ported vs. sealed

Systems

I was wondering if a sealed box offers any more protection to a sub over a ported enclosure. Myself and a few friends have noticed that more subs tend to wear out/blow sooner in ported boxes and were wondering if anyone else has noticed this trend.

exalted512

the only reason that would happen is due to over powering them or if the box isnt built to the specs of the sub
-Cody

Systems

i'm not saying that the subs will crap out abnormally soon, just that if you looked at the average life of a ported enclosure vs. sealed, i think the sealed lasts a little longer. as far as power and design, both were in alignment with the parameters listed by polk and other manufact's. my guess is that the damping provided by the pressure build up in a sealed box will prevent bottoming out.(to some extent anyway, probably minor)

exalted512

a ported box has more back pressure than a sealed box
-Cody

MacLeod

You sure about that? I admit subs aint my area of expertise but I wouldve thought the sealed would have much more pressure seing as how theres nowhere for the air to go.

exalted512

yes sir

AustinKP

In a correctly designed ported box, the air in the port and the sub are in relative phase, meaning, the air is moving in the same direction. Both are going out or in. Thus, the pressure in a ported box at tuning can actually be double that of a sealed box. Let me know if that doesn't make sense.
-Austin

Systems

ok, you might be right but i still don't understand why. in a true sealed enclosure there is no way for air to get in or out. you will always be compressing the same amount of air inside the box. so the longer back stroke the driver travels, the higher resultant pressure inside the box. if the pressure is increasing inside the box at high volumes, then wouldn't this act as a crude shock absorber? a ported box seems like it would provide little to no lasting pressure inside... kinda like a sheet flappin' in the wind

i'm confused:)

VR3

What does it matter?

The life span of a speaker has crap to do with the enclosure design...

Speakers blow because people don't use their brain. If your woofer is crackling - it is distorting/bottoming.

If you are turning your music up and your bass dosnt get any louder while you keep pressing the up button. Your amp is clipping.

Sealed or not, dosn't matter.

Under-powering or overpowering (which usually isnt that big of a problem) can also blow a speaker if you dont pay attention.

Polk isnt known for high SPL applications anyways...

exalted512

i AM right;)
basically, when the air rushes out, more air will rush in than it would at an "at rest" state
thats about as simple to understand as i can get it, its not rocket science.
-Cody

Mjr7531

It mostly depends on how you tune the ported box, if you tune it too high for your application, then you can possibly unload the woofer, not good.. this doesn't happend with a sealed box. However, like the aforementioned, common sense, like anything else in life, will get you very far.

i AM right
basically, when the air rushes out, more air will rush in than it would at an "at rest" state
thats about as simple to understand as i can get it, its not rocket science.
Exactly! Its Physics Science.

audiobliss

Sid, the enclosure has everything to do with it....I don't know much about this, but I have picked that up. If you have a ported box and don't tune it right, you can essentially end up with no resistance which, of course, ain't good.

That's all I understand about it.....:p

exalted512

Originally posted by audiobliss
Sid, the enclosure has everything to do with it....I don't know much about this, but I have picked that up. If you have a ported box and don't tune it right, you can essentially end up with no resistance which, of course, ain't good.

That's all I understand about it.....:p

he was talking about the original question, that it does not matter if it was ported or sealed--you are not more likely to blow your sub with one or the other if both are built correct
-Cody

audiobliss

oh, I see.......you mean.....I still didn't contribute anything to this.....?:(

Systems

cody- i did a little research last night and it confirmed what you were saying about the directionality of the air when the port and driver are in phase. but that is only at or above the tuning freq.. in almost any sort of music there is bound to be notes lower than that freq. causing the unloading of the driver.
a sub is a mechanical device and all mechanical devices have a finite lifespan. a ported box playing notes at ANY volume below its tuning freq. is unloaded therefore relying purely on its own suspension. if a sealed box always has resistance behind it then it takes a measure of stress off the mechanical parts of the sub.
anyways, this whole question wasn't a basis for selection, just kind of a theoretical, so i'll put it down:)

AustinKP

Originally posted by seatown12s
in almost any sort of music there is bound to be notes lower than that freq. causing the unloading of the driver.

That's why one uses a Subsonic Filter. That way, no notes lower than tuning are played, thus, no unloading of the driver.

Do you understand the part about more pressure in a ported enclosure now? Just in case, here's a potentially easier-to-understand explanation. In a properly tuned box, when the sub is playing notes at or near the tuning frequency, air is moving IN the port at the same time the cone is moving IN. Thus, there is actually more air inside the box than there would be in a sealed box.

a ported box seems like it would provide little to no lasting pressure inside... kinda like a sheet flappin' in the wind

You're correct here, in that it doesn't provide any lasting pressure, but neither does a sealed box. When the speaker is at rest, the air inside both boxes is just the ambient pressure. When the speaker starts flappin' is when you start seeing differences. A sealed box only has the internal volume of air to cushion the speaker, whereas a ported box can have twice the backpressure to cushion the speaker.

