Internal / External bracing questions

[Kohen36]

I have a MDF box made by cherry man customs .the box is 3 cubic ft with 2 XFL 10”s .I am having problems with box vibration. The box man told me putting drywall screws in the box where the go through the first wall and hit the port wall.Will these screws actually help prevent the box vibration at all or will I need to go back in the box and add some more internal bracing such as dowels? When I put my hand on the box when playing loudly it’s almost hard to even keep my hand on the box

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[Kohen36]

Another question I have is if I go with the dowels or a 2x4 or something is it going to noticeably affect the air space and how it plays?
Also my box is a wedge shape so I need the bracing to go from the back to the front side but the front side the the peice that slants down so would just putting an angle cut on the dowel work or what?

 

[hispls 5,000+ posts]

Can you post some pictures of the box and explain which areas are flexing?

Just guessing here, but I'd use some 1" dowel and drill right on through the box on each side, run the dowel through both holes like you're skewering a kebab, glue the hell out of it, then cut it flush and sand it down to the outside of the box. You could get something in there sturdy and look pretty seemless. A lot of folks use threaded rod with nuts and washers to brace box panels.

 

[Kohen36]

 

[Kohen36]

The front panel that the subs are in is the panel that is flexing . I’ll have to take the subs out to know forsure but if I did and could get up in there would it be better to get a dowel cut to length and jam it between the 2 panels so it’s pushing against the 2 sides?

 

[Kohen36]

I went ahead and did what the guy recommended and threw 2 screws near the top and did actually help a good bit and I can play it louder than i ever have before but it still needs some more reinforcement

 

[2RZ-FE 10+ year member]

All you need is a few mdf wedges that go from the back of the box to the front use the side of the box to get the correct angles and glue them in take the subs out to reach up in there

 

[Kohen36]

All you need is a few mdf wedges that go from the back of the box to the front use the side of the box to get the correct angles and glue them in take the subs out to reach up in there

Okay so do you mean a wedge the size of the side of the box that would go from the whole top to bottom? or small wedges at the top and use the side of the box to measure how wide they need to be to stick up there and screw?

 

[Kohen36]

And btw the part that flexes the most is directly in the center of that front panel

 

[hispls 5,000+ posts]

Okay so do you mean a wedge the size of the side of the box that would go from the whole top to bottom? or small wedges at the top and use the side of the box to measure how wide they need to be to stick up there and screw?

I'd think just a smaller wedge centered on that large face would go a long way. Keep it short enough that you can easily manage it through the speaker mounting hole. I'd definitely brace that front to back along the center and I think the screws into the port should do nicely to keep that a bit more rigid.