Can you use car speakers in a home theater? (Yes, here’s how)

Car speakers can be used in a home theater. However, car speakers run on lower impedances than conventional HT speakers. The impedance will need to be matched with that of your AV receiver/integrated amp/power amp. Car speakers also need enclosures to house them for use in a home theater.

This should work, in theory, but due to the different design specifications, car speakers may not reproduce sound to match the quality of home theater speakers in this setting.

With that said, I going to guide you on how you can convert can speakers for use in a home theater. But before we get into that, let us look at the differences between car and home theater speakers.

Differences between home theater and car speakers

There are 2 key differences between car speakers and home theater speakers namely;

  • Design
  • Impedance rating

There is also one major similarity between these speakers, they are designed to reproduce sound. All speakers reproduce sound and but in different environments. Functionality remains the same at the basic level.

A home theater will not have the same cabin gain effect as your vehicle. This means that speakers that sound incredible in your car may not always work as well in a large space such as your HT. Car speakers are designed with account of your sitting position.

Design

Car speakers are designed to fill smaller spaces and for harsher environments such as rapid changes between cold and hot temperatures, moisture when the car is being washed, humidity, and so on. This is why you will often find car speaker cones made of polypropylene (PP) resin sheet material. PP cone speakers are great for harsh environments as they have low distortion and do not absorb moisture.

On the other hand, home theaters are more controlled and HT speakers are, therefore, not built for such rugged conditions. Car speakers are designed and build with materials that can withstand harsher conditions without damage.

It is also common for car speakers to be multiway, either 2 way or 3 way. In the case of a 2-way speaker, the speaker has both a woofer and a tweeter (s) as one, splitting the audio frequencies into 2. 3-way speakers have 3 drivers with an extra mid-range driver (super tweeter) where the audio frequencies are split into 3.

Multiway speakers are great for cars but are not the most ideal for home theater setups. Home theater speakers are split and have better coaxial units. However, you will also find costlier car speakers that are component split but these speakers are generally made to service the smaller car spaces.

And because these speakers are designed for close listening fields, when used in a home theater, the comb filtering effect is common. Comb filtering effect occurs at the crossover points when audio signals are amplified or delayed causing interference.

Car speakers are also designed to look appealing with colorful, chrome, techy, or flashy cosmetics. This does not affect the sound characteristics on an audible level but can have a slight effect on the notes.

Impedance

Impedance in the speaker is the resistance to current flow and is measured in ohms.

Home theater speakers have a higher impedance usually 6 or 8 ohms while car speakers are made to handle smaller loads usually about 4 ohms.

This is because a car’s battery can output between 12 and 14 volts while a home power outlet can output about 110 volts. Therefore, a car’s amp should be able to take in the lower voltage and output a higher amperage hence lower speaker resistance is required.

A home theater’s amp, on the other hand, should be able to take in the higher voltage and output a lower amperage. The speakers should thus have a higher resistance to the current flow.

The speakers’ impedance needs to match with that of the amplifier. This is why car speakers are rated at 4 ohms to match with the impedance of the amplifier with a lower power intake but less resistance to current flow.

An amplifier that would output 60 watts of power at 8 ohms in a home theater, outputs 80 to 120 watts on a 4-ohm load. This is enough watts to power the car speakers for an immersive sound.

With that in mind, we can now get into how you can turn car speakers into home speakers. 

How to turn car speakers into home speakers

One of the biggest advantages of car speakers and electronic equipment is that they are fairly inexpensive when compared to home equipment of the same quality.

With a reasonably standard budget, you can have yourself a pretty good sounding system. However, this cannot match the sound quality of a costly hi-fi system.

Granted, turning a car system into a home system will also not be as easy.

Here is how to build fairly inexpensive music or movie system;

  • Get the right materials for the build.
  • Match the impedance of your car speakers to your home receiver, amp, or integrated amp.
  • Get a dedicated amp for the subs and a 12-volt DC power supply for the sub-woofer or subwoofer amp.
  • Wire the system.
  • Buy or build the right cabinet/enclosure for the speakers.

