Boxes pretty much done. Questions on bracing - AVS Forum
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post #1 of 64 Old 08-04-2014, 04:16 PM - Thread Starter
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Boxes pretty much done. Questions on bracing

Hello all,
I had a friend help me with making some vertical front ported "mini marties" for my Dual SI-18's
They are pretty much all buttoned up, but have to cut the holes yet and add the bracing. I suggested doing bracing before buttoning up the boxes, but he swears he can get them in there no problem. He used to build car boxes back in the day, but its been quite a few years.
He doesn't think they are going to flex at all, but I wanted to get some suggestions on brace locations on these things just for added piece of mind.

Just do a couple 1x24's or 2x24'sfrom front to back and side to side?
Here is a side shot before the side went on.
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post #2 of 64 Old 08-04-2014, 04:35 PM
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Is that 3/4" MDF?

And yes that single layer of MDF will definitely flex. I thought there was a build thread with pictures of bracing and everything for the Mini Marty?
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post #3 of 64 Old 08-04-2014, 04:38 PM
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Something like this will give the best results. Maximum spacing should be about 8 inches.




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I suggested doing bracing before buttoning up the boxes, but he swears he can get them in there no problem... He doesn't think they are going to flex at all
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post #4 of 64 Old 08-04-2014, 04:43 PM
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post #5 of 64 Old 08-04-2014, 04:55 PM - Thread Starter
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Yes its 3/4 MDF.
I read through a ton of threads, but looks like everyone does something different with bracing.
3/4 mdf will really flex that much? He thought the dual front baffle was more for aesthetics to flush mount.. He did not think the MDF would flex, but said we could brace for good measure.

So Bill you are with me thinking those braces are going to be a PITA to get in? Do you think the bracing will take care of any flex from not having another baffle?

Wouldnt running screws along all the port backs and sides help reinforce everything pretty much? The thought was that the sides and back and bottom would be pretty darn secure with all the glue and using the port rails as bracing


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post #6 of 64 Old 08-04-2014, 05:02 PM
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He gave you the wrong advice your friend. Always put bracing in before last big piece installed. Bill is right and easiest way is with two horizontal window brace.

Then attach vertical pieces like bill showed. without proper bracing you will lose the advantage of diy. the walls will definitely flex without bracing.
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post #7 of 64 Old 08-04-2014, 05:14 PM - Thread Starter
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Sigh

Ill give him a chance to see if he can get some bracing in there before we rip a panel off. Im sure thats gonna be a total nightmare to do.
What if he can squeeze the bracing in there by chance in some fashion. Maybe doing like an angle bracing. . . Any better if he cant get in like suggested above? Or that along with another front panel? Or basically trashed at that point and need to break the seals and sand down glue and redo one of the panels?

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post #8 of 64 Old 08-04-2014, 05:19 PM
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No need to take stuff apart. Make window brace in half, like a L. In this shape you can fit it through the driver hole. Then install and put in second half. Use cross lap joints and brad nail and glue. Once you get two horizontal pieces in put vertical. Use one inch wide pieces.
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post #9 of 64 Old 08-04-2014, 05:47 PM - Thread Starter
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thanks guys. Ill see what we can come up with later this week.

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post #10 of 64 Old 08-06-2014, 05:21 AM - Thread Starter
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OK, So I got the boxes home and I am on my own for the bracing. For the ones from front to back where they will touch the port, is glue enough since I cannot get screws threw due to the ports?
I think I may try the dowel type approach as I do not have the tools to do fancy cuts that will be straight. I only have tools for simple cuts.

Also some other questions:
1. We put together with Liquid Nails wood glue. Any need to run additional beads of sealant of any kind on the insides for good measure and maybe around the dowels for bracing?
2. Anyone know the whole size for the speakon terminals? I dont have one with and wanted to get a hole bit today while Im running for other stuff
3. Suggestions for something to line the inside of the box with from preferable lowes or home depot? I saw someone reccomend this to someone else and they have at Home depot, but was planning on getting everything else at Lowes http://www.homedepot.com/p/UltraTouc...6482/202709974
4. If I use like the deck restorer stuff or rhino lining, any primer or anything I need to do to the box first?

I think thats it for now.
Thanks in advance guys. Hopefully I can to filler and sanding today and finishing this weekend.


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post #11 of 64 Old 08-06-2014, 05:34 AM
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Quote:
Originally Posted by PM-Performance View Post
OK, So I got the boxes home and I am on my own for the bracing. For the ones from front to back where they will touch the port, is glue enough since I cannot get screws threw due to the ports?
I think I may try the dowel type approach as I do not have the tools to do fancy cuts that will be straight. I only have tools for simple cuts.

