When searching for car speakers, one of the parameters you will notice is the impedance of either 2 ohms or 4 ohms.
But, what is the difference between 2 ohm and 4 ohm speakers?
The main difference between 2 ohm and 4 ohm car speakers is the amount of energy they draw from the amplifier. 2 ohm speakers require a more powerful amplifier than 4 ohm speakers. Thanks to this, 2 ohm speakers play louder than 4 ohm speakers but the sounds they produce are of lower quality.
In the article below, you will find more information about how to choose the right impedance for your car speakers, and how to match them with amplifiers.
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What Is Impedance in Car Speakers?
Impedance is the resistance of the voice coil wire against the flowing current from the amplifier. The vast majority of car speakers are manufactured in either 2 or 4-ohm impedance.
Although you can find exceptions, like Kicker CompRT 10″ subwoofer with a 1-ohm impedance, it will be difficult to find car speakers or amplifiers over 4 ohms, because of the low 12V voltage.
Kicker CompRT 10″ is a great choice when you are looking for strong “kicks” and do not have much room for a deep woofer. It is available on Amazon and if you want to try its real power, click this link and check the latest price.
When you see 4 ohms on the speaker, it does not mean its impedance is 4 ohms constant. In reality, this value constantly changes, because it depends directly on the speaker’s current frequency and can be as low as 0,3 ohm, or as high as 30 ohms.
The impedance will be higher for the lower frequencies, and for higher will be lower. This is one of the reasons why voice coils in tweeters are so little.
To summarize, the 4-ohm value placed on the speaker is the “nominal impedance” representing the average of all impedances the speaker has been designed to work with.
Because speaker impedance is related to wattage, the higher the impedance, the lower current will flow from the amplifier. That means an amplifier that works with higher impedance speakers will be less loaded.
For example, a 100W 4-ohm speaker will draw a 100W from the 4-ohm amp, while a 2-ohm speaker will force the same amp to produce 200W. As a result, the amplifier can be overloaded what can lead to overheating the amplifier or its further damages.
If you would like to know about overheating amplifiers, I wrote a short article about it, so check it out.
Low impedance speakers can force amplifiers to work too hard.
As a result, its fuse can blow, or the protection circuit will be activated, and the amp will be shut down to protect other parts of the audio system. In extreme cases, an overloaded amplifier can blow.
When we design the car audio system, we have to match the speakers’ impedance with amplifiers. But, because of many different installation types in the car audio, it is not always possible to have all components with the same 2 or 4 ohms.
Further down in this article, we will go through different impedance combinations.
Why Do Car Speakers Have Different Ohms?
We often wonder why some speakers have 4 ohms and the other 2 ohms. This depends primarily on the speakers’ requirements in terms of their quality of produced sounds and efficiency.
The only constant in the car speakers is voltage, while power and impedance depend on each other. In the case of coaxial speakers or a component system, the car amplifier, when connected to the crossover, recognizes the impedances of the whole set and not individual speakers, which can be different in reality.
4 Ohm speakers will demand less current from the amplifier than a similar 2-ohm speaker. At the same time, higher impedance means less distortion in the amp and more stable current flow, however more and more modern amplifiers can remain stable while delivering large amounts of power to the speakers with low impedance.
The major advantage of having less impedance is more power coming from the amplifier, which is important inside a noisy car. The road or wind noise has to be compensated by the better speakers’ performance, and this is where low impedance speakers will do better.
Can I Use 2 Ohm Amp With 4 Ohm Speakers or Vice Versa?
In most cases, we should aim for speakers’ impedance to match amplifiers, so when you have a 4-ohm amp, buy all speakers also 4 ohms. But when you have designed a sound system with correctly calculated all resistance, these values can be different.
You can also connect 2-ohm speakers to a 4-ohm amplifier, but in order not to damage it, remember that 2-ohm speakers should have half of the amplifier’s RMS power. Otherwise, the amplifier will be overloaded with different impedance, and transistors can even blow.
For example, when you have a 2x120W amplifier working at 4 ohms, you can pair it with either 120W 4 ohm speakers, or 2x60W 2 ohm speakers. Both sets will drive the same current from the amplifier, but the 4-ohm speakers will make a better sound.
