Alright, vehicle is a 99' infiniti i30, 4 door sedan, I have two 15" Q's on a crunch 3000d-pro. The enclosure is 7.2 cuft after port, and displacement, tuned to 32.5hz.

It gets pretty loud, but kind of a empty not real full sounding bass. The enclosure is built into the trunk with the woofers mounted invertedly, so that the magnets are pointed toward the back of the backseat. the port is firing out of the top of the box through a hole in the rear deck. It sounds like there is a lot of cancellation, and when I open the trunk and crank the system it sounds way better and hits the lows way better. I understand this is some sort of phase issue I believe, and have had one person tell me to seal off the box from the cab, so that the woofers and port are in the same air space as the cab, and everything else in sealed into the trunk.

Can anyone explain why this would happen, what causes this, and how to fix it? If I need to rip out the box and rebuild it a different way, I'm game, this thing will def. be in SBN, whether I have time to do finishing work or not lol.

so basically, the box is port up through the rear deck, and subs mounted on side of box facing the front of the car.

sorry for long post, just trying to give as much info as possible.

thanks in advance and quick replies are much appreciated as time of the essence!

well i have no experience with subs in trunks, but from what i've read on the forums i bet if you were to cut a slot above the port in the rear deck, it sounds to me like that is make it amazingly clearer.

if not that, then even if you build another box, say rear facing port and subs. and you still have the port in the rear deck, that will help alottt of the bass getting to the cab.

I don't know, I mean the hole in the rear deck that the port opens at is already much larger than the port, and the installer I spoke with told me to seal that off, so I guess I really don't know what to do then...trial and error! lol

please more replies if you have some input on the matter

try turning your box around so that the subs are facing the back of the car instead of the front.

try turning your box around so that the subs are facing the back of the car instead of the front.

yeh, that was my original design and i was told that would be bad, but now i'm questioning whether or not it would it would have been, that's a lot of work though considering the box is built into the car, so that is basically what im going to try if a couple other ideas fail...

i agree though i almost thing that would fix the problem.

try turning it around or seal everything off from the trunk

A picture could help us.

oh yeh pics, i guess so...well its 1 am now, i will post pics after class tomo morning, I think i am going to seal everything off from the cab, so that the port and the woofers are in same airspace as the cab obviously, then everything else sealed off from there. will def. post pics though tomo morning for final input.

I do have to say though, I have sat in systems doing 148, 149, and with the trunk open (by ear mind you) I would crush them!

oh yeh also a note, I have my vents in the trunk that go to outside of the car sealed up from my last install, guessing i should leave it that way if i'm going to seal off everything else?

You need to move the box all around your trunk and see what works best. All cars and installs are different. However, normally rear firing would be where I would start.

i just wish I could move my box around, well sealed up part of it last night and it made a big improvement. will finish doing that today, then post pics later hopefully with a vid of the results. my goal is to compete in BR 140-149.9 class.

alright, problem fixed, sorry didn't post pics today, but I fixed the problem, will run it at SBN this weekend and come back sunday night and post a vid of the car bein metered... and hopefully some others.