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Larger sealed box better for SQ?

Old 03-19-2011, 09:09 PM
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Larger sealed box better for SQ?

I'm thinking about running 2 JL 8w7's in a sealed box. JL recommends .875CF net volume for each sub. Would I gain anything (better efficiency? hit lower notes?) by going to 1CF or a little more per sub, or should I stick to specs?

I was also considering running one sub in a ported box and the other sealed. Would this improve overall frequency response or is it not a good idea?

Thanks in advance for any wisdom you can share!
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Old 03-19-2011, 09:47 PM
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Usually sticking to specs is the safest way to go. Or designing a box from T/S parameters would allow freq to be taylored to your needs. If reference material is available for those subs sometimes manufactures suggest multiple box scenarios.

As far as running 1 ported and 1 sealed I would imagine you could end up with cancellation issues and totally different power handling curves but would really like to hear others opinions as it is an interesting question. You'd probably need to amplify each individually , but again, other opinions?

Last edited by Mr.DatSubishi; 03-19-2011 at 09:53 PM. Reason: Adding info
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Old 03-19-2011, 09:56 PM
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Hmmm. I never really thought of cancellation issues, but that's possible. The timing of the subs could be off a little too maybe?

Do most SQ competitors stick to sealed boxes or no?
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Old 03-19-2011, 10:03 PM
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I've got an engineered SQ ported box tuned for a fairly flat response curve. Peaks in my vehicle at 51hz but has good output across all frequencies. But then again I do not compete in SQ.

I think the sub timing and difference in excursion is what would cause the cancellation. Would also like to know about SQ competitors using sealed or ported.
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Old 03-19-2011, 10:20 PM
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Originally Posted by Bumpin Balt View Post
I'm thinking about running 2 JL 8w7's in a sealed box. JL recommends .875CF net volume for each sub. Would I gain anything (better efficiency? hit lower notes?) by going to 1CF or a little more per sub, or should I stick to specs?

I was also considering running one sub in a ported box and the other sealed. Would this improve overall frequency response or is it not a good idea?

Thanks in advance for any wisdom you can share!
Stick with one type of box for them.....mixing types is generally a bad idea.

Considering how much effort JL puts into research, I would stick with the recommended enclosures. They probably know better than any other manufacturer how to use them.....

HTH
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Old 03-19-2011, 10:48 PM
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^any idea of specific drawbacks of running different enclosure types. Just wondering. And I meant that in the JL manual that came with the subs there may be a couple of different suggested designs.

Do SQ comp guys mainly run sealed or ported?

Last edited by Mr.DatSubishi; 03-19-2011 at 10:50 PM. Reason: Adding info
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Old 03-20-2011, 12:28 AM
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the newest competitors buy the wrong ported box, then by the end of the season they go sealed. The experienced competitors used sealed boxes or ported boxes as it doesn't matter both sound good when done well with the right woofer that is.
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Old 03-20-2011, 12:52 AM
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Originally Posted by Mr.DatSubishi View Post
^any idea of specific drawbacks of running different enclosure types. Just wondering. And I meant that in the JL manual that came with the subs there may be a couple of different suggested designs.

Do SQ comp guys mainly run sealed or ported?
Subwoofer box theory - http://www.mobileinformationlabs.com/HowTo-1Woofer-BoxPaid-New.htm

You can use any type of box to do well in an SQ comp. It's the raw sound of a sub that's more important, the box will just change the response. If using a sealed box than the response is entirely dependant upon the sub. If the sub doesn't model well sealed than obviously ported would have to do. Not a lot of SQ subs are better in sealed than ported unless you're trying to have lots of < 25 Hz output. Ported doesn't diminish SQ although many swear that a sealed box provides a tighter sound (really depends on the ported design). It's all personal preference. Maybe you do have the best sounding stereo ever, but maybe a judge doesn't think so. This is why SQ comps suck, it's a box of chocolates.

Model sealed box frequency response - http://www.carstereo.com/help/Articles.cfm?id=30

My best consideration of sub-SQ is a flat response (in the car, not on paper) to within 1dB from 20 Hz to 100 Hz, and it has to sound good and be tight (4th-order bandpass would do it with lots of testing). It's unfair to judge the raw sound, so I'd probably vote for the flattest frequency response, and save the imaging & transient-response for the fronts.
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Old 03-20-2011, 01:17 AM
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^^VERY informative! Thanks! So doing one of each is a NONO?
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Old 03-20-2011, 01:23 AM
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^sorry I was asking about what we were previously talking about, benefits or drawbacks of running 1 box ported and 1 box sealed in the same car. I will read those links on box theory and will probably learn something.
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