# porting riser question



## eurovw89 (Feb 25, 2010)

here in the bottom part of my riser. I couldnt find 2 x 12's so im using 2 x 6's. I am framing out both sections then laying the other on top and securing them. 







My question is this. I ported the bottom part but block it in, and also going to port the top section in front as well. Since there are to separate chamber on the bottom section, would I have to port the rear of the bottom section even though I am porting the top half?

I didnt do the "calculations" on how much to "port", i just dont want it to be a "boomy" box.

thanks,
Jeff


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## NBPk402 (Feb 21, 2012)

Are you porting it to make a bass trap? If so I would think you would want to port all the chambers in the platform, and fill with fiberglass batting. I would use some plastic or something similar to prevent the fiberglass fibers from getting into your carpet. I assume you are going to cover the platform with carpet so you don't get the fiberglass into the air of your HT... :T

If you are going to stack 2 layers I would also caulk the 2 layers or use construction adhesive to seal them.


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## eurovw89 (Feb 25, 2010)

ellisr63 said:


> Are you porting it to make a bass trap? If so I would think you would want to port all the chambers in the platform, and fill with fiberglass batting. I would use some plastic or something similar to prevent the fiberglass fibers from getting into your carpet. I assume you are going to cover the platform with carpet so you don't get the fiberglass into the air of your HT... :T


I bought some 3.5mil plastic to put on the bottom to keep the fiberglass from getting out, and some acoustic fabric to cover the inside of the ports. 

After I attach the 2nd frame to the top I am putting 2 layers of 3/4 ply then padding and carpet.

Also I was going to cut some 1in pieces from the scrap wood and attach to the bottom of the platform so it wont ruin my carpet, well it will but not as bad. would you know of another solution?


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## NBPk402 (Feb 21, 2012)

I think it will work fine, but I would get some plywood, and cut it into strips that are equal 2 the 2 platforms total height and add them to the inside of the outer fame all around it to make it nice and strong and as one. I would get some construction adhesive and use it for attaching the plywood strips to the frame and then use some wood screws to attach the plywood to your 2x6 frame. I would then make holes all around the frame (inside beams and outside beams) work so it becomes one big bass trap... I think the more space you have for the bass trap the better off you will be. That is the only changes I see needed to your original plans.


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## eurovw89 (Feb 25, 2010)

ellisr63 said:


> I think it will work fine, but I would get some plywood, and cut it into strips that are equal 2 the 2 platforms total height and add them to the inside of the outer fame all around it to make it nice and strong and as one. I would get some construction adhesive and use it for attaching the plywood strips to the frame and then use some wood screws to attach the plywood to your 2x6 frame. I would then make holes all around the frame (inside beams and outside beams) work so it becomes one big bass trap... I think the more space you have for the bass trap the better off you will be. That is the only changes I see needed to your original plans.


i bought some metal "strapping" to attack between the two frames, and are 18ga. so you think ripping down the plywood would work better?


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## NBPk402 (Feb 21, 2012)

eurovw89 said:


> i bought some metal "strapping" to attack between the two frames, and are 18ga. so you think ripping down the plywood would work better?


Yes. If you use construction adhesive for the whole strip you will have a nice solid piece of wood. I would make the strips the whole length of the platform (front, rear, and sides). If you use 3/4" plywood you will have a 2" thick piece of wood once you have glued and screwed them together. You could also use 1/2" if you like or even use OSB which would save you some money, and be strong still. When you cut your holes you will be weakening the frame, but by making the wood thicker you will be giving some of the strength back. I am not sure if you need to drill the holes on every side but I would drill them on all the interior boards to allow the sound to move through to the other compartments.


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## eurovw89 (Feb 25, 2010)

ellisr63 said:


> Yes. If you use construction adhesive for the whole strip you will have a nice solid piece of wood. I would make the strips the whole length of the platform (front, rear, and sides). If you use 3/4" plywood you will have a 2" thick piece of wood once you have glued and screwed them together. You could also use 1/2" if you like or even use OSB which would save you some money, and be strong still. When you cut your holes you will be weakening the frame, but by making the wood thicker you will be giving some of the strength back.


so you are saying to "glue/screw" the plywood strips to the sides/front/rear, then drill through both the 2 x 6 and the plywood for the ports?


