Pros and cons of ported boxes


Bronze Member
Username: Langless28

Post Number: 45
Registered: Dec-04
im most likely getting an infinity perfect dvc 12" or one from polk audio. i have a sub in a ported box in my car now, what are the real advanages over a ported box and how does the sound change from box type to box type. a good post here will shut me up haha cus im confused>

Silver Member
Username: Jmloughrey

Farmington, CT

Post Number: 617
Registered: Jul-04
Basically a ported box will get you a little louder on your SPL side, I beleive power handling does go down a little bit and it'll take up more room. You'll gain a much deeper responce from your sub on those lower notes.

A Sealed box will be able to handle more power (dont quote me on that again) as well as take up less room. Your sub will have a more all around frequency responce. You also dont have to worry about tuning a port...

Gold Member
Username: Jonathan_f


Post Number: 2842
Registered: May-04
Power handling actually increases when using a ported box, and it's also more efficient. Cone excursion will be less with a ported box at any point above the tuned frequency, and since the port exposes the sub to outside air, the voice coil cooling is a little better as well. Ported boxes have more group delay and worse transient response than a sealed box. Sealed boxes have little boost in output at certain frequencies other than resonance, so response is flatter, especially in a car where cabin gain helps compensate for the rolloff of the box, which isn't as steep as a ported box. A sealed box controls the cone at really low frequencies, so subsonics are no problem, but they aren't as authoritative as a ported box.

Bronze Member
Username: Cheapskate

Post Number: 58
Registered: Mar-04
pros: higher efficiency and more extended bass when properly tuned.

cons: that extra "boom" is pure distortion. it's not the sound of the music, it's the sound of the air inside your cabinet "echoing". it's the same kind of distortion you get if you speak into a paper towel roll. ported bass is sloppier and slower. i hate ported! yuck! LOL

acoustic suspension:
pros: tighter faster transients as the air inside the cabinet acts as a spring. much lower distortion.
cons: won't impress anyone who thinks that sloppy ugly booming is "real music". requires more power. bass is less extended.

"ultimate" = isobarik or push-pull. two woofers working as one either one behind the other, or one facing the other but wired out of phase.

pros: even faster than one acoustic suspension woofer. even less distortion. doesn't require as large a box. can go deeper than acousic suspension. basically, you're using two woofers to move the same amount of air. the second woofer helps the first.

cons: more expensive. some might consider seeing only the back of a woofer ugly (in the facing each other setup) you need to either build the box around the woofers or create a removeable side. requires 2X the power for the same dB.

then there's
bandpass (sealed within a ported enclosure... even more boom than plain ported)
transmission line (1 giant mega port)
passive radiator (sealed but port like)
aperiodic (sealed with a damped breathing hole eg. a port stuffed with a sponge)
horn loaded (maximum SPL)
free air which is terrible for woofers as the back wave cancels the front.

Bronze Member
Username: Cheapskate

Post Number: 59
Registered: Mar-04
2 more ported cons...

occasional port noise called "chuffing" depending on port size and shape. flared and dimpled ports reduce port noise.

the dreaded "one note bass" as the resonant frequency is heard over other bass frequencies.

i can tell that my knuckleheaded bass freak neigbor's speakers are ported because EVERY note has the same annoying *boom* regardless of the notes in a bassline.

Bronze Member
Username: Cheapskate

Post Number: 60
Registered: Mar-04
as to acoustic suspension handling more power... that's not 100% correct, but there is some (qualified) truth to the statement.

in an acoustic suspension stereo speaker that you buy, it might have a higher power rating as it was designed to handle more power due to lower efficiency. an acoustic suspension speaker has to have more power to play as loud as a ported one.

the same DRIVER will have the same power rating no matter what type of enclosure you put it in. acoustic suspension designed drivers will tend to have higher power ratings to compensate for their intended use.

Gold Member
Username: Jonathan_f


Post Number: 2847
Registered: May-04
You obviously know very little about ported boxes and are obviously too biased to give intelligent information about them. You need to listen to a well built SQ ported box, not the typical 45hz tuned premade crap someone bought at Best Buy. Ported boxes have LESS distortion than sealed boxes at any point other than below tuning, you'll especially notice a difference at high volumes. Remember ported boxes control a subwoofer more than a sealed box above tuning, excursion is less. That "boom" you're talking about isn't distortion, it's resonance and is totally different. Air excites (resonates) at a certain frequency, it isn't distortion, if the box is built well it will sound as if it were the driver producing it and have no port noise or extra mechanical noise to affect the sound quality. The added resonance increases output within the range of the tuned frequency, so if you tune high, it's noticeable because when tuned high, regular box sizes will create a hump in the response. This is because you're closer to the downpoint of the enclosure, the rolloff of the enclosure doesn't come into play and level out the output. BUT if you build the box well it won't result in a boomy response or a huge hump in the frequency range, you just have to match output by tuning low and building a box with a higher downpoint. If you accomplish this, you'll get great sound quality and (basically) free output.

