Should a Subwoofer Face the Wall
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There are many ideas out there about the best subwoofer placement options. One of the common questions people ask is, should my subwoofer face the wall? In this article, we discuss whether or not it’s a good idea to have your subwoofer face the wall.

First, here’s the short answer:

Should your subwoofer face the wall? In most cases, we do not recommend it because this will cause too much bass reflection in the room which may affect bass quality. On the other hand, aiming the sub towards the wall can have certain benefits such as attenuating harmonic distortion and improved bass quality from boundary gain, depending on how the sub is setup. Additionally, if you have a downward-firing sub, it doesn’t matter if it faces the wall or not.

Below, we dive into a detailed guide about the pros and cons of aiming your subwoofer at the wall.

Reasons You Should Not Aim Your Subwoofer At The Wall

Placing your subwoofer towards the wall can cause a number of issues. Below are the main cons of aiming your subwoofer at the wall:

1. Bass Reflections Cause Interference (Speaker Boundary Interference From Reverberation)

Even though bass waves are omnidirectional (meaning they radiate in all directions), if you aim your subwoofer at the wall, then the bass waves will get directed to the wall and then bounce off in different directions.

Bass Reflections Cause Interference

The waves will then criss-cross each other when they bounce back and result in muddy, harsh bass tones and weird rumbling sounds. In other words, bass reflections will cause interference. This phenomenon is called speaker boundary interference or SBIR

To explain further, consider ported subwoofer placement. It is for the same reason that we normally recommend that these subs are not placed too close to walls.

In general, we recommend that ported subwoofers be placed at a distance of 1-2x the diameter of the port away from a wall.

For example, if your subwoofer has an 8” port, it should be placed 8-16” away from a wall.

Some people chose to plug up the port with something, such as socks or softballs. Of course, we do not recommend this because while it will reduce the amount of reverberation which will certainly affect the quality of your bass.

So, this is the primary reason it is generally not recommended that you place your subwoofer right against the wall. 

Can I Predict Bass Reflections?

In theory, you can predict bass reflections, but in practice, it is very difficult to predict where and how bass waves will reflect. 

Can I Avoid Bass Reflections?

While it’s very difficult to accurately predict and avoid bass reflections, there are steps you can take to reduce it.

The easiest way to fill in the dips related to reflections is to place the sub in close proximity to the wall.

This way, you may end up with higher frequencies that may even be outside the bass bandwidth.

In other words, placing the subwoofer closer to the wall will push the reflected frequencies higher and therefore make them more easily treatable with absorption treatments such as acoustic panels or bass traps. This may help with lowering distortion. 

On the other hand, some people avoid bass reflections altogether by aiming their subwoofer at the longest leg of the room. 

2. Subwoofer Out of Phase Issues

If you are having issues with bass reflections, then you will likely have issues with phase at higher volumes.

subwoofer phase switch

This is because as the soundwaves bounce back to the subwoofer, these reflections will cause the sub’s cone to vibrate and so kick it out of phase. 

This can cause boomy sound issues and other forms of sound coloring that can over time damage the sub. [find out more about how to tell if your subwoofer is out of phase and how to set your subwoofer phase].

3. Bass Travelling Through Walls

Bass soundwaves can easily travel through walls. This is because the waves are rather large. In fact, the lower the bass, the larger the waves.

These waves can go through walls and enter another room quite easily. They can also create resonance walls which makes it even easier to pass bass through. 

Now imagine if all this heavy bass is carrying through the walls into the adjacent room. This will certainly interfere with your neighbors’ peace if you live in an apartment.

For this reason, you may choose to soundproof your home theater room and specifically soundproof your home theater walls. However, doing so may just dampen the soundwaves and reduce the overall bass strength in the room.

 

Why Should Your Subwoofer Face the Wall?

If you decide to aim your subwoofer towards the wall, you need to take advantage of the fact that bass waves are omnidirectional. This means bass waves travel in all directions.

Here are some reasons to aim your subwoofer towards the wall:

1. Smoothing Bass At The Crossover Region

Bass can be rather muddy at the crossover region and at the upper regions. Placing the sub towards the wall is a good way to smooth over bass at the crossover region and upper bass range (greater than say 70Hz). 

Phase and Crossover Frequency on Your Subwoofer

In addition, if you have multiple subwoofers, having your sub face the wall will allow for greater integration at the crossover region and more importantly, make it less localizable.

