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How Many Watts Is Good For A Car Stereo? Let’s Talk RMS!

Last Updated on: August 30, 2022

Car stereos are an essential part of the driving experience for many people. When upgrading your stock model with an aftermarket car stereo, knowing the car stereo wattage will help you decide the best head unit for your car.

Just so you know…

Manufacturers typically highlight the peak wattage on their equipment, which does not indicate the performance of your car stereo system. 

So, if you want to know how wattage affects the sound quality of your stereo, you’ll need to consider RMS wattage. Let’s delve into it a little deeper below. 

Understanding Peak Power vs RMS Wattage

RMS & PPO
RMS & PPO

Power ratings can confuse some people, especially if they are unfamiliar with audio equipment. The main thing to know is that car speaker wattage refers to how much power the car speakers can receive from the amplifier. 

On the other hand, amplifiers generate power, and the wattage rating typically indicates how much power an amp can output to the speakers. 

With that out of the way, let’s look at some of the power ratings found on audio equipment.

Peak Power Output

The peak wattage is the power metric that most people know as it is touted most by audio equipment manufacturers.

Peak wattage rating measures the maximum power your sound equipment can handle over a short period. 

For example, your car speaker may have a peak power rating of 60 watts. That means the speaker can allow occasional bursts of up to 60 watts of power. 

However, peak power does not reflect the speaker’s performance under normal conditions. For that, one needs to look at the real world RMS rating.  

Root Mean Square

Root mean square, or RMS for short, is the amount of power a piece of equipment can handle in normal usage. It is a more realistic metric to use for measuring the performance of your car audio system. 

RMS wattage value is typically lower, so manufacturers like to highlight the peak power value on their equipment instead.

Following the example above, your 60 watts speaker may have a continuous power rating of 30 watts. Therefore, the speaker will run with 30 watts in normal usage but can withstand occasional power bursts of up to 60 watts.

How Many Watts Is Good for a Factory Car Stereo? 

Car Stereo
Car Stereo

Most stock car stereos typically produce between 10 -15 watts per channel from the built-in amplifier chip. Generally, this RMS power is too low to enjoy your music above the ambient noise of the car and external environment.

An aftermarket car stereo can have between 20- 28 RMS watts per channel, which delivers clean sound at a high volume in comparison.

Therefore, most car owners prefer upgrading their standard factory car stereos with aftermarket components like subwoofers and external amplifiers to improve power handling.

While more RMS output means more power and better audio, one also needs to consider the speaker’s sensitivity rating and other factors responsible for excellent wattage.

1. Speaker Sensitivity

The speaker sensitivity (decibels) is the sound pressure exerted by the speaker over the power input at a given distance. 

A typical car stereo with a decibel rating of 85 dB means it delivers 85 decibels of sound at one watt of power per meter.

To add the loudness capacity, you would need more car stereo wattage. Generally, the human ear will notice a difference in loudness when you increase the sound pressure level by three decibels.  

For example, a 20 watts aftermarket car stereo is louder than a 10-watt factory stereo. However, while the aftermarket model is double the wattage, it does not mean it is twice as loud. 

To put it simply, if you increase the sound level by 10 dB, it would be twice as loud. However, if you double the amplifier wattage, it would only increase the loudness by 3 dB. 

 So, you would need ten times the wattage to achieve a 10dB increment. Therefore, you will need to consider installing a suitable external amplifier to give your system more power.

2. Amplifiers

While factory car stereos have built-in amps, installing an aftermarket amp will amplify the sound level and improve the audio experience.

Ideally, if your car speakers put out 92 dB and above, but your stereo is at 50 watts ( 10 -15 RMS watts) per channel, you would still not enjoy loud music. 

So using our example above, to double the loudness of your sound by 10 dB, you may want to consider installing an aftermarket amp with 60 – 80 RMS watts. 

However, the amplifier’s power output and the speaker wattage should match for synergy and prevent damaging your sound system. Therefore, we also need to consider the impedance rating of these components.

3. Impedance

Impedance is the electric resistance produced by a piece of equipment, measured in ohms. Speaker impedance is the voice coil resistance to the electric current input from the amplifier. 

The typical impedance ratings for car sound systems are two and four ohms. While you can find 1-ohm sub-woofers in the market, it is uncommon to find components above four ohms for car stereos due to the low 12V. 

When designing your car sound system, it is necessary to match your speaker’s impedance with the amplifier. Low impedance components like subwoofers require more power to operate, while high impedance speakers, like tweeters, use less current.

For example, a 100W 4-ohm speaker requires 100 watts from a 4-ohm amp. Using the same amp with a 2-ohm speaker overloads it as the speaker will be drawing in 200 watts. 

However, if the 2-ohm speakers have half of the amplifier’s RMS power, they will draw the same current as the 4-ohm speaker.


Frequently Asked Questions

Do more watts mean better sound quality?

More power in your audio system enables you to listen to loud music with less distortion. However, you should know the difference between peak wattage and RMS power, which determines the sound quality.

Additionally, other factors such as impedance and sensitivity of the car speakers play a key role in improving the audio quality of your system. If you are upgrading your factory car stereo, then you’ll need to know how many watts each component has to achieve the best results.

How many watts are factory car speakers?

Most standard factory stereos feature a built-in amp chip rated 10 – 15 watts of RMS power per channel. In contrast, aftermarket car stereos can have between 20 -28 watts of RMS power, which delivers better audio quality, especially at high volume.

To improve the sound quality of a low-powered factory car stereo, you can opt to upgrade your stock speakers with high sensitivity car speakers with 90 decibels and above.

On the other hand, you can consider adding an external amp to your stereo to play loud music without distortion.


Conclusion

The standard factory car stereo feature 10 – 15 watts per channel on average, which, for most people, is inadequate for their audio requirements. However, if you know how many watts is good for a car stereo system, you can replace your factory system with a better car stereo headset.

Alternatively, you can install an external amplifier with better speakers to boost the power handling of your stereo. I would recommend both options.

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