# Sub enclosure...MDF or birch plywood ?



## UNBROKEN (Sep 25, 2009)

Also...this will be a pass through box in my Superduty...what's the best thing to seal the box from water? LineX ? Something like Thompsons Waterseal or something similar? 
The same question applies to the trim panels that will be in the bed. 

Sealing the cab/bed junction is easy and I have a hard bedcover but it does seep some water past the hinges up front so I need the trim panels and enclosure completly waterproof.


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## TJ Mobile Audio (May 6, 2009)

Yes.

MDF is most common, birch plywood is also fine. If you use plywood, I recommend asking for Void-free 3/4" Baltic Birch, 5-ply or better. Actually, 7 or more plies is probably more common and better overall. If you're covering it anyway, MDF will be cheaper and still does the job.

LineX or other spray-on bedliners should do fine at sealing up the enclosure, I've often seen it done that way.


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## mitchyz250f (May 14, 2005)

I have had it working with mdf, it makes a mess, corners break off and it splits. It is also hard on tools. I use birch when I can get it, and plywood when I can't.


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## freemind (Sep 11, 2008)

Are you kidding?

Given a choice and budget, Birch all the way baby!


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## emperorjj1 (Sep 10, 2008)

messed with birch for the first time a few days ago. sorta half and half. pros of birch are... lighter, less sawdust. cons... over double the price of mdf, wood chips, predrill predrill predrill, sands like ****

pros... of MDF cheap, easy to sand/shape cons... now heavy compared to birch, insane amount of dust


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## rak_24540 (Sep 27, 2009)

Are there more than one grade of MDF?


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## 2DEEP2 (Jul 9, 2007)

I would get a marine grade birch, b/c it's treated for water, and seal it with fiberglass resin.

It will last forever! 

Yes, you should pre-drill holes when using birch. I also use wood inserts with machines screws to hold the subs to the enclosure.

There are several grades of Medium Density Fiber board. Some MDF is better than others. All grades of MDF once wet will be destroyed. Show me a boat with water resistant MDF if you can. I'll show you two boats with marine birch. Birch in water applications are easier to find simply because birch last longer, not to over look birch is also lighter. 

However, MDF is much cheaper. Some people like the sound of MDF box, b/c they flex more than birch and you hear the box as well as the sub.

Pay now or pay later, it's your choice.


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## woodcrafter (Oct 21, 2009)

TJ Mobile Audio said:


> Yes.
> 
> MDF is most common, birch plywood is also fine. If you use plywood, I recommend asking for Void-free 3/4" Baltic Birch, 5-ply or better. Actually, 7 or more plies is probably more common and better overall. If you're covering it anyway, MDF will be cheaper and still does the job.
> 
> LineX or other spray-on bedliners should do fine at sealing up the enclosure, I've often seen it done that way.



Well if you are looking to use Baltic Birch Plywood, then make sure you buy sheets that are WBP (water boiling point) glue rated. This is the best for moisture resistance, but make sure that Baltic Birch that you get is made in the same area where it grows I(Russia or Finland), and definatelly not China. See here shop.eastcoastplywood.com


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## DaveRulz (Jun 22, 2006)

Just because it is birch plywood does not mean it is good for building subwoofer cabinets. If I remember correctly (from my pro-audio days) to get similar results as MDF you need to get the 13 ply, void free variety. This is not commonly stocked at home depot and is NOT cheap. Also, you should be pre-drilling regardless of if you are using MDF or Plywood, or any wood for that matter, it's good practice and not doing so is pretty much just lazy. 

As far as protecting the enclosure in your bed, I would say that coating it with line-x or similar would prevent pretty much any problems you could possibly have.

I would say build the enclosure with MDF to save yourself a bunch of cash, and then seal every surface of it with line-X.


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## kyheng (Jan 31, 2007)

I will use MDF but with proper treatments(shellac and carpet it) applied to it.


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## spork (Jul 1, 2008)

MDF is a pain and is heavy, but its just so easy to sand and shape.


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## Qicker306 (Oct 2, 2009)

rak_24540 said:


> Are there more than one grade of MDF?


Yes, just like any plywood there are different grades based on finish and density. Graded; A, AA, AAA etc. at least from what I have seen. AAA would be the product with the best finish, usually harder and denser then cheap stuff, less likely to split... I'm not sure of price difference however, don't think it would be too substantial.


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## NSTar (Feb 24, 2010)

I used birch and no drilling necessary... I used some sticky ass glue. That thing bonds. Of course, you gotta hold it or clamp it for atleast an hour. 24 hour cure and you are golden.


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## passtim (Sep 30, 2009)

Used both, but for the toughest boxes, I've used HDF, though it actually throws sparks when you cut it, also hard to find.


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