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How to Install Subwoofer in Old Car?

Installing a subwoofer in your old car can significantly improve the sound quality and overall driving experience.

While it might seem like a daunting task, with a bit of patience and some basic knowledge, it’s not too difficult to do in most cars. But how to install a subwoofer in an old car? Let’s find out.

To install a passive subwoofer in the old car:

#1. Run the power wire from the battery to the amplifier.

#2. Connect the stereo with the amplifier using a remote wire.

#3. Run the RCA signal wires between the stereo and the amplifier.

#4. Connect the speaker wires from the amplifier to the subwoofer’s terminal.

#5. Ground the amplifier with the grounding point on the chassis. 

#6. Turn on the stereo and test the subwoofer.

#7. Make gain and volume adjustments on the amplifier.

To install an active subwoofer in an old car:

#1. Connect the power wire from the built-in amplifier with the battery.

#2. Run the remote wire from the amp to the car stereo.

#3. Run the RCA signal wires between the amplifier and the stereo.

#4. Ground the amplifier with the grounding point on the chassis.

#5. With all connections done, turn the stereo on.

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Tip: In old or classic cars, sounds created can sometimes sound sharper compared to modern vehicles. This is because the subwoofer is trying to reproduce the low-end sounds usually damped by the car body.

To solve this, try adding sound-deadening materials to the area where the subwoofer is placed. This will help to minimize the subwoofer’s vibrations and improve its sound quality. 

There are many soundproof panels you can use, but I recommend Klimat, made from butyl rubber (link to Amazon).

In the article below, I will show you how to install a subwoofer in an old car and what subwoofer types can be used in old cars.

Which Subwoofers Are Good for Old Cars?

Many subwoofer types can be used in old cars; the actual limit is the space you can use to accommodate the enclosure.

Although the space should not be an issue for older SUVs or trucks, it can be for smaller cars.

The most suitable subwoofers for those smaller trunks in old cars are 10 or 12-inch subwoofers in sealed boxes. If you have more space to work with, go for a 15-inch subwoofer.

As for the subwoofer box, there are three main types you can choose from:

#1. Sealed subwoofer box – smallest in size and offers the best sound quality.

#2. Ported subwoofer box – larger than sealed subwoofer boxes, and thanks to the port, they are tuned to a specific frequency.

Ported subwoofers require more free space due to free airflow from the inside box.

#3. Bandpass subwoofer box – the largest of the three box types. They have two or more chambers, which can be either fully sealed, partially sealed with one port, or with both ported enclosures.

When it comes to the way of powering the subwoofer, there are two ways to do it:

#1. Passive Subwoofer

The passive subwoofer is powered by an external amplifier.

The subwoofer box is usually smaller because there is no need for an internal amplifier, but passive subwoofers are often more powerful than other types.

#2. Active Subwoofer

The active subwoofer has an internal amplifier that powers the subwoofer.

The driver is usually smaller and less powerful than the passive subwoofers.

Excellent solutions from the active subwoofers group are the shallow under-seat subwoofers (link to Amazon) which you can install in any tight spot in the car when there is not much space in the trunk.

Many subwoofer brands offer subwoofers for old cars, but my favourite is SKAR (link to Amazon).

They offer both sealed and ported subwoofers and a wide selection of powerful models to choose from.

Where to Place Subwoofer in an Old Car?

The most suitable place to install a subwoofer in an old car is the trunk. 

The subwoofer box should be placed close to the trunk’s centre, with the cone facing up or towards the back of the vehicle. This will help to distribute the bass evenly throughout the car.

If you have a smaller car, you can also place the subwoofer box under one of the front seats.

This place however is not ideal because the subwoofer box will take up some of the passenger’s legroom, and also, because of its smaller size, you cannot expect too much of the boom effect.

How to Connect Subwoofer in Old Car?

Installing a subwoofer in an old car is easier than in most modern cars because the older cars have more space behind the dash and easier to remove interior panels.

