Sealed or ported
The differences in subwoofer enclosures
In the 1950's, I'd take the family television's vacuum tubes down to Willow Grove Radio and TV Repair, check them with the giant tester machine, buy new replacement tubes, and reassemble the repaired television, so my mom and dad could enjoy their precious, respectively, Dean Martin and Red Skelton shows. In the 1960's, I studied radio and electronics at the Franklin Institute in Philadelphia. After college, in the early 70's, I joined a rock 'n roll band as the soundman, learning how to operate the electronics that make music sound good. Then, I worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems and components for recording studios, nightclubs, and touring bands. I moved back to Charlottesville permanently in 1984 and opened a little demo recording studio. I also attempted to put to practical use the creative writing degree I had picked up along the way. In 2006, I finally came to my senses and got this job at Crutchfield where they actually pay me to ramble on, rant, and explain the things I love about music, electronics, and getting good sound.
More from Buck Pomerantz
The only way you're really going to get full, rich-sounding bass from your car stereo is to put in a subwoofer. Adding a sub to your 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. To demonstrate this, we brought a small group of Advisors into the Labs, played different kinds of music through the same component subwoofer loaded in two different kinds of enclosures, and had them vote for which sounded best to them for each song.
Camp A: I want to hear bass, not thunder
Each beat in a tight bass setup plays crisply, accurately, and with no ringing after it hits. The easiest way to achieve this is with a sealed sub box. 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 subs are generally more compact than ported subs, so they fit in more vehicles.
Sealed air moderates the cone’s motion.
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.
Camp B: I like it loud
Boomy bass has more punch and reverberance in each of its beats. This is easily attained, without using any equalizer or processor, with a ported sub box, where 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.
Air flows in and out of the port.
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.
Which sub enclosure do you prefer with different kinds of music?
Crutchfield Advisors often ask their subwoofer customers what styles of music they like, so that they can recommend a sub that will match the customer’s tastes. The panel of Advisors who participated in this demonstration were all eager to listen to the two subs as part of their ongoing efforts to improve the quality of their advice to customers. The results, and some of their comments, are charted below.
The lineup of listeners
The small crowd consisted of Advisors Duke (who, at the time, had been here for almost 5 years), Dolly (4 years), Daniel (almost 2 years), and Dylan and Larry (1 year each). Travis, a Graphic Designer at Crutchfield for over 12 years, decided to join the fun, too.
The listening setup
We loaded Sound Ordnance sealed and ported enclosures with identical Alpine 10" subs, and powered them with the same mono amp mounted in our car listening room. The only change that occurred, when we switched between the subs every 10 seconds, was the kind of sub enclosure being played. We played various kinds of music both with and without full-range speakers, so our listeners could judge the sound quality of the bass, with minimal influence by the change in volume due to the different efficiencies of the subs.
(We didn't play any subwoofer mounted in an "infinite baffle" or "free air" setup, or in a bandpass enclosure, because these hybrid systems usually need sound processing to sound right, and would be difficult to compare fairly in the Labs.)
Two of our listeners, Travis and Dylan, compare notes in the Labs
|The Votes||Sealed box||Ported box|
- Pop: “The ported had more punch but sounded muddy. The sealed sounded better to me on this one.” – Travis, Designer
- Rock/Alt: “The sealed sub delivered more emphatic bass. The ported was louder, but it got away from the music.” – Duke, Advisor
- Classical: Two Advisors heard no difference for the cello-heavy piece we chose to play.
- R&B/Rap: “The bass definitely sounded more natural with the ported box for the Rap.” – Dolly, Advisor
- Electro/Dance: “The ported sub sounded and felt better to me for this song. It accentuated the quality of the bass.” – Larry, Advisor
Daniel, Advisor: “The sealed sub was definitely tighter and more accurate which some may prefer for listening to certain styles of music, like maybe Country or Classic Rock. I liked the ported mostly for the heavy bass.”
Dylan, Advisor: “When I preferred the ported it was because it seemed to fill out the music with something that was missing from the song itself. When I preferred the sealed it was because of the quality of the bass. It would hit on every note, keep a perfect beat, and make the song flow more appropriately.”
The mixed reactions and the tie votes reinforce the notion that it basically comes down to taste in music. “Accuracy” and “tone fits the music” were two sound qualities cited by Advisors who liked the sealed sub for the Classical piece. But those same Advisors thought the sealed sub’s sound did not fit with the Rap and Dance songs—it depended on the quality of the bass in the songs themselves.
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.