We live in a world surrounded by speakers. There are home theater speakers, car speakers, not to mention speakers on your phones, televisions, and even doorbells. You might be wondering if all of these speakers are the same and if they are interchangeable. But even though speakers all serve the same general purpose, the environment in which you use them differs significantly.
While car and home speaker setups generally include the same equipment such as amplifiers, subwoofers, tweeters, and so forth, the components differ significantly. The most significant differences between car and home speakers are in the impedance, design, and aesthetic.
Some other key differences between car and home speakers are:
The reasons behind these differences are not always obvious. It can be helpful to take a closer look at each to understand why they exist.
The most significant difference between car speaker and home theater speakers is the impedance rating. The impedance of the speaker refers to the electrical load a speaker places on the amplifier. More specifically, it is the measure of resistance the speaker produces against the current from the amplifier.
When you measure resistance or impedance, you measure it in 'ohms.'’ The most common analogy to explain impedance is to compare it to running water. The more resistance - or the higher the ohms - the less water - or electrical current - is able to pass through. If the resistance is too high, the current will build up, and the amplifier will fry out.
Check out our article that explains all of the specs for home theater speakers!
Car speakers are likely to have 4 ohms of impedance, whereas your home theater speakers will have 8 ohms. It is extremely rare for car speakers to have more than 4 ohms of resistance. There are a couple of reasons for this.
A car battery typically produces between 12 and 14 volts, compared to a home outlet which delivers around 110 volts. Because of this, the amplifier in your car is usually going to be low-voltage and high-amperage. As you might expect, the amplifiers in your home will likely be the exact opposite - low-amperage and high-voltage.
Since your car has a lower voltage, the speakers will need less resistance to get the amount of power necessary. An amplifier that can deliver 50 watts of power at 8 ohms will be able to deliver 75 or 100 watts of power at 4 ohms because the current is less restricted. Because of this, most companies design car amplifiers explicitly for 4-ohm speakers.
As you might expect, the opposite reasoning is true of your home speakers. Since your home outlets offer a much higher voltage, it needs a smaller percentage of that to be passed along to the speaker and is likely to have a higher impedance rating. There are 4-ohm home theater speakers out there, but it is rare for car speakers to have a higher impedance than 4 ohms.
The most obvious difference between car subwoofers and the ones used for home theaters is the size. Not only does the cabinet size of the speaker make room for a more powerful subwoofer, but it is also necessary if a subwoofer is going to be active.
An active subwoofer is a subwoofer that has an internal amplifier built in. It does not need to rely on the stereo amplifier for power, and therefore has a lot of flexibility and can be a lot more powerful.
Active subwoofers, since they have their own amplifier, also need their own power source. The easiest way to tell if your home theater subwoofer is active is by determining if it needs to be plugged into a power outlet. Passive subwoofers only need to be plugged into the amp. Active subwoofers require a wall outlet.
As you might imagine, the subwoofer in your car is going to be passive - unless you really put the effort forth for something active. When you can hear the bass coming from a passing car 3 blocks away, you can be reasonably sure they’ve installed an active subwoofer.
The size difference also creates a difference in efficiency between the two subwoofers. The subwoofer in your home is designed to move a lot of air and produce sound for a large area. The subwoofer in your car is designed to fill the vehicle cabin with sound, which is a much smaller space.
Manufacturers design Car speakers for an entirely different environment than home speakers - in more ways than one. The inside of your car goes through a lot - temperature changes, extreme freezing, high humidity, the heat of the sun.
Your home theater speakers will obviously live in your home. Since your home is likely mild and climate controlled, they don’t have to be as rugged. This allows for more flexibility in aesthetic design and other features. These design choices won’t put the speaker at risk of failure due to exposure to the elements
When you look at car speakers and home speakers you will notice they are distinctly different. If you were to remove the home speakers from their cabinets however, they might look somewhat similar.
Car speakers are usually, one way or another, built directly into the car itself. This means that there is no cabinet for car speakers, just the bare features with a grill or cover. There are of course exceptions to this, mainly when building powerful speaker systems into the trunk of a car.
Car speakers and home speakers are functionally the same, with specific design differences to suit them for different uses.
There are very few reasons you would ever want to use one in place of the other, but it is possible if you were truly inclined!
The best speaker in any scenario depends on the amplifier you are connecting it to.
4-ohm speakers have 4 ohms of resistance. 8-ohm speakers have 8 ohms of resistance.
This means that the power current that the amplifier passes on can move more freely through a 4-ohm speaker than an 8-ohm speaker. This measure is called 'impedance.'
Lower impedance means a higher current at a given voltage. 4 Ohms speakers need more power from an amplifier than 8 Ohms speaker for the same volume. When an amplifier is designed for 8-ohm speakers, then 4-ohm speakers might result in cranking the volume all the way up to get decent sound.
You can double up and connect two 4-ohm speakers to a single 8-ohm terminal to create 8-ohms of resistance. This will not necessarily give you better results than an 8-ohm speaker.
You could - in theory- wire a home audio subwoofer into a car. The process is difficult, and not recommended unless you are incredibly knowledgeable about electronics and wiring.
Whether or not the process would actually work would depend on the capabilities of the amplifier and stereo system in your car, and the exact subwoofer you are using. Attempting to wire an active home subwoofer into your cars stereo system, for example, is much more dangerous.
Because active subwoofers require their own power source, you would need to find a way to connect the subwoofer to the battery. Connecting it directly to any source output on the amplifier alone would not be enough.
I highly recommend that you choose a subwoofer designed for a vehicle instead of attempting to modify a home subwoofer. They are designed to be compatible and look great in your car. This active subwoofer from Rockville is a great, low profile example.
The reasoning and consequences of these differences are nuanced, so you should take a closer look at each to understand why they exist.