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How to Make a Sealed Box Louder?

A sealed subwoofer box is a closed type of speaker enclosure. Sealed enclosures are widely used in car audio systems to produce good quality bass frequencies.

The bass response in the sealed subwoofers is considerably better than ported subwoofer boxes with similarly sized speakers, but can we make a sealed subwoofer louder? Let’s find out.

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Generally, to make a sealed subwoofer louder, you have to provide more power from the amplifier. Another way is to replace the speaker with a stronger one, but it is important to remember that the air pressure in the sealed box cannot be too high.

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Tip: Sealed boxes are preferred for some types of music, especially those that require tightness and accuracy in the bass frequencies reproduction.

If you have a speaker and need a box, try using some ready-made enclosure, for example, Atrend Bbox E10S. With 0.67 cf volume, it fits most of the not too powerful 10″ speakers, for example, a 4 Ohm Skar VD-10.

In the article below, I will show you how to make a sealed box louder, changes to the design, and if it is worth adding a port to the sealed enclosure.

Can a Sealed Box Be Loud?

While the main reason for a sealed box to exist is its accuracy and clarity in the bass reproduction over the loudness, they certainly can be loud enough to shake the cars.

You also have to keep in mind that this type of enclosure’s size can vary from tiny ones made for space-saving purposes so that they would fit under a seat or a rear shelf.

This type of subwoofer enclosure is even more suitable for deep bass response. The internal air volume in the sealed boxes, enabling them to create stronger pressure inside the box itself, so installed speakers that are larger than 10″ although clear may not play efficiently enough.

The internal pressure affects how large sound waves will be produced, meaning that it will generate more intense output per unit power with a significant influence on the final sound quality.

Do Sealed Boxes Hit Harder?

Sealed subwoofers do not hit as hard as ported or bandpass subwoofers. Especially ported box generally gives more sound than a sealed, for the same amount of power.

This is because the port on the enclosure’s back wall acts as an opening to let more air out. Because the port releases created air pressure, and it can hit harder than a sealed one.

At the same time, the escaped air causes a lower frequency response, and in effect, it reduces the bass quality.

There are some ways to make a sealed subwoofer hit harder, such as adding another speaker inside.

This adjustment, however, won’t change anything about its sound quality as it will still be a sealed box with air pressure issues, only a bit louder.

It is also difficult to add another box to the same enclosure since the box size should be precisely measured for the specific speaker.

What Makes a Sub Box Louder?

The first thing you are probably thinking about is more power. And this is right, but the amount of power also depends on the peak frequencies to be amplified, which must be strong enough to hit hard.

For example, if you have a sealed subwoofer box that hits only below 30 Hz, it will not produce many audible sounds because its peak frequency can be more felt than heard.

Therefore, the simplest way to make a sealed subwoofer box louder is by changing the speaker you’re using from, for example, 8″ to 10″ within the same box.

This upgrade, however, has to be carefully checked with the original specification not to create too much air pressure inside the box.

The only thing you will have to modify is the increasing size of the mounting hole.

All in all, it’s not impossible to make your speaker louder. However, you’ll need time and money or use another box type instead of changing the speaker inside it.

Can Sealed Subs Handle More Power?

When making the sealed sub box louder, the next question is usually related to power handling.

It’s easy to assume that since you make the subs louder, it should handle more wattage. But this is not always a correct assumption for sealed subwoofers.

When going for a sealed subwoofer, you need to ensure that modification will not damage the speaker if you push it too much power.

The reason is that the air pressure inside can be too high for the stronger speakers. Again, each sealed enclosure has been designed for the specific speaker, and you should rather replace the whole sub than change the speaker itself with a stronger one.

Does Sealed Subwoofer Box Size Matter?

Subwoofer box size matters, of course, but not as much as sealed subwoofer box volume.

The bigger the box is, the better you will hear low frequencies. If your car can handle a specifically sized enclosure without trouble, then definitely go for it.

That is important, especially for vehicles with smaller trunks, because you need some free space in front of the cone so the speaker can play freely.

