How to Choose an Amplifier (2020)
You’ve got the car that you love, it’s a dream to drive, and you’ve never had more fun on the freeway or on the open road. Everything’s there, but you’re missing one thing – an audio system that delivers knockout bass, crystal clear highs, and punchy midrange frequencies. It doesn’t matter what kind of music gets you moving, everybody loves a good sound system.
No matter how advanced modern cars get, the sound systems will always be a compromise. Car manufacturers can use big name speakers and head units, but at the end of the day, the audio experience is never the main focus.
If you want in-car entertainment that literally makes you stop and listen, then you’re going to need to upgrade to an aftermarket amplifier. We’ve already taken a look at some of the best amplifiers of 2020, but if you’re looking for a complete overview and buying guide, then this is the place to be.
From knowing how many channels you’ll need to finding the right place to mount a new amplifier, this is everything you need to know about choosing an amplifier for your vehicle.
Understanding How Your Amplifier Works with Your Existing Audio Components
Although amplifiers are relatively complex in design and manufacture, they serve a simple purpose. They take the audio signal from your in-car head unit and amplify it to be distributed to component speakers and subwoofers. In a basic sense, an amplifier allows for more volume, but can also increase the quality of sound by reducing distortion and providing a better signal to noise ratio when compared to a head unit alone.
An amplifier can be used with any vehicle where the head unit has independent outputs (usually RCA connectors) for line level signals. You’ll still use your main unit for playing and controlling your music, but the actual sound delivery will be taken care of by your amplifier, bypassing the built-in speaker outputs on the head unit. Some factory head units come provided with line level outputs, however, most enthusiasts prefer to use an aftermarket head unit to allow for greater control over their overall sound.
Purchasing an amplifier doesn’t mean that you’ll need to change your speakers, but this is always an option. Factory speakers are usually rated and matched to the factory head unit, and may struggle to accept the power delivery of an aftermarket amplifier. Using speakers with a peak power rating below that of an amplifier will lead to problems with distortion, and will cause damage at high volumes.
Most enthusiasts who are upgrading an amplifier for their speakers, as well as subwoofers, will choose to install aftermarket speaker solutions. Component speakers are typically smaller and combine a 6.5” driver with a smaller tweeter. Full range speakers are also used in vehicles, with the most common being the 6×9” configuration. Full range speakers provide well-rounded frequency response but they won’t deliver the chest rumbling bass that a subwoofer can.
When purchasing speakers, always check the power rating so that they can be paired with the amplifier of your choice. Take a look at this Kenwood KFC-P709Ps speaker set as an example. They’re rated for 80W RMS or 280W peak power. Matching them with a multichannel amplifier with a similar power rating will be ideal, and something like the Pyle PLA2200 amplifier will easily power two sets of these speakers.
Remember, every component in your vehicle will have an impact on your system design. To get the basics down, always keep in mind that:
- You’ll need a head unit with RCA outputs to connect to an amplifier, such as the Pioneer DEX-X6900BT.
- Your amplifier will need to be powered directly from your vehicle’s battery.
- Speakers (including subwoofers) will need to be matched to the output power of the channels on your amplifier.
Let’s take a look at what a basic setup might include:
- The Pioneer DEH-X6900BT is an affordable option with RCA outputs.
- For a set of component speakers, we’ll choose the aforementioned KFC-P709PS sets. You can run up to four of these speakers directly from the Pioneer head unit with good results.
- For some low-end presence in your sound, we’ll add a monoblock amplifier and a subwoofer. You’ll be able to connect the amp directly to the subwoofer output on the pioneer head unit. The Rockford Fosgate R500X1D is a reliable amp that will power a P2D4-10 subwoofer.
Amplifier Channels – How Many Do You Need?
Take a look at a few amplifiers online, or even the models in our roundup of the top 10 car amplifiers, and you’ll find that they come in various configurations, each with a different number of channels. Typically, you’ll see two channel, four channel, monoblock, and five channel amplifiers.
