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Discussion Starter · #1 ·
I have been using the same amp/speaker combo for YEARS in several of my vehicles ie: 93 Grand Cherokee, 04 Chevy Aveo, 87 Subaru Justy..
And, Now

my 2009 Ford Focus.

In the past, the bass would kill you if you would let it (keep in mind, same setup being a 200 watt rms lanzar amp and Bumper 10inch woofer in ported box).

Well, the Focus sedan's trunk is WAY too air tight that the bass just doesn't transmit into the cabin area.. If you open the trunk, it thumps like hell.

I believe the trunk is too air tight that when closed, it acts like a "spring" against the speaker. I also don't think notes are getting transmitted into the cabin area.

How have others solved this? I was thinking about cutting some holes into the rear deck and installing some finished speaker ports and glueing some black cloth around the bottom, that way it would look really nice and transmit air pressure and bass notes.. Does that sound like a good idea?

I am sure somebody has worked on this before.. what did you do to solve this?

Thanks!!!!

/mike
 

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on my 08 coupe, the sub sounds great in the trunk. i put it so that the middle of the sub is where the split in the seat is. it seems to get pretty good air. the only problem i had is i blew my sub last night. but it was old and the amp was way to much for it.
 

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Are the rear seats foldable in the coupes? If not you could just cut out a couple of vents and throw some speaker grille over the openings for a stock look.
 

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ive always just rolled with one of the seats folded down when I had my SVT contour....seemed to do the trick
 

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OK, so no one is really answering your question here. First of all, if the trunk is sealed from the passenger compartment, which they rarely are, then it would kill the output of your subwoofer. The real issue is two-fold. First is that the box design is wrong for the car. Second, is that the interior is too isolated from the trunk, which you have already started figuring out how to solve.

The ideal solution for a car whose trunk and interior are so well isolated is to build a band-pass (also sometimes known as a 5th or 7th order) box and have the port exit into the interior through the rear deck. All of the output of a band-pass box comes from the port because the subwoofer is contained completely inside the box. These are not hard to design, but do require a little trial and error to tune properly to the specific vehicle.

I won't go into further detail here, but let me know if you are interested and I will help you design a new box.
 

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Discussion Starter · #6 ·
I have designed and built bandpass boxes.

Ok.. I am 35 and have built speakers since I was a teen.. In fact, back before the internet, my friend and I actually wrote a great little program to design bandpass boxes based on speaker specs.. off of a bunch of charts and grids from one of the old autosound bbs's.. I also have the original Blaubox program somewhere that also designs isobarics and the like.

I have been around a while..

OK, yes the trunk in the 2008 and 2009 SEDAN is completely isolated from the passenger compartment.

Bandpass box's ports are tuned specifically and making it longer to vent to the cabin would work and probably sound good, but would alter the tuning unless you did not push it down into the enclosure.

I am too lazy to build another, so I was thinking of purchasing an empty bandpass box for my woofer.

The Bumber woofer is a great woofer tho.. takes 500watts in a 10 inch woofer with a rubber surround.. I just don't want to spead any extra money but I just may.

I was thinking of just getting some prefabbed 3 inch speaker ports and cutting a couple of hole through the rear deck, install the finished port tube and be done with it.

the new Focus's are really air tight.. the trunk is really that tight and I don't want to ride around with one of the seats down... I like stock appearence.

all my other rides were hatchback types and that setup worked awesome. I did not need a bandpass box to hit in the 30hz range...

I am a little more grown up now and while I do enjoy some low bass (love Eminem), I also want some mid-bass as well.

Thanks for the suggestions..

/mike
 

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Some of the programs for designing enclosure will allow the user to select if the position of the port on a band-pass design. Fully in, fully out or half way. Unless the port is unusually large, say a 4" or 6" diameter with a lot of length, the the port position matters little.
 

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im running two 12" kicker L5's with a jl audio g-max amp in a slot ported sub box in my 08 sedan. i really dont know much about boxes but i dont have any problem with it. the subs rattle the hell out of my entire car. possibly the wiring got messed up this time around?
on a side note, and i dont mean to cross thread, i dont really want to invest in sound deadening, but i just want my trunk lid to stop rattling, any suggestions?
 

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ive never had any problems with bass from my car. maybe its the box the sub is in. how big is it? i blew my sub 2 weeks ago, and i borrowed my gf's sub and box, and the smaller box sounds alot better. it could just be the sub. i had a cheap lightning audio sub and it blew, so i have a 10" sony xplod in the trunk now in a truck box. the lightning was in a bigger box, but not a bandpass box. my trunk is not airtight at all. it could also be your system is getting old and the internal parts are going bad. the same system in different cars will sound differently. maybe the system is 2 much for the focus? try changing the components, and see if anything changes
 
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