Dimensions for sealed 18" sub box - Page 22

It looks like the boxes for the 18" Dayton and the 18" LMS will need to be different. Well, same box shape, but different bracing.

The goal with the Dayton is to allow room for the 1000 watt plate amp to be installed if needed. It's about 5.25" deep. So that means a vertical brace that was 2" thick that can interlock with the other braces would come off the back roughly 8" to give safe clearance. That leave plenty of room for the 9" deep Dayton to sit in front of those braces. But the LMS is 11.5" deep, which would not fit in the box. So I'm going to have to redesign the bracing system to drop back further in the box for this one. That won't be a problem because no one is using a plate amp with this driver anyway.


The Dayton design has 2 horizontal and 1 vertical brace. inside unbraced spans are about 8.75" on the vertical and 7" on the horizontal. I think that's very good for this driver.

If these boxes are going to be different, I'm thinking the LMS should get a second vertical brace.

Both boxes could be the same if the bracing style was similar to the one discussed last week. I'll get some photos up later.

Here's a quick idea for the 18" Dayton box. Yes, I stink at Photoshop, no reason to say it. The square in the middle that shows the amp will not be cut through. I will have the outline carved on the inside of the box with a router bit around .1" deep. Measurements are rounded a little bit.

To install an amp in this box would be very easy. First cut the amp hole, then assemble the box. Then just cut the extra wood away from the horizontal shelves.....done. You still have the cross bracing, and the amp fits just fine.

The box is 4.25 cuft gross. After bracing it should be right around 4 cuft net internal volume.


If the cross bracing gets moved back about 1.5" so the 12" deep LMS can fit, the cross brace is only going to be about 6.5" off the rear panel. At that point, I'm not sure it's worth a full length cross brace because it's so far off the center anyway. I'll try to draw it up later to explain better.

Now if we went back to the triangular style braces that run from front to back, and about 8" across the rear panel, then we could put 2 on each panel and then one box would work with all woofers and plate amps.

A picture will be better than my typing.

It was hard, but I somehow lowered my Photoshop skills even more on this drawing! This would be the other idea for the 18" Dayton that would use the same amount of area on a sheet of wood. The braces are smaller, but we get 2 per vertical span. I like this idea better than the previous one.




Those smaller braces are similar to the ones Zaph Audio uses and how we thought they should be last year. Mine are beefier than these and run up to the baffle which is better, but still the same concept of locking neighboring panels together so neither can flex:




Now if we did that on the horizontal braces as well, then one box could be used with both 18" subwoofers, and still allow for an amp to be installed on the back panel. There would be a total of 8 braces running up the side and attaching to the subbaffle. To me, this is the best way to go because once that 18" LMS magnet is pushed back in the box that far, a cross brace would only be about 6" - 7" off the rear panel. That far back, the cross brace does no more for the side panels than the other style brace.
Edited by Erich H - 11/19/12 at 8:50am

I thought about that and did draw it up. But the magnet is about 11" wide. Inside the box is 18.5" wide. So the vertical braces would literally be about 3.5" away from the corners and wall, which is the strongest part of the box already.

If the box was 2" deeper, then we would be up to the volume in the beginning of the thread where people said it was too much for the LMS. 4.25cuft will be about 4.05 net, probably closer to 4. That seemed to be exactly what people were wanting for the LMS.


I think either way this is done, we're going to need 1 box size with 2 different brace styles to accommodate either an amplifier of the back panel, or a deep magnet off the front panel.

The only other way to do it would be to use 8 of those 'L' style braces.

I need to draw up a brace to show how far back the the cross member would be in the LMS box, then decide if it's even needed at that depth. I'll try to do that this morning so we can decide. I have to send these designs in very soon because the other sub boxes are getting cut and they need to be done at the same time.
Edited by Erich H - 11/20/12 at 6:35am

Here's the other idea I had that would work for both boxes, laid out on a cut sheet. The braces would be done on a second sheet which is good because they have to be different anyway. This is a pretty tight fit between some of these panels, and I'm not 100% sure they can do it just yet, but I will check.




This gives 2 braces for each top and bottom panel, and then the 2 horizontals. The space taken up by those 4 braces on the sheet is roughly 38" x 10.5". I could design 2 long vertical cross braces shaped like a 'U' that would fit in that area. They would be about 6" deep, but could interlock with the horizontals. I'll have to do that later because I've got to go to work right now.

So we could get half the boxes done like that picture above for the Dayton. Then half done like that picture above with 2 of the U braces.

Then the sheet of horizontals could have 2 of each style. I'll draw the U brace later today and see if it will work. But it would only come up off the back panel about 6" before hitting the rear of the deep subwoofer. Personally, I'd rather have the longer braces going up the top and bottom than interlocking with the horizontals.

Yes, blank baffles will be able to be ordered, but I'll be getting some made up for a couple different 15's. I changed the layout in that above picture to cram all the different braces on the panel, but then do the subbaffle and outer baffle separately. That way I can get a decent number of boxes and switch out the baffles as needed.

The 3 cuft boxes are also aimed at the 15" drivers. And there will be a dual opposed 12" model for the Dayton RS series. I think that box was around 2.5 cuft.

I'm assembling a 12" model with dual 12" passive radiators right now. It's in a small 15" cube.

There's also a super small 12.5" cube with a 10" driver and dual 10" passive radiators.

The small cheaper models are being tested first. I'll have the 12" woofer model finished up shortly.


Gentlemen, I do believe I have designed a dual opposed box that will work for dual Dayton 18's, dual 15's and also a very nice ported 15" tuned to 18hz.

22" tall x 23" wide x 31" deep (not counting double baffle)

Net after bracing is 7.25 sealed.

Same box after port volume of two 4" ports, woofer, and possible amp would be right around 6.5 - 6.7cuft. Easy to tune low with long straight ports. The 23" width should allow for a 15" woofer and two of the wide flanged 4" Precision Ports to fit on the baffle.

I just need to figure out what wood to use in order to keep shipping weight okay. These will need to be shipped in 2 boxes either way, so maybe these should be mdf to keep prices okay too.