Two Channel amplifiers are full range models that are used to power a single set of speakers (left and right). These are extremely popular for people who are looking to provide power for their aftermarket speakers. They will accept a left and right input using RCA cables, and often have an output so that the line level audio signal can be chained to another amplifier. If you need to power only a single pair of component speakers or 6×9” speakers for your car, then this is the type of amplifier that you’ll be looking for. The Rockford Fosgate R150X2 Prime 2-Channel amplifier is an affordable and capable model in this category.
Four Channel amplifiers provide the same features but add two more channels into the device. Most vehicles have two sets of door speakers in the front and rear, and a four channel amp will allow for powering all of these speakers from a single unit. Additionally, four channel amplifiers will sometimes have a bridged mode so that all the power can be sent to two speakers. The Kenwood KAC-8406 is an excellent example of a four channel amplifier that can provide up to 100W per channel when running at 2 ohms.
Monoblock amplifiers, as the name suggests, are used for single channel applications. In a vehicle, this means using them to power a subwoofer. They combine an audio signal into a single channel, making them ideal for sub bass frequencies. Monoblock amplifiers are efficient because they don’t have to deal with multiple speakers, and they generally offer high output. If you’ve purchased a subwoofer for your car and you’re going to be running your component speakers directly from a head unit, then a Monoblock amplifier would be the most ideal purchase for your sub. If you’re looking for an example of a quality monoblock that has been highly praised by both reviewers and consumers, then take a quick look at the Rockford Fosgate R500X1D 500W amplifier.
We’ve now looked at some examples of amplifier types for both speakers and subwoofers, but what if you wanted to go with a single amplifier that could power a full set of car speakers and a subwoofer in a single package? If this sounds like your scenario, then you might like to look into a Five Channel amplifier. This type of amp combines what is essential a four channel circuit with an additional mono channel, allowing you to power four door speakers as well as a subwoofer. By going for a solution like this, you won’t need to worry about mounting and wiring two or more amps in your car, allowing for an easier overall installation. Again, due to extremely high customer satisfaction and review scores, we’re going to point to an excellent
By going for a solution like this, you won’t need to worry about mounting and wiring two or more amps in your car, allowing for an easier overall installation. Again, due to extremely high customer satisfaction and review scores, we’re going to point to an excellent Alpine unit that we have already reviewed here on this site. The Alpine V Power MRV V500 offers 500W of power distributed over 5 channels. It has a built in crossover so it will be perfect for full range speakers paired with a subwoofer.
You’ll also find that there are larger specialty amplifiers, including eight channel amps for extreme setups. If you want up to eight channels available for different combinations of speakers and a subwoofer, then a large amp like this could be easier than going for a number of smaller amps. These amplifiers fit into a very small enthusiast niche and can sometimes be difficult to find, but you can take a look at the Lanzar HTG888 Heritage Series amp as an example of just how much you can do with a single amp.
When you’re choosing a car amplifier, think about convenience as well as power. If you use multiple amps, you’ll need to find a space for each one, and you’ll also need to chain the audio signal that is coming from your head unit. This can mean using more cables, introducing noise or signal degradation, and it also means that you’ll have more points of potential failure. For simplicity’s sake on your first car audio installation, choosing a single amp that meets all of your needs will be the best solution.
Also, keep in mind that purchasing a subwoofer doesn’t mean that you have to power your component speakers from an amplifier. In many cases, you will be able to run your subwoofer from a monoblock while keeping your speakers wired to the standard outputs on your head unit. If you’re aiming for the best sound improvement on a budget, then choosing a quality head unit, monoblock and subwoofer will often be enough for your needs.
Here are a few recommendations if you want to improve your car audio for a wallet-friendly price.
- The Pioneer DEH-X6900BT has great features like USB play and Bluetooth and will power your factory component speakers.
- You can connect the affordable Rockford Fosgate P300-10 Punch subwoofer directly to your head unit, and it even has a built-in monoblock amp, making it a simple install for beginners.
