Is there any problem with sealing up the underside of the rear deck if I were to do an Infinite Baffle installation?

No there is no issues. You can use dynamat to seal it off 100% then cover it in carpet. Which direction are you planning to face your sub?

If you have the fold down rear seats, the audiophiles say you will also have to seal the entire area between the trunk and the seats.

Philip Bradley

I cut out the 8"+/- diameter holes on the underside, outside of the 3" knockout but within the depression area. I planned on a 3/4" mdf baffle board to mount the speakers firing upward, plus some 1/4" mdf to fill in beacuse the rear deck has 3 levels. Then high density foam (or DOW Great Stuff spray foam within plastic sheeting) to help seal things up, and finally carpet on the exposed wood. I do not have fold down rear seats, and there is no ski pass.

Would you put the Dynamat on the underside or the top side, inside of the car? I have not used it before, do you need multiple layers, etc?

I took my rear speakers out, made a steel piece the same size as the opening, riveted to the deck, dynamatted 3 layers, dynamatted the rear deck, and am now in the process of redoing the rear deck piece in black suede with "shaved" grilles. It'll be perfect for my IB 15's!

2-15's, wow. I have settled on 2-10's, quite a bit less SPL. One 10" did not make it, since I was not willing to sacrifice the trunk space to make it work. Now I am trying this route.

So there is no problem with air flow between the cabin and the trunk if the deck is sealed up? Seems like there are a lot of voids left on purpose by BMW, in addition to the air vents next to the rear window. I live in southern California, and my air conditioner smells musty in the summer. The dealer suggested I blast the heating duct intake in the engine compartment with Lysol, or pay them $250 to perform essentially the same treatment. I have had moderate success doing it myself, but it is a pain. I do not want to make the situation worse, or make my amps overheat, or anything else I have not thought of.

Most of what I have read says a baffle board under the deck is required to keep separation between the two compartments. Does using Dynamat make this redundant or better?

I took my rear speakers out, made a steel piece the same size as the opening, riveted to the deck, dynamatted 3 layers, dynamatted the rear deck, and am now in the process of redoing the rear deck piece in black suede with "shaved" grilles. It'll be perfect for my IB 15's!

Is using the deck, with sound deadening, acceptable for the top of a box? In other words, if I mount my little 7 inch subs to the top of the deck, can I just build a contoured open top box that will then seal against sound deadening on the bottom of the deck?

Philip Bradley

Bump

I think you would have a hard time sealing a box to the deck and keep it air tight.

low expansion "great stuff" foam. It'll do the trick.

DLS OA8 Subwoofers A+++++ (http://www.avincarstore.com/index.php?main_page=product_info&cPath=37_38&products_id=226)

More later, just wanted you to know I got your PM

bump

im going with a set of the oa8's in the stock rear speaker locations, and i also do have the fold down seats. I already have one layer of sound deadening on the underside of the rear deck. When i install the subs im going to put another layer on to cover up anything i missed and to cover all the holes, then a nice layer of v3 liquid e-dead.

im going with a set of the oa8's in the stock rear speaker locations, and i also do have the fold down seats. I already have one layer of sound deadening on the underside of the rear deck. When i install the subs im going to put another layer on to cover up anything i missed and to cover all the holes, then a nice layer of v3 liquid e-dead.

The audiophiles here say that the split fold down seats prevent a complete seal. The photo at the JL website for the JL Stealth for the E36M3 shows them installed on am M3 with split fold down rear seats. I am not an audiophile, but I think there is some benefit to using the stock mounting locations so that the subs fire directly into the passenger compartment. I am going to make sure I seal the sub well to the rear deck and am leaning towards trying to build a small box underneath -- the JL Stealth did not use a fully enclosed box.

Philip Bradley

I thought about a completely sealed box like the ones BSW sells, which are nice, but i've got my heart set on a set of IB's, and dont want to extra headache of building a box like that.

I asked eD if you could use eDead v1SE2 to seal the trunk from the cabin, and they did not think that was what the product was intended for. I would be interested in seeing how it worked out for you once you are done. I have a baffle board partly constructed, which covers the underside of the deck but if I could seal the top side of the deck with several layers of a deadeining material (dynamat or eDead) with the same result, that would be a much cleaner install. AudioDesignsATL says that this will work fine, so I assume he has a track record doing this. I started this thread to ask if there were any issues with air flow between the cabin and trunk, but maybe I am over thinking this.