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Old 16th March 2013, 03:24 AM   #1
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Question Sealed vs Ported subwoofer??

I am curious what's the difference between these two.
How does a sealed sub work??
after researching this all I can find are opinions

How does this sub sound in a sealed vs ported
15" big xmax sub 25mm & 43mm Xmech
This thing looks like a Monster & better than Dayton Titanic
Stereo integrity HT 15" Dual 2 Ohm subwoofer

Last edited by Kingnoob; 16th March 2013 at 04:40 AM.
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Old 16th March 2013, 05:12 AM   #2
DUG is offline DUG  Canada
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"How does a sealed sub work??"

Speaker compresses the air in the box...acts as shock absorber or damper.

Could you post a synopsis of the opinions you have found...Then we can offer more opinions on those opinions (and possibly some facts).

There is a lot of information on DIYAUDIO on this subject, answering this same question.

Happy Hunting.
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Old 16th March 2013, 05:19 AM   #3
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These two subs are almost identical in design and purpose. Both could be described as "universal".........what does that mean? Calculating to determine if either driver would be best used as a ported type or a sealed type...the designers have "split the difference"... Efficiency bandwidth product is a calculation to determine if it is best to port it or go with the sealed enclosure. By splitting the difference compromises have to be made....rendering the outcome mediocre at best. Both have a giant Xmax which lends itself to less than optimal performance...another compromise. Essentially the more Xmax you have the more likely you will not be getting pure linear cone movement.
Cone control gets harder & harder the more travel you get. These HT drivers are simple extensions of drivers used in the Car Sub-woofer market......that of which has been overwhelmingly dismissed as suitable for Home use.
I would look elsewhere for a suitable driver....one that has "chosen" to be used in a port or not.

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Old 16th March 2013, 05:35 AM   #4
OscarS is offline OscarS  United States
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Designed for sealed or ported...explained! - DIYMA Car Audio Forum

from a JBL engineer. You can pretty much take all of that as fact and not opinion. It is all rooted in physics. If you need to know more...

http://commonmode.blogspot.com/2008_01_01_archive.html

and if you still need to know more, pick up any college level University Physics 101 textbook and look up the chapters on damped harmonic oscillators.

Last edited by OscarS; 16th March 2013 at 05:38 AM.
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Old 16th March 2013, 12:07 PM   #5
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Quote:
Originally Posted by Richard Ellis View Post
These two subs are almost identical in design and purpose. Both could be described as "universal".........what does that mean? Calculating to determine if either driver would be best used as a ported type or a sealed type...the designers have "split the difference"... Efficiency bandwidth product is a calculation to determine if it is best to port it or go with the sealed enclosure. By splitting the difference compromises have to be made....rendering the outcome mediocre at best. Both have a giant Xmax which lends itself to less than optimal performance...another compromise. Essentially the more Xmax you have the more likely you will not be getting pure linear cone movement.
Cone control gets harder & harder the more travel you get. These HT drivers are simple extensions of drivers used in the Car Sub-woofer market......that of which has been overwhelmingly dismissed as suitable for Home use.
I would look elsewhere for a suitable driver....one that has "chosen" to be used in a port or not.

__________________________________________________ _Rick.........
Don't dismiss car drivers with strong motors and huge X-Max, in the end it is all about moving air. The 18" SI is a great value HT sub driver.

Last edited by mr. doom; 16th March 2013 at 12:11 PM.
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Old 16th March 2013, 03:22 PM   #6
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yeah SI 15" is a beast sub also.
beats all 15" dayton subs

very popular on home-theater shack
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Old 17th March 2013, 02:15 AM   #7
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BUMP- can I get some help on this topic??
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Old 17th March 2013, 03:43 PM   #8
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Quote:
Originally Posted by Kingnoob View Post
BUMP- can I get some help on this topic??
Simple answer. Ported boxes need to be much larger but will give you more output per watt around the tuning of the port (20-30) hz. etc.

A small sealed box will need EQ and more amp power to get those same frequencies and then you can run out of travel (x-max) or exceed the thermal rating of the driver and get (power compression/cooked voice coils).

As to which is best it depends on the driver/room/application and how big of a box you can accommodate.
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Old 17th March 2013, 05:18 PM   #9
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by Kingnoob View Post
BUMP- can I get some help on this topic??
What more help do you need?
With 15" subwoofer (which surely can go low whatever the box alignment), just build sealed box if you don't have a problem with big size. Whichever the alignment, you need to know the math to make it work anyway. But sealed has better transient, and more tolerant.

People usually design (in simulator) both types, then choose the best one based on simulation result.

If your system contains opamps, you can build a compact sealed sub with Linkwitz Transform circuit, as shown in ESP site.
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Old 17th March 2013, 05:43 PM   #10
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Stereo Integrity site suggests a 3 cubic foot sealed box
Any Tips on bracing? or building box.
I take it Dampening material inside makes the box sound louder?

If MDF better than plywood for sealed box?
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