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Stereo Amplifiers: What Are They & How Do They Work?

Updated: Oct 26, 2021


A complete guide to stereo amplification


When we perform professional car stereo installation in New Orleans, we’re often asked whether an amplifier is necessary. In fact, all car stereos require an amplifier, even if it’s built into the stereo itself.


In this guide, we’ll outline what amp systems do for home stereos and car audio in New Orleans, and why amps are essential to any good audio setup.


What do amplifiers do?


An amplifier takes a small electrical signal and enlarges it.


There are two main types of amplifiers to consider, the pre-amplifier and the power amplifier. A pre-amp amplifies a signal enough for it to be acceptable for a power amplifier. Power amplifiers need to perform a bigger job, amplifying a small signal enough for it to power car speakers or loudspeakers.


The fundamental working principles of amplifiers are very straightforward, despite their appearance as complex, enigmatic boxes. An amplifier takes a signal from a source (a mobile device, a turntable, a car stereo, a CD player, etc.) and converts it into a larger version of the original signal.


Input from the sound source, an output to the speakers, and a power supply are the three fundamental connections of an amplifier. In the US, the power required for a power amplifier in the home comes from a 110-volt wall socket.


How do amplifiers work?


Whether in a car or a home theater system, amplifiers generally work in the same way. They take the power from a power source (like your 110-volt wall socket) and convert it from AC (alternating current) to DC (direct current). DC is the same type of power you’ll find in batteries, with electrons flowing in a single direction. AC has current flowing in two directions.


Now we have power, it’s sent to a transistor, also known as a variable resistor. This works somewhat like a valve, varying the amount of current that flows through the system based on the source input signal.


When the input source signal is bigger, the transistor lowers its resistance so more current flows. More current means more amplification. The input signal frequency also affects how quickly the variable resistor opens and closes. A 100Hz tone will open and close the transistor 100 times each second, whereas a 1000Hz tone will result in the transistor being opened and closed 1000 times each second.


Do you need an amplifier?


People ask whether you need an amplifier for a car stereo system because amps are generally out of sight, out of mind. But every single car audio system has an amplifier. If you don’t have an aftermarket car audio system, the amplifier for your car’s audio is most likely built right into the head unit.


But not so fast! These built-in amplifiers are typically not very good. Amplifiers built into head units lack power, which is one reason factory car stereos can distort badly when turned up to the max. If you plan on changing your car speakers, you’ll need an amplifier that’s able to send enough power to those speakers. If you want to add some real oomph with a subwoofer, you’ll undoubtedly need an amplifier.


Finding the right amplifier


Your head unit with a built-in amp may not have preamp outputs. In that case, you won’t be able to use it with another amp so you’d need to buy a new head unit (or call us for information on speaker-to-line level converters, you might be able to continue to use your factory unit).


Amps often have additional features that make them useful in car and home audio setups. Amplifiers are often multi-channel. A four-channel amp can power four speakers, for example. Some amps have space for more channels, so you can include additional subwoofers and tweeters, or you can use separate mono amps for those lanes.


Many amps include equalization, low-pass filters, and high-pass filters, so you can use them with a wide range of speakers. For home and car audio, getting the right balance of speakers with the current frequency response being sent to each is an art, and being able to adjust the settings at the touch of a button makes it a lot easier to get the sound you want.


Ultimately, unless you want to stick with a bland, low volume, flat sound in your vehicle, you’ll want an amplifier. And amps have so much utility that you’ll be able to continue to use the same great amplifier in multiple projects.


Get professional car stereo installation near you


For the best possible sound, you’ll want to have the pros at Mobile One install your new car stereo system and amplifier.


We guarantee our work, so we know our customers drive away satisfied, listening to their favorite music with the crispness and clarity only available from a quality stereo system.


Contact us to learn more about car stereo installation options in our New Orleans car audio shop.


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