Wattage – How Much is Enough?
Wattage depends entirely on your needs, and also on the size of your vehicle. You can use some rough guidelines to get an idea of your power requirements when choosing an amplifier.
- Most factory head units output to speakers at 50W – 75W. If you want to go louder, you’ll need to exceed this value per channel/speaker. A good starting point is 100W per channel.
- With speakers running at 100W per channel, you’ll need some decent power from a subwoofer. At least an 800W monoblock amplifier would be ideal if you’re running four speakers at 100W RMS each from a separate amplifier. This would provide enough power to a 12 inch (or larger) subwoofer to cut through your sound mix.
If you’re simply adding a subwoofer to a system where speakers will still run from a head unit, then a monoblock amplifier of at least 200W will make for a good pairing.
Here’s an extra tip – make sure you check the impedance of your amplifier before connecting it to a subwoofer. Both should be matched, or you run the risk of overheating your amplifier or not being able to run a sub at all. Impedance matching is important because it deals with the transference of power from an amplifier to a speaker. If the impedance is mismatched then you’ll end up wasting power in your signal chain, and your speakers won’t be getting what they need to produce the best sound. Use speakers with an impedance that is too low for an amplifier, and that’s when overheating can occur. Most modern amplifiers are designed not to overload when the impedance is mismatched, however, for your safety and the best sound, always check the impedance of ALL of your components before purchasing or installing a system.
Let’s take a look at an amplifier we’ve already reviewed as an example. The JL Audio JX1000/1D is a 1000 Watt Monoblock amplifier. It can provide 500W at 4Ohms impedance, which would pair nicely with a Skar Audio 500W 12” subwoofer.
Is it Necessary to Run Your Component Speakers Through an Amplifier?
The majority of people looking for a basic audio upgrade will purchase an amplifier so that they can add a subwoofer to their vehicle. A subwoofer boosts the low-end frequencies and creates a more rounded sound in your car. While most would consider a subwoofer as something more suited to electronic music, or even hip hop, the reality is that an amplified subwoofer will improve the listening experience for any kind of music or in car entertainment.
Acoustic music, rock music, metal, pop, and even classical music can be heard with more definition when using a subwoofer. For many car owners looking to upgrade, they will have questions about whether they need to amplify their speakers as well as a subwoofer.
The simple answer – not necessarily.
Head units typically come with at least four channel output for component speakers. Take the Pioneer AVH280BT DVD receiver as an example. This unit provides four channels rated at 50W, which would be sufficient for powering all component speakers in most vehicles.
However, if you’re looking to increase volume levels for high-quality aftermarket speakers then you will probably want to bypass the head unit and run your speakers through a separate amplifier. The additional wattage provided by an amp will provide more volume headroom, and can help to improve the overall quality of sound.
Professional builds, such as audio systems for competitions and show cars, will always use a separate amplifier to power component speakers in addition to any subwoofers that are installed in the vehicle.
Do You Need to Upgrade Your Battery to Power an Amplifier?
At this point, you have a good idea of the type of amplifier you might need to install in your car, and you may have even checked out a few of the options here or on our top 10 page. However, simply knowing the amp to buy is only part of getting your car ready for an awesome listening experience.
Having a great amplifier will mean nothing if you aren’t powering it from a capable battery, and this is something that many people overlook when building their first car audio system.
Amplifiers need to be powered directly from a 12V battery, so virtually every modern car will be capable of delivering enough power to a high-end car audio system. While you might have read or heard that a separate battery is needed for your system, this is not true. In fact, adding another battery could be detrimental to the performance of your system, as well as other electronic components in your car.
When your car is running, the alternator will continually charge the battery and provide electricity to other electrical components. Adding a second battery will put additional strain on the alternator, and is simply not necessary. Because you’ll be listening to your system while the car is on, you won’t have problems powering everything. Even with a relatively high demand 1200W system, a standard battery and alternator will provide plenty of power.