Also some other questions:
1. We put together with Liquid Nails wood glue. Any need to run additional beads of sealant of any kind on the insides for good measure and maybe around the dowels for bracing?
2. Anyone know the whole size for the speakon terminals? I dont have one with and wanted to get a hole bit today while Im running for other stuff
3. Suggestions for something to line the inside of the box with from preferable lowes or home depot? I saw someone reccomend this to someone else and they have at Home depot, but was planning on getting everything else at Lowes http://www.homedepot.com/p/UltraTouc...6482/202709974
4. If I use like the deck restorer stuff or rhino lining, any primer or anything I need to do to the box first?

I think thats it for now.
Thanks in advance guys. Hopefully I can to filler and sanding today and finishing this weekend.
Here we go:
1. If you are confident about how tight the boxes joints are, then there is no need to run additional sealant around the inside edges. It will certainly not hurt anything if you do it anyway.
2. The hole for the Speakon will depend on the specific one that you bought. There are all different sizes and shapes; some square, some round. I'd suggest waiting until you have it in your hand before you bore out a hole.
3. The Ultra-Touch stuff is supposed to be great for ported box applications and won't leave you with the itch. If that's not available to pick up locally for you (my local HD's do not stock it), you could find an eggcrate type foam to glue to the walls or even just use pink fiberglass insulation. Just don't line the port (obviously).
4. I would recommend some type of sealant/primer for the MDF before you apply anything else to it, but I'm sure there are lots of different opinions on this and I personally have not used any of those bedliner products, so I don't really know.

Good luck!
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post #12 of 64 Old 08-06-2014, 05:45 AM - Thread Starter
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Every board got a thick bead of liquid nails before setting and screwing into place. There are a few places the glue did not seap out of, which is why I was thinking maybe extra security.
I just noticed that Ultratouch stuff is not stocked locally. Thanks for pointing that out, saves me a wasted trip.
What about using Roxul? Are those "batts" as they call them just rolled up, or are batts sliced up individual pieces? They look to have no fiberglass, so that is nice and the amount I need is cheaper than the Ultratouch
Do any brick and mortar places carry that egg crate foam? I have not seen any at Lowes and Home Depot atleast.


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post #13 of 64 Old 08-06-2014, 06:31 AM
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Do any brick and mortar places carry that egg crate foam? I have not seen any at Lowes and Home Depot atleast.
Walmart does. It's called a mattress topper. Make sure you get standard grade, not memory foam, as memory foam is too dense. BTW, convoluted foam doesn't work any better than plain. Your eyes may tell you that it does, but convoluted foam is 1/3 air, and air doesn't have damping properties. You can find plain foam at stores that sell upholstery materials, including fabric stores.

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post #14 of 64 Old 08-06-2014, 06:44 AM - Thread Starter
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OK, cool.
Ill check that out and see what fairs better price and avail wise. Should i completely line all the inside panels (minus the insides of the ports of course) or is that overkill?

Looks like all the toppers are convoluted foam and dirt cheap, but if it wont work as well as roxul or the ultratouch, then I rather get that stuff. Joann's has reg density pads, but not enough in stock by me to get both done


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post #15 of 64 Old 08-06-2014, 06:44 AM
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I was at lowes the other day trying to find some 1 inch square dowel and they didn't have any. I started wondering around and found some yard stakes that are exactly 1 inch. They were bundled in groups of 6 and were relatively inexpensive compared to the dowel rods of equal size. Not sure if you bought your bracing yet but you might check those out if you still nee some.

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post #16 of 64 Old 08-06-2014, 07:16 AM
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Originally Posted by PM-Performance View Post
OK, cool.
Ill check that out and see what fairs better price and avail wise. Should i completely line all the inside panels (minus the insides of the ports of course) or is that overkill?

Looks like all the toppers are convoluted foam and dirt cheap, but if it wont work as well as roxul or the ultratouch, then I rather get that stuff. Joann's has reg density pads, but not enough in stock by me to get both done
Buy the topper. Put it everywhere but port.
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post #17 of 64 Old 08-06-2014, 07:34 AM - Thread Starter
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Quote:
Originally Posted by action_jackson View Post
I was at lowes the other day trying to find some 1 inch square dowel and they didn't have any. I started wondering around and found some yard stakes that are exactly 1 inch. They were bundled in groups of 6 and were relatively inexpensive compared to the dowel rods of equal size. Not sure if you bought your bracing yet but you might check those out if you still nee some.
OK, I gotta run to Lowes for some other stuff at lunch anyway so Ill check for that stuff

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Buy the topper. Put it everywhere but port.
Crap, I just did the measurements and I would need two kings and they only have one in stock anyway. Any other place only has smaller units which will end up costing more than the denim. Im just gonna order the denim online for $36 for 6 rolls.