If you want to make your existing box speaker louder and clearer, you should consider adding chambers in a specific place inside the box.

Adding extra walls inside the subwoofers is needed for one reason only: to lengthen the sound waves’ travel time so that they will get more time to resonate inside the enclosure and be amplified by its walls.

The more chambers your sealed subwoofer has, the louder it will get. If you want to go this way, you will change the characteristic of the box, and in effect, it can peak at a slightly different frequency than was initially designed for.

If you want to go this way, you will have to look at the sealed subwoofer design and tune it by adding chambers.

After all of these modifications, remember that there is a limit that can be reached if you keep on adding things.

Your sealed subwoofer box should not be over-filled with the chambers inside because its internal volume will decrease.

Does Speaker Box Shape Matter?

When you are building a sealed subwoofer enclosure, it is good to know that the internal shape of the chamber is going to make a difference.

Do you want it round, or square, or rectangular?

All box types will react differently, and this is due to the size, cross-section with height ratio, and more.

The ideal way would be to prepare your design of the sealed subwoofer box based on the speaker’s factory recommendation regarding the box’s shape and size.

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How Big Should a Sealed Subwoofer Box Be?

Although they are available and can be made in any size that matches the speakers, the most common one is the 12-inch sealed subwoofer box.

For a sealed subwoofer, the size of the speaker determines its peak performance, low-frequency extension, and efficiency.

If you have a larger speaker that produces more bass, you’ll need a bigger box to allow it to play lower frequencies.

What Happens if a Sealed Box Is Too Big?

Everything goes right if the box matches the speaker, but you lose bass punch when your box is too big.

An oversized box does not create enough air pressure, and the speaker cannot create strong push, acting more like free air subwoofer with massive cone movement.

Such large movement of the cone in the box that is too large can also cause damage to the speaker, especially its suspension or surrounding.

What Happens if a Sealed Box Is Too Small?

When the box is too small, it also cannot act as a perfect enclosure for any speaker.

This can result in some frequencies being canceled because the subwoofer’s cone will not move as far due to too much air pressure created inside the box, and in the worst case, the speaker can get damaged.

Can a Sealed Box Play Low?

Sealed subwoofers are known for making high-quality bass at low frequencies.

If the air pressure created inside the sealed box is optimal to move the subwoofer’s cone, this type of enclosure is perfect for making powerful, precise bass.

Nowadays, sealed subwoofers are preferred over the ported boxes by most audiophiles or anyone who values the quality of the sounds over the loudness.

Do You Need to Tune a Sealed Subwoofer Box?

Tuning of the sealed boxes is not necessary unless you’re aiming for some specific sound characteristics.

However, if you plan to tune your sealed subwoofer box, you must maintain the correct air pressure inside the box.

The most common way of tuning the sealed box is to remove the speaker and fill the enclosure with the filling material.

Note that sealed subwoofer boxes do need an adequate amount of power to allow them to work. If you don’t drive the sub with enough power, then it won’t play correctly.

Can I Make My Sealed Box Ported?

Making a ported box out of the sealed enclosure is not the right way if you are planning to make the ported subwoofer.

You can add the port by drilling the hole in the sidewall, but just by adding the port to the sealed box, you will not improve the sound if you do not change the speaker to match the new air volume space.

Each box has to be designed for the specific speakers, and sealed boxes are smaller than ported ones for the same speaker. More importantly, sealed enclosures have a completely different interior design.

If you want bass accuracy, go for a sealed car subwoofer box. If you want maximum loudness from the lowest possible frequency response with as little distortion as possible, opt for a ported model.


Depending on your preferences and budget, there are different ways to make the sealed subwoofer box louder.

However, a better way to do that is by purchasing another type of speaker instead, because it will improve both sound quality and bass response.

If you want to make an existing sealed box louder, you have to meet some strict criteria like the volume, shape, or power from the amplifier.

Without them, you might make your sealed subwoofer box sound worse or even damage the speaker.