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Hey all, im making a 2x15 right now and ive hit a design pickle.

I want this thing to be uber strong as ill be stacking 2 more cabs and 3 heads on top. SO i was thinking of bracing the shit outta the inside, from side to side/baffle to baffle and corner braces as well. My concern is ill make the cab too "stiff" and im worried it might sound dead and not that great if i do this.

WHo has experience that can help out? SHould I beef this thing up or let it breathe more? theres gunna be a lot of weight on it and it scares me...

Could you use a material that wasn't so dense that still possessed the structural strength and could support the weight? Maybe a metal?

I'm no expert, but I know a guy who is. He runs this place- http://www.theloudspeakerstore.com/ I mentioned earthquake cabs and he knew exactly what I was talking about. We went on to have a 2 hour long conversation about sensurround and frequencies and shit that was mostly way over my head. the dude geeks out on it. His take and my understanding on it is that in non ported cabs a higher interior volume helps because there is more space for the air to compress and decompress from when the speaker is moving into the cab. Large powerful speakers need more volume as they move more air which creates resistance keeping them from moving to their full potential. We also talked about batting and the freq's bouncing off the inside and coming back at the cone. I dont claim to understand it all but batting or damping materials increase vitual interior volume and stop sound pressure waves from coming back and hitting the cone which also inhibits the speaker from its full potential.
Fucking science man... How does it work?
I've put fiberglass insulation into several cabs now and have noticed a difference in clarity and an increase in low end.

The bracing and internal structure becomes more important with ported and folding horn cabs. If the sole purpose of the port is to relieve internal pressure I would think where and what the bracing is would be less important. If you are wanting the ports to be part of the sound then you will want to construct something that enables sound waves to move in the direction you want them to. I think you could come up with something that reinforces and directs the sound waves at the same time but I have not gotten into that with any of my projects yet.
Good luck with it man, let me know what you come up with.

Ahhh thank you for your help. It will be ported, but if i dislike the sound of the ports i will block them. Sounds like the stiffer the better to get the air moving the direction I want, I think ILl beef it up, but ill wait to get some more opinions.

And Dan, this fuckers getting big andd heavy fast, I dont think metal should be introduced or ill never move the thing haha. Although I am gunna have to put castors on it.

What materials are ou using for this 2x15 killer, mdf, ply, pine...?

Birch ply, 3/4 inch thick all around, baffles included. I mean its pretty fucking strong already but i feel like stacking a few cabs on top might abe a bit harsh.

It will be layed down long ways with the speakers next to each other and have 2 vertical 2x12s stacked on top of it, plus at least two heads...SO i think a support in the center from top down would be a good idea, but Id hate to kill the box by over engineering ya know.

Well I ain't a cab expert, but when I made my 2x12, I went with the basic philosophy of the stiffer the better. But if you are using the 3/4 ply for the back (closed) that should do it... But if you want more peace of mind, that hardwood beam idea would work, and they can always be removed later if you feel like it.

Gotta see some pics.... Love homemade cabs. Tolex? Dovetails?

will be stained, likely red/black burst. hardwood nosing (havent picked one yet) red grill cloth. No dove tails this time, too fucking huge for that. plus i gotta pump this out before I lose my shop...

sneak peek, its massive...

dude, 3/4 birch is burly as hell. you've got nothing to worry about. as long as your corners are adequately braced and glued and sturdy then you're fine. in many cases, the floor you'll be putting it on won't be any stronger. with the front and back baffles you've got around an 18" open span with that thing it looks like at most. you will have no flex at all, i'm sure. let it breathe a little. i like a 5/8 cab myself and even then i wouldn't be worried about it.

its going to be layed on its side like that though and all the weight on the "long" dimension. but yeah its super buff now but im kinda insane about strength. Just the way I build things I guess lol.

I think you are good. Maybe one center piece of hardwood and if you want to direct the sound waves some thin but stiff bits to save weight. This is going to be beautiful. can't wait to see what you come up with.

kinda ot, but I'm wondering what would happen if you soaked balsa in wood hardener.

The Wood Wizard wrote:its going to be layed on its side like that though and all the weight on the "long" dimension. but yeah its super buff now but im kinda insane about strength. Just the way I build things I guess lol.

yeah, i was thinking the long dimension. about 18" by maybe 40", right? you'll be totally fine. think about it this way, a building made with wood has the floor joists on 16" centers. on a lot of the old houses i work on you'll find weird shit and sometimes they'll be at 18 or so inches. not a big difference really if you're a piece of plywood. the long dimension can be 20 or 30 feet. with plywood especially, you're not worried about the long dimension. and that subfloor will be made of 3/4" plywood, sometimes even OSB, and it will be pine or fir depending on where it came from and that will not be near as stiff as birch, particularly if you're using the cabinet or marine grade 13 ply birch. as long as the short dimension can't flex, there's no way the long one can. you could make that cab ten feet long and it won't matter. there will be no flex in that short run and you've got solid pieces running to the floor 18" apart all the way down the long run, your back and baffle.

people put furniture and appliances and dance parties and vehicles on floors that aren't as strong as your cab. you should be fine.

but you know, if you want to put a center brace, you should. it ain't gonna hurt. just weight and resonance really, but if it's your peace of mind then by all means do it.

THat is true, ive seen some scary ass framing in my time as well haha. Ive also walked across boards with 8 foot spans on top of ladders instead of scaffolding and survived. the cabs internal measurements are 16 inches deep, 24 inches tall, and 42 inches long. maybe I am being a touch parranoid, ill go without uber supports for now, and just do some bits in the corners and the baffle to baffle brace and call it a day. ill stand on it and see if it moves.

still need to get some parts before i get much further but ill be sure to post progress. I cant wait to finally have a triamp setup