Dimensions for sealed 18" sub box - Page 3

mdf is a good bit more than $10-$15 per sheet. If they were to get two of the boxes for 10" woofers out of one sheet, you're guess would make them only $20 each. But I know that's not going to be their price. The Overnight Sensation MTM cabinets were just a bit under $20 before I added in a shipping box and packing material. And the larger boxes use over 1 sheet.

I've gotten plenty of price estimates for other boxes and this company has always been way under what others charged. The Anarchy TH flat packs from this company were almost half the price of 3 other bids I got.

We'll see how it goes.

They do have double baffles on the front and they could be added to the back as well. But dual opposed boxes will have to have completely different bracing on the inside.

I'll have to figure out how the grills will work out. Haven't given it a lot of thought yet but I'm sure it can be done pretty easy.

I was figuring about the same as TundrSQ. It would be longer than 10 minutes because they roundover the baffles afterwards and sometimes chamfer around the back of the woofer hole by hand. Plus every panel has rabbet joints or dados except the rear panel. I think the machine could probably cut each box in about 12 - 15 minutes? That might be tough if they use over 1 sheet per box though. But then cleaning up each piece, stacking everything on pallets, clean the machine's table, load the next piece, etc.

If it was 4 per hour and they charge $90 for each cabinet: $360 per hour minus $140 in wood (1.5 sheets per box). Down to $220. I'd think they'd have to figure around $100 per hour just for the $250k machine itself. That leaves $120. It wouldn't surprise me if they have to figure $80 - $100 per man hour for the employee to cover all costs. Down to $20-$40 left to pay for design work, a secretary, the big cheese, and a few other pencil pushers upstairs.

TundrSQ might be closer to the price than I am.

These are $139 and the regular birch used on them is probably just a bit more than mdf costs, and the bracing isn't quite up to what we need and no roundovers or double baffles:

http://www.parts-express.com/pe/show...number=245-328

As long as you have the room to store it all!

BWaslo came to the shop for the first time yesterday and he probably thought I was nuts. Boxes of sample waveguides over here, stuff left over from the JBL group buy over there. A few pallets of flat packs down that way, pallets of new flat packs still wrapped up waiting for the crossover over in that corner. Shipping boxes piled up on shelves down the wall.......packaged up waveguides and horns stacked nicely on another pallet about 7' tall.


My spare building next to my landscape shop has turned into an audio storage warehouse. I should take some pictures.

Some photos.


I didn't get chance to take photos of the box for the 18", Ill get them tomorrow. It looks very similar to the 15" sub box though, with a little more bracing.

These are the prototype boxes that I got first. You'll notice that the baffle installation was different on the 10" and 12" and 15" box. I wanted to see which was the best way to go. I decided the larger box had the best method. I was worried that the inner baffle could cause an installation problem because it has to drop in on all 4 sides. If the box was glued up a little "off", it might not fall in really easy without a hammer. But I've put a few of these together and it doesn't seem to be a problem.

The shelf braces go all the way to the rear panel. But I designed them so you could cut a hole for a plate amp and still have plenty of clearance. I'll get some better photos with the top of the box removed. If you look close you can see how installing a plate amp would be very easy if you wanted to.


The one for the sealed 10" should be cheap and very easy to assemble. I had the company cut 2 different style braces, but the ones with heavy curves caused the 10" Titanic to rub on the magnet's rubber bushing. So they made the braces more squared off to increase the clearance. These will also hold a 12" driver. Again, the first baffle layer installs different on the finalized model, these were just prototype photos I took a little while ago. Bracing divides the panels at about 6".

This is about as simple as it gets: 1.25 cu ft





The box for the sealed 12" comes in around 2.25 cu ft if I recall. I forgot to grab my notes before I left work. These could probably be used for some ported 10's just by changing the baffle. The bracing clears most woofers with no problem. But I should ask them to make some with squared up braces to allow drivers with bigger magnets. Might do a 50/50 mix to be on the safe side. The inner baffle dropped in differently for this actual prototype. I didn't like this method as much because for some reason they didn't put rabbet joints on the top and bottom. The actual run does have them though, so it drops in place.




The box for the sealed 15" comes in around 3.5 cu ft, but I'll have to check my notes and post actual dimensions. It can also be used for some ported 12's. The box is 18" wide, 23" tall, and 20" deep. It can also be used for ported 12's. The photo of it by itself wasn't the best, so you can see these 3 side by side.


