# JL 12W6v3 - Sealed



## joms (Mar 10, 2005)

How would the 12w6v3 perform in a 1.2cuft sealed box? A lot of people say that increasing the box slightly will make the subs sound better/softer which was true with the old JLs. Does this apply to the new 12w6v3 as well or is 1.0 cuft really the best size for this?

Also, would it be better to put some fiberfill inside the box or would that ruin the SQ?


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## qwertydude (Dec 22, 2008)

Almost all subwoofers that sound good in a sealed box benefit from using larger boxes. I don't know what you mean by "softer" but it will flatten the response curve. A smaller box does give a slight boost in efficiency but generally only in boomier sounding frequencies.

Larger boxes though do tend to reduce power handling in lower frequencies but it's normally made up for with increased efficiency in those lower frequencies so output isn't changed much. It's just you'll reach the mechanical limits of the subwoofer sooner so you have to match the power or gain settings correctly so you don't end up with over-excursion.


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## joms (Mar 10, 2005)

So if it was you who is going to do it, would you put the 12JLw6v3 on a 1.0cuft sealed box or a 1.2cuft box? Would you also put fiberfill in the box or not?

Thanks.


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## qwertydude (Dec 22, 2008)

1.2 will work, 1 cubic foot will be a little punchier but the difference would be negligible. It also depends on the installation different vehicles will affect the sound. A hatchback tends to benefit from having a smaller sealed box as the punchiness and midbass response will actually make it's way to the listener. In a trunk with the seat and firewall blocking sound the midbass response is completely muffled so a bigger box will let the lower frequencies be reproduced on less power.


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## Bluliner (May 16, 2011)

If you're making the box yourself go pick up some t-nuts and socket head cap screws; makes taking the woofer in and out a lot easier. 

Make a 1.25^3 box - listen to it
Fill with poly - listen to it
Stick in a few pieces of 2x4 or whatever else to take up air - listen to it. 

Report back. 

I'm interested in this as well. If I had to guess, every JL sub I've owned, old & new W6s and a couple W3s and 1's for good measure, has liked a larger box than recommended. However, I've always stayed well within reason when it came to power. No idea on the new ones


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## qwertydude (Dec 22, 2008)

I haven't owned a W6 but have owned W3's. The suspension on that sub was so loose it could easily bottom out if overpowered or used in a ported box without a subsonic filter.


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## audiozone (Jun 1, 2013)

Qweetydude, then you recommend keep with the sealed box slightly bigger than jl recommendation? How much bigger? Could you share tour config whit those w3?


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## qwertydude (Dec 22, 2008)

The W3's I've tried sealed and ported I had a 10w3. With ported boxes they definitely need a subsonic filter but tended to be really boomy and not have too much bottom end not to mention needing quite a large box for a 10" sub. I used a 1.75 cubic foot box tuned to 28 hz to really tame the boominess and get a flat response.

Sealed they work like a charm. With the 10" sealed in 1 cubic foot they're typical of sealed response, -3 db at 50 hz. There is a slight boost in efficiency from about 60hz to 80 hz with the recommended .625 cubic foot but those coupled with poorer sub-bass response means a boomier sounding subwoofer.

While the recommended .625 calculated to about -3.5 at 50hz. Not much difference but the smaller box falls off faster; -1 db at 40 hz, -1.5 db at 30hz compared to the 1 cubic foot box. So you can see the larger box is definitely better.

Now the big difference is in lower frequency efficiency. All else being equal, deep bass pretty much will be just as loud, sealed box to sealed box, when excursion is equal. With only 225 watts the JL10w3 will reach maximum linear excursion and therefore loudness in 1 cubic foot while in .625 cubic foot it will take 400 watts.

It is a compromise though because ultimate SPL will be louder in the .625 cubic foot box but will be peakier and boomier, the larger box will be flatter and play deeper on less power. So you kinda have to pick one, it's Hoffman's Iron Law.


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## joms (Mar 10, 2005)

subjectively though, what sound did you personally prefer? when it was in a .625cu or 1cuft?


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## qwertydude (Dec 22, 2008)

1 cubic foot definitely. I have a hatchback car which is ideally suited for using a sealed box since the midbass response and low frequency rolloff matched well with it, calculated it was just about a perfect .707 Qtc. Since the subwoofer was in the same cabin as the listener and I didn't need maximum loudness and wanted better flatter frequency response, larger boxes allow for that.

