How to choose an amplifier for car speakers

Amplifiers are the control center of a car audio system. The Amplifier increases the power of the audio signal, which it then sends to the speakers. So, it would be great if you could ‘feel the music while driving. 

Choosing the suitable Amplifier is not an easy task, considering the different aspects that need to be considered before making the final buy.  This blog will  guide you to choosing an amplifier for car speakers that will help you make the right decision.

How to choose an amplifier for car speakers?

When choosing a suitable Amplifier, several aspects of the car audio system need to be considered. These are:

Car’s Battery/Alternator System Peak power requirements of speakers Type of Speakers RMS requirements.

The first thing you should do is determine the peak power requirement of your speakers. It can be done by multiplying their RMS power by 4. So if your speakers have an RMS rating of 40 watts, they will need 160 watts of peak power. However, this number is not required to be the same as the one given on the Amplifier.

How does an amplifier work?

The Amplifier boosts (increases) the signal that it receives and then sends the signal to the speakers. The Amplifier has two units inside, called the ‘gain’ and ‘power supply’.

The gain control allows us to increase or decrease an audio signal, making it louder or quieter so that you can hear it clearly while driving. This process happens in decibels; units used to measure sound levels. A decrease in 10 dB means the sound will be 1/10th as loud.

In terms of power supply, it’s a unit that contains a circuit board and a transformer. The circuit board controls the flow of electricity to the speakers and acts as a protective unit for all components inside. The transformer is needed because most cars run on 12 volts, whereas the Amplifier requires a higher voltage to work. Hence, the transformer takes care of this too.

Choosing an Amplifier

There are three types of amplifiers – Mono, 2 Channel and 4 Channel. A mono amplifier has only one gain control for all speakers connected to it, which means that they have equal sound levels at all times. 

A 2 channel amplifier has a gain control for front speakers and one for rear speakers so that each can be adjusted separately. A 4 channel amplifier is the same as a two-channel, but it also has additional gain control for an external subwoofer unit.

How to choose an amplifier for car speakers?

Choosing an amplifier can be a bit confusing, considering many types of amps are available in the market. A 4 channel amp is better than a two-channel one because it drives the speakers to greater sound levels. Also, an amplifier with at least 80 watts per channel (4 channels) should be enough for most car audio systems.

Remember that the number of watts that the Amplifier claims to power your speakers is the RMS rating, not peak power. Peak power is used as a reference point as it provides an accurate measurement of how much more power you can get from the amp.


An amplifier is an essential part of a car audio system, as it drives the speakers to give you precise sound levels. It’s advisable to choose an amplifier with 80 watts per channel or more so that your speakers can be driven to greater sound levels.

A 4 channel amp is better than a two or mono one because it includes extra channels for more speakers, allowing you to have a more powerful audio system.



How do I know what size amp I need for my subs?

It would help if you considered the ohm’s law formula to determine what size amp you need for your subs. For 2 voice coil subs, simply calculate R(total resistance) = R(sub1) + R(sub2). 

The subwoofer’s total resistance will help us determine how much power can be drawn by it based on its impedance rating.

For multiple voice coil subs, you will need to calculate the total resistance using the ohm’s law formula (R=V/I) so that you can figure out how much power is being drawn. You can find out which voice coil each subwoofer has by referring to the owner’s manual of your car audio system.

How does a mono amp give me a more powerful sound?

A mono amp has only one gain control for all speakers connected to it, which means that they have equal sound levels at all times. It enables you to utilize the full potential of your speakers without requiring other controls. However, it’s only suitable for smaller speakers as larger ones need multiple channels to produce more sound.

What is the difference between RMS and Peak Power?

RMS stands for Root Mean Square, a unit of measuring power in an electrical system. It only represents the average energy that can be continuously delivered to a speaker. It is different from peak power as this only provides an accurate measurement of how much more power you can get from the amp.

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