I am building a sealed box for a single 8" woofer to go behind the rear seat of my SuperCrew. There are alot of wierd angles and although my box came out pretty good, I've still got a few small cracks. My question is should I fill with wood putty (the kind that dries hard and can be sanded) or should I just use silicone? Also, will the angles cause any problems with the sound(most boxes I see are pretty much rectangle shaped)? Last question is: I had to remove some of the insulation material from the rear wall of my truck(just the part behind the new box). Will I have rattles if the bare wood of the box touches metal? What should I put behind it for insulation(it would have to be really thin)?

Thanks!

 

The box must be completly air tight. I would use silicone, putty will crack and chip and leak. How big is your box?

 

I've read not to use silicone because the off gasing as it dries can cause damage to the cone materials of the speaker. I heard Acrylic Latex caulk was better. I personnally used a hot glue gun and it worked great. The box needs to be as air tight as possible. When assembled you should see that the speaker can not move easily because it is pushing against the air back pressure. Wood on metal probably won't rattle. Maybe consider some Dynamat material to cover the metal of the truck, then a thin plastic sheet so the box doesn't rub through it.

 

Hot glue works as well. That is what we used at EPI. If you let Silicone dry you should not have any problems.

 

Norm,
The box has about .38 cubes without the sub. I say about because of the complex angles involved I could not get an exact measurement.

One other question: I am debating on whether or not to use poly-fill. What do you guys think and how much should I use(I'm thinking 3/4 lb.?)?

Thanks for the input!

 

In most cases you will not notice a difference with fiberfill or without, but it is so cheap most people put it in anyway with the idea that it cant hurt. Stuff some in loosely, don't pack it tight or you will lose box volume. There is some value to fiberfill at higher frequencies than subs because you get echoes in your box. Most people figure that you may get some higher frequency harmonics which may "muddy" up your sound even in a sub so they stick some fiberfill in to be safe. There has been informal testing done that shows that you can not tell between a stuffed or empty box. This is of course with a correctly designed box for the woofer used. I guess fiberfill could be used as a fudge factor on less than optimum boxes. I will post the address of an interesting thread on the subject.

 

Here it is:

http://www.carsound.com/ubb/Forum1/HTML/011849.html

 

Your box is .38 unloaded?

Then the actual volume is about .30-.28, your 8" subs basket will take up about .08-.10 cubic feet inside the box. Just want to let you know that when the manufacture sugests a certain box volume, they do not include the basket volume. No big deal though, unless your using some monsterous magnet subwoofer. Also I would use liquid nails to seal up the cracks, it seals and doubles as a adhesive. I also coated my boxes with fiberglass resin on the insides alot, it does sound better, reduces if not eliminate resonance from the wood boxes.

GOOD LUCK>

 

I just make sure i use enough constructiion adheasive to seal the box air tight. I find a liberal coating of that inside the box around all the joints, once it's together does that very well.

 

Robdude30,


I also made my own box because what is available sucks!!! I have a supercab so I had more room to play with. I went with 2-10" subs...if you deside to build a new box in near future drill pilot holes where you are going to drill the box together this will keep it from cracking & use a latex seal....

 

HuskerF150,
The number I'm shooting for is .3 loaded, so I should be close. I do have the room to increase size if it doesn't sound right, though.

Thanks for all the info, guys!

 

In the side of my box, I put in a speaker terminal plate. The plate required a rectangle hole about 1 3/8" X 3/8". I soldered the speaker wire on the inside. My question is can I fill this hole with silicone. If I do, the bare speaker connections will be encapsulated in the silicone. I guess the main question is: Is the silicone electrically conductive and will the speaker short out?

Thanks again, Rob

 

If your speaker has a foam surround give the silicone a day to cure before installing the speaker into the enclosure. If its rubber, plastic, or cloth...dont worry about it. Some foam surrounds (JL comes to mind) have foam surrounds that arent effected by the silicone.

Use a grip of silicone on your terminals. Those bloody things love to leak air especially if they are the kind without the foam or rubber gasketing around the edges. They also leak air through the terminals themselves so load those things up with silicone. No, it does not conduct electricity.