Car Amplifiers

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What Car Amp Do I Need?

If you are looking to improve your car’s sound system, getting a new car amplifier is the best way to do it. An amplifier’s job is to improve the speaker’s ability to produce quality and volume in any music or sound it puts out. Here are some things to consider when deciding what car amplifiers might be best for your vehicle’s audio system.


This may seem obvious, but the first thing you want to check with any potential new amp is if it will fit. There are some areas in a car that are better suited to holding an amplifier (alongside the passenger-side firewall, in the trunk, or under the seats, for example). If you get an amplifier that is too big to fit in these spaces, your installation just got more challenging. Worst-case scenario, you wasted a purchase and may need to return the amplifier in lieu of a smaller sized one that fits the space you have available.


One thing to take note of is the number of channels an amplifier can serve. A channel is a unique power source used to provide a single speaker with power in a sound system. To know how many channels you will need, you should first determine the full expanse of your car audio system. How many speakers and sub-woofers you have will both make a difference in the total count. For example, getting a mono-block amp (a one-channel amplifier) will not power a system with two speakers and a subwoofer or two. That would require a 4-channel amp. You can also find 2-channel amplifiers and five-channel amplifiers.

Once you know how many speakers and subwoofers you will have in your car stereo system, you can make sure to get the right number of channels in your amp. However, the answer may not be as direct as you might expect. While a two-channel amplifier can power two coaxial speakers or woofers (one channel per speaker,) it can also power two sets of coaxial speakers at a time. Assuming the speakers are 4-ohms each, is done by wiring two speakers in parallel to each channel, creating a 2-ohm load on the amplifier, which most are stable to that impedance.

If you want to boost power and add a subwoofer to your rear full-range speakers, a four-channel car amplifier might be ideal. You will have enough power and channels to run the full-range speakers off the front channels, then bridge the rear channels to power the subwoofer. You can also power the coaxial speakers with the amp and use a mono-block amplifier for the subwoofer. There are many ways to tackle the same problem.

So, while there is no absolute “right” number of channels for a given sound system, your specifications, needs, and tastes for putting it together will determine the amount you want. Start by deciding on the arrangement of speakers and subwoofers, and that will give you the necessary number of channels for your audio system.


Getting the right amount of power from your amplifier to your speakers is vital to ensure you get the best sound quality. Like with channels, there is no absolute, set number. You will need to look at a variety of factors in your speakers and amplifier(s) to make your decision. Start with the speakers. Getting the amplifier first makes it more challenging to properly match all the system components. Get to know their power range and the speaker load (impedance.) These tell you just how much power the speakers can handle at a maximum, and also how much effort your amplifier will need to apply at a given time.

Your car amp should be able to provide 50-120% the amount of power as the speaker’s continuous or RMS power rating. This will allow the amp to handle any spikes and reliably deal with the car speaker’s peak power. Underpowering your speakers can not cause a great deal of distortion to the sound. However, overpowering your speakers can damage and possibly blow them.

If you are also looking to run subs off the same amp that you are using as your speakers, careful arrangement and amount of power should be taken into consideration. As mentioned above, you can bridge amp channels to power a sub, but this isn’t always ideal. You need to make sure the amp can supply enough power to match the needs of the subwoofer. Otherwise, it might be best to get a mono-block amplifier for the sub.

System Compatibility

If you are starting from scratch with your car stereo system, then one necessity is a source unit with preamp outputs. Another is an amplifier with line-level (speaker line) inputs. This will allow you to wire the amplifier to a factory radio or source unit. If a pure, un-amplified signal enters the amp, you will get the clearest sound output.

However, most factory source units that come pre-installed, and many other aftermarket units, do not come with preamp outputs that provide a clear connection to an external amp. If your current source unit is one such device, you will need to look for an amp with speaker level inputs to keep your devices compatible. This will result in much better sound than if you’d gone without the external amp. You will also avoid messing around with installing an additional adapter or wiring.


Installing a car amp is not as difficult as one may first assume. The most difficult and most crucial, step is finding where to place your wires and your amp around the car. As stated above, some places in a car are better than others (the trunk, under the seats, etc.,) so find a spot in your car that will fit an amp that also offers maneuverability for wires to be routed to and from the area.

Keep in mind that you will also need to be able to provide power to the amp in the place you have chosen, and so you will have to run additional wires down to this spot. Furthermore, you will need to be sure your car’s alternator has enough power to handle the draw from the amp.

Choosing an Amp

Now that you know the factors to look for, you have a starting point in your search for a new car amplifier. No one magic product is one size fits all, but rather many quality products that may or may not work for your vehicle depending on the sound system you are building. Rockford Fosgate is happy to answer questions you have about your chosen amp, how it will integrate into your car’s audio system, or any other thoughts you may have. Rockford Fosgate offers many quality amplifiers to choose from to provide you with the best sound possible.

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