Any suggestions on sealant for some added piece of mind?
Also any concern with putting the speakon connection above where the port lets in in the back? Or just do on the side where it will not affect the port at all?


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post #18 of 64 Old 08-06-2014, 12:48 PM - Thread Starter
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Ok. I got 3 1x48" dowels to try some bracing tonight. I plan to cut them snug to make sure they fit in good with some glue, but will glue only hold these things with the subs banging around?
I can get screws to most of them if needed, except the ones that will be toward the port area. Worse case I could get a spade bit and bore into the port area a little for a dowel to sit in and then screw in the top part of the dowel

Final suggestions before I possibly make a mess of this?


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post #19 of 64 Old 08-06-2014, 01:52 PM
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Originally Posted by PM-Performance View Post
Ok. I got 3 1x48" dowels to try some bracing tonight. I plan to cut them snug to make sure they fit in good with some glue, but will glue only hold these things with the subs banging around?
I can get screws to most of them if needed, except the ones that will be toward the port area. Worse case I could get a spade bit and bore into the port area a little for a dowel to sit in and then screw in the top part of the dowel

Final suggestions before I possibly make a mess of this?
I haven't posted up the images in my thread yet...mostly cause I need to take new ones since I just snapped them real quick last night (was tired..had to sand out the driver holes cause they were to small!) but you can kinda see how I did my bracing and stuffing. This is also a vertical mini marty cut out.

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post #20 of 64 Old 08-06-2014, 01:59 PM
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I haven't posted up the images in my thread yet...mostly cause I need to take new ones since I just snapped them real quick last night (was tired..had to sand out the driver holes cause they were to small!) but you can kinda see how I did my bracing and stuffing. This is also a vertical mini marty cut out.
Your top and bottom panel are basically entirely unbraced.
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post #21 of 64 Old 08-06-2014, 02:01 PM - Thread Starter
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Your top and bottom panel are basically entirely unbraced.
Other than that do you consider the rest aqequately braced? I was thinking from the posts above that bracing along board barriers were not going to really help much. Except his couple cross braces.

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post #22 of 64 Old 08-06-2014, 02:04 PM
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Other than that do you consider the rest aqequately braced? I was thinking from the posts above that bracing along board barriers were not going to really help much. Except his couple cross braces.
No, looks poorly done tbh. The bracing on the side should be stood up and not flat, not enough cross bracing, etc.
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post #23 of 64 Old 08-06-2014, 02:11 PM
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Your top and bottom panel are basically entirely unbraced.
I mainly just followed the spec for the build including the bracing image that chalugadp posted. Suppose I could throw up another small piece on the top and bottom from the cross section.
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post #24 of 64 Old 08-06-2014, 02:14 PM - Thread Starter
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I mainly just followed the spec for the build including the bracing image that chalugadp posted. Suppose I could throw up another small piece on the top and bottom from the cross section.
This is the fun of DIY I guess lol.
I'm fixing mine as I go too
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post #25 of 64 Old 08-06-2014, 02:17 PM
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This is the fun of DIY I guess lol.
I'm fixing mine as I go too
well chalugadp has built a lot of these and has had that image posted for a while and I haven't seen it discredited. With that said obviously notnyt has built his fair share also so I guess I don't know what to tell ya, I just built off the spec provided.
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post #26 of 64 Old 08-06-2014, 04:50 PM
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No, looks poorly done tbh. The bracing on the side should be stood up and not flat, not enough cross bracing, etc.
Actually you are not right this time. This bracing

Is absolutely fine. When he puts the top on he should put one strip going horizontally across in the middle.

This kind of post really frustrates me. The overkill I see in many diy builds is fine. It's people's money and if you want to build something that withstands a nuclear bomb, go for it. Using gorilla glue(not original) or titebond glue does 0 % to strengthen your build over Elmer glue . Why do I recommend gorilla (not original) ? It pours nice and drys fast.

The bracing strategy he has and any other bracing will produce zero difference in sound. The point of bracing to me is something that reduces panel flex so it doesn't effect sound and glue surface is enough that pieces don't move or crack/break over time. Beyond that is a waste.

I built a clone of a funk audio sub. I asked the person to take out the driver from his existing funk sub(and take pics) so I could see the bracing and copy Nathan. His is very similar to the one in this post. No big crossbraces, just a skeleton around the pieces. Now that's in a 3k sealed sub with 3k of power. Much more force produced and applied to the cab then the ported cab. Don't know anyone saying Nathan does shotty work.