By localizable, we mean your ability to detect where the basis coming from. When a system is not well integrated, you can easily locate the sub by listening. 

2. Benefits of Speaker Boundary Interference (SBIR)

boundary interference sound waves reflecting off wall
Image credit: Arqen.com

There are actually some benefits of having your sub aimed at the walls and the resulting reflections.

Image/animation credit: Arqen.comRemember, subwoofer bass waves radiate spherically or omnidirectional. If you place the sub towards the wall, much of the bass waves will push the reflected frequencies higher than normal.

This will make it easier to treat these bass waves with absorption treatment materials such as acoustic panels and bass traps. For example, a 250hz peak is much easier to treat with absorption panels and bass traps than say a 30hz peak.

The benefit of doing this is to prevent too much boundary cancellations of reflected bass that messes up your frequency response.

The closer the driver is to the wall, the higher we push the cancellation in frequency. In fact, if the sub is close enough to the wall, the cancellations will occur above the operating frequencies of the subwoofer and become less of a concern.

Keep in mind that reflected bass often causes cancellations and dips in the frequency response which then affects your sub ability to produce smooth bass. 

3. Boosting Bass Waves

How can aiming your subwoofer at the walls improve or strengthen bass waves? Won’t it just cause reflections and cancellations? 

Well, it depends on how close your sub is to the wall.

Firstly, you will need to determine how far away from the wall a wavelength is. 

Once you have determined that, if you are careful to place the sub 1/2 a wavelength away from a wall, at the frequency that corresponds to that wavelength, the bass will be reinforced significantly. 

However, the main disadvantage of this is that if this particular frequency is muddy or boomy, it will not sound too great.

Also, if you make a mistake and place the sub 1/4 a wavelength from the wall, then the bass will be canceled significantly, by as much as 15dB.

The quick solution to this is to ensure that you place the sub 1/2 wavelength (of your lowest frequency) from the walls.

Here how you calculate how far a wavelength is based on frequency:

 vw = fλ, where vw is the speed of sound (340 m/s), f is its frequency, and λ is its wavelength.

In this case, let’s say we are working with a frequency of 41Hz (low E). The calculation becomes:

λ = vw/f 

   = 340 ms / 41 f

   = 8.29m (27.20 feet)

So half a wavelength is 

In this case, if you are working with 41Hz, you should place the sub 4.14m or 13.6 feet from the wall.

4. Corner Loading To Improve Sub Loudness

Let’s say you have a small sub in a large room. How will the tiny sub pressurize enough air to fill the room? 

An easy solution is to aim the sub at the wall. 

Doing this will make the subwoofer more efficient because there will be less space for air to move in front of the sub driver facing the corner.

corner loading subwoofer

In this case, it will pressurize air much more than it would when facing the open air. More pressure means the soundwaves will have greater energy and so sound louder to you. This is referred to as corner loading.

In reality, it is really a situation where the sub is the sub creating harmonics that emphasize certain frequency ranges.

Of course, there is a disadvantage to this as well. If the sub is already large and powerful, corner loading will cause the sub to sound boomy. In fact, when you turn up the volume, this may worsen sound reflections. 

5. Improved Bass Quality

after pointing your sub into the corner or wall, you may notice that the bass sounds tighter and less localizable. The trick of using a corner to reinforce very low frequencies.

6. Improved Qts and Fs

Qts and Fs refer to Total Q-Factor(Qts) and Resonance Frequency(Fs) of a subwoofer. Resonance Frequency(Fs) refers to the resonance of the system in a free-air environment and is a guide on how the sub will hit – lower or higher.

subwoofer Qts and Fs

More importantly, Total Q-Factor(Qts) dictates motor force and what kind of enclosure a speaker should be in.

Now keep in mind that subwoofers work by pressurizing air in the room. When the subwoofer’s cone is close to the wall, say within an inch or two, it will pressurize the air much more. This will slightly raise the Qts and slightly lower the Fs. 

These parameters working together will then boost the very low end a little bit relative to the rest of the frequency spectrum.

We are able to achieve thee benefits without having to use a down-firing subwoofer which often leads to cone lag after a while.

Remember, down-firing subwoofers are built with the reflect port facing down on the floor. If you are using such a sub, the bass waves are sent directly towards the floor and not directly towards the wall.

Doing so maximized the benefits of country gain depending on if you aim the down-firing sub at a concrete or carpet floor.

 

Where Should Your Subwoofer Face?

