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How to choose a subwoofer box

Sealed vs ported vs bandpass — what's the best?

In this article, we'll discuss the different types of subwoofer boxes available, why the box is so important, and help you figure out which is the best subwoofer enclosure for you.


he only way you're really going to get full, rich-sounding bass from your car stereo is to add a subwoofer. Adding a sub to your audio system will greatly improve the fun and impact of your music, no matter what kind of music you listen to.

Generally speaking, there are two bass camps—those who like it “tight” and those who like it “boomy.” The style of bass you prefer ultimately depends on your personal taste—and can even vary depending on the style of music.

Alpine subs in Sound Ordnance Ported and Sealed Boxes

Sealed box vs ported box – what's the difference?

The secret to which type of bass you'll get lies in the type of subwoofer box you use. If you prefer bass that's "tight" and focused, go for a sealed box. If you want your bass to boom and you want maximum volume in your music, then you definitely want a ported box.

Type of subwoofer box Impact on bass sound
Sealed box
  • Tighter, more accurate bass.
  • Smaller box size
  • Needs more power for louder bass
Ported box
  • Bass is louder and more boomy, less accurate
  • Larger box size
  • More efficient, doesn't require as much power

What about bandpass boxes?

We'll get to those later...keep reading. First, we'll focus on the two most popular types of subwoofer enclosures.

Sealed boxes – for deep, precise bass

A sealed box is an airtight enclosure housing your subwoofer. A sealed box is best for any music that demands tight, accurate bass. Expect flat response (not excessively boomy), deep bass extension, and excellent power handling. Since a sealed enclosure tends to require more power than a ported box, use an amplifier with ample wattage for optimum performance.

If you want to hear bass, not thunder

Each beat in a tight bass setup plays crisply, accurately, and with no ringing after it hits. The sealed air inside one of these enclosures acts like a shock absorber, smoothly modulating the subwoofer cone's back and forth motion, so all the notes get produced evenly.

Sealed box

A sealed box moderates the cone's movement

Another effect produced by the air pressure behind the cone is that it takes more power to produce the same volume as it would in a comparable ported box. What a sealed sub rarely does is roar, thunder, or boom. That's because a sealed sub has very flat frequency response and tends to play tight, full bass that provides a level low-frequency foundation to your music. Sealed boxes are generally more compact than ported subs, so they fit in more vehicles.

[See our selection of sealed subwoofer boxes]

Ported boxes – for forceful bass

Ported boxes use a vent (called a port) to reinforce low bass response. You get more output than you would from a sealed box at any given amplifier wattage. Some people prefer the sound of ported boxes for rock, heavy metal, or any hard-driving music. Ported boxes can deliver deeper bass than sealed boxes, though they need to be much larger than sealed enclosures to accomplish that.

If you want your bass to be loud

Boomy bass has more punch and reverberance in each of its beats. The cone has greater freedom of motion. The port redirects sound from the rear of the cone and adds it to the sound coming from the front, making the bass louder. This increase in efficiency lets you use a smaller amp than you would need with a comparable sealed box to play at the same volume. Another long-term advantage of choosing a ported enclosure is that the air flow keeps the subwoofer cooler, so it will live longer than it would in a sealed box.

Ported sub box

Air flowing through the port adds to the boom

Another reason ported subs hit so hard and deep is that the air flowing in and out of the port creates an audio effect like that made by a whistle or blowing across the mouth of a bottle, and that tone adds to and strengthens the note the cone plays. Ported enclosures tend to be much larger than a comparable sealed enclosure, so space availability becomes a factor when deciding on a ported sub.

[See our selection of ported subwoofer boxes]

Bandpass boxes – for maximum slam

A common question we get from subwoofer customers is, "What is a bandpass box?" Bandpass boxes are a special type of ported box designed for maximum slam. The woofer is mounted inside a dual-chambered box (one chamber sealed, the other ported), with the sound waves emerging from the ported side. The sound that comes out of the port is extra loud within a narrow frequency range.

bandpass sub box

Like a ported box, but louder

Because bandpass boxes are super efficient within that range, they tend to boom. Hard. Their aggressive sound is great for rap, reggae, and hard rock. Not all subwoofers work well in bandpass boxes and they can be tricky to tune. It's usually best to buy a preloaded bandpass box so that you know the woofer and box will work well together.

[See all of our bandpass subwoofer boxes]

Free-air subwoofers

A free-air system (also called "infinite baffle") consists of woofers mounted to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk of the car acts as an enclosure which houses the subwoofer and isolates sound from the back of the speaker, solving the sound cancellation problem of subs without an enclosure.

Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use. The lack of a box makes them more convenient to install, but their power handling levels are usually much lower than their boxed counterparts.

