# I need some help with Enclosure design



## OGJordan (Sep 26, 2006)

OK, I bought a tow vehicle and I'm putting a nice budget system in. It's an 04 Cadillac Escalade ESV (the Suburban sized one). I've already installed a Pioneer AVX-8500 headunit and Polk MM6501 in the front. I'm using PPI Black Ice amplifiers, the sub amp is the 1800x1 @ 1ohm model. I already had 3 JBL GTO 12s waiting for a project car I'm building, but that won't be done for a couple years. So I picked up a 4th since the Escalade will obviously fit them easy. 

I listen to hip hop, but HATE the one note rattle traps most hip hop heads like. I currently have an Xcon 15" on 1500W of Arc Audio power in 4.0 cu ft ported in my daily,sealed into the cabin through the ski hole and I like it quite well. 


I want to keep plenty of storage room behind the enclosure, so the enclosure will be up against the 3rd row seat. I had planned to just do the 12s sealed to save room. But now I'm kicking around a ported enclosure. 

I'm going to do a basic 6 sided rectangular box. Subs up, ports back. Maximum width I want to go is 46". That leaves room to remove enclosure when necessary without any issues. So interior dimension will be 44.5". I'd like to keep the "length" of the box around 16" so I can save as much cargo space as possible. To fit 4 12"s wide into 44.5" they need to be staggered a bit, and I think 16" leaves room to do so. Height is the real variable.

All subs facing up, port back at the bottom would be ideal. Can someone guide me to the best online calculator or even help me with a quick design? I'd to tune around 30 hz. Recommendation on the literature is 1.75cu ft tuned to 34hz. for one sub, but we know how that goes.


Here's a pic of what I envision the finished product will be, but it's in a normal Escalade. I have much more room, and the subs will be on top, with a grille to cover them.






I really like this, but want it to be a little more stealth:




Thanks for any help!


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## OGJordan (Sep 26, 2006)

Here's the T/S parameters. 

http://www.jbl.com/resources/Brands...uments/en-US/BoxesandParameters/GTO1214TD.pdf


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## BP1Fanatic (Jan 10, 2010)

http://www.diyaudio.com/forums/subwoofers/160879-build-your-own-2x12-th-kraken-212-th-8.html


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## Hispls (Mar 12, 2008)

Those pictures are terrible. Generally you don't want the port crowded into the rear hatch so much. Also having a large ratio of width to height on the port can cause some real irregularities especially with so much air displaced. They say 8:1 is the highest ratio you want, with performance improving as you approach a perfect circle being optimum.

I'd never tune to 30hz unless you plan on listing to whale songs, slowed music, test tones, or pipe organ music you will sacrifice much and gain little. If you're going to tune below 36, may as well go down to 26-27 so you can play down to 18 or 20, though apart from movie sound effects you'll be hard pressed to find any material that low.


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## BP1Fanatic (Jan 10, 2010)

Dubstep and Rap music go down to 30hz. You also have bass cd's that go below 30hz.


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## Hispls (Mar 12, 2008)

BP1Fanatic said:


> Dubstep and Rap music go down to 30hz. You also have bass cd's that go below 30hz.


Right, and tuning to 36hz with some good subs will allow you to play down to 30 no problem. 

Hell if all you listen to is slowed music or bass CD's tune that low, but IMO you lose a lot up high where actual music happens. Also there aren't even many tracks on your average bass CD that play too far below 40hz.

You sacrifice a lot to play into the low 20's and IMO isn't worth the space or loss of output in the critical 55-60hz area that's almost unavoidable with most high powered car woofers in ported alignment.


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## amalmer71 (Feb 29, 2012)

I agree with Hispls as far as tuning too low.

I have a pair of RF 10" P3's in a box with 1.1 chamber per side, tuned to 40Hz and they played nicely. I obtained a pair of 10" MTX Thunder 8000 8 ohm subs and wanted to try them in the same box. They dug a lot deeper, or at least seemed like it to my ears. I have no RTA to confirm that, but I had those P3's in the car for 2 yrs prior, so I knew what they sounded like.

