# HT design



## stevestudio (Jun 22, 2006)

Used the Room Mode calculator. Not sure what it means. Getting ready to build a 2 story garage with a room upstairs for the HT. 11 7/8" floor trusses. Limited to 9' ceiling was thinking of a curved one, from 8 to up to 9' with soffits on the sides. I have a Barco 1209s and a NTSC 96w motorized screen. Seating would be 8 max more likely 6. I really do not care about a awesome looking room. Just want a good sounding room as cheaply as possibly. I can do/build almost anything. Room could be from 10' to 12'w X 12' to 14' in length.
What would be the best size based on the numbers provided?
Any help would be appreciated.


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## Ethan Winer (Jul 21, 2006)

stevestudio said:


> Used the Room Mode calculator. Not sure what it means.


I'm not familiar with the calculator in this forum, but maybe my own version will be clearer and easier to understand:

www.realtraps.com/modecalc.htm

Understand that the main point of a mode calculator is to determine favorable dimensions when building a new room. If you're using an existing room, and have no plans to move walls etc, then a mode calculator is of little use.

--Ethan


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## bpape (Sep 14, 2006)

Please avoid a curved ceiling. It will do exactly the opposite of what you're looking for. It will cause a lot of focusing issues of sound toward the center fo the room. 

Bryan


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## stevestudio (Jun 22, 2006)

So is there not an idea room? It seems everyone has their own opinion. Based on science is there not one?


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## bpape (Sep 14, 2006)

There is no perfect room. All you can do potentially is get the best minimization of modal buildup issues. However, generally in a smaller room like that, you're better off with more space to avoid other potentially larger issues like having to shove speakers in corners, sitting against a wall, etc.

Bryan


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## Ethan Winer (Jul 21, 2006)

stevestudio said:


> So is there not an idea room? It seems everyone has their own opinion. Based on science is there not one?


Nope. If there were a perfect / best room, then that's what everyone would have! :nerd:

So it more comes down to "Which do you prefer, a peak at 100 Hz or a null at 90 Hz?" :dontknow: :dizzy:

(Gotta love those smileys!)

That said, sufficient bass trapping transform make almost any room from bad to excellent.

--Ethan


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## Guest (Apr 18, 2007)

I am the creator of the model calculator that I think stevestudio is referring to. In looking at Ethan’s calculator it appears that his and mine do about the same thing. Now if I had only stumbled upon Ethan’s calculator sooner…

Sunny, where my calculator requires Excel to work, I suggest you remove mine and replace it with Ethan’s if he is ok with it.

I am pleased to see Ethan is part of this forum (moderator). I have a ton of questions! :bigsmile:


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## Ethan Winer (Jul 21, 2006)

hardman said:


> I suggest you remove mine and replace it with Ethan’s if he is ok with it.


Of course. But it's best to link to that page on the RealTraps site, rather than copy the files here. I'm not opposed to HT Shack hosting my files! But this way I can update and improve the explanation text at will, and only have to do that in one place.



> I am pleased to see Ethan is part of this forum (moderator). I have a ton of questions! :bigsmile:


Hey, I have a ton of answers! 

--Ethan


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## stevestudio (Jun 22, 2006)

I have a question concerning the sheetrock? I have built the walls with 12" spacing. I was told this would do more for the sheetrock in making it solid. Question is this, is the double sheetrock for keeping sound in/out? I read the other day, one quys regret was using the GreenGlue. Any thoughts? I have 4" of complete seperation between my house and the garage except for the roof, which only about 15 percent of it is attached. I will try to post some plans and pics. Is there a free 3d program out there? I have Autocad, its hard to do 3d in this.


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## bpape (Sep 14, 2006)

Did you mean he regretted NOT using Green Glue - I suspect so, it's a great product.

Double drywall does both - keeps sound from getting out and getting in.

Bryan


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## stevestudio (Jun 22, 2006)

No he's regretted using it. He didn't think that the $1200 it cost him to apply it himself was worth the cost. If I have this much seperation, my bedrooms are at the other end of the house which is about 70 feet away would it be worth the double sheetrock?


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## Guest (Nov 7, 2007)

Stevestudio,
Here is some information that may help you in deciding how to construct your walls. Sorry if this is redundant.

Wall systems are rated by how much sound they keep in/out. The measurement is given as an STC rating for the wall system. As sound travels from one side of the wall to the other a transmission loss occurs in db (STC rating). Usually a reduction of 10 db is perceived by the ear as a 50% noise reduction.

Here are a few STC ratings for a couple wall systems.
Standard 2” X 4” wall with 5/8” sheetrock on both sides = STC 34 db (1/2” sheetrock would be a little less)
Same as above with insulation = STC 36 db (as you can see the insulation does little for increasing the STC value, but is still used to help control sound resonating between the sheetrock layers).
Staggered stud wall (2” X 6” top and bottom plate with 2” X 4” staggered studs) = STC 42 db
Same as above with insulation = STC 46 to 52 db.

The use of decoupling materials (green glue, resilient track) will further increase the above STC ratings above.

Additional layers of sheet rock will lower the frequency at which the walls inside your room resonate as well as helping to keep less LF leaking into adjacent spaces. How much I don’t know, but I don’t expect is would be much (control LF leakage).

When I get the chance to build a dedicated room for home theater, I plan to use staggered stud construction (most bang for the buck) and then do some more reading to understand the wall resonate frequencies for multiple layers of sheetrock (I think a normal ½” sheetrock layer resonates around 40 Hz but don’t quote me). The final decision on multiple layers for me will come down to what lower frequencies need additional controlling within my space.


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