YACT: Custom Speaker Boxes

[cremator]

I have a 95 Cavalier with 2 subs in the trunk. I was curious, what's the best materials to use to make a "flush" box? Basically I want the subs to seem like they are part of the car. See example here:
http://www.coolcats.net/tech/general/radio/boxinst2.jpg

If it's as simple as cutting some plywood and using carpet to finish then it should be no real problem, but what do you guys suggest for the wood materials? Or does anyone know of any guides?

 

[Heisenberg]

I would use at least a medium-density particle board, not plywood. When you make the box, be sure to seal the inside joints with a silicon-based sealer to make it airtight (assuming sealed subs...). I built a custom box for my Firebird, and it was pretty simple.

 

[MichaelD]

Do you know that in order to have your woofers in that arrangement, you must give up your spare tire? That setup uses the space normally occupied by the spare for airspace for the subs.

Bass is not worth getting stranded for.

 

[DurocShark]

I've seen some great work with fiberglass.

 

[cremator]

Originally posted by: Heisenberg
I would use at least a medium-density particle board, not plywood. When you make the box, be sure to seal the inside joints with a silicon-based sealer to make it airtight. I built a custom box for my Firebird, and it was pretty simple.

Also for speaker placement, is it best to have the back of the subs enclosed and the actual top exposed? Currently my speakers are totally enclosed but the magnet parts of the subs have blow holes

 

[Heisenberg]

Originally posted by: cremator

Originally posted by: Heisenberg
I would use at least a medium-density particle board, not plywood. When you make the box, be sure to seal the inside joints with a silicon-based sealer to make it airtight. I built a custom box for my Firebird, and it was pretty simple.

Also for speaker placement, is it best to have the back of the subs enclosed and the actual top exposed? Currently my speakers are totally enclosed but the magnet parts of the subs have blow holes

It depends on what type of subs you're using - sealed, ported, free-air, etc. I assumed you were talking about sealed.

 

[cremator]

Originally posted by: MichaelD
Do you know that in order to have your woofers in that arrangement, you must give up your spare tire? That setup uses the space normally occupied by the spare for airspace for the subs.

Bass is not worth getting stranded for.

I'm considering side mounted subs so it doesn't take up the spare tire. But currently my box is like 120 pounds so it'd still be trouble to get a spare tire out.

 

[bdjohnson]

Originally posted by: DurocShark
I've seen some great work with fiberglass.

I really doubt that fiberglass can give you good sound that you get with wood.

 

[AlienCraft]

Oriented Strand Board is ok as it is all wood with no voids. Particle board is expensive, imo and doesn't like water or the elements. Anything you put in should be primered with good quality Oil based primer, and if you want to go all the way, completely painted to match.
Air moving around the magnet structure and voice coil will keep the voice coil cooler and avoid failure. But if there isn't the proper volume of air retained in the enclosure, effiency will suffer and it'll flap and crap. It's a balancing act.
Calculate how much volume you have to work with and find the correct driver for that size of an enclosure. There are MANY books out there to help you.

 

[AlienCraft]

Originally posted by: bdjohnson

Originally posted by: DurocShark
I've seen some great work with fiberglass.

I really doubt that fiberglass can give you good sound that you get with wood.

Community Loudspeakers, among others have been making Pro Audio Quality Subwoofers from fiberglass for years.

 

[jteef]

MDF is the best material to use. maybe with some fiberglass too if you want to get really exotic.

I know its not a cavalier, but here's a bimmer with the setup you speak of... http://www.sounddomain.com/memberpage/489838

still can access spare tire. One thing you need to make sure of if you attempt an install like this is that you need to use a sub that works well in small boxes. Get the rough dimensions of volume you'll have to work with, and then use a program like winISD along with the MFGR's published Thiele & Small parameters to see if the speaker will work properly in the small volume.

 

[MichaelD]

Originally posted by: AlienCraft

Originally posted by: bdjohnson

Originally posted by: DurocShark
I've seen some great work with fiberglass.

I really doubt that fiberglass can give you good sound that you get with wood.

Community Loudspeakers, among others have been making Pro Audio Quality Subwoofers from fiberglass for years.

The key w/fiberglass enclosures is adequately bracing them and making the walls thick enough so the whole enclosure doesn't vibrate and/or flex.

The BEST subwoofer enclosure is a concrete box; zero resonance, zero flex. Not exactly practical, though. 😉

 

[Viperoni]

Originally posted by: bdjohnson

Originally posted by: DurocShark
I've seen some great work with fiberglass.

I really doubt that fiberglass can give you good sound that you get with wood.

Fibreglass is stiffer but more resonant than MDF.
You should be using MDF, and nothing else for speaker cabinets. It machines and cuts very well, and is much more damped than plywood or OSB.

As mentioned, you will have to give up your spare for an enclosure like that.

Search for fibreglass enclosures, you will find plenty of info as to how to do it.

Follow the sub manufacturer's specs for the subwoofer's air volume.

 

[AlienCraft]

Originally posted by: MichaelD

Originally posted by: AlienCraft

Originally posted by: bdjohnson

Originally posted by: DurocShark
I've seen some great work with fiberglass.

I really doubt that fiberglass can give you good sound that you get with wood.

Community Loudspeakers, among others have been making Pro Audio Quality Subwoofers from fiberglass for years.

The key w/fiberglass enclosures is adequately bracing them and making the walls thick enough so the whole enclosure doesn't vibrate and/or flex.

The BEST subwoofer enclosure is a concrete box; zero resonance, zero flex. Not exactly practical, though. 😉

There is a studio in France (Switzerland??) that used concrete to make their sub. The enclosure is part of the sub floor structure. Trying to find the links at ProSoundWeb.com

 

[voodoochylde]

Fiberglass is a decent material with which to build a subwoofer enclosure mostly because you can't really do things with MDF that you can with 'glass (extreme curves, fitting into tight spaces). To the OP, try my idea - build a couple of enclosures outta fiberglass in the two deep areas at the very rear of the trunk (where the hooks for the cargo net are). You wouldn't lose much useable trunk space that way and you can still likely get 1.0 - 1.3 cubes pretty easily.

Fiberglass, when properly laid, is considerably stronger than MDF and can resist vibrations much better. To help with the enclosure's acoustic characteristics, you could try lining it with a 1/2-inch layer of modeling clay...also, don't forget that you can make it horrendously strong if you incorporate other materials *ahem MDF* into your design.

One other point...I seriously doubt the OP is looking to compete in the IASCA. Sound quality may have some importance, but I'd wager that louder thump out back would rank higher in what s/he's looking for.

For some decent info on how to use fiberglass to build a custom sub enclosure, try: http://web.njit.edu/~cas1383/proj/main/ or http://www.e-kittan.com/fibre.html