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work in progress
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yup, mdf is da shit. 3/4" should be fine unless you are using some bad ass subs, then you might want to go up to 1" or larger.
 

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Truckin' on a budget
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Discussion Starter #5
hey i plan to run 2 re xxx but im seperating the boxes should i use 1" for those if im pushing them with 2 JBL 1200.1s thanks
 

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the spl king
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5/8 or 3/4 mdf is good

i used 3/4 mdf on my wifes box i made for a 12

i made a box for my dad for 2 8's and i used 5/8's, it was a small sealed box, 200watts for the pair, it was going in a 75 mini copper, so size mattered alot
 

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MDF is used because of the weight!! Strength is a factor too but its the combination of strength and weight that make's MDF ideal. I wouldn't use anything thinner then 3/4 unless the box is vary small. Also no matter what you use, if any side is more then 1 1/2 square ft you should brace it.
 

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dB Zac said:
MDF is used because of the weight!! Strength is a factor too but its the combination of strength and weight that make's MDF ideal.
that doesn't mean plywood is weaker, the way the sheets are laminated together in ply gives strength without the added weight. imo the extra density of mdf isn't needed in a system that won't play over 155db, any more than that and you'll need every little bit you can get.
 

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Project: Sabriel
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plywood isnt the greatest material. we used a lot of different forms when we built houses, and when i do my sub box, ill be using MDF. plywood is also rather flexible, so you can imagine the flexing an unbraced, large panel of plywood would do. anyway, MDF is cheap.
 

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ever see a house built with laminated joists in the floor? it's basically thick plywood used to replace 2x's because they won't sag like a long 2x will. you can have them 40+ feet long and they won't sag.

price is another consideration though, where i live cabinet grade birch ply is $50 a sheet and mdf is $42 a sheet. i'd rather pay more and have a lighter box, especially when i'm building an spl system that uses several sheets.
 

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93ex said:
holy crap! mdf is like 21 bucks a sheet here
that's the downside of living in BFE, the mdf has to be ordered at an extra expense to the lumber yard and myself.
driving to a city and bringing some back isn't worth the time or gas unless i buy more than my truck can carry.

if a friend asks me to build a box for everyday listening i use particle board, it's cheap and readily available.
 

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Crazy J said:
that doesn't mean plywood is weaker, the way the sheets are laminated together in ply gives strength without the added weight. imo the extra density of mdf isn't needed in a system that won't play over 155db, any more than that and you'll need every little bit you can get.
Ply or laminated wood is vary strong, it can flex without braking far better then MDF thats why they build skateboards out of it. Those aren't really traits we need a box to have. Any vibration can and probably will cancel out some of the sound waves, sound waves we want weather it is 155 db or 125 db. The shear mass of MDF or even HDF will help to resist vibration and thats what we want. If Weight is an issue then yes ply wood is a great alternative, but it isn't with out compromise. PA systems use plywood for there speaker cabs for the weight issue, but in a car the difference in weight will hardly be noticed.
 

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I built a big speaker box, and I used 3/4 MDF. It's well over 3 cubic feet and I did not brace it. HOWEVER, I used drywall screws in every portion AND subfloor glue. I had to drill holes for the screws, and even then they split the wood in certain areas. The box is ultrasturdy. Just use screws, glue, and drill the areas where the screws will go in. Do you guys mean brace it if you won't be screwing it or gluing it, because this box is very sturdy.
 

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no, the bracing is a separate issue. Thats great that you screwed it together and as far as the splitting goes, thats just something that you have to get a feel for how to ovoid. The bracing is for when you have large areas of wood that has no support. Say you have a box that is 14x14x30. You prob will not need to brace the 14x14 ends but those 14x30 pieces will need some added bracing, especially the side with the speaker holes. You may not even know you have a prob, I had a friend that came to me saying that he knew his system should be louder. I looked at his box and asked him if he had braced it, he said "what". So I had him crank it, them I stood on the longest piece(yes stood on it) and it got louder. Now he braces all his boxes....
 

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dB Zac said:
no, the bracing is a separate issue. Thats great that you screwed it together and as far as the splitting goes, thats just something that you have to get a feel for how to ovoid. The bracing is for when you have large areas of wood that has no support. Say you have a box that is 14x14x30. You prob will not need to brace the 14x14 ends but those 14x30 pieces will need some added bracing, especially the side with the speaker holes. You may not even know you have a prob, I had a friend that came to me saying that he knew his system should be louder. I looked at his box and asked him if he had braced it, he said "what". So I had him crank it, them I stood on the longest piece(yes stood on it) and it got louder. Now he braces all his boxes....
Mine's like 17.5x45x10. I might brace it in the middle now that you say that.
 
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