[See all of our free-air subwoofers]

Watch the video

Crutchfield editor Ken explains how to choose a subwoofer enclosure:

So, when choosing the subwoofer and enclosure for your system, don’t forget to consider what sound qualities you like in the music you listen to, so whether poppin' loud or humming low, you’ll end up getting the kind of bass you want.

Next steps in building your bass system

Now you know why your choice in subwoofer box matters. After deciding what kind of bass sound you want (that is, which type of box), you still need to choose your subwoofer(s). For that, we'll point you to our Subwoofer Buying Guide. If you have any questions or want help selecting your subwoofer or box, give us a shout.

Last updated 8/4/2021
  • Corey from Fort wayne

    Posted on 11/10/2021

    I just got a spl SPLW-15 and need help figuring out best box setup

  • Roy Orona from Monrovia

    Posted on 7/7/2021

    I would like to know how it sounds using a ported box and a sealed box in tandem for the same music played. I have done that at home with my surround sound running off of an Onkyo receiver.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/8/2021

    Roy, If you like the sound of the two styles blended together, go for it.
  • Hoi from Sudbury

    Posted on 5/31/2021

    While cello music is great for tuning a sub because there are pitches, I wonder what the advisors might hear if they tried a pipe organ piece that reach down to the 16 Hz area (e.g. The Best of Michael Murray by record by Telarc).

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/1/2021

    Hoi, No one really "hears" a 16 Hz tone - it is felt as bodily vibrations, if the subwoofer and amplifier can actually reproduce such a low note with any kind of audible volume.
  • David from Sacramento

    Posted on 4/26/2021

    How about a Bandpass Enclosure?

  • Smokee Long from Springfield

    Posted on 4/14/2021

    So if i take a ported box( single 12") and a sealed box (single 12") and installed them in the same vehicle. Hooked up the same and dialed in the same. Would the ported box overpower the sealed box? Or would the sealed box clean up the sound of the ported?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 4/15/2021

    Smokee, Mixing a sealed and ported in the same system will result in muddy, indistinct bass - one won't "clean up" the sound of the other. As to one over-powering the other - it completely depends on the sensitivity of the specific subs and enclosures.
  • Shridhar from Chennai

    Posted on 11/28/2020

    In ported subwoofer I'm getting the most demanding sound while watching movies but while in music it is not giving clarity so can you suggest me a good subwoofer box.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 12/6/2020

    Shridhar, It's best if you visited a home stereo store, so you can audition first-hand what the best sounding suboofer would be for you.
  • bruce from jersey city nj

    Posted on 10/14/2020

    All those people standing in diffrent places. What kind of test is that? The bass response in that boxy untreated room is going to vary a whole lot depending on where one is standing

  • david from newark nj

    Posted on 10/14/2020

    Ported only gives you more bass atthe resonant frewquency of the port, BELOEW that you actually get less bass. Since the bass response at the portfreq is out of phase with the driver you realy need to make sure it is tuned low enough that you are extendng response not overlapping too much with the native low end reponse of the driver lest you cancel some bass.

  • Jayanta Palit from Kolkata

    Posted on 9/5/2020

    Hello From India, Purchased Morel Ultimo SC 122 -12" (2 Ohm) SC series Sub woofer. I prefer only SQ sound quality with accurate , tights beats. Not like SPL blust. There is huge confusion between me & my installer. Kindly suggest, for me as a real SQ lover what I am going for, either Sealed or Ported Enclosure & what kind of board (MDF or any other). By the way purchased Morel Virtus 602 for only passive 2way setup. Thank you.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/9/2020

    Jayanta, I strongly suggest you go to a car stereo shop and give the two kinds of subs a good listen, and then pick the style you like best, not what someone tells you you should like.
  • FlukeLSX from Clinton Township

    Posted on 7/25/2020

    I am installing 2 x 12" Alpine Type S (600 watt RMS), with an Alpine Amp at 1200 watts (600 RMS) Now unfortunately the custom box designed for my vehicle doesn't allow a lot of air volume. 0.55 Cubic Feet per speaker. I was thinking about drilling small ports into the box for each speaker. Question is size of the hole. I know 3" will be do much, I was thinking along the lines of 1.5" It doesn't allow as much air to flow out but just enough to deepen the base while retaining the tight clean bass sound of a sealed box. I listen to rock and Rap and instrumental bass (Trance, Electro, Trap etc.) Would a smaller port hole be of benefit for my needs given the smaller air volume I have to work with?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/29/2020

    Fluke, Ported sub enclosures don't just have a hole in the outside of the box, the port also has the length of its tube-like structure inside the box. But go ahead and experiment - it may work out just fine.