Gold Member
Username: Jonathan_f


Post Number: 2848
Registered: May-04
"transmission line (1 giant mega port)"
It's much more complicated than a "mega port". You are tuning the enclosure to a certain fraction (1/4 wave is most common) of the wavelength of the resonant frequency of a driver. It controls the cone of a speaker totally differently than a sealed or ported box, and is actually better than both from any way you can slice it because it has better transient response, lower distortion, AND more efficiency. The output of the port arrives in phase with the driver, so there are no phase shifts. It also allows the driver to play below it's resonant frequency without losing damping.

"free air which is terrible for woofers as the back wave cancels the front."
That's why you add a baffle, then no cancellation occurs. Free air will work with many drivers and can still work well, hence all component systems for car audio.


Bronze Member
Username: Cheapskate

Post Number: 71
Registered: Mar-04
yes, i AM totally biased against ported speakers as i just don't like their sound. i don't care for paradigm or B&W bass one bit. don't try and call those crappy speakers.

i'm not as ignorant as you seem to think. i know what i like, and i like sealed speakers because they punch so much quicker.

if you claim that ported speakers are less distorted, then it is YOU that doesn't know as much as you think. ported speakers are little more than bass echo machines. how you can call out of phase soundwaves and RESONANCE distortion less distortion is silly. porting increases efficiency by adding soundwaves that shouldn't be there to begin with.

a port's tuning can ONLY be "in phase" for specific frequencies whose wavelengths match the box geometry. you know that different frequencies have different wavelengths right? from that, you can also know that geometries that don't match wavelengths are bad and cause cancellations.

if you can talk through a toilet paper roll and not hear distortion, then you need new ears.

properly designed ported boxes are better than crappier ones, but they all still add "non program" fundamentals to the music that are delayed from the original impulse. that is a fact. no matter how well you tune a ported speaker, it's output will ALWAYS be delayed behind the speaker as sound only travels 700 and some odd miles per hour. adding ANYTHING a few milliseconds after an impulse is pure distortion. there should be total silence after an impulse, NOT distortion related to blowing air over a bottle's opening.

calling transmission line "mega ported" was an over simplification, but the idea behind it is similar to porting or passive radiators. all 3 add frequency specific distortion to a speaker's output to make the bass louder.

bass cancellation increases the deeper you go. magnepans are 100% free air and pretty flat except for the bass range where they roll off. if i take my 12" out of it's box, it becomes almost silent.


Jonathon, where can I get information on how to build this proper ported box you speak of?

Gold Member
Username: Jonathan_f


Post Number: 2897
Registered: May-04
"a port's tuning can ONLY be "in phase" for specific frequencies whose wavelengths match the box geometry. you know that different frequencies have different wavelengths right? from that, you can also know that geometries that don't match wavelengths are bad and cause cancellations."

"no matter how well you tune a ported speaker, it's output will ALWAYS be delayed behind the speaker as sound only travels 700 and some odd miles per hour. adding ANYTHING a few milliseconds after an impulse is pure distortion. there should be total silence after an impulse, NOT distortion related to blowing air over a bottle's opening."

I'm very well aware of acoustic phase. Measure your speakers in your car. Chances are the right speaker is farther away from you than the left. If you have components, it'll be even worse. This equals acoustic phase issues, delayed response, and causes cancellation and boosts at different frequencies. Exact same situation as with a ported box. People seem to deal with pathlength differences very well, though, and with a ported enclosure it's no different. It's not an ideal situation, but it's inevitable nonetheless. I guess you'd label pathlength differences as pure distortion as well since you're adding right channel information milliseconds after it should arrive, so all of us who drive cars just listen to pure distortion all day long and love every minute of it. By the way, I was referring to driver distortion. Sealed boxes resonate as well, you failed to mention that on your whole "ported boxes suck" crapathon. Sealed isn't a perfect alignment for sound quality either, the driver is less controlled than ported anywhere above tuning. The difference at resonance is that a ported box exerts maximum control at resonance, equalling lower distortion while still boosting output. Sealed boxes have the least control at resonance, and still boost output at that frequency while the driver goes near maximum excursion and increases distortion.
So in your words, both enclosures add "non program fundamentals". The only difference is that ported boxes add a boost at that frequency, whether you want it or not is subjective. Transient response and group delay are totally different from driver distortion, and that's where the sealed box excels. But, it doesn't mean a ported box will sound like a$$ either. A subs suspension compliance ALSO effects transient response, you have to choose your enclosure based on what driver you intend to run. Once you get into the down and dirty acoustics of a system, you realize that every driver in your vehicle is out of phase to a certain extent, not just because of the enclosure and pathlengths, but because of the inductance of the drivers, suspension compliance, motor strength and design, etc., but you don't notice it because of the limitations of the human ear. I too prefer sealed over ported, but you have to weigh out your options and not put some childish remarks on a board like "yuck" and describing a bunch of common misconceptions about the box design. Just because you don't like it doesn't mean someone else won't. If you really want a system that provides a tight sound quality, flat frequency response, low resonance, you need to consider aperiodic. It mechanically dampens the resonance of the driver via resistive material. It results in excellent driver control and a flatter, more predictable frequency response without the resonance issues of sealed or ported boxes.

