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Discussion Starter · #1 ·
I have spent the better part of two days installing my system:
Business CD
EQX
Nakamichi PA304 (90wx2)
JL 250/1
Focal components
JL 10w3v2
I wrapped everything up, did a final check... where's the bass?! It was very weak. I thought I forgot to connect something, but when I opened the trunk...bass! I checked all gains, levels, eq settings etc. I don't have fold down seats or ski pass, but did remove the rear speakers. Are the BMW trunks that well insulated?! What can I do?!
 

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Post some details on the configuration: ported or sealed, in floor or raised box, etc so we can get a better understanding of what the problem is.

And yes, the trunks are that well sealed. You may need to "direct" the sound a bit more.

Mark
 

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yeah.....
sedan trunks are SEALED
i had two 12" w6v2s put in, and when i first listened, i could barely hear it.

this is what you can do... pull away your trunk liner against the rear seat.
you'll see a rectangle in hte middle of the metal pannel. take a hammer and a flat head and start pounding at the edges.
my installer was able to get it out, then start pulling away the insulation/padding.
pull up your back seat, and pull out the rest of the padding. then you should be able to stick your hand from inside the car into the trunk....
then you can either get a custom hole cut out/stiched, or trade/buy a seat with an armrest.
what i did was i just left my back seat up... so its not totally pushed down anymore.
its kinda ugly, but it lets the bass in. im gonna do that temporarily until i can figure out what to do.

let me know what u end up doing
 

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Mine is "direct coupled" to the ski pass (what Presns323i is referring to) and it works very well. Kinda the opposite to your issue - open the trunk and you can barely hear it.

The other thing to try which has worked for others here is to reverse the phase on your sub(s). AKA connect + from the amp to - on the sub and vise versa for the other wire. Just make sure all subs are wired the same way. This made a huge difference for mine too.

Mark
 

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Canuck328i said:
Mine is "direct coupled" to the ski pass (what Presns323i is referring to) and it works very well. Kinda the opposite to your issue - open the trunk and you can barely hear it.

The other thing to try which has worked for others here is to reverse the phase on your sub(s). AKA connect + from the amp to - on the sub and vise versa for the other wire. Just make sure all subs are wired the same way. This made a huge difference for mine too.

Mark
how does switching the wires change anything?

what do you mean by direct coupled?
do you have an armrest? or do you just have the metal and foam taken out.
 

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its called bridgeing or something like that. Google it. I dont think that would work though, I think your problem is the seal.
 

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Discussion Starter · #11 ·
I found this pic tonite. I'm considering redoing my enclosure to a ported design with the woofer facing back and the port to the front aimed into a larger port. Anyone seen or heard this set-up?
 

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yeah... i posted that pic. got it from some guy's m3 in the showroom.
i was told itd cost about 150$ to do. but its not recommended.
the installer said tha it owuld make the bass sloppy. i dont know why.

if you do that, tell me how much it cost to put the hole+tube in.
also, if you DIY, DEFINANTLY tell me how yo u did it.
 

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Discussion Starter · #13 · (Edited)
I guessed it may cause problems from port noise, but can't think of another reason it would cause sloppy sound...? I have seen other cars (on the internet tonite) with a similar set-up, ports going thru the rear deck. Right now, this idea is in the lead. I will definitely post a DYI for whatever I do.
 

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well, i wanna do the same thing.
but i wanna DIY to save money...
let me know if you know where to get the tube, and how to keep the leather/leatherette from fraying at the cuts
 

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Discussion Starter · #15 ·
I'm gonna remove the seatback tomorrow and do a mock-up with a friends ported sub. (Infinity Perfect 10) If it doesn't go well I'm going to place an order for stealth box. I want better sound than they offer, but I'm tired of messing with it. I have other hobbies too!
 

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Presns323i said:
how does switching the wires change anything?

what do you mean by direct coupled?
do you have an armrest? or do you just have the metal and foam taken out.
Reversing the phase changes how the subs will interact with the speakers that are already in the car. I have heard that the rear firing setup will do this - because the woofer is not firing in the same "direction" as the existing speakers they have the effect of cancelling out the existing speakers in the car at certain frequency ranges. Simply reversing the terminals at the amplifier is a very easy thing to try.

And no, it does not hurt the sub. Speakers receive AC signals from amplifiers - all it does is push the woofer out when it would otherwise go in, and vise versa. As I said, I did this to my setup and it worked wonders. It has nothing to do with bridging.

"Direct coupled" just means that the front of the woofers is right tight up against the ski pass, and does not leak any sound into the trunk. I have the factory ski pass with the armrest. If you look at the design pics in the website on my sig, you will see how it is done. This way there is no convolution of the sound - you are actually listening to the woofer as if it was mounted in a door.

When the woofer is firing back into the trunk, you have effectively built a fourth order box (a woofer in a sealed box firing into a ported enclosure, that enclosure being the trunk and the port(s) being those removed deck speakers). The same is true of the pic posted of the vert - if this is not done right, there will be port noise and the tuning of the port will be all wrong. That is why it will likely sound sloppy and/or boomy.

Mark
 

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If you have two subs, are they out of phase? check to make sure both subs are wires correctly. If one of the two is backwards, they will cancel each other out.

Punching out the ski pass metal helps. Also, wiring the sub(s) 180 out of phase works well in E46s with the subs behind the seat facing towards the back.

Yuu might also want to consider getting a bogger amp. A 250/1 is not enough power. My rule of thumb for system design is to get AT LEAST twice as much power to subs than other speakers, so if you have 180 watts for your focals, and you like JL, a 500/1 would be better (personally, I would get at least a 1000/1 to make sure the sub (s) get enough clean power. I am assuming you are looking for a SQ setup, not SPL.
 

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Ok, so Im getting set to install by box this weekend and I had planned on firing the subs into the trunk mounted in my sealed box. The subs are going to be running in 2 ohm stereo with 400W each. Do you think that Im going to run into the same problem with my install? If so would it be better to fire the subs into the backseat?
 

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DarrenE46 said:
Ok, so Im getting set to install by box this weekend and I had planned on firing the subs into the trunk mounted in my sealed box. The subs are going to be running in 2 ohm stereo with 400W each. Do you think that Im going to run into the same problem with my install? If so would it be better to fire the subs into the backseat?
No, subs will sound better firing towards the back of the car. The reason is that is you aim the towards the front, you will have cancellation.
 

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you know what, my head unit actually has something in it where i can choose to reverse the phase of the subs.
i like it better when its normal.
is this the same thing?
 
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