What are Free Air Subwoofers? 

Norvan Martin
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Subwoofers are a must-have for anyone who desires quality bass and powerful performance in the comfort of their home. They are specifically designed to produce low-frequency sound and come in different types. Today, we will discuss free air subwoofers. 

What is a free air subwoofer? A free air subwoofer is a specially designed subwoofer that does not need an enclosure to increase bass performance. They are normally mounted on any kind of baffle with an air space behind it (like a car trunk or in a boat).

The main benefit of using free air subwoofers is that they save a lot of space because they don’t need a large enclosure.

Let’s take a deeper dive into what free air subwoofers are, their uses, misconceptions, advantages, disadvantages, and more. 

What are Free Air Subwoofers?

Free air subwoofers are subs that do not require an enclosure to increase their bass performance.

A regular enclosed subwoofer uses an enclosure because they produce sound from the back and front. You can check our our complete guide on enclosed vs free air subwoofers to learn more. 

Free Air Subwoofers

Without an enclosure, the sound frequencies from the back of the speaker would cancel out the frequencies from the front of the speaker.

The enclosure forces the frequencies to be generated at the rear of the sub and so maintains uniformity.

Additionally, the type of enclosure that you use will determine the type of bass that you will get. For example, if you prefer bass that’s “tight” and focused, go for a sealed box. If you prefer bass that has more boom and max volume, go for a ported box.

Free air subwoofers don’t use enclosures and work like passive speakers. So, for you to power these subs, you must connect them to external amplifiers. The benefit or advantage of free air subwoofer is that they save space. This is why marine free air subwoofers are so popular because space is very important on a boat. 


How Do Free Air Subwoofers Work?

Like other subwoofers, free air subs produce low-frequency sound by moving air at the required frequency.

How Do Free Air Subwoofers Work

They achieve this with the same basic idea of moving the voice coil within a magnetic field which moves the cone to produce vibrations.

The only difference is that the subs lack an enclosure which is used to attain better bass performance. Due to this, the resistance of the speaker is significantly diminished. And this can make the cone to move extremely fast.


Common Free Air Subwoofer Issues

What happens in case a speaker cone fails? If this happens, your free air subwoofer automatically stops working. Other factors that can make your subwoofer to stop working are:

  • Driver magnet failure: A faulty electromagnet cannot attract and repel the electromagnet to cause the desired movement
  • Short circuit: Can prevent the signal and current from reaching the free air subwoofer. A short circuit can also reduce the amount of power that the electromagnet produces.
  • Lack of adequate power:  Without adequate amperage reaching the electromagnet coil, the permanent magnet and the electromagnet field can never successfully interact.


Free Air Subwoofers Pros and Cons

Like everything else on the planet, free air subwoofers come with pros and cons, which makes them unsuitable for some people.Free Air Subwoofers Suitable for All Users

They can add decent bass without using too much space. So, you can easily mount free air subs in a limited space. Moroever, they are not as heavy as their enclosed counterparts. For example, a bandpass box is a large enclosure that can weigh over 40 lbs!

Even though they can deliver better bass, there are many pros and cons of sub enclosures like bandpass boxes to consider. 

You can even choose to install them on the doors of your vehicle. This means you can have a complete audio system with multiple free air subs.

Free air subwoofers are also highly attractive due to their cost-effectiveness. As we have seen, these subs do not come with enclosures. They also require external amps. This means they are more affordable than their enclosed counterparts if you already have an amp. Here is a walkthrough of how to connect passive subs like these to external amps

Free air subs also demand less power. They work in an open-air environment, as the name suggests. As such, the air encounters limited resistance, which ultimately translates into a significant reduction in power demand.

But what are the shortcomings? Free air subwoofers deliver bass that is not very tight since they operate in an open-air environment. The bass may also not boom a lot. However, if you have an external amp and are on a tight budget, free air subwoofer is the most suitable for you.


Infinite Baffles Setups vs Free Air Subwoofers

Many people struggle to differentiate these two terms. You will hear they are the same and you will hear otherwise.

People say they are the same because they are under the impression that infinite baffles setups, too, do not require an enclosure.

Infinite Baffles Setups vs Free Air Subwoofers

The truth is that infinite baffle systems use massive, enclosed spaces. However, both of them are mounted in the same way. So,  they do share some similarities. 

However, installers of infinite baffle systems do a lot of work to ensure that the waves do not interfere with each other. They use baffle boards to modify the systems extensively, which involves lots of design work and careful constructions.

But with a free air subwoofer, you do not need to struggle with the same complexities of infinite baffle setups. In other words, they give you the best option to create exceptional bass without the tedious effort of sealing enclosures. 


Free Air Subwoofer Installation Tips

Even though free air subs require relatively less degree of sound-wave isolation, you need to pay some attention to this area.

Your ability to isolate the sound waves has a direct relationship with the sounding of your sub. Where applicable, the installation should include lots of materials for absorbing vibration, sound, and rattles. By doing this, you get a more rigid surface, which is required to improve the speaker’s phase.

You also use a baffle board to seal your listening environment. In most cases, free air subs do not produce punchy bass. So, your effort to create a sealed surround is necessary to increase your audio system’s efficiency.

Tips for Getting Free Air Subwoofer Alignment Right

Besides getting the installation procedure right, you need to align your sub with your main speakers to get the best home theatre experience.

Tips for Getting Free Air Subwoofer Alignment Right

The sub and the speakers need to be in phase with each other. If your sub comes with an in-built phase adjustment feature, use it to correct the phase differences.

Whenever you set up a free air subwoofer in your home, position the subwoofer in the right listening position, and then set the desired volumes levels.

As you listen to your favorite music, slowly change the listening position until you feel satisfied with the bass.

If you are using a single subwoofer, consider positioning it in front of the listening area rather than behind.

Also, please keep it away from the corners but in front of a wall. But free air subs should not be too close to the walls or be at the centre of the room.

Are Free Air Subwoofers Any Good?

Free-air subwoofers are an excellent way to boost bass in your automobile without taking up a lot of room with an enclosure. Free-air systems are also less heavy. Know that there are many traditional subwoofers out there that perform fantastic in a box, but won’t sound good when installed in a free air setup.

Things To Consider Before Buying Free Air Subwoofers

While your budget and vehicle will have a big impact on the free air subwoofer you buy, what else should you think about before making a decision?


Because your sub will not be enclosed, make sure it has enough power to deliver powerful bass despite the disadvantageous configuration. It’s crucial to keep in mind that peak power isn’t the most essential factor here. The RMS rating is important because it represents the average power that your subs will provide.


Remember, you need a sub that will last the test of time, which means it will be particularly durable and reliable even if you use it every day.

Frequency Range

Wider frequency ranges will be better at playing all genres of music, however, low-frequency ranges will have a greater bass.

Voice Coil

You’ll have to do extra wiring if you have more voice coils. While it may be tempting to settle with a single voice coil for ease of installation, twin voice coils provide greater flexibility and tend to last longer.



Free air subwoofers are a perfect solution for those who love decent bass and powerful performance but do not have a lot of space.

If you buy a quality sub designed for free air mounting, power it with an efficient amp and insulate the listening area, if possible. Also, install and properly align the subwoofer, and you will get a nice bass response.

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin