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Topic: Car Audio Amplifiers

Amplifier Types: 2-Channel, 4-Channel, Class D / Mono, and Multi-Channel

We receive quite a few amplifier questions. And it seems to me one of the most common misconceptions about amplifiers is the number of channels an amplifier has (I.E. 4 Channel) refers to how many subwoofers or speakers the amplifier is able to handle. Well that is actually not the case. I will break down the choices for amplifiers and offer some of my own personal suggestions for running an amplifier.

Right off the bat the most common types of amplifiers you will see on the market today are Class D, Class AB, Class A and Class T. Now we will go over each type and the advantages and dis-advantages of each type but first you need to be familiar with the following terms that will be found on any amplifier regardless of the brand, model, or type.

First up is Crossover. Almost every amplifier sold today has a built in crossover. What does a crossover do? Well the easiest way to picture a crossover is as a frequency filter. It is designed to keep the frequencies within a certain range. Most 2 channel and 4 channel amplifiers will have a low pass, full range and high pass setting and Class D amps will only have a low pass setting. The Low Pass filter is used when connecting subwoofers to an amplifier will filter out the higher notes. A Full Range setting is used when the entire frequency range is desired and in most cases you would use a separate set over passive crossovers at the speaker themselves. And last is High Pass which is used for mid range / full range speakers. There are also two types of crossover settings depending on the amp. Variable which allows the frequency to be adjusted anywhere between two listed points and Selectable which means you can choose set frequency points.

Next is RMS Power and Peak Power.  Every amplifier will list the power handling capabilities of the model. By far the MOST important factor you need to be concerned with is the RMS rating. This is how much continuous power the amplifier is able to produce over a long period of time. The higher the RMS rating the cleaner and louder you system will sound. Peak Power is a musical burst of energy such as a quick drum beat. Many manufacturers post the peak rating right on the amplifier and its packaging but DO NOT judge the amplifier by that. You must pay attention to the RMS range when shopping for an amp. One of the best ways to calculate what the maximum power an amplifier is able to produce is by looking at the fuses. So lets say an amplifier has (2) 40 amp fuses built in. To calculate how much power that amplifier can handle max safely you would take the fuses amp ratings and add them up. So using the amp mentioned above that would equal 80 amps. Then take 80 amps and multiply it times 12 volts. That means the maximum wattage that amplifier can handle safely is 960 Watts.

The last major feature we will look is Ohm Rating. Every amplifier will be rating at particular power rating at various Ohm ratings. Now to get the most from your amplifier you would want to run it at the lowest possible Ohm load it can handle. The lower the resistance (Ohm) at the amp the more the power (Watts). So in theory if you were looking at two Ohm ratings on an amplifier such as 200 watts @ 4 Ohm and 400 watts @ 2 Ohm you would want to run the amplifier at the lower resistance (2 Ohm) since the amplifier would produce twice the power. We also have a more in depth article on Ohms which can be found here: Ohm's Law Car Audio


There are many other terms and features that can also be considered when choosing an amplifier but if you follow the guidelines above you will be off to a great start making the right choice. We will now take a look at a few different model amplifiers and features.

Next Page: Amplifier Types

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2-Channel Amps - 4-Channel Amps - Class D Amps - Multi-Channel Amps