Silver Member
Username: Johnnylemoine

LaPlace, Louisiana United States

Post Number: 349
Registered: Aug-04
sound moves at 343 m/s
haha , i know something

Unregistered guest
Well, Jonathan and Budget Minded, sounds like both of you know what you're talking about. I prefer the sealed box. It has tighter bass and a much cleaner bump than a ported. A bandpass seams to extend the bump for a longer period which i also like. yeah man.

I was wondering, is in it better to follow the recomedations of the speaker manuals. I have always followed them and they have not dissappointed me yet.

Anyways, both of u argue to much. The answer is very plain words that someone like me would understand, sealed is better.

Ported boxes suck, tuned or not tuned, they all suck, i would never buy and i would never make one.


Unregistered guest

I have 2 RF punch HX2 10", and in the manuals they state sealed boxes offer better better spl then a ported.

While that's the specs for these speakers I don't know if it's true for all. That's why I said it's better to follow the manuals.

Bronze Member
Username: Cheapskate

Post Number: 78
Registered: Mar-04
i don't have or want a car. i actually visited this forum because i want to build a high efficiency sound system for a custom bicycle i plan on buying for next year.

all of my home speakers are sealed, and the foam plugs NEVER come out of my little missions even when i'm using them as "midbass subs". to me, those missions just sound slow and sloppy uncorked. plugging them back up makes them sound clearer.

i really wish that i could remember the article that i read that discussed distortion levels in sealed vs ported, but that was many years ago.

in a way... i do prefer distortion as i hate flat bass response. i prefer rolled off tight bass. that's a distortion of the frequency response.

regardless of what the technical papers say, to my ears, ported speakers go *wuh wuh whu* while small sealed speakers go *bump bump bump*. to me, that's less distortion. rounding of transients is a form of distortion too.

one note bass happens. LOL

alot of this debate really boils down to personal preferences. some prefer huge cavernous bass while others prefer punchy detalied bass.

my first experience listening to real hi-fi was a friend's pair of 4 1/2" sealed infinity $100 speakers. from that day... i've been a militant acoustic suspension advocate.

planar bass is the best though. ;)

Bronze Member
Username: Wojopro

Post Number: 81
Registered: Nov-04
Hehehe... Funny thread here! Battle over sealed vs ported... Ive had a good ported box... It was homemade... I prefer my sealed box though.

Unregistered guest
"alot of this debate really boils down to personal preferences. some prefer huge cavernous bass while others prefer punchy detalied bass."

well said....

punchy detailed bass here, all the way......peace!

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7042
Registered: Dec-03
jsut as a point of reference, I used a ported enclosure for my IASCA vehicle which was aimed strictly at SQ, and managed to win just about every event I entered. Prebuilt/prefab enclosures will never sound that good.
Isobaric enclosures have a lot of drawbacks and really offer nothing audibly advantageous.
Transmission Line enclosures are fantastic, but are huge, so not often used in cars with larger subs.
folded horn, and higher order bandpass boxes are also difficult to build and design so pros/cons aside they are large and very expensive or hard to build.

Everything Jon objectively pointed out is completely correct in regards to enclosure function.

A lot of people get hooked on coin phrases like "a sealed box is more accurate" but really don't know what that means. A sealed box can sound very boomy at higher frequencies as well, and have their own issues, but they are "flat" in response, so they sound closer to the original source material.
A lot of folks prefer more bass than "flat" though and want it to spike at lower frequencies. Especially since the human hearing range is far less sensitive at low frequencies than it is at upper midrange. For this reason, the ported box is a good choice to compensate for the natural lacking response of human hearing.

just food for thought.
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