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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.

  • Mr bill from New york

    Posted on 1/14/2023

    Wished I would have known about this article before I built my box.. I have a 2000 crv limited space and made a ported box.. not the sound I was looking for.. so back to build

  • Michael Ross from Iloilo

    Posted on 1/5/2023

    If yu use both types of boxs, you would get the best of both worlds???

  • Phil from Green Brook, NJ

    Posted on 4/3/2022

    Would there be any benefit to having both a ported and an enclosed subwoofer in the same space, like in an SUV? Would you get both the precise punch and the boom associated with both types of boxes, or would the sound just get lost?

  • Trenton Merklin from Show Low

    Posted on 3/6/2022

    In my pickup, I have 2 kicker 10"compvx in a ported enclosure powered by a 2000W amp AND 2 kicker 10" compvx in a sealed enclosure powered by another 2000W amp. The ported hits harder. (More boom and vibration from bass) However, in my car I have 2 MTX 12" subs in a sealed enclosure powered by a 500W amp AND 2 JLAUDIO 12" subs in a ported enclosure powered by a 250W amp. (It was a quick throw together system) The sealed hits harder. Plus the car is waaaay louder than the truck. This is a battle everyone has. 12s vs. 10s and sealed vs. Ported. Can you shed any light on the situation?

  • Jonathan Kuykendall from Little Rock.

    Posted on 12/24/2021

    I have a 1997 dodge 2500 ext cab. No room in rear so I want to put a great sounding woofer a good 8in or 10in. Just one to add that great bass sound to my mids and hi. I love all music rap country rock whatever. Do you Carrie a woofer that would fit underneath back seat ?

  • 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.

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