as of right now, i have less then half an inch of airspace between the back pole vent on my sub and the back of my box. i dont think this is enough room and i think its hurting the performance of the sub at higher volumes (it sounds great untill it really starts cranking, then it starts to make a muffled sound as iff the pole-vent cant move air quick enough).

im planning to cut a 4.5"x4.5" section out of the back of my box, replacing it with a ~7"x7" backplate that will be about .25" thick. this will make my box 3/4" deeper behind the sub, and i think it will sound a lot better.

my question is this: what should i use to really seal up the backplate and the box together? the seat will be sitting ontop of it so i doubt it will break open but i really want it to be on there tight.

 

If you have a 1/2" air gap on the pole vent, you should be fine...thats about all I have in my custom built box.... pole vent needs to draw air in and out with cone movement, it helps cool the motor and voice coil... as to muffled sound, I don't think air movement in pole vent is going to do it unless its totally blocked and over heating the voice coil.... but your call....

to answer your question, cut carpet back to 7 X 7, then liquid nails for MDF and small screws about 1" apart all the way around the magnet relief plate..

 

ya but it is less then 1/2" of space more like 1/4". thanks for the tip.

what else could be causing that muffled sound? its so crisp and clear, even at loud volume untill a certain point, then it creats a muffled sound, loses a lot of volume, even though the cone is still moving violently. i know it isnt overpowered, is my sub just that ****ty?

 

Box may not be sealed good, take the box out then gently and evenly with both hands using as many fingers as you can, push the cone in slowly and hold it in for a minite, not beyond Xmax for your driver, then let it go, if it pops right back out or comes back out really fast, you have a air leak... on my box it takes a little over 15 sec to come back out.... which is a very good seal.....

 

I cant remember for sure, but you are running the stock HU arent you???

 

sadly, yes. but i always have, and my last couple setups have been perfectly fine. the only difference now is that the stock amp wires where i clamped to LOC to are cut from the stock sub, but they still give signal so i dont think that is the problem...or is it??

edit: as soon as i can get more money i want to replace the head unit and get some amped speakers, but i dont see it happening too too soon. maybe by christmas or so. but when i do, expect me to ask for advice on a budget amped system.

 

crap now that i think about it, you could be right. i added a thin layer of MDF to my front plate for more strength and maybe i didnt seal it well enough. ill check in the morning and try what you said...

 

actually that's kinda bass ackwards.. if you push in your subs and they slowly come back to center then you have a small leak somewhere. they should be hard to push in and spring right back if the box is sealed up air tight.

 

That's the way mine does also.
BTW the way you descibed adding the piece of mdf to the back and cutting out the hole is the supercrewsounds does theres.