4 Channel Amplifier Complete Guide

Buying an amplifier is one of the best ways to upgrade your factory audio system. The first place to start for many people is a 4 channel amplifier. It’s not something to purchase blindly without general knowledge, so that’s the purpose of this article. Prepare to become an educated consumer on car audio amplifiers, and you will enjoy kick-ass audio soon enough.

4 Channel Amplifier Basics

Before purchasing a 4 channel amplifier, it helps to know the basics around the product to make sure you receive the best sound quality possible.

What is a 4 channel amplifier?

4 channel amplifiers offer a wide variety of options. These amplifiers are best for powering a couple pairs of speakers in the most cost-efficient way. The main advantage of a 4 channel amp is that it can be used as a very versatile audio component. It can also be wired in multiple different ways to produce the best sound for your vehicle.

Do I need a 4 channel amplifier?

This question is hard to answer without knowing your specs. Chances are, you will need a 4 channel amplifier if you are attempting to power two pairs of door speakers. If you are looking to power a pair of door speakers and a powerful subwoofer, this is also a great use for 4 channel amps. You would accomplish this by bridging two channels to the subwoofer.

Car Audio Amplifier

What are some common 4 channel amplifier brands?

When purchasing audio equipment, brands can be an important indicator of the product you are buying. Speakers and amplifiers have different sound signatures internally developed by the brands. Some of our favorite brands are:

Rockford Fosgate

We think this brand is great for amplifiers because they build very rugged products. Often times, we mount amplifiers in places where they receive a lot of wear and tear, such as a trunk or passenger footwell. Rockford Fosgate amplifiers are built to handle abuse and last longer than some other brands.


Alpine products are pretty renowned in the car audio space. I think that for car audio signatures, alpine provides the best general sound quality for most of their components.


Pioneer has been in the car audio game for a long while, and generally they make good products. We like the form factors that pioneer amplifiers provide. They are often small and can be used in places other amplifiers can not.

Where can I put a 4 channel amplifier?

Three Places to Mount Car Amplifiers, Passenger Footwell, Under Front Seats, In the trunk

It is most common to mount a 4 channel amplifier in one of these three places:

  • Trunk
  • Below a seat
  • In the Passenger Footwell

The location will change based on the car you are driving. For example, if you own a roadster, you will have to mount it in the passenger footwell or (maybe?) in the trunk. If you drive a truck, you can’t mount the amplifier in the trunk bed. You will need to take a look at your vehicle and find the best spot.

Copper Speaker Wire

4 Channel Amplifier Wiring

This part of the guide is dedicated to helping you wire your amplifiers for best results. With custom car audio systems, it makes just as much difference on how you use the components as the components themselves.

What is amplifier bridging?

Many amplifiers support bridging channels. This is the process of wiring the negative of one channel and the positive of another channel to produce a more powerful single channel.

How do I bridge a 4 channel amplifier?

You should look at the wiring diagrams provided by your 4 channel amplifier to get the best results for this. Different amplifiers support bridging differently, and therefore it just depends on the amplifier you have. If your amplifier doesn’t directly support bridging, we recommend that you purchase one that does. For more information on bridging amplifiers, check out this article on Crutchfield.

Is there a downside to bridging an amplifier?

There are typically a few disadvantages to bridging an amplifier. It costs more channels on the amplifier to bridge it, reducing the number of speakers and subwoofers you can drive with the amplifier. It’s also common to increase impedance on the line, and you will need to consider that when deciding to bridge an amplifier.

Can I bridge a 4 channel amplifier to 2 subs?

We don’t generally recommend doing this unless you absolutely know what you are doing, and you know what you are powering. Most of the time, it is best to get a more powerful monoblock amplifier and run the subs on the same channel. You will get a higher quality of sound for the price from this solution in our experience.

Can I use a 4 channel amplifier to power 6 speakers?

You can not use a 4 channel amplifier to power 6 speakers because it takes the balance out of the speaker system*. A possible alternative is using the head unit to directly power two speakers in the back and using the amplifier to power 4 speakers in the front. Another solution is to use a 6 channel amplifier for the speakers but may require additional equipment purchases.

* it is possible to wire 6 speakers into a 4 channel amplifier, we just don’t recommend doing it if you’re not a professional or sound engineer.

Picking a 4 Channel Amplifier

When picking out a 4 channel amplifier for your next purchase, it’s best to look at a couple of things to make sure your amplifier will be the best fit for your audio system.


You will need to look at the wattage required for your amplifier. You want the channels to be able to support the most needy speaker in your ca audio system. It is generally okay to overpower speakers as long as you are not drastically overpowering them. Check the spec sheets for the continuous power RMS, and use this figure as a rough estimate for the power your amplifier channels should produce.


If you are installing the amplifier in a place that it will face some abuse, it is best to get an amplifier that will not break down when kicked and vibrated. We personally like amplifiers with aluminum casings because they tend to be more durable.

Heat Management

If your amplifier overheats, you will not be able to enjoy music from your new car audio system. You should look for an amplifier that has great heat management and heat sinks. Make sure not to overwork your amplifier or you will possibly face overheating issues.


Many amplifiers come with LED indicators that will tell you if you’re an idiot. Misconfiguration is the most common way to destroy your new amplifier purchase. Unless you are hiring a professional, you should consider the purchase of an amplifier that will show the problems before they cause components to get destroyed.


In this article, we tried to answer some of the most common questions regarding 4 channel car amplifiers and give you the knowledge you need to start upgrading your car speaker system. We wish you luck on your journey, and if you are looking to purchase a 4 channel amplifier, check out this article.