SQ sealed vs SQ ported?

[tlee2]

from the box recommendations your sub is calling for i think sealed will do it. I dont think "loud" is what you will get though

[notorious97200]

Go ported if you have room. You will love it.

Shoot for the biggest recommanded box, in case you want to change your sub later.

[raytard]

textbook flat responses usually only come from ib, sealed with external tuning, or ported in a big box tuned low with external tuning

its incredibly uncommon to get any speaker to give a perfectly flat response without tuning IN CAR because of the car's individual transfer function, but a sealed box comes closer than ported most every time.

my personal preference is a big ported box with a big port tuned low with a little eq and DBO (dynamic bass optimization, jbl amps have it, basically a bass boost where you can choose the freq it boosts at, real nice if you have a dip in the response and want to smooth it out).

then again, most sq guys swear by sealed. i know one who swears by a single 8 in a ABC box.

get to building and see what you like most, unless you're competing, sq is purely in your ears and 100% preference. for all we know your preference is a 4th order with a linear array transducer...

[Jbiddle530]

How so?

just like army guy posted. sealed box has a flat response curve. a ported box will peak around the boxes tuning. ive built many of both and you can hear a difference.

dayton 12" ultimax sub

here i have two response plots on here for the same sub yellow is 12" sub in 3 cubic foot box sealed

and the grey line is that same sub in a 4 cubic foot box tuned to 20 hz with a -1db @ 40hz

the ported has the same great flat response that the sealed box has.. at that point the ported box really doesnt even get louder than the sealed box but look how much lower the ported will hit compaired to the sealed.. that is my take on why you would run a ported box in a sq system.. im working on building that ported box personally my self right now with a two 3" flared aero ports

[john253a]

my 2c

youll never see any highend stuff in sealed boxes weather it be home or mobil.

and if you do its only highend on your budget,

[skittlesRgood]

How so?

just like army guy posted. sealed box has a flat response curve. a ported box will peak around the boxes tuning. ive built many of both and you can hear a difference.

dayton 12" ultimax sub

here i have two response plots on here for the same sub yellow is 12" sub in 3 cubic foot box sealed

and the grey line is that same sub in a 4 cubic foot box tuned to 20 hz with a -1db @ 40hz

the ported has the same great flat response that the sealed box has.. at that point the ported box really doesnt even get louder than the sealed box but look how much lower the ported will hit compaired to the sealed.. that is my take on why you would run a ported box in a sq system.. im working on building that ported box personally my self right now with a two 3" flared aero ports

1st off, this is a 2 year old thread, who gives a shit?

2nd, thats a computer plot. its not even close to real world output.

[White Lightning]

My SQ enclosures are ported ...

[IKnowImLost224]

A speaker has damping parameters (numbers) like the Qes (Electrical damping), Qms (Mechanical damping), and Qts (Total damping). Once you put the woofer inside a acoustic suspension (sealed) box, the Qts will change to a larger number called the Qtc (enclosed damping). These damping parameters are just a way of saying how the cone motion is controlled. In a bigger sealed box, there is more air inside to support the cone motion. A huge volume of air has much less resistance to being compressed with a certain size piston (your sub), so the Qtc total damping will not rise as much inside a large sealed box. In a small sealed box, the qtc will rise much more.

Typically, guys shoot for a Qtc of about .707 for SQ. This allows the woofer to have a maximally flat response and as much low-bass extension as the sub will allow in a sealed box. A Qtc of .707 is called "critically damped" because, after that, making the box larger will have diminishing returns. The output will be much less for hardly any additonal low-end extension. A critically damped sealed box can be almost a big as a ported box, but it won't be nearly as loud. Depending on the sub, however, it will be deeper and more controlled.

In my own personal experience, building for a Qtc of around .9 sounds great once inside the vehicle. Some guys even go a little higher on the enclosed damping with 1 - 1.3. That provides for additional (more peaky) output and greater power handling than a .7 Qtc.

In a sealed box, the Qtc formula is:

Qtc = Qts * [ ( Vas / Vb ) + 1 ]1/2

A lot of good info here. Need more responses like this on the forums!