I have done demo testing with the above style and added more bracing on top of that. Zero difference in performance.

Bassthathz measured one of my cabs with his expensive toy. Bass was tight, clean and impressive. I'm not saying for people to change there bracing strategy. Put what you want in yours . This one in this post is totally fine.
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post #27 of 64 Old 08-06-2014, 06:49 PM
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Actually you are not right this time. This bracing

Is absolutely fine. When he puts the top on he should put one strip going horizontally across in the middle.

This kind of post really frustrates me. The overkill I see in many diy builds is fine. It's people's money and if you want to build something that withstands a nuclear bomb, go for it. Using gorilla glue(not original) or titebond glue does 0 % to strengthen your build over Elmer glue . Why do I recommend gorilla (not original) ? It pours nice and drys fast.

The bracing strategy he has and any other bracing will produce zero difference in sound. The point of bracing to me is something that reduces panel flex so it doesn't effect sound and glue surface is enough that pieces don't move or crack/break over time. Beyond that is a waste.

I built a clone of a funk audio sub. I asked the person to take out the driver from his existing funk sub(and take pics) so I could see the bracing and copy Nathan. His is very similar to the one in this post. No big crossbraces, just a skeleton around the pieces. Now that's in a 3k sealed sub with 3k of power. Much more force produced and applied to the cab then the ported cab. Don't know anyone saying Nathan does shotty work.

I have done demo testing with the above style and added more bracing on top of that. Zero difference in performance.

Bassthathz measured one of my cabs with his expensive toy. Bass was tight, clean and impressive. I'm not saying for people to change there bracing strategy. Put what you want in yours . This one in this post is totally fine.
I'm not one for overkill bracing, and I did miss the fact that the port was spraypanted, I didn't see it there, and the braces in the vent are good there for that panel. However, the other side seems largely unbraced, and there are large areas in the side panels and back that have virtually no added support. I haven't seen the Funk audio bracing, but just because someone sells something for 3k, doesn't make it good. Also, sealed boxes are smaller, they have less distances to edges and corners and hence, more stability.
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post #28 of 64 Old 08-06-2014, 07:08 PM
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Nathan at funk is renowned for his craftsmanship

On his single driver version there is just rib bracing around horizontal center. No vertical bracing and nothing on underside of top. Now I know curved walls add strength but it's 20" across in both horizontal planes. It doesn't matter if the box is 30 cuft. The horizontal window braces break down the box into sections.

There isn't pressure on the box from one side like a wind storm on a tall building. Pressure is pushing out evenly.

I built a martycube box for myself a few months ago. Somehow (brainfart) I forgot to put any glue in the back piece. Only thing holding it in was 20 brad nails. In a big bass scene I could hear box rattling. Checked on it and felt it and when , jeez what a dummy. Driver was uxl18 with 2200 watts.

I put piano hinge around outside edge of all four sides. Nothing in the middle. Problem was solved. No flex in piece, no noise.
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post #29 of 64 Old 08-06-2014, 07:17 PM
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Nathan at funk is renowned for his craftsmanship

On his single driver version there is just rib bracing around horizontal center. No vertical bracing and nothing on underside of top. Now I know curved walls add strength but it's 20" across in both horizontal planes. It doesn't matter if the box is 30 cuft. The horizontal window braces break down the box into sections.

There isn't pressure on the box from one side like a wind storm on a tall building. Pressure is pushing out evenly.

I built a martycube box for myself a few months ago. Somehow (brainfart) I forgot to put any glue in the back piece. Only thing holding it in was 20 brad nails. In a big bass scene I could hear box rattling. Checked on it and felt it and when , jeez what a dummy. Driver was uxl18 with 2200 watts.

I put piano hinge around outside edge of all four sides. Nothing in the middle. Problem was solved. No flex in piece, no noise.
A box like that barely needs any bracing due to the size and shape. The box above has very large areas without any bracing or with minimal bracing. Stand those flat pieces up on the short size instead of the long side for added rigidity, add some bracing to the back, as it has none in the center. I don't know what bracing was used on the missing parts in those pics, so can't say anything there.
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post #30 of 64 Old 08-06-2014, 07:28 PM
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The top of the funk sub is the same size as the back wall between the window braces. The curved walls have no impact on strengthening the top. Center of the top would flex the same with curved walls or straight wall.

The back wall should have vertical piece dividing unbiased section to 12". Thought he had a piece under the foam.

Edit :
The back wall has port rails supporting it. Forgot about that. That piece is supported.

Last edited by chalugadp; 08-06-2014 at 09:07 PM.
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