So, to answer your original question: It depends. The reason you probably notice more ported subs blow quicker is that it's pretty easy to tune them wrong, thus causing premature wearing of the suspension leading to failure.

-Austin

audiobliss

wow.....that is all very interesting.......glad you posted and I read......lol

MacLeod

Originally posted by AustinKP
That's why one uses a Subsonic Filter. That way, no notes lower than tuning are played, thus, no unloading of the driver.

Well, actually sub sonic filters are used to spare the sub from having to reproduce notes it aint gonna be able to do very well, say like 15 Hz. Most ported boxes seem to be tuned to around 40 Hz if Im not mistaken. Cutting off frequencies below 40 Hz would leave quite a gap.

VR3

Sounds like to me....

CA newbies shouldnt be allowed to touch ports...

How come you guys dont use PRs? eh eh?

Definetely looks cooler than a port, same general properties, helps effeciency and extention

MacLeod

I dont like ports at all. Theyre great for impressing your friends but when you want SQ, sealed is the only way to go!

exalted512

someone hasnt heard a properly SQ tuned ported box...
-Cody

VR3

You got that right...

A properly tuned ported enclosure can be every bit as accurate as a sealed enclosure, easily...

Even some of the best subs in the world. Infact, I know of a 10,000 dollar passive subwoofer that has two gigantic ports...

http://www.wilsonaudio.com/products/xs/index.html

Dual 18" woofers

MacLeod

Right, you take a ported box and put a lot of work into calculations and work and time and tune it just right and itll sound as good as a sealed.

Or you can just be a sealed and get the same results in half the time with half the work with a box about half the size!

Mjr7531

Originally posted by Vr3MxStyler2k3
You got that right...

A properly tuned ported enclosure can be every bit as accurate as a sealed enclosure, easily...

Even some of the best subs in the world. Infact, I know of a 10,000 dollar passive subwoofer that has two gigantic ports...

http://www.wilsonaudio.com/products/xs/index.html

Dual 18" woofers

Dunno about the just as good Sid...
http://www.adireaudio.com/Files/TechPapers/GroupDelay.pdf
Eh, it's all personal preference anyways...

Edit: As good, I don't know, hmm... 'different'. (No hard feeling intended)

exalted512

Originally posted by MacLeod
Well, actually sub sonic filters are used to spare the sub from having to reproduce notes it aint gonna be able to do very well, say like 15 Hz. Most ported boxes seem to be tuned to around 40 Hz if Im not mistaken. Cutting off frequencies below 40 Hz would leave quite a gap.
Right, you take a ported box and put a lot of work into calculations and work and time and tune it just right and itll sound as good as a sealed.

Or you can just be a sealed and get the same results in half the time with half the work with a box about half the size!

most sub sonic filters are around 28Hz, some being adjustable, most ported boxes designed for SQ are tuned to ~28Hz, for SQL around 32Hz, and for pure SPL, can get around 45+Hz. you can get ported boxes to sound better than sealed which is why a lot of people use them for SQ. since every car is different, the cabin on vehicles will exert peaks in certain frequencies, you can counter this with your tuning frequency. you can also get a ported box to sound just as good and be much louder than a sealed box.
-Cody

AustinKP

Originally posted by MacLeod
Or you can just be a sealed and get the same results in half the time with half the work with a box about half the size!

But at a cost of -3dB... Many people choose ported just because it gives a free 3 dB.

MacLeod

Ya know how miniscule 3 db is? Barely noticeable.

I agree if youre going for DB Drag or other SPL competitions then ported is the way to go if you need to wring out every last bit of output.

Me, I could really care less about bass. All I really want is good extension of my mids/highs.

AustinKP

Originally posted by MacLeod
Ya know how miniscule 3 db is? Barely noticeable.

Agreed, but you do also realize that it takes a doubling of power to get a 3dB gain, right? So just by changing box type and doing some extra work to tune it right, you CAN get the same sound -or possibly better- and get the equivalent of double the amp power.

Now, we all know that you only need like 15 watts to be happy, but for someone like Cody who wants Loud AND Clear sound, that application could be very useful, given enough space for the enclosure.

exalted512

Originally posted by AustinKP

Now, we all know that you only need like 15 watts to be happy

aint that the truth!?!
-Cody

MacLeod

Yeah, me and my measly 135 watts per channel to my mids/highs. :rolleyes:

exalted512

damn right its measly, talk to me when its over 200;)
-Cody