Can I MIX 2 Ohm and 4 Ohm Speakers?
Most cars have installed two pairs of speakers in front and at the back, but do they have the same impedance? The vast majority, yes.
When we install 4-ohm speakers, they can be from a different brand, have different sizes or power, and also impedance can be different. However, this is rare.
When you wire 4-ohm front speakers and 2 ohm rear speakers to the 4 channel amplifier, you have to be careful with the power level of these 2-ohm speakers to not overload transistors and not damage the amplifier.
Another point to consider is the volume level of these speakers. As we already said, 2-ohm speakers can play louder with the same power, so in our example, when mixing 4 ohm and 2-ohm speakers, you can hear too much from the back of the car.
If you want to have a different impedance in the front and the back of the car and one amplifier, make sure 4-ohm speakers have twice as much power as 2 ohms. In this case, you will ensure leveling out amplifier output to all channels.
It is much easier to manage different speakers’ impedance, when your amplifier is designed to support 2 and 4 ohms on different channels, then you have to match the power of speakers to the max amplifier output, and you will be okay.
Nevertheless, the best and safest way is to use all speakers in the car with the same (either) impedance. Your system will be stable, and you will not have to make too many adjustments to make it work.
How to Connect a 2 Ohm vs 4 Ohm Subwoofer?
Subwoofers are different, and when you see a typical car audio system, the speaker with a different (usually lower) impedance will be the subwoofer.
They can work with 4, 2, or even 1 ohm in some cases and also can have either one or two voice coils, so the number of variations in subwoofer connections is much higher than for the typical car speakers.
The most significant factor in the subwoofers is their ability to create loud and strong bass, and that requires a lot of power. The more powerful the subwoofer, the lower impedance it will have.
A 2-ohm subwoofer will play louder than 4 ohms with the same power, but how strong bass will be generated also depends on the enclosure type.
If you want to make a really loud bass in your car, buy a 2-ohm subwoofer and a large power station to supply enough current. However, with the impedance reduction, you also reduce the quality of the bass, so you have to prioritize either music quality or loudness.
A similar approach is for subwoofers with dual voice coils. Although you physically have one speaker, the connection with the amplifier is the same as for the two independent woofers. Depending on how you will connect it, you will determine the overall resistance of the dual voice coil subwoofer.
When you connect both 2-ohm voice coils in series, the impedance will double, and it will become one 4 ohm speaker, or when you will wire them in parallel, the impedance will be divided and will be 1 ohm.
To decide about subwoofer impedance, you have to decide which bass quality you want to achieve, and this is the starting point. If you wish to hear hi-end perfect kicks but with a moderate volume, go for a 4-ohm subwoofer.
By doing so, you can still connect several subwoofers in the car and further increase the quality of the lowest sounds.
On the other hand, if you want to create thunders in your car and make it shaking with every kick, you should consider a 2-ohm subwoofer or even 1-ohm. And for even more bass, you can connect multi subwoofers in parallel to reduce impedance and make them play even louder, but this approach is right when the decibels are the only priority.
Can I Replace 2 Ohm Speakers With 4 Ohm Speakers?
Generally, you should be fine when replacing 2-ohm speakers with 4-ohm speakers. But keep in mind that 2ohm and 4ohm speakers have different power requirements.
4-ohm car speakers usually have a lower wattage rating than 2ohm speakers because they’re less efficient at converting electricity into sound.
When replacing speakers, we are not always checking impedance carefully, and new ones can be different from old speakers.
This simple overlooking can cause damage when replacing 2-ohm speakers with 4 ohms (or vice versa) that have the same power because they can overload the amplifier. If the amp was not designed to work with lower impedance, such change could cause the amplifier to overheat, or other damages to the car audio system.
In the vice versa scenario, when we will increase the speakers’ impedance, all audible sounds will become quieter, and although you will not damage the system, this change will not make you happy.
Can I Use Car Radio to Power 2 Ohm and 4 Ohm Speakers?
You can use your car radio to power 2 ohm and 4-ohm speakers. But you should know that playing 2ohm speakers on a 4ohm amp will eat up more power than usual because 2 Ohm speakers require more power to play at the same volume as the 4-ohm speakers.