How to Port a Sealed Sub Box (Complete Solutions)

Are you tired of the same old sealed subwoofer box sound? Getting a new system installed can be complicated and expensive – but porting a sealed sub box can help you get the bass punch you want without breaking the bank!

To port a box, you must determine the resonance frequency of your subwoofer and the volume of air in the enclosure using a subwoofer enclosure modeling application or software. With this info, determine the port length before drilling the required hole and securing the tube (port) with silicon glue.

Porting your sealed sub-box is a great way to upgrade your subwoofer’s performance without breaking the bank. Follow this guide to learn how to port your sealed sub-box and enjoy deeper, punchier bass.

How to Port a Sealed Sub Box

Can You Port a Sealed Box?

Porting a sub-box involves adding a port tube, such as a PVC pipe, that enables air to move freely in and out of the box. When appropriately sized, this port tube allows the driver to produce precise low-frequency tones and create greater sound pressure.

While porting a sealed box may not be as effective as an industry-ported subwoofer enclosure, it is an accessible and excellent way to upgrade the quality of your subwoofer system.

Choosing the Right Port for Your Subwoofer Box

First, determine the resonance frequency of the subwoofer (the very low frequency that the subwoofer’s driver rolls off). You can use a subwoofer enclosure modeling application for this.

Measure the internal dimensions of your subwoofer enclosure, then calculate its volume, roughly equating to the volume of the air inside the enclosure. A subwoofer enclosure calculator can also help you make this estimate, provided the sub-box dimensions.

Use an online vent size calculator to estimate the best diameter and area for your subwoofer driver size.

Now knowing the resonance frequency, the volume of air in your sub-box, and the port area, you can calculate the port length you need using this formula:

F= (V/2Π) √(A/VL)


F= Resonance frequency

V= Velocity of sound– 343 m/s

Π= 3.14

A= Area of the port

V= volume of the air in the sub box

A subwoofer enclosure modeling software can still calculate your port length if given all the other variables mentioned above.

After figuring out what port size and length you need, it’s time to do some drilling to install the vent and crank up the bass!

How to Port a Sub Box

Forget about buying expensive pre-built ported subwoofer boxes to get the right sound you’re looking for. With a few simple steps, you can easily port a sub-box by yourself.

So, let’s get started with the essentials needed.


  • Sub box port tube- e.g., a PVC pipe (Outer diameter should match the port opening diameter)
  • Hand saw
  • Hole saw- attach
  • Drill
  • Silicon glue
  • A piece of sub-box cover fabric
  • Cross bracing
  • Sandpaper
  • Heat gun
  • Marker pen

Porting Instructions:

  1. Attach your hole saw to the chuck of your drill
  2. Use a marker pen to trace the desired PVC circumference (port opening) on the subwoofer box. Ideally, the port should be placed on the same side as the subwoofer for optimal acoustic performance. Otherwise, use the enclosure’s back.
  3. Turn on your drill and make a hole that corresponds to the size of your PVC pipe outer diameter. Use the sandpaper to sand down the edges of the cut hole.
  4. Cut the PVC to the desired port length using a hand saw and file its ends using sandpaper.
  5. Insert the PVC into the hole and use your heat gun to flare the opening of the PVC pipe.
  6. You can also use a sub-box fabric to cover the sides of the PVC pipe opening. This will smoothen the opening improving airflow and reducing port noise at high volumes.
  7. Apply silicon glue all around it to fix it firmly on the opening and seal any air leaks on the port opening.
  8. Reinforce the ported subwoofer box, as it will move much more due to increased sound pressure. You can add cross-bracing to your subwoofer box for this.

How Does a Subwoofer Box Port Work?

A subwoofer box port is crucial to getting the best bass production out of your audio system. The box port is designed to relieve the pressure on the woofers and make it easier for them to move. This is done by pushing air out when the woofers move back and sucking it in when they move forward.

By using this?? With the push-pull effect, you can achieve great-sounding bass from your system. The port allows the woofers to move more freely and extend the system’s frequencies into the lower range. This allows for deeper tones and a far tighter sound.

Alternative Methods to Make a Sealed Subwoofer Box Louder

If you have a subwoofer lacking a bit in volume but impossible to port, consider other alternatives. Here are 5 alternative methods you can use to make a sealed subwoofer box louder without any fancy modifications:

1. Install an Active Equalizer to Adjust the Frequency Response

Installing an active equalizer to adjust the frequency response of a sealed subwoofer box is a great way to get a louder sound. By fine-tuning the frequency response, you can effectively increase the loudness of the sound while preserving clarity and richness.

2. Use A More Powerful Amplifier

Using a more powerful amplifier is also a great strategy to emphasize the sound of your sealed subwoofer box. Adding a more powerful amp to your setup can deliver more energy to the speaker and make your subwoofer sound as loud and clear as you desire.

3. Use an Enclosure-Damping Material

Adding an enclosure damping material such as polyfill to a sealed subwoofer box helps reduce air leakage, leading to improved sound quality and increased loudness. The material reduces resonances, producing a tighter and louder bass response.

4. Change the Position of Your Subwoofer Enclosure

Additionally, ensuring your subwoofer enclosure is optimally positioned can also make a big difference in the loudness of your system. Experiment with different angles and positions to find the one that produces the best bass response and highest volume.

5. Utilize A Higher-Efficiency Subwoofer Driver

Finally, a higher-efficiency subwoofer driver is also an excellent way to make a sealed subwoofer box sound louder. High-efficiency drivers typically require less power from your amplifier to produce a louder and clearer sound.


Q: What Are the Limitations of Porting A Sealed Subwoofer Enclosure?

Ported subwoofers have their constraints! While they provide deeper, punchier bass, they also introduce specific issues to be careful of – like sudden reduction in volume at low frequencies (below tune frequency), chuffing noises when too much sound is driven through the port, and interaction between sound from the driver and the port itself. So even though they can be great, they need to be designed optimally.

Q: Can You Seal a Ported Subwoofer Box?

Yes, you can seal a ported subwoofer box to effectively alter the sound of a poorly performing ported sub-box. As discussed above, ineffective porting has its limitations, and one option to address this would be to seal the box, which can help maintain a tighter sound. To do this, you can fill the port opening with tightly sealed acoustic foam.

Q: What Sounds Better: A Ported or Sealed Subwoofer Box?

It depends on what sound you’re looking for! Ported boxes offer punchier, louder bass, while sealed boxes are better for tighter, more accurate sound. Ultimately, it’s up to your own preference!

Q: Does the Shape of a Subwoofer Port Affect the Sound?

Yes, the shape of a subwoofer port can affect the sound. Generally, rectangular ports provide the most accurate sound, while round ports are best for deeper and tighter bass. A triangle port offers mids and lows with a little more kick, lending a fuller sound.

The Bottom Line

With the right materials, you can easily design and drill the perfect-sized port and customize your sub-box sound to your desired levels. Although a sealed box provides tight and accurate sound, porting it offers a full and louder sound.

Additionally, there are alternative methods you can use to make a sealed subwoofer box louder, like installing an active equalizer, using a higher-efficiency driver, or changing the position of your subwoofer enclosure. So go ahead, get creative, and let the bass flow!