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subwoofer box size

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=71217
Printed Date: July 03, 2025 at 3:22 AM


Topic: subwoofer box size

Posted By: monorail
Subject: subwoofer box size
Date Posted: January 21, 2006 at 5:50 AM

I've got 2 12" Precision JW12 subs. The recommended sealed box size is 1.75 cubic feet per speaker. My question is what is the absolute minimum box size I can use with batting. I'd like to keep it around 1.5 cubic feet or less, is this feasible?



Replies:

Posted By: stevdart
Date Posted: January 21, 2006 at 9:58 AM

Is this it?  I'm highly skeptical that this is an identical copy of a JL 12W6.  I'll be up front about this type of sub (category - brand name knockoff):  you don't design boxes for these.  You buy a prefab box, put them in it and hope for the best.  But otherwise, to be a litlte nicer about this...polyfil stuffing will give you a net increase of air space of 10 to 30%.



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: monorail
Date Posted: January 26, 2006 at 7:18 PM

stevdart,

Yes, those are the ones. And yes, they are cheapos. My 16 y/o son bought them online without a clue, so that's what he's getting installed.

I never had any intention of building a box, it's gonna be prefab for sure. I can get a 1.25 cu.ft. per side box for $35 at the flea market. I figure with a little polyfil it'll be close enough. Like you said, hope for the best.

I do have one other question though. They are rated at 450W rms each (6 ohm DVC). If I wire the speakers in parallel and the voice coils in series, do I have 450W or 900W rating if driven by a single channel? The reason I ask is the amp he has (another cheapo) is rated at 720W rms bridged mono into 4 ohms. I know the output will drop into the 6 ohm load, but I want to make sure the speakers won't be overdriven.

If you're interested, the amp is an SPL ST2-1440.

Flame away if you like, and thanks for any replies.





Posted By: geepherder
Date Posted: January 26, 2006 at 7:22 PM
The power supplied by the amp will be divided by the subwoofers, so you'll be fine.

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My ex once told me I have a perfect face for radio.




Posted By: monorail
Date Posted: January 26, 2006 at 7:36 PM
Thanks geepherder! I was hoping that was the case.




Posted By: stevdart
Date Posted: January 26, 2006 at 7:49 PM
I, too, have a son who is a bit older than that now...and I myself have made some very foolish "got to have it now" online buys at one time.  So I know where you're coming from.  What geepherder said...you won't have to worry about overpowering.  In all reality, at least you're dealing with apples-to-apples.  There will probably be no more than 200 watts going into each of those subs on a fair day with a strong wind at the back of the amp, and the subs can probably handle that amount of RMS power all day long.  But get the gain adjustment right.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: monorail
Date Posted: January 29, 2006 at 5:56 PM

Hey guys, did the install this weekend. No problems and it sounds remarkably better than I had imagined. The subs work fine and the amp is definitely not being overpowered.

Thanks for the help!






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