# jbl w15gti mkii ported and box building tips



## deadcold94 (Mar 27, 2011)

hello,

just recently bought the jbl w15gti after much debate as to what i wanted.

now i was wondering if anyone could offer some specs on how to build the box. in winisd when i model the sub with 20hz tuning it wanted 8 cubic feet.
which is fine. but does that sound right?
and does anyone have anytips with on buding box and is pvc tubing better then sloted? how do i know how big to make the slot? any helps and tips will be appreciated


----------



## BigRed (Aug 12, 2007)

you want to model the box for 28hz. according to jbl, you will need a 4.00 cu. ft. box to do that.

http://www.jbl.com/resources/Brands/jbl/Products/ProductRelatedDocuments/en-US/BoxesandParameters/W15GTi_rev_f.pdf

I have mine in a 5 cu ft box per driver because I changed woofers and the old box was already at 5 cu ft. I basicall adjusted the port to 28 hz. they sound great


----------



## AndyInOC (Jul 22, 2008)

I agree, JBL is one of the few companies who's manufacturer specs work pretty damn well most of the time.

Need another meet soon Jim and bring the red beast this time, I want to hear the GTI's lol



BigRed said:


> you want to model the box for 28hz. according to jbl, you will need a 4.00 cu. ft. box to do that.
> 
> http://www.jbl.com/resources/Brands/jbl/Products/ProductRelatedDocuments/en-US/BoxesandParameters/W15GTi_rev_f.pdf
> 
> I have mine in a 5 cu ft box per driver because I changed woofers and the old box was already at 5 cu ft. I basicall adjusted the port to 28 hz. they sound great


----------



## BigRed (Aug 12, 2007)

will do Andy!!  they get up and boogie and sound real good doing it


----------



## Eastman474 (Jan 8, 2010)

I actually have mine in 4 cubes net each at 32hz and love them.. They get LOUD and plenty low. Although I never tried them down at 28 hz people that ive talked to have said they like them a little higher tuned.. Mikey7182 has tried them in couple different tuned enclosures i believe, maybe ask him  

But great sub choice, best woofers I've heard


----------



## BigRed (Aug 12, 2007)

I had my first design tuned to 35hz, and I don't know if it was the fact that the box was oversized or what, but it just did'nt sound great. This new port tuned to 28hz really has put a smile on my face.


----------



## Eastman474 (Jan 8, 2010)

Hmm that's interesting..
I actually will be building a box for 1 for my girlfriends charger this weekend so maybe I'll give the lower tuning a try and compare them


----------



## onebadmonte (Sep 4, 2008)

I've got a pair in separate boxes. A whisker under 4cuft ea with two 4" aeroports ea tuned to around 28hz. They rock, in my house. The boxes are actually old Jensen CS-315 3-way floor stander cabs.  I'm using a Behringer EP-2500 for amplification.  It's like a night club in my living room. o_o


----------



## viscious350z (Jun 30, 2011)

Does anyone have box designs for 1 15 jbl gti mkii 4.0 cu ft tune to 28hz?


----------



## BigRed (Aug 12, 2007)

http://www.jbl.com/resources/Brands/jbl/Products/ProductRelatedDocuments/en-US/BoxesandParameters/W15GTi_rev_f.pdf


----------



## XtremeRevolution (Dec 3, 2010)

See the first link in my signature.


----------



## eviling (Apr 14, 2010)

so, JBL is telling me that a box of 4CF with a 6" round port will give me 28 hrz? does the depth of the port matter? im gonan be building a box soon, ive not honestly done one. nothing out of my technical skills..but the finner details ive yet to learn  ive talked about it and read about things in the past and understand a few things but not many


----------



## AndyInOC (Jul 22, 2008)

eviling said:


> so, JBL is telling me that a box of 4CF with a 6" round port will give me 28 hrz? does the depth of the port matter? im gonan be building a box soon, ive not honestly done one. nothing out of my technical skills..but the finner details ive yet to learn  ive talked about it and read about things in the past and understand a few things but not many


The spec sheet says 6" round by 15.13" long for that tuning. You can fiddle around with winisd or whatever with their box and port measurements and watch how different lengths affect the tuning frequency, its quite a trip. If it were me i would just go with their volume, add a ton of bracing (keep in mind braces change volume) and let it rip.