1.      Get the right materials for the build

You are going to need;

  • Car speakers.
  • A car subwoofer.
  • An enclosure for the speakers and the subwoofer.
  • A DC power supply unit (PSU).
  • Insulation tape and wire strippers.
  • Speaker wire. This can be 12-gauge or 16-gauge for the speakers and 12 or 14-gauge for the sub but it will depend on the manufacturer’s recommendation.
  • A car amplifier and RCA cables for the amp.

2.      Match the impedance

As I mentioned earlier, you will need to match the impedance of the speakers to that of your home receiver, integrated, or amplifier.

Connecting the speakers without matching the impedance will damage your gear. One way you can combat this is by using a car stereo but this will be great for listening to music and will not do much for movies. With a car stereo, you may also lack an HDMI connection.

The second method to match impedance is connecting the speakers in series. So, if your receiver or amplifier has an impedance rating of 8 ohms, wiring two 4 ohms speakers in series will give you 8 ohms. You can do this by connecting the positive terminal on one speaker to the positive terminal on the other using the appropriate wire. Do the same for the negative terminals.

However, hooking up speakers in series may not always yield the highest SPL and sound quality. Speakers wired in series consume more power, stretching the amp hence the reason for this.

Some receivers and integrated amps may have an impedance switch and so remember to check that out. The switch allows you to change between 4 and 8 ohms. This is because there are also home theater speakers that have an impedance of 4 ohms.

However, when using a receiver, integrated, or amplifier that you already had, you will need to make sure that they are powerful enough for the speakers. If your speaker is rated at 70 watts, your equipment should have a higher power rating than the speakers for each respective channel, in this case, 70+ watts per channel.

3.      Get a car amplifier

If you are using a car stereo, you will also need an amplifier to drive the speakers and the subwoofer.

This will also apply in cases where you can’t perfectly match the impedance of the speakers to that of your AVR without significantly affecting the sound quality. And because most car subs are passive, you will also need an amplifier that can drive them.

The amplifier needs to be powerful enough for the speakers at a lower impedance. Pay attention to the power rating of the equipment. I would recommend getting a class D amp for the sub and a class AB amplifier for the mids and highs. This is because class AB amps have better sound characteristics while class D amps have better power efficiency required to run the subs.

You will also need a power inverter for the amplifier and the stereo such as a 12 V computer power supply unit (PSU). An LED power supply can also work for this setup. As mentioned above, home outlets output about 110 volts when compared to 12 volts from the car’s battery. The power supply should output a high enough current continuously for the amplifier.

To know how much power the amp will need, multiply the power consumption by 1.5 for class AB amps and 1.2 for class D amps. Therefore, a 600W AB amp will draw about 900W+ and a 600W class D amp will draw about 720W+ of power.  Divide the amount of power consumed by 12 V and you get around 75 amperes for the class AB amp and around 60 amperes for the class D amp. This will give you an idea of how much current the amp will draw from the power supply.

Remember that power is equal to current times voltage (I * V).

*Do not use a car battery in your home for safety purposes.*

4.      Wire the system

Speaker and sub wiring

If your receiver/amp meets the requirements to run the speakers, you can connect the car speakers to the receiver in respective channels ensuring the polarity is matched (positive to positive and negative to negative). You may need 2 speakers for the front (left and right) and 2 back (left and right) speakers.

Connect the car subwoofer to the car amplifier and then connect the amp to your receiver/pre/pro. The amp then needs to be connected to the power inverter.

Use the wire gauge specified by the speakers’ manufacturer.

Connecting a car stereo

If you are using a car stereo as your audio processor, strip the red (switch ignition) and yellow (battery lead) wires, solder them and connect them to the yellow wire on your power inverter. Strip the black wire and connect it to the black wire on your power inverter for the ground. Test to see if the stereo turns on then disconnect.

Then connect your speakers to the car stereo with the white and gray stereo wires going to the front left and right speaker and the green and purple going to the back left and right speakers. Match the polarity by connecting the speakers’ negative terminal to the stereo’s wire with a stripe and the positive terminal is a solid color.

Make sure that you properly insulate your wire after connecting them.

Connecting a car amplifier to a receiver or preamp

Your receiver should have a preout section for the sub out, front and rear channels for this to work. The sub out will go to the subwoofer amplifier, the front L and R pre-outs to the front speakers, and the surround L and R to the rear speakers. Plug in your RCA cable to the respective ports on the amp and receiver’s pre-outs.

