[krem8tr]

First let me start with saying hello to everyone!!! I have found this forum to be a wealth of information and I've only been here 2 days.....As a proud owner of a '11 Koup silver I have a question.

I've built an enclosure (sealed) for my 3 10w7's and it sounds remarkable with or without my Epicenter but when the rear seats are up(closed) performance is greatly reduced. Has anyone "ported" their rear package shelf in this vehicle? Any improvements? With the trunk and package shelf being sealed we are effectively creating a bandpass enclosure with no output for the bass. My idea was to either create two 6 inch openings in the shelf to utilize the 6db gain by the subs firing into a "corner". Any suggestions?

 

[Derek P]

it is possible to work, but why not just drive with them down? usually what i do, and if you have passengers then just fold up half the seat... unless your fully loaded then you just live with it for those times... kinda better then hacking up the car

 

[D113]

I would recommend against it. The steel there is quite thick and it's 'corrugated' to some degree making me think it's structural. Ours cars are affordable as it is... Hence my guess. Also, since the trunk isn't sealed like an M5, even more reason for the added strengthening and stiffening. While 6inch slots may not weaken it much if at all, i think the seatsdown idea is better anyway. You could be suffering from backwave issues too. What type of Box do you have? Sealed or pitted? If sealed, what shape/cOnfiguration is it in? Is this box from a different car?

Your claims of 6 db gain by simply firing at the corners of the trunk is a little unwarranted. True, gains can be had by finding the sweet spot but sub positioning is not an exact science or at least the average enthusiast does not have the time or computing power to calculate this. Raw science says 6th can be gained by doubling power and doubling cone area.. But it has to be both. A 6th gain out of the same subs will be incredibly difficult to achieve in the fortes trunk by mere placement, especially with your subs. Regardless of sealed or potted, 3 10w7s take up a legend amount of room if you've built both boxes to spec. Coupled with the fact that the space inthe trunk alone will barely be enough afterwards to give birth to full length waveforms. You may be able to get a gain in db due to the fact that in their current configuration the box is inappropriate and a better box might see you get back to an 'at-par' scenario. I have 2 10w6v2s and I know they suffer immensely by the lack of space, versus, how I wanted my box to look.

 

[D113]

Forgive my spelling mistakes, iPod touch autocorrect. Th=db, potted = ported.

 

[krem8tr]

Thanks for all the quick replies. The 10w7's are in a sealed enclosure 3 across....similar to the stealth box JL makes for the Camaro. The box has a 1inch mdf mounting face with the rest being 3/4 mdf and heavily braced internally. The rear of the box is angled to match the back seat. I used foam inside the box to minimize standing waves so i don't think that's the issue...With the back seats down it sounds wonderful but with the seats up it suffers a bit. Oh trust me it sounded even worse before I used two layers of dynamat on the rear shelf. I think I'm just gonna have to deal with it because I really don't want to keep the backseats down. Again thanks for all the help though.

 

[Serdarat493]

There could be some danger with riding for extended periods with your back seats down. Malfunctioning exhaust or ideling in traffic can lead to carbon monoxide entering through the unsealed trunk bay, thus entering the passenger cabin if the seats are down.

Just a heads up sometimes something (or someone) that looks good and sounds good isn't always healthy...

Also, none of us should have exhaust issues yet that the warrenty wouldn't cover.

 

[D113]

What are you powering them with?

Check out my thread on how duct seal massively helped the back shelf rattle.

 

[krem8tr]

All three are powered from a jl slash v2 monoblock. 1000 watts at 1 to 4 ohm.

 

[noodile]

D113,

No mean to hijack the thread but a quick question; do you know of any good powered subs. I was looking into something for under my seat. I don't want too much power.

 

[krem8tr]

A sub under the seat in a koup? I'm just going to say I barely had room to fit my amps under each seat so I think a sub under the seat isn't really viable unless u do a 6 inch.

 

[littlejake]

From what I have read I have a good feeling that your box is not big enough. Each woofer requires 1.25 cubic feet of air space. Take that X 3 and add 0.09 each for displacement and that is a 4 cubic foot box. For that set up JL recommends an enclosure that is 46" wide!!! I just don"t see how its going to fit. Take a picture please. I am curious to see how the box is built and how it fits. They also require 500W each!!!! Are you pulling a trailer of batteries or a small nuclear power plant? I had my alternator re-wound to put out 180 amps and that is just enough for 2-300/2 and 1-500/1 JL Slash. I need more info and pictures please.

Thanks

 

[littlejake]

PS I would not use foam inside the box. If you want to slow waves down use polyester. Foam is to dense.