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## NBPk402 (Feb 21, 2012)

eurovw89 said:


> so you are saying to "glue/screw" the plywood strips to the sides/front/rear, then drill through both the 2 x 6 and the plywood for the ports?


Yes, If you had started with a 2x12 you would have one solid piece of wood... Since you are using 2 2x6s stacked you can regain the structural strength of the 2x12 by gluing the pieces together. The reason for screwing them together is to hold them while the glue is drying. After you have the pieces glued together then drill your piece. You can drill your pieces (Plywood, and 2x6) before you put the whole platform together if you like. It might make it easier to drill your holes, plus you could use a bigger holesaw as you would be doing both levels at one time. Does this make sense? :T


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## eurovw89 (Feb 25, 2010)

ellisr63 said:


> Yes, If you had started with a 2x12 you would have one solid piece of wood... Since you are using 2 2x6s stacked you can regain the structural strength of the 2x12 by gluing the pieces together. The reason for screwing them together is to hold them while the glue is drying. After you have the pieces glued together then drill your piece. You can drill your pieces (Plywood, and 2x6) before you put the whole platform together if you like. It might make it easier to drill your holes, plus you could use a bigger holesaw as you would be doing both levels at one time. Does this make sense? :T


yea i smell ya lol. thanks


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## NBPk402 (Feb 21, 2012)

eurovw89 said:


> yea i smell ya lol. thanks


No problem... Anytime. :T
Also in the pic, I would drill a whole to connect the small side chamber to the other chambers too. If possible I would make each chamber connect to the others in all directions. I think this will make the most of your bass trap.


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## NBPk402 (Feb 21, 2012)

One last thing... Make sure that if someone leans back in a chair or steps on the edge of the platform that neither the chair or the platform move at all (it shouldn't but just to be safe check it out). If it does I would either attach it to the floor in each corner or box in the bottom corners and put a weight on it (like a gym flat weight). :T If your chair has holes in the feet I would attach it to the platform top with some screws to keep it stable once you have the ideal seating location. If you have kids, and the chair is reclined and they play around on it the chair might flip back onto them unless it is attached to the platform. :T


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## eurovw89 (Feb 25, 2010)

ellisr63 said:


> One last thing... Make sure that if someone leans back in a chair or steps on the edge of the platform that neither the chair or the platform move at all (it shouldn't but just to be safe check it out). If it does I would either attach it to the floor in each corner or box in the bottom corners and put a weight on it (like a gym flat weight). :T If your chair has holes in the feet I would attach it to the platform top with some screws to keep it stable once you have the ideal seating location. If you have kids, and the chair is reclined and they play around on it the chair might flip back onto them unless it is attached to the platform. :T


i was thinking the same exact thing. A sofa is going on the platform, I have my recliners in the front. now that you brought up the question....good way to attach the sofa to the top?


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## NBPk402 (Feb 21, 2012)

eurovw89 said:


> i was thinking the same exact thing. A sofa is going on the platform, I have my recliners in the front. now that you brought up the question....good way to attach the sofa to the top?


I am assuming it just has wooden legs... Maybe you could remove them and attach a 2x4 on it's side to the bottom of the couch and then use a little "L" bracket to attach it to the platform. I'm thinking along the front edge and the rear edge... I would try and get the screws through the plywood and into the 2x6 if possible. :T

I am suggesting removing the legs so you don't damage them, but you might be able to attach a bracket to them too.


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## NBPk402 (Feb 21, 2012)

I just thought of another way that might be even easier to do... Get 2 2x4s or 2x6s about the width of your platform, and lay the 2xs down on their sides (raises the least amount). I would put them a few inches back from the front, and rear edges of the couch and attach them to the bottom of the couch. Once you have that done get a little carpet and cover up the ends of the 2xs that are going past the edge of the couch and then put a couple of lag screws in each end of the 2xs to hold it to the platform (legs must be removed for this unless you use thicker wood).


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## eurovw89 (Feb 25, 2010)

ok thx


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## Blaze98 (May 4, 2014)

This is seriously making me want to build some risers for our Theater Room.


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