box

I'm planning on building a ported/sealed box for my 2 12inch JL audio w6's.

Some of my questions may be stupid but I've never built a box before so I apologize in advance.

I'd appreciate it if you would comment/correct my inquires to help me build a good box.

I've been told ported boxes are better for rap music than sealed.

1. I guess basically I would need to buy 3/4 MDF, cut it to factory recommendation length, width, and height, then screw/nail them together and seal the edges with ????

2.  Also, to connect the 2 sub boxes, I guess I would double the length and place a piece of wood in between the two equal size enclosures? 

3.  Would I even need to put a piece of wood between the 2 subs if they are both running off the same channel (mono) for both ported and sealed?  If I used an unseperated ported box would I have to use 2 ports or 1? 

4.  Also if I do a ported box, just use correct size PVC pipe and cut to factory recommendations, then cut a hole in the box, and seal the port/pipe in place with ????

5.  Does it matter where you place the port?

6.  I would like to brace the box, just not sure where to brace it, guessing 2-3 braces per side would be adequate.

7.  One more thing, how would I seal the subs to the box?

Don't even want to get into carpeting yet, I'll worry about that later.

Sorry for sounding like a dumb ass, I just want to get it right the 1st time.

Thanks so much for all your help.

I'll do my best to answer your questions to the best of my knowledge.

1.  Yes on the 3/4" MDF.  When you test-fit the panels and you are sure you have them cut correctly, drill pilots for your screws (not nails).  Then apply a small bead of wood glue on the surface to be mounted and screw them together.  Later you can use some caulk to seal.  I prefer silicone, as it is pretty easy to work with, but let it cure for a few hours before you mount your subs to insure that the surrounds will not be harmed due to the silicone fumes (really shouldn't be a problem with JL subs).

2/3.  You can separate the two boxes with a panel, but for the W6 series, I would recommend double thick panel as they require high power and move a lot of air.  It isn't really necessary since you will be driving them with the same signal.  Look at JL's website in the tutorials for box building.  It will give you a good idea of box building and will explain in detail better than I can how to use multiple ports or one port for your enclosure.

4.  You can use PVC pipe, and it's easy to get, but you may want to look into getting an actual port tube.  They are less prone to port noise and whistling.  Try partsexpress.com in the speaker building section.

5.  On placing the port: I think the JL site has some info on this as well.  I have experienced that the port placement is best when parallel to the sub, but then others might disagree.

6.  On bracing:  a very good idea, expecially when using high excursion subs.  I like the type C bracing technique outlined in JL's bracing technique tutorial.  It isn't that difficult to make and helps tremendously in rigidity in the box.

7.  Sealing the subs to the box is not that difficult.  Sometimes manufacturers will supply a gasket to affix to the mounting surface of the sub.  If you have this, use it.  If not, try to find some sealing caulk, not silicone.  Parts Express has this item, but it is a bit difficult to work, and large quantities of it works well, especially when mounting to a non-caperted surface.

I hope I have been of some assistance to you.  By the way, what amp are you planning to use?  Let me know if you need any more help.

I appreciate your reply.  I really needed some help!

Couple questions:

What do you mean by "double thick panel" in between the subs? 

1.5 inch MDF?

Since I don't have a gasket I guess I will just seal the sub directly to the box.  Should I seal the sub to the carpet or the MDF? 

And how would I ever get the sub off of the box if I ever needed to? 

I don't see how I would if it's sealed directly to the box?

I plan to use a MTX Thunder81000D.  Its selling cheap online and will leave me room to upgrade.

Double thick panel is when you basically use two pieces of in your case 3/4 inch mdf in the center to divide the two chambers instead of just one piece of 3/4 mdf.

For sealing I use liquid nails(construction)(red label) where you can find it at Wal-Mart. Just my preference.

by double thick, I mean use two 3/4" mdf panels mounted together as one, so yes 1.5"  It's not really that critical, but in some SPL conpetitions it has been known to make a bit of difference.

Getting the sub off the box will not be a problem as the weight of the sub will allow you to rock it back and forth to remove it.  you can always clean an old gasket off and apply a new one.  whether mounting to carpet or wood, you want a clean, sealed mount.  air leak = SPL loss, and usually SQ loss.

The MTX amp you mentioned is a good amp, and from everything I have read, it provides good clean power.  It might be a bit over rated in its power department, but still a very good amp.

I'm not sure which box to build, ported or sealed?

I've read alot on the two, but still cannot decide.

I listen to rap rap rap and more RAP.

Not sure if that helps, but it may.

Thanks again for your help.

Sealed boxes offer better transient response, which I find nice when listening to rap.  Ported boxes usually extend frequency response a bit lower than sealed boxes...also nice to have low bass in rap songs.  Ported designs are easy to screw up if you are not experienced or skilled, but if you take your time, it's not that bad.  I prefer sealed, but you ought to find some sealed and ported designs in a local installer's garage and listen to each to decide which you like better.  Let me know what you decide.

I'm going to use sealed just for ease of installation. 

Couple more questions:

How do you calculate the amount of space the braces and the termanals take up?

I was thinking I wouldn't worrk about it because it so little it probably won't matter.

Luckily JL already calculated the amount of space the sub takes up.

Can't wait till Monday!!!!!

I'm going to order the MTX Thunder 8100D!!!!!!!!!!!!

And I'm getting O gauge wire, RCA interconnects, ground wire, speaker wire, fuse, EVERYTHING for $20.  All MonsterCable

I wouldn't worry about terminals, but the braces should not pose a problem.  Draw or sketch the brace you plan to use if it is not a familiar shape.  Find its volume by the correct geometrical formula.  Subtract that volume (in the correct units) from the volume of the box.

It sounds like you have everything all ready to go.  One more thing: you might want to search the other forums for info on box shape.  Don't make a square box, unless it can't be helped.  You want to keep the front baffle from being parallel the rear panel of the box.  This will reduce box resonance.

Good Luck, and tell me in what vehicle and where you are installing.

1993 Chevrolet Suburban

It's really nice Leather and everything.

Looks like a 1997.

Put new speakers in, modified the hell out of the door panel to fit them, and a new head unit.  Took me 2 whole days!!!

I think JL's recommendation for these subs is a cube which does make the front and bake panel parallel.

http://www.jlaudio.com/subwoofers/pdfs/detailedpdfs/W6/12W6Normal.pdf