THIS is the way the other boxes now assemble. Notice that the first baffle will completely drop into the box so the outer baffle lays flush. Again, bracing is about every 6". This box can be dry fitted together with masking tape in less than 5 minutes!! Braces slide in pretty easy.

Bracing divides all panels up around 6" and everything locks together and slides in from the front if that's how you wanted to assemble them.



Keep in mind, this following picture doesn't show the outer baffles, only the first layer dropped in flush.

You can see how each box was done differently for experimenting. The final method is the box on the left. Obviously these boxes are only held together with tape. Actually, the inner baffle is just sitting inside the box without tape, so it might look a little lose. It's not once you squeeze the sides together with your hands.....or glue.







To be honest, I liked how easy the first baffle installed on the smaller box. It looks better here, but it doesn't matter because all will be covered up with the outer baffle anyway.

The only reason I didn't like the 10" method was because from above, you would see the seam of that baffle, and the seam for the outer one as well.

Then you can see the progression to the 12" model where it dropped in, but only rabbets were cut on the side panels. At that point, I saw no reason why rabbet joints should just be cut all the way around.

Ha, don't get too excited until you see the big boy for the 18".

If I have time tomorrow, I'll get them all laid out side by side.


Keep in mind, I'm going to have them cut different baffles, and a couple more designs to allow for dual opposed set ups. The finalized versions of the prototypes above are pretty much ready to go, but I need to get definite prices with shipping boxes and packing material. I want to box some up this weekend to see how everything goes.

When finished (very shortly) this entire sub project should have all the designs I've asked for........that would be 14 if I counted correctly. The main ones will be made in a higher quantity while others will be made in smaller numbers so I don't run out of room!

I will, don't worry.

But with that type of internal bracing, there really won't be much difference between the two in the end. Even the weight would be about the same.

I agree 100% and I will be getting different ones done for the Baltic birch like we discussed in the other thread.

But on these, the bracing slides into place really nice. And it does break up the panels into smaller spans when the brace goes all the way across a panel versus a brace that only contacts the sides at the dead center of the panel.

For DIY guys, I think some of the bracing also has to look like it's overkill. If you recall that thread about bracing, even though a wooden dowel directly in the center of a panel works pretty good, others wanted more.

So I just figured to do a little overkill on the first designs to make it an option.


I'm not sure the picture of the larger box shows the bracing very good. It does span the rear panels as well.

The larger boxes use 1.5 sheets though. So the time goes up by 50% and the cost of material goes up by 50%. In the end, his numbers would also be at least $90. Possibly pushing closer to $100 because there's more involved than just the CNC run time. But either way, it seems that as long as the current CNC company comes in around $90 - $100 it looks to be pretty good.

The 12" box only uses 1 sheet of wood, and I think I was guessing around the $60 mark for the CNC company to cut those. So if that's close then we know we're on the right track.

I need to figure out shipping boxes still. Hopefully that can be done around Thursday. I'll also try to post the photo of the big 18 box tonight. I forgot that I had them make it 23" x 23" x 20" deep. I was originally going to have them 22" x 23" x 20" deep but they can always be changed back though.


I'll also try top get all the current dimensions as well.

I do have a good brace design for the cabinet that was discussed last year that ties all side panels together. It was my design that Notny helped tweak with his CAD skills. I have the photos on my site. That box still needs to dip into a second sheet of Baltic though.


A beam in the middle of each panel works fine. But on larger boxes with 23" x 23" panels, it still leaves spans that are 11" x 23" unbraced through the box. I realize that's not a huge problem, but not everyone else does. And that's an issue when I have to order a decent number of them and some people might think the bracing looks weak. One concern is what it actually looks like with just some stick bracing inside. Of course it works just fine. But I think most people want to see "substantial" bracing which is how I figured we'd start out. I've been working on a bracing system for quite some time.....these first boxes don't use those yet. They're just beefed up boxes like the majority of people seemed to want.

The LMS is nearly 12" deep, and you can't put a brace directly behind the magnet because I'm sure there's a vent back there. So if you move the brace 3" off the back of the LMS, you now have one stick brace dividing a panel into 15" x 23" and 5" x 23". I think a 15" x 23" panel would need extra bracing?



For what it's worth, there really isn't much weight savings with real Baltic birch. Plain birch plywood is lighter though.