Car & Truck Amplifiers

You know that you need an amplifier in your car’s audio system if you want thumping, window-rattling, trunk-vibrating bass, but adding such a device will provide so much more than you expect. With a high quality unit, you’ll get much better overall sound quality. And if you’ve upgraded your speakers or added a new subwoofer, a separate amplifier will provide the power needed to get the most out of them. It will do the job a dash-mounted receiver just can’t handle. In this article, we will discuss some of the matters influencing the resulting sound quality in your vehicle, including:

• amp classification
• speaker setup
• power rating
• frequency filters
• bass boost

Big Bang for Your Buck

Amplifiers are categorized according to their classification, number of channels, and power rating in watts. The class of the device refers to its circuit design. There are Class A, B, A/B, and Class D amplifiers, with the last two being the ones most commonly used in car stereo applications. Class A units feature a simple design, the highest linearity over other types, and produce the best sound quality. However, they are inefficient because current flows through their output transistors all the time.

Energy Savings = Distortion

Class B amplifiers are the most efficient because the output transistors pass current only when there is an audio signal, but they produce a lot of distortion. The A/B type is a combination of the Class A and B amps, with a small amount of current flowing all the time, even when there is no audio signal, which results in greater efficiency with almost no distortion. Such devices are one of the most commonly used types of automotive audio amplifier design. In Class D units, the transistors are switched on and off. These amps are more efficient than their A/B counterparts but produce more distortion. However, this distortion can be removed with a filter.

Understanding Channels

Before choosing an amplifier for your audio system, you need to decide how you intend to use it and how many channels it should have. Usually, the number of channels should match the number of speakers in your system. As the name suggests, a mono amp is designed for one speaker, usually a subwoofer, however, two subwoofers can be connected to such a device. 2-channel units are for two speaker systems, and so on. For example, 5-channel amplifiers are for 4 speakers and a subwoofer. Some equipment can have a “bridged” structure, meaning that 2 channels can be combined into one for more power. A 4-channel amp could power two speakers and then have the remaining channels bridged to hook up a subwoofer.

Root Mean Square

The amplifier’s power rating should coincide with your speakers’ RMS or continuous power rating. If this rating is given in a range, go with the higher number. This is especially important to get maximum performance from aftermarket speakers. For best sound quality the amplifier should deliver at least 75% of the speaker’s RMS rating, and the average setup can handle up to 150% of this rating without any problems. It’s always better to overpower speakers rather than under power them. The distortion caused when you make the most of a weak amp is more likely to harm a speaker than too much power. If you’re building a system from scratch, a small car won’t need as much oomph as a larger vehicle.

It’s All About the Bass

In addition to the mentioned above, there are other features that you’ll commonly see in amplifier listings, like filters and bass boost. There are high pass and low pass filters. A high pass filter removes low frequencies so the amp is only boosting the high frequencies sent to small speakers for high notes, while the low pass filter takes out the high frequencies, such as would be common when powering a subwoofer. Variable filters allow you to select the frequency to be filtered. Variable bass boost control allows you to increase the bass level to tailor the sound quality. Whatever amplifier you need, on our website you'll surely find the right product for your audio system.