher quality.

Getting An Amplifier For Your Subwoofer

As already stated, most subwoofer amplifiers are one-channel mono subwoofer amplifiers, and they’re designed to run subwoofers at around two ohms of impedance.

Getting the right amplifier for your subwoofer is important

You can get 1 ohm or 4 ohm subs, and those are fine as long as your amp can drive subs at that impedance. Two ohms is the most common impedance to use with a subwoofer in a sub amplifier, though.

Getting the right amp for your subs depends on your car audio system, and there are many possible variations. If you’re just adding a sub to your factory set up, anywhere from 50 to 200 watts of power for a subwoofer should be ok.

If you have more powerful speakers, however, your sub will probably need more power. Getting an amp to power your new speakers and a subwoofer means you will need a more powerful amplifier.

For example, if you have an amp that is powering around 50 watts per channel for your speakers, your subwoofer is going to need between 250 and 500W of power just to keep up with your speakers.

And if you’ve really gone for it and you have some powerful speakers, let’s say 100W by 4 channel amp, you will probably need up to a 1000W subwoofer amplifier to help it match the sound and give an overall balanced sound.

As always when choosing an amp, you want to know what the sub’s maximum RMS power is, and you need to be within at least ¾ of that power, although better to match it.

For example, if your subwoofer can handle 400 watts RMS, an amplifier that can handle a minimum of 300 watts will be sufficient, but don’t go for more than the 400W RMS of the sub.

Another thing to think about when matching subwoofers with an amplifier is impedance. This is important because you can get subs that are 2 ohms, 4 ohms, 2 and 4 ohms dual voice coil subs etcetera, so matching everything so you only arrive at 2 ohm impedance for your amplifier is important.

For example, if you’ve got two speakers that can handle 400 watts and they’re 4 ohms each all wired in parallel, you will need an amplifier that can push out 800 watts at 2 ohms.

How Much Should You Spend On Your Amplifier?

As you already know, matching the amp with your other parts is more important than the amount of money you intend to spend.

The cost of amps can vary a lot, and sure enough the more you spend the better quality you will likely get. Amps are set into classes, with AB and class D being the most common and versatile.

installing your amp next to your subwoofer is a good idea

The main difference with Class D is that they’re smaller and offer the highest efficiency and create less heat. The AB class are bigger, the power will be beefier but the sound quality will be better than the D class.

You can get amps with basic controls, which is good enough for most people. With these you set it when you install it and you’re pretty much done unless something goes wrong.

If you’re an audiophile connoisseur, however, you might want a car amplifier that has different settings that give you much more control over the sound.

With these you can use them to control the crossovers, base boost and level controls, and you can change them individually to test the best sound quality for you.

The tuning equipment can be either on the amp, or if you get a flashy one you’ll be able to control it all through an app on your smartphone. There are settings on the amp or your smartphone that show you have the optimum sound, but of course there’s no better judge for that than your ear.

Getting A Good Car Amp

You can’t get crisp and clear sound from under-powered speakers; you need an amplifier to make the best sound system. Getting some aftermarket speakers and/or a subwoofer deserves amplification, so they can perform at their best.

Getting the right car amp isn’t a straightforward choice. There’s lots to consider. The number of channels, how much RMS, impedance, how many speakers, where it will go in your car? etcetera.

But once you’ve done your research and you’re confident you know which amp you want, it goes without saying that your driving experience will be louder and more energized.

2 thoughts on “What Is a Car Amplifier and What’s Its Use?”

  1. I’ve been installing my own car audio systems since my first car at age 16 (i’m now 52 and near deaf lol). I have not kept up on some of the new tech that has come out in the past 10 years. Your site has helped with my upcoming build in a lexus es330. I’ve always run a tri-amp system with an electric crossover. After checking out your site I’m thinking about trying a 5 channel amp for the ease of installation vs a tri-amp system. Thank you for the great information on this site.

    • Thanks for the kind words, and sorry about your hearing difficulties. There are some great 5 channels amps and it makes much more sense to get a single amp rather than tri-amping, in my opinion.


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