----------



## BigRed (Aug 12, 2007)

build one of these for those jbl 15's...insanely loud and clean.


----------



## Riveted1 (Oct 23, 2008)

Pardon my ignorance, but what kind of box is that? ABC? Some kind of bandpass? Look killer BTW.


----------



## BigRed (Aug 12, 2007)

6th order bandpass...I love it!


----------



## minbari (Mar 3, 2011)

BigRed said:


> 6th order bandpass...I love it!


its actauly a quasi 6th order. a true 6th order, would have 3 ports the exterior of the box. yours have one exterior port and 2 of the ports join in it. 




quasi 6th order:









true 6th order:


----------



## Riveted1 (Oct 23, 2008)

BigRed said:


> 6th order bandpass...I love it!


Do you have specs that you would be willing to share? I've got a couple W15GTi's that I want to put in a suburban. I tried to model one of those boxes in WinISD, but it won't do the quasi-6th order.


----------



## BigRed (Aug 12, 2007)

^^ email address?


----------



## stony22 (Apr 24, 2011)

Insert IPAD HERE----> LOL


----------



## stony22 (Apr 24, 2011)

BTW Red wish I got there in time to hear that thing, the box looks clean. GREAT JOB


----------



## subwoofery (Nov 9, 2008)

BigRed said:


> 6th order bandpass...I love it!


Who modelled it for you? 

Kelvin


----------



## BigRed (Aug 12, 2007)

next time stony

it was designed by Pk designs. Great design, but apparently he is quite busy so make sure you have some time to wait if you decide to get one done by PK


----------



## stony22 (Apr 24, 2011)

BTW Red if you want to share, I would love those too [email protected]


----------



## MrEvo (Jun 12, 2013)

BigRed said:


> build one of these for those jbl 15's...insanely loud and clean.


hi would you be willing to share the details of this design please. My email [email protected] thank you very much appreciated.


----------



## BigRed (Aug 12, 2007)

email sent


----------



## MrEvo (Jun 12, 2013)

BigRed said:


> email sent


Thanks a lot for sharing.


----------



## Flipper245 (Dec 3, 2014)

Holy crap! This has inspired me.  I have a single 15gti in my '91 turbo sprint. It's sealed right now in about 2cu'. The enclosure is mostly in the spare tire well and the bottom of it has been cut out, dropped and fiberglassed back in. Very solid! The total of the spare tire well I estimated at 1.4cuft. So was guessing i would just build the hatch area into a box on top of the well and including the well and hope for around 8cuft. Just measured the hatch area, top of rear seats slanting down to bottom of hatch, and it's exactly 6.6cuft! Thats measuring small for wood thickness. Probablty fiberglass in sides to add rigidity to box and car and to add size to box. Most of the rear of the car is fiberglass and expanding foam now anyway. I think it was meant to be. I'm amazed how well it sounds with just 1 sealed. Plays so deep and musical. Tons of output. Can't imagine with two ported. Tricky part will be to accurately measure the internal volume. Sub is getting about 900 watts of audison power but I would like to do about 2500 for the pair. 900 seems fine and it can be heard very well with very little power. Thumbs up jbl!


----------



## ndm (Jul 5, 2007)

BigRed said:


> build one of these for those jbl 15's...insanely loud and clean.


I know this is old but can you share the specs for this enclosure with me? I just so happen to have two of the w15gtimkii's and space to use it in my 72 Blazer. I can pm you my email if you like.


----------



## daloudin (Nov 2, 2020)

ndm said:


> I know this is old but can you share the specs for this enclosure with me? I just so happen to have two of the w15gtimkii's and space to use it in my 72 Blazer. I can pm you my email if you like.


OP "Last Activity" was 5 years ago... doubtful they will reply. 

Sent from my SM-G965U using Tapatalk


----------



## ndm (Jul 5, 2007)

daloudin said:


> OP "Last Activity" was 5 years ago... doubtful they will reply.
> 
> Sent from my SM-G965U using Tapatalk


Well that sucks.


----------