In a trunk if you can afford the space ported does work better, if you want it to be louder and not need a huge box, then sorry you need to pick a subwoofer better suited to smaller ported boxes. The W6 and W3's just require bigger boxes to perform well.


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## joms (Mar 10, 2005)

Im going to use it on a hyudai santa fe 2013 - suv and my amp to run it is a JL HD750. I guess it would be best to fit the JL 12w6v3 on a 1.2cuft box as per your explanation.

Question now is, should I put fiberfill or not? 

FYI, im not making the box. I will have someone make it. 

Tnx


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## qwertydude (Dec 22, 2008)

I wouldn't use it, even though it makes the box seem as if it were bigger by flattening the frequency response by adding dampening, it also reduces efficiency and in a sealed box does a double whammy of also insulating the subwoofer magnet assembly. This traps heat in and reduces long term thermal power handling.

The only reason in a sealed box to really use fiber fill is as a last resort if you can't make the box a large enough size due to space restriction but still want to flatten the low frequency response.


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## joms (Mar 10, 2005)

So you wouldn't use fiberfill due to: 1) reduces efficiency 2) adds heat which reduces thermal handling

But I have a 750w amp so the efficiency reduction should be that a big of a hit. Now for the thermal handling, I don't really play things loud and if i do, it would only be for a short while. If this is the case, do you think it would still NOT be good to use fiberfill and get that smoother response advantage?


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## qwertydude (Dec 22, 2008)

The smoother response advantage is already accomplished by using the larger than recommended box. Depending on the driver, Let's say you're choosing between a 12w3 and 12w6. For best frequency response for the W3 you'd need a 2 cubic foot box, for the W6 you'd need a 1.5 cubic foot box. These will get you a Qtc of right around the ideal of .707. This doesn't include box stuffing. Those box sizes without stuffing maximizes frequency response and efficiency.

So it's still better to build a sealed box right and make it nice and solid rather than rely on fiber fill. 750 watts is a lot of heat, and heat kills efficiency. So you're not doing yourself any favors by purposely crippling the efficiency of the system and trying to make up for it with power when it's just as easy to simply make the box the right size and get the proper frequency response.

If you're only at this point of experimenting with audio and haven't done the research to come to any conclusions you're on the wrong site. This site is DIY audio not tell me everything I need to know audio.

To me it seems like you're simply trying to throw money at a problem without first having done research if you're not at the point of understanding what fiber fill is for or how box size affects speaker output. If you ask me I wouldn't even get JL Audio subwoofers, for the money you could easily get better subwoofers, if you can have boxes custom built by competent people I'd steer towards a JBL WGTI, better sound quality, higher power handling, more efficiency. Or if you can get them RE Audio, or Image Dynamics all of which offer better performance for the dollar than JL.

The only real advantage JL Audio has is being able to brag to your friends how much you spent on your system.


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## abe_thietten (Aug 12, 2013)

I have the 12w6v3 and my box was 1.35 minus bracing and woofer it was 1.22, it sounded good but I really wanted to make the box smaller so I filled the back wall with sheets of mdf to effectively make the box 1.0 cubes and it sounds way better. I also tried adding egg crate foam to the back of the box and it made the sub sound "mushy" and didn't hit as hard. Hope this helps


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## UNBROKEN (Sep 25, 2009)

My 12W6v3 in 1.25 ft^3 sealed with no fill does things my 12W6v2 couldn't do.
Could it be better? Possibly but I'm VERY pleased with it as is....so much so that I have no intention of messing with it.


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## Mcnulty (Aug 1, 2013)

UNBROKEN said:


> My 12W6v3 in 1.25 ft^3 sealed with no fill does things my 12W6v2 couldn't do.
> Could it be better? Possibly but I'm VERY pleased with it as is....so much so that I have no intention of messing with it.




That means the w6v2 will need more space than a v3 to do the same thing?


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## msmith (Nov 27, 2007)

Looking at theoretical Qtc to define your box design target is misguided and can lead to flabby bottom end when combined with a low Fc. You cannot ignore the car's transfer function and it's effect on the real Q of the system. T/S parameter modeling is not adequate to predict real world response. 

I can assure everyone that our recommended enclosures are arrived at through a lot of testing aimed at delivering great sounding bass in a typical vehicle.


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