Most people will place their subwoofer facing the listening room. If you choose to face the sub towards the wall, there can be benefits of doing so, but you need to understand the risks as well.

Let’s see what you should do:

For the best results under normal circumstances, you should put your subwoofer facing out to the listening room.

This way, you minimize sound reflection. This is the same reason why we place ported subwoofer ports away from the wall.

However, if you are using a small sub in a large room and you are looking o take advantage of boundary gain, you can try aiming the sub towards the wall.

Where Can You Put a Subwoofer in Your Home Theater?

Place Your Subwoofer Anywhere It Sounds Best

Many people would love to have a high degree of flexibility when placing their sub. The fact is considering the many factors that go into placement, the best option is to chose different places and test the sub. Consider the following:

  1. Move your listening couch away from your normal sitting position
  2. Put the subwoofer in the original couch’s position
  3. Cut loose with some low-frequency content
  4. Walk and scrawl around the listening room for timbre and the notes’ texture
  5. If you identify several options, choose the big winner as the new listening position

Put it Anywhere in the Front  

If you lack the kind of flexibility we have described above, you can gladly opt for the “Rule of Thirds.”

This means you measure your room from the wall and place your subwoofer a third of the way inside.

By doing this, you effectively reduce standing waves and nulls. So, with this guide, you can significantly increase the sweet spot without any difficulty.

Can I Put My Subwoofer In a Corner?

Many people place their subwoofers in corners to get more bass. Nevertheless, as we have said, this doesn’t guarantee you the best bass output.

But if you have a better solution, you can do a few things and then put the subwoofer in an intersection.

Here are the best ways you can mitigate the risks associated with putting your subwoofer in a corner:

  • Stuff the port: If you are using a subwoofer with a ported rear, you can use rolled-up socks, rubber balls, and tennis balls. This way, you will reduce its interaction with the two walls, but please note it will decrease the quality and strength of your bass. 
  • Move the subwoofer from the corner: As a general rule, the distance between a subwoofer and the wall should be at least 6-and-12 inches. Move it from the wall till you get the ideal spot. Of course, your aim should be to have the subwoofer face the listening position.

Can I Put My Subwoofer Under a Coach?

Instead of placing your subwoofer facing the wall, you can put it under a couch. This is not the best option and we generally do not recommend that you put your subwoofer under your couch, but it offers more value.

Is It Ok To Place My Subwoofer Under The Couch

If you have a small satellite speaker that relies on the sub for 120Hz and more frequencies, there can be a hole in the sound if you use this.

Can I Put My Subwoofer Inside A Cabinet?

We do not recommend this option. However, we understand that some circumstances in your home theatre may require extra-ordinary solutions.

Can I Put My Subwoofer Inside A Cabinet

Even though you may get the best quality sound, the non-directional low-frequencies will suffocate due to the lack of adequate breathing room.

The good news is that you can mitigate the problems by leaving the cabinet’s door open.

Can I Put My Subwoofer Iside the Wall?

Due to the emergence of custom installers, this option is becoming increasingly popular by the day.

Can I Put My Subwoofer Iside the Wall

You can use it if you are right are repairing drywall and have good neighbors who don’t get angered quickly.

What’s more, you must professionally install the subwoofers with special boxes designed to hold the cabinet and isolate it from the rest of the room. Moreover, you should have external amplification and crossovers.

Overall, it is costly but offers better value than putting your sub facing the walls.

The Golden Principle: Work with the Wall

Some people spend a lot of time tweaking various system settings to get quality sound from their subwoofers.

This is a great way to create the desired experience, but it cannot work if you ignore the golden principle-work with the wall, not against it.

This means you should be ready to tweak your room so that the wall doesn’t affect the sound quality.

Some of the best ways to achieve this are putting some acoustic treatment in the walls and corners. You can try using sound-absorption devices created for this specific purpose or bass traps. You can also place a piece of furniture in the room’s corners to remove the acoustic mess.

The overall idea here is that you cannot place your subwoofer facing the walls and force it to give you the best sound quality. It pays to be flexible and improve the room.

Conclusion

In general, a subwoofer should not face the wall since it will cause bass reflections which may cause distortion.

However, there may be certain benefits of doing this including improved bass as well as Qts and Fs if you set up things right.

If your subwoofer has to face the wall, it might take you a while to get things right, so ensure you understand how doing so will affect your bass output. Once you understand that, carefully setup your system, and test. Good luck!