However, one thing that you do need to be aware of, is that using your upgraded system could quickly deplete your battery when your car is not running. Using a powerful system, even for as little as 30 minutes, could mean depleting your battery to the point where there isn’t enough charge to turn your starter motor. The best advice is to keep your car running if you’re using your system at moderate volumes or limit your listening to 30 minutes at lower volumes. Because battery age, capacity, and ambient heat can all have an impact on reliability and ability to hold a charge, there’s no hard rule that will tell you how much time your battery will give you before your amplifier and stereo system will deplete it.
Choosing the Best Cables for Your System
You’ve probably noticed that we’ve gone into much more detail than just amplifiers alone, which is essential when you’re looking at any car amplifier buying guide. Just like any serious purchase, there are a number of accessories and components that will impact the performance you get, and whether or not the system actually works.
When purchasing and installing an amplifier, you’ll need high-quality cables to get audio and power to the amp, as well as to distribute the amp signal to any speakers that will be connected.
One thing you can be sure of is that poor quality cables won’t suffice. Low-quality cables can reduce sound quality, affect amperage, and in the case of a low-quality power cable, could even be at risk of shorting out and causing a fire or damaging your equipment.
The best way to ensure that you have everything you need to wire your system is to purchase a set of cables that are intended for car audio wiring. When purchasing, make sure you choose a kit that is matched to the power of your system. Using the wrong kit with a powerful system will reduce efficiency, and will introduce heat into the power cable which could then turn into a fire hazard.
Here are three examples of cable kits, with some details about the power that they can handle.
- The Boss Audio 8 Gauge kit is suitable for systems up to a maximum of 800W in power. If you’re running something like a single monoblock, or a two or four channel amplifier, this kit will usually be enough for your needs. It includes the cable to run power from your battery (including a safety fuse), as well as audio and speaker cables for connecting your individual components or a subwoofer.
- If you end up going for a more powerful amplifier, you could consider the Pyle PLAM40 kit that has been designed to handle up to 1600W of power. It comes with everything that you need to wire an amplifier to multiple speakers and a subwoofer.
- For systems of up to 5000W in power, you could choose a zero-gauge kit, like this Soundbox amplifier install wiring kit.
These kits are all good starting points from where you can explore your options. No matter what you end up choosing, make sure it’s rated for the total power of your system (important if you end up buying multiple amps), and check consumer reviews to get an idea of the quality and reliability of any particular kit. Each of our suggestions has been positively reviewed by a large sample group of consumers.
Where to Mount a New Amplifier
Car amplifier can generate a significant amount of heat, and larger more powerful amplifiers have fairly large physical footprints. In a car, you’ll have two options for mounting.
The first is under the driver or front passenger seat in the main cabin. You’ll first need to make sure that there is nothing obstructing the amplifier underneath the seat, and that there is at least an inch of clearance between the top of the amplifier and the underside of the seat. Without enough clearance, there won’t be enough airflow and the amplifier could overheat and fail. This position is best for smaller two channel, four channel, and monobloc amplifiers.
With a larger amplifier or with multiple amplifiers, you’ll usually need to perform mounting in the trunk storage compartment. This can be on the rear side of the seats, or directly to the floor or side compartments of the trunk. If you have the time and the tools, you could even build your own amplifier rack using ply or particle board and automotive upholstery. Alternatively, you could have a professional install your system.
While a professional install will be the easiest method, it will also be the most expensive, and there is something deeply satisfying about installing your own system, especially once it’s finally up and running.
Take Your Time to Choose the Right Solution for Your Needs
Everybody’s needs are different. How loud your system is, how much bass you’ll have, and how much it costs, will ultimately be determined by the amplifier that you choose. An amp is only worthwhile when you use the right components, subwoofer, and even the right speaker and power cables. Take your time to select an amp that is right for your needs and budget, and you can always refer back to My Car Needs This for advice on the best amps, aftermarket head units, and buying guides on all of your car enthusiast products.