Just out of curiosity, I put the MTX subs in a box that was one large chamber, 3.28 cu/ft tuned for 32Hz. OMG!!! I could feel the bass in "Bass, I Love You" moving my shirt even with both front doors wide open. It was impressive. 

When I played "normal music", however, like pop or hip-hop, even some classic rock, the musical output of the subs diminished considerably. The subs were very loose and sloppy. 

I see people tuning down to the low 30's all of the time, so I figured I'd try it. While the low bass was impressive, I didn't like the overall dip in accuracy of those subs. Not saying all subs will suffer from the same problem, but those MTX's sure did.


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## Hispls (Mar 12, 2008)

amalmer71 said:


> I see people tuning down to the low 30's all of the time, so I figured I'd try it. While the low bass was impressive, I didn't like the overall dip in accuracy of those subs.


My thoughts exactly. Being able to play in the 20's is really neat, but that tuning doesn't help "normal" music IMO. That being said, I've done 5.1 surround in a car before and for movies low tuning is rather critical for realistic sound effects.


I don't enjoy my system by playing pink noise and watching the graph on an RTA, I enjoy throwing in some music and listening to it.


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## BP1Fanatic (Jan 10, 2010)

Look fellas, the link was just a suggestion for the OP. I'm quite sure none of you read the whole thread to see what type of enclosure was being built for those jbl gto's. That tapped horn can be made for a shorter length, higher tune, more efficiency, and a smaller enclosure.


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## BP1Fanatic (Jan 10, 2010)

Here is some education for you.

Simple Tapped Horn Tutorial using Hornresp


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## cubdenno (Nov 10, 2007)

Hispls said:


> Right, and tuning to 36hz with some good subs will allow you to play down to 30 no problem.
> 
> Hell if all you listen to is slowed music or bass CD's tune that low, but IMO you lose a lot up high where actual music happens. Also there aren't even many tracks on your average bass CD that play too far below 40hz.
> 
> You sacrifice a lot to play into the low 20's and IMO isn't worth the space or loss of output in the critical 55-60hz area that's almost unavoidable with most high powered car woofers in ported alignment.


What if its not extension you are wanting but the response curve? Tuning in the 35 and higher frequencies gets you an appreciable bump often but then you have to have serious midbass drivers to keep up. Or else you get that huge peak 35-60 that over whelms everything else.


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## amalmer71 (Feb 29, 2012)

cubdenno said:


> What if its not extension you are wanting but the response curve? Tuning in the 35 and higher frequencies gets you an appreciable bump often but then you have to have serious midbass drivers to keep up. Or else you get that huge peak 35-60 that over whelms everything else.


That depends on the subwoofer being used. 

Some subwoofers can be used in an enclosure that's tuned higher without creating that peak. Some can't.
Some can be used in an enclosure that's tuned low with no loss above 40Hz. Some can't.

That was the point of my post. 

Each application is different. It just becomes so monotonous after a while because (as with everything on the internet) everyone thinks "since it worked for that person in his/her car, with that particular subwoofer, it'll work for me" even though the subwoofer and car are completely different.


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## cubdenno (Nov 10, 2007)

amalmer71 said:


> That depends on the subwoofer being used.
> 
> Some subwoofers can be used in an enclosure that's tuned higher without creating that peak. Some can't.
> Some can be used in an enclosure that's tuned low with no loss above 40Hz. Some can't.
> ...


Totally agree. 

Or thinking what I like in an in car response is the same as what you like. 

To many variables to just say tune here and you will be happy.


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## porscheman (Jan 1, 2012)

according to term pro, with the max width at 46" and with a 16" depth you get a box that is 24.5" tall and a 5"x10" port 16.4" long. that gives you a 30hz tune with fairly low port noise.
the box including vent and a guess at the displacement of the drivers is 7.8 cubes.
i would double check to see if all 4 drivers fit in that area on top, it might be close


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## ndramountanis (Apr 23, 2013)

Very nice box. Looks clean and stockish lol


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