Well looks like I will end up with 17.87cu before bracing and sub displacement. I really want to end up with 17cu total after.

This is for 2 18in FI Q's on 3k watts.

Box dimensions will be Outside 35h x 54w x 27d.... All sides double 3/4 MDF except front baffle will be triple. (may use some Birch for weight reduction)

Usable inside demensions are 32h x 41.5w x 23.25d = 17.87cu

Port is 8 x 32 = 256in total

Sub displacement = .24... but I will be triple baffled so what maybe .22 or less??

Total of six 2in hardwood dowels for bracing =.35

2in wide 45's in corners =.10

So this leaves me with 17cuft tuned at 30hz after all is said and done. I may glass the inside as well? whats the benefits?

Anybody see anything I am missing? Will six 2in hardwood dowels be enough fr bracing? 2 top to bottom, 2 front to back and 2 side to port wall. Plus with all double walled and triple baffle this mofo should be solid I would think.

With that much space just grab another q and run them. That is too big for those subs unless you ran like 500rms

It's perfect for them, it 2 18's.... They call for 6-10cu each. I'm at 8.5

"Sub displacement = .24... but I will be triple baffled so what maybe .22 or less??"

What did you want to say ? Sub displacement and the number of baffle are 2 different things !

You have 2 subs ? Total subs displacement is .48 ft3.

When looking for net volume, just take the internal dimensions of your box, no matter how many baffles you use !

"Sub displacement = .24... but I will be triple baffled so what maybe .22 or less??"

What did you want to say ? Sub displacement and the number of baffle are 2 different things !

You have 2 subs ? Total subs displacement is .48 ft3.

When looking for net volume, just take the internal dimensions of your box, no matter how many baffles you use !

No I realize that there is two subs. I meant each.

It will matter how many baffles used if you get technical, because the more baffles used the less displacement the sub will occupy inside the box.

So are you saying in if I used 10 baffles and only 2 inches of the sub were inside the box it would still take up .24? See what I'm saying....

I have a very good feel for calculating internal volume, I was just curious with such large panels doubled up how much bracing would I need and if what I designed would be sufficient.

My math was

17.87 cu

- .44 subs

- .35 bracing

- .10 45's

= 16.98 net volume

Edited April 12, 201213 yr by swift

To get the most out of the bracing I would use some sort of metal tubing with plates on each end. If you can weld it would very easy to make them, if not then you can ask a local or have a shop do it. Won't cost all that much really and it is the best bracing per displacement you can get.

Thanks PM sent

Ok looks like I will stick with about 14cu and start building. Thanks for all opinions

To get the most out of the bracing I would use some sort of metal tubing with plates on each end. If you can weld it would very easy to make them, if not then you can ask a local or have a shop do it. Won't cost all that much really and it is the best bracing per displacement you can get.

Could you get some plate steel then center drill and tap for all thread? That way you can adjust it to fit how and where you want.

I like that idea. Usually I just use dowel rod.

You could yes. That is like make a cheaper adjustable brace so it is reusable. Just need to ensure you have found a way to keep it tight and secure so it won't become lose or fall out once actually playing.

No I realize that there is two subs. I meant each.

It will matter how many baffles used if you get technical, because the more baffles used the less displacement the sub will occupy inside the box.

So are you saying in if I used 10 baffles and only 2 inches of the sub were inside the box it would still take up .24? See what I'm saying....

good point..