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Post by stidrvr on Apr 16, 2009 10:47:07 GMT -7
Well I just temporary installed my IB. The room is partial finished mainly the outside of the room isnt. Here are my specs:
- 13x22 Room
- 4 FiCar IB18's
- QSC RMX2450
- Denon 3808ci
- 2 19.25x24 manifolds front wall mounted
So I tried to test the IB today. It works, the only problem is that all of the bass is on the outside of the room, which is the rest of the basement. Theres a "teeny" bit in the room, but when you go outside the room facing the manifolds, OMFG!! I thought maybe switching the Phase from the 2 manifolds would help, so I unplugged on completely and still, same thing.
Is there some VooDoo IB wiring that I didnt do? What do I have to do to get the bass in the room?
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Post by ThomasW on Apr 16, 2009 11:48:58 GMT -7
What do I have to do to get the bass in the room? Finish enclosing the space. |
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Post by stidrvr on Apr 16, 2009 12:22:53 GMT -7
The room itself is finished, the only thing left is the wall outside the room with the door. I guess I don't underrstand why it's awesome outside the room in a huge open area, but inside in a smaller space there's nothing.
Could you maybe explain alittle bit or point me to what I don't understand?
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Post by ThomasW on Apr 16, 2009 13:49:50 GMT -7
Probably relates to the rearwave interacting with the nonabsorbent concrete walls, and the HT not being sufficiently closed off. A single layer of drywall on one side of a set of studs doesn't sufficiently seal an HT.
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Post by stidrvr on Apr 16, 2009 14:23:09 GMT -7
Hmm, I'm wondering if I should have went the ported box route.
So then what is recommended wall construction for an IB in a basement? I was planning on leaving most of the walls unfinished on the outside of the theater.
Oh man I'm so confused.
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Post by ThomasW on Apr 16, 2009 14:42:18 GMT -7
Regardless of the being sub used most people choose to isolate their HT from the outside world.
So typically they use 2"X6" studs, or staggered 2"X4" party-wall construction. Then they put up doubled drywall on the inside wall, fill the stud spaces with packed fiberglass insulation, and often use doubled drywall on the outside of the walls.
Some go so far as to use a layer of 3/4" MDF on the walls then cover that with drywall to meet fire-codes. Others have used Durock (concrete board) as their drywall.
As long as your walls are a single uninsulated layer of drywall the lowest frequencies from any sub will penetrate them. Since low bass moves easily through anything other than 6" of sold wood or 4" of stone.
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Post by stidrvr on Apr 16, 2009 17:49:37 GMT -7
Ok, I think I get it. Even though there's "wall" there, the subs don't "see" a "wall" there.
So then let me ask you this, for my screen wall where my manifolds are mounted, what would you recommend for "finishing off" the other side? I'm stuck with 2x4 walls, here are some ideas:
- another stud wall with an airspace between stuffed with insulation, although this will lengthen the manifold
- 3/4 mdf with insulation inside current stud wall
- 5/8 and 1/2 drywall with insulation, much cheaper then mdf and more mass just not as dense
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Post by stidrvr on Apr 17, 2009 10:03:29 GMT -7
Okay, new idea.
If I built a room around the manifolds, following the 10X vas rule, that would give me a 538 cubic foot room. I think this would help with the leakage, which is pretty bad, not looking to silence just to muffle. If I insulated the crap out of the inside and double drywalled on the outside.
What would be the difference vs using the whole basement for the rearwave?
And if the room is 10x vas do standard contruction rules apply? or box building?
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Post by ThomasW on Apr 18, 2009 8:02:55 GMT -7
Sorry for the delay in responding I've been down with a nasty cold...
Basically what you're hearing is the concrete walls amplifying the low bass. Part of this is a function of there being nothing on the basement to breakup the bass waves.
Yes you can build a chamber and box-in the drivers if you want it doesn't need to the exactly 10 time Vas.
The thing is the HT room itself needs to be sealed. On the wall there the manifold is don't worry about a staggered studs, just insulate the stud bays and slap on a layer or two of drywall then give a listen. On the other 3 walls you can use staggered studs or 'sister' 2"X6"s on the existing 2"X4"s. Add heavy insulation and use doubled drywall on at least one side of the wall, doing it on both sides would be better.
Understand any flexing of the walls cancels out sound coming from the speakers. So the walls need to be as stiff as possible.
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