Need help, sealing off trunk?

[ShaneSauce 2]

I have a ton of questions coming, I need them answered so I can get my bass back!

So today I decided I'm going to make a new box for the SSD.

Current box is 3.5cuft @33hz 40sqin of port, sub is firing UP and port is firing towards the back of the car.

New box, 5cuft@30hz 78sqin of port sub AND port firing towards the cabin it should be tons louder without all the trunk rattle.

(I know this is a little much for the ssd but a btl is going in place of it in the next month or two.)

In order for this box to fit in my car we have to build it inside the trunk, I already tore out the back seats and had to take a grinder to the metal behind the seat.

The seats are going back in they are not staying out..

About 50-75sqft of deadening is going in at the end of the week, components and 2 channel amp will be here then also.

Also took out the 6.5's

Now onto the questions

What exactly is "sealing off the trunk" how do I accomplish this and what will I gain and lose from it?

Can I screw down the bottom plate of my box to the trunk floor so the box doesn't move around? Or is there a better way?

Will my ssd be louder and lower in the new box until I get the btl?

Whats the best way to go about assembling a box in a trunk.. Back plate first then side plates then front plate?

I'm not going to be able to get screws in the sides of the box so I will have to rely on the glue to hold?

Edited July 13, 2009 by ShaneSauce

[Impious 1,476]

What exactly is "sealing off the trunk" how do I accomplish this and what will I gain and lose from it?

You are basically creating a wall that separates the trunk from the cabin of the car behind the rear seats, with the sub and port firing through this wall into the cabin.

John of Acoustic Elegance had a good recent post that shows some issues that can arise from the sound wave deflecting off the rear of the trunk;

http://www.caraudio....7&postcount=221

So you have the advantage of pressurizing the cabin directly and not the cabin & trunk and having that extra sound wave potentially causing some interference issues. In theory I suppose there is also less air to pressurize (since you are now "eliminating" the trunk's airspace), so you might gain some SPL also. But I don't care much about SPL so I've not done any hands-on experimenting with this to know for certain.

Can I screw down the bottom plate of my box to the trunk floor so the box doesn't move around? Or is there a better way?

Well, you could. That's probably not the best method though.

A lot of people just use some L brackets to secure the box to the trunk. A little less sightly, but a little easier to access and less room for error (such as accidentally screwing into your gas tank.....which would be bad).

Will my ssd be louder and lower in the new box until I get the btl?

Well, I can't run the numbers at the moment......but your enclosure will be larger and tuned lower, so intuition tells me you'll lose peak output but gain some low frequency extension/output.

I'm not going to be able to get screws in the sides of the box so I will have to rely on the glue to hold?

Technically the glue is what holds the enclosure together. The screws are really just there to hold the wood together until the glue dries . Many people don't use any screws or nails in the enclosure, they just glue and clamp that panels.

You will want to make sure you can clamp the panels until the glue dries to get a solid, tight bond between the panels with no large gaps.

[ShaneSauce 2]

Ah squeak thank you so much for answering those questions.

So to seal it off I'm going to need a good amount of expanding foam right?

I'm going to secure the bottom plate to the trunk floor with L brackets.

I just know its going to be very difficult actually assembling the box inside the trunk and gluing each piece to the bottom plate and then waiting for it to dry.

What should I spray on the inside of the box to make sure the box is sealed?

[Impious 1,476]

Do your seats fold down?

As for expanding foam.....I honestly wouldn't worry about going that far with it unless you plan on competing and are worried about tenths of a decibel. My setup is IB and I didn't use any expanding foam/etc and IMO still have great results. I would personally just build enough of a wall to separate the cabin from the trunk and not worry about filing minor gaps with foam as the difference would be miniscule.

But that's just me.......

[ShaneSauce 2]

Alrighty then

No my seats don't fold down.

I finally got the box built just finished about a hour ago.

Dad told me if I don't find a place to put my spare tire I have to take out the box though..

And it has to be in or on the car somewhere...

CRAP

[shizzzon 461]

for future reference-

If u have to build a box in the vehicle and you can't screw adjacent panels together, try the following-

Even using Titebond, it NEEDS some sort of bonding pressure for several minutes while the glue cures.

I used 6" L brackets every 18" then immediately ran Liquid Nails thick beaded along all joined corners to ensure everything is being bonded together and tightly.

After everything cures, run back over with Silicone II.

If u have to tear the box down because of the spare tire, let me know.

I will need VERY specific dimensions for your trunk so i can model it in AutoCAD and give u a design to build that would incorporate your tire in the car still.

I love math

[ShaneSauce 2]

Well everything was glued, some panels were clamped that I could get to.

I ran screws where I could, then ran caulk along all edges of the box on the inside to make sure it was airtight.

Box is very sturdy I must say.

Gonna wait for it to dry then I'm gonna pop the woofer in tomorrow and give it a run.

And shizzon there is no way..

The only way I could get my spare tire in and out is if I had a box that I could take in and out of my trunk.

The reason I made this box is for better sound in the cabin and less trunk rattling, if I go back to a box that I can slide in and out of my trunk the woofer has to fire up and port fire back or forward resulting in rattling and less sound..

I HATE HAVING A SMALL CAR

[Impious 1,476]

Hope it works out well.

I personally have never had much luck firing into the rear seat (unless it's through a ski hole like my current setup). Doesn't seem to allow enough unrestricted airflow to properly pressurize the airspace in my experience.

[jcarter1885 995]

Hope it works out well.

I personally have never had much luck firing into the rear seat (unless it's through a ski hole like my current setup). Doesn't seem to allow enough unrestricted airflow to properly pressurize the airspace in my experience.

Yeah thats the same reason why I didnt build my box in the car and seall off the trunk since I dont have a ski hole like some people do. I took my spare tire out since it was under the box and would of been a hassle to get to it everytime I got a flat. I would rather get a used tire to use until I get a good tire on my car than a spare (just dont trust spares especially with the extra weight that my car has in it).

[ShaneSauce 2]

I don't see this working out well, the box is losing pressure somewhere..

I'm gonna try to re-seal where I couldn't get last time, get some more screws in it and see what happens.

If it doesn't work out how I like I'm going to scratch the box, get 2 nightshade 12's and make a new box that I can slide in and out of the trunk and fire everything to the front and deaden the shit out of my rear deck.

Edited July 16, 2009 by ShaneSauce