You may also need to tell your receiver/preamp that you will be using the preout section but some should automatically recognize it.

If your receiver or preamp does not have a preout section, use speaker wire to RCA adapter cables to connect to the amplifier. You will also need to match the gain on the amplifier to that of the receiver’s output.

Once you connect the amplifier to the preamp or receiver, connect your speakers and sub to the amp.

Connecting the amplifier to the Power supply unit

On the PSU, find and mark a green and black wire that are next to each other. Bridge these wires and add a piece of insulation tape to prevent the bridge from undone.

Find the yellow and black wires, strip the 2 wires then connect the black wire to the ground terminal and the yellow wire to the battery terminal. Then find yourself a bridge wire, strip the ends and connect the battery terminal (end of the yellow wire) and connect it to the power connection terminal.

It is important to make sure that you properly ground your amplifier for a noise-free sound. Also, do not run the power cables close to the speaker wires.

5.      Get or build an enclosure for the speakers and sub

There are 3 types of enclosure that you can use with your car speaker;

  • Sealed enclosure/infinite baffle enclosure/acoustic suspension enclosure– With this type of speaker cabinet the rear soundwaves will not cancel out the front soundwaves. This is the best but least efficient type of enclosure that you can buy or build for your car speakers for home use. They have great audio reproduction but the rear soundwaves are usually wasted.
  • Aperiodic/poorly sealed enclosure– Aperiodic enclosures are leaky speaker cabinets sealed ports. These ports are sealed with damping material to allow venting inside the cabinet. For an enclosure with a volume of below 0.05M³, there should be one port, for a volume of between 0.05M³ to 0.08, two ports and 3 ports for a volume of above 0.08M³.
  • Bipole enclosures– Bipole enclosure will work best with the rear surround car speakers as they will house 2 speakers that face away from each other. This will allow for better sound direction and reflection. The biggest drawback with these enclosures is that phase cues and timing is lost due to the numerous sound reflections in the room.

Note: 0.05 cubic meters are equal to 50,000 cubic centimeters which are equal to 5 liters. This means that 1 cubic meter is equal to 1,000,000 cubic centimeters which is equal to 1000 liters. Use this when you are doing your conversion from whichever value you find easier to use or use online volume conversion calculators.

How to build an enclosure for car speakers

Before you begin building your DIY speaker enclosure, you will need to check the speaker’s T/S parameters. Qts (Driver Total Q) is the most essential parameter. This will help you determine the type and size of the cabinet you are going to use for the speakers.

What is a Qts parameter? Qts or Driver Total Q is a parameter is a numerical figure that describes the mechanical and electrical parts of the speakers to tell you how powerful the speaker’s motor and magnet are. It combines the speaker’s mechanical properties known as Qms and electrical properties known as Qes to give you the total Q.

Qts= Qes + Qms

Here are the guidelines to use for building your enclosure depending on the Qts parameter;

  • For a Qts of below 0.4, the enclosure should have one or more ports.
  • For a Qts of between 0.4 and 0.7 the enclosure be sealed.
  • For a Qts of above 0.7, the enclosure should be an infinite baffle.

If you cannot determine the type of enclosure to use based on the Qts parameter, you can use volumes as a guide. To get the volume, you can use the speaker’s impedance rating. A 4-ohm speaker will need an enclosure of about 0.02 cubic meters/20 liter, 8 ohms 0.04 cubic meters/40 liters, and so on.

A DIY enclosure may not be the best quality but it will get the job done.

How to build an enclosure for the car stereo

If you are using a car stereo as your audio processor, you will need to measure the width and length of the stereo and cut a hole on a cardboard/box according to the measurements. You can also attach your power inverter to an enclosure making sure that there is enough airflow to cool it.

Once you have everything connected you can power your system on and listen to some music or watch a movie.

Final verdict

You are always better off using HT speakers for your home rather than car speakers because they are better designed to sound great in that environment. However, high-quality home theater speakers are not always cheap and if you have some decent car speakers lying around you can also use them, at least for standard audio setup. You can also get yourself some fairly priced car speakers and sub.

This audio setup will work great for a typical and standard movie and music room. But if you are an audio nut looking for a top-tier, super clean, and dynamic hi-fi system, you are better off building a costlier Hi-Fi system.

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