How to install a subwoofer in an old car depends on the subwoofer type, and the main differences come with the design:

  • active (powered)
  • passive

I detailed below both connection types, so follow those steps, and you will be able to enjoy your subwoofer in no time:

Installing a Passive Subwoofer in the Old Car:

#1. Run the power wire from the battery to the amplifier.

This wire should start at the battery and end at the terminal on the amplifier. Do not forget to install the main fuse close to the battery’s positive terminal.

#2. Connect the stereo with the amplifier using a remote wire.

The remote wire is a crucial connection with the stereo to control turning the amplifier on and off.

#3. Run the RCA signal wires between the stereo and the amplifier.

RCA wires (link to Amazon) should not run together with the amplifier’s power wires. If you have a factory stereo or the model without the RCA output, you can use a high voltage connection instead and run the speaker wires from there to the hi voltage input in the amplifier.

#4. Connect the speaker wires from the amplifier to the subwoofer’s terminal.

This is the easiest part of the subwoofer installation in an old car. Remember not to mix positive with negative wire because incorrect polarity reduces the sound quality and can damage the subwoofer.

#5. Ground the amplifier with the grounding point on the chassis.

Make sure to clean and sand the ground connecting point because electricity does not flow well on a painted, dirty or rusty surface.

#6. Turn on the stereo and test the subwoofer.

At the first run, do not forget to set the volume on the amplifier and the subwoofer’s gain lower than usual because you can damage the subwoofer if it is turned up too loud.

It is also a good practice to break in the new subwoofer by playing at moderate volumes for the first few hours.

#7. Make gain and volume adjustments on the amplifier.

The last step is the final tuning and adjusting the sound settings to match your taste.

Again, there are no general rules for those because the bass experience is personal, so you must play with different gain and crossover settings for the most suitable effect.

Also, the same subwoofer can play differently in different cars because of specific acoustic and different interior materials, so your settings may not be suitable when you move the same subwoofer into a different vehicle.

To Install an Active Subwoofer in an Old Car:

#1. Connect the power wire from the built-in amplifier with the battery.

This is the most critical wire that should have a solid connection with an installed in-line fuse close to the positive battery’s terminal.

#2. Run the remote wire from the amp to the car stereo.

If you do not want the amplifier to drain the battery quickly, you must connect it with the radio using the remote wire.

#3. Run the RCA signal wires between the amplifier and the stereo.

As in the passive subwoofers, you have to connect the stereo with the amplifier using RCA wires to transfer the signal.

#4. Ground the amplifier to the chassis.

You can also run the ground wire to the battery, but this should be necessary unless there is a risk that the old car does not have good metal connections within the chassis.

For the ground wire, make sure to use wire of the same gauge as the power wire.

#5. With all connections done, turn the stereo on.

On the first try, do not put the volume too high. This is a test run to adjust all settings and tune the bass to your preference.

Should I Soundproof Old Car for Subwoofer?

Soundproofing an old car before installing a subwoofer is a good idea because subwoofers can create rattling sounds.

Unfortunately, factory soundproofing and rattling protection were mediocre, especially in old vehicles, with most of the bodywork being bare painted metal.

Therefore, it is recommended to soundproof the car before installing a subwoofer, especially in an area close to the enclosure.

You can use different soundproof materials like a butyl rubber mat, neoprene foam, or mass-loaded vinyl. My favourite is the Klimat (link to Amazon), made from butyl rubber because it is light, easy to work with and provides good results, especially on the floor and under the carpet.

Conclusion

Installing a subwoofer in an old car can be easy or difficult, depending on the model and make of your vehicle.

It is important to take your time with the installation and to make sure all connections are secure and properly made.

Also, be careful when choosing the subwoofer’s type and size because it has to fit in the allocated space without being too tight.

Last but not least, you may need to soundproof the area around the subwoofer to minimize rattling and improve the subwoofer’s sound quality.