Subs MUCH louder with trunk open (mid mounted box)

[djbass101 10+ year member]

man I hope that works, it sounds AMAZING when the trunk is opened, and horrible with it shut. Again just to verify, you are talking about sealing it from AIR, or making it airtight.. correct. (as apposed to from the reverberations/sound waves, and meaning that I can achieve this by wood and sealant/caulking) I know this sounds like a REALLY stupid question, and sorry for me being nieve, but spent 2 weeks trying to get this working good.

 

[SQ Monte 10+ year member]

Yeah man, you're gonna have to make sure no air can get into the trunk from inside the car.

 

[Neel 10+ year member]

block off where the backs of your rear seat use to be.

 

[djbass101 10+ year member]

Well I will try that tomorrow night, I am going to use a combo of wood, caulk and I think I am going use "Great Stuff" foam to help with the rear deck, since I think it is the only way of making sure all the little nooks and crannies are airtight. Apparently they market the "Big gap filler" as airtight.

Again I find it strange that it feels like they don't have enough "air" and by sealing the trunk it is being counter intuitive, but at this point I am up to try anything. But then going on myself again I should hear a difference with my windows closed/open, and there is really no difference in sound, only when I pop my trunk again... releasing the air pressure I guess from in there.

 

[djbass101 10+ year member]

Thank you Everyone!!! for their input, I have been racking my brain on this, and do not understand it enough apparently to know the problem. I think this will be the quickest easiest fix. I know most won't care but I will tell the verdict if that fixed it tomorrow night.

I am hoping and guessing it will fix it as multiple people on the thread have told me to do the same thing.

 

[SQ Monte 10+ year member]

Well I will try that tomorrow night, I am going to use a combo of wood, caulk and I think I am going use "Great Stuff" foam to help with the rear deck, since I think it is the only way of making sure all the little nooks and crannies are airtight. Apparently they market the "Big gap filler" as airtight.
Again I find it strange that it feels like they don't have enough "air" and by sealing the trunk it is being counter intuitive, but at this point I am up to try anything. But then going on myself again I should hear a difference with my windows closed/open, and there is really no difference in sound, only when I pop my trunk again... releasing the air pressure I guess from in there.

What's happening is the sound waves are cancelling each other out in the trunk and you're getting major cancellation. Seal off the trunk and that won't be an issue because all of the sound waves will be kept in the cabin area so you won't have the issue with standing waves like you are now. My boy has a 300C with 2 12" Type R's in a forward firing box and it's sealed off from the trunk and that thing bangs! The fact that your box is subs up/port forward only makes that problem more noticeable due to the front and rear waves not aligning as they should. So I can't guarantee you that your cancellation issues will be 100% solved but I will assure you it will be a noticeable improvement!

 

[on1wheel01 10+ year member]

Wow that looks terrible. You should just wall it.

 

[djbass101 10+ year member]

Wow that looks terrible. You should just wall it.

Funny you say that it was walled... but I found the box/airspace was WAY too big.

Yah I agree it looks horrible, but because I have rebuilt it so many times I want to make sure it sounds good first, then I will worry about aesthetics later. Going to build the box to the edge and carpet it all. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Wingman0121 10+ year member]

Yep seal up the trunk(backseat and reardeck) and tell us how it sounds then.

 

[ahole-ic]

if I worked for memphis I would break in and steal your subs so we wouldn't be represented in that janky *** install. That looks awful and there is no way it's loud. I don't want to offend anyone but let's just be honest here.

 

[djbass101 10+ year member]

if I worked for memphis I would break in and steal your subs so we wouldn't be represented in that janky *** install. That looks awful and there is no way it's loud. I don't want to offend anyone but let's just be honest here.

Good thing I asked you for your opinion on how stage 1 of my install looks... may not have realized at this stage it looks like crap... *looks at posts above yours* oh wait I did say it looked bad already..... and that I am going to fix this...

 

[djbass101 10+ year member]

Anyways, the foam dried and WOW huge difference. I still get a "noticeable" gain when I pop the trunk (but not nearly as extreme as before), but I have a feeling there are some air leaks that I know of that still need more attention/foam, but I ran out until tomorrow.

Kudos on everyone who told me this was my problem, once I finish foaming I can start looking at finishing the install and making it actually look like it belongs there.

 

[cupid6969 10+ year member]

or instead of having your ports facing forward face them to the back if your going to run a wall then go forward other than that face the back you will see a differents and sound proof your trunk for sure and if your worried about the price pick up sound ash fault underlay it sound proof really good or rock gaurd works good too

 

[djbass101 10+ year member]

Yah that was going to be my last option if sealing my trunk didn't go well (that is facing the port to the trunk). It seems like so far the foam is doing the trick, and wow they bang. As for the wall, I was hoping to do that originally, and I did, but became way too big for these small 10" subs and they just "free aired". After looking up that 2 of the subs require 2.75cu. ft MAX, that doesn't make for much of a wall, so I ended up rebuilding the box to meet the exact specs for these subs and happy I took the time to do so.