My Man Cave - Read a lot but still need help

It's not clear how the room is currently built, so I have trouble knowing what changes you're making, but here's some things that look like you might be missing.

When you fire up the system, the sound will cause the walls to vibrate. The vibrating walls will cause the rest of the house to vibrate. The vibrations in other parts of the hose turn the walls into speakers - this is one way to think of sound moving through your house. This works both ways - so if a refrigerator or A/C unit is vibrating in one part of the house, the rest of the house is vibrating as well - and the walls in your theater become speakers for you to listen to you A/C. Another way to look at sound into and out of your theater is to think of your theater as an aquarium. The sound will leak out anywhere water would - windows, doors, ventilation ducts, electrical outlets. Of course, this works the other way as well - any opening is a way for outside sound to get in.

Looking at your diagram, I don't understand how the walls near the screen are built, and how that relates to the ceiling or floor - why aren't they planned to be like the side walls? The way the walls come together at joints can be a problem for containing sound. The way the walls and ceiling connect to other parts of the structure is another way you can change the movement of sound through the house. What can you tell us about these aspects of the design?

"Looking at your diagram, I don't understand how the walls near the screen are built, and how that relates to the ceiling or floor - why aren't they planned to be like the side walls? The way the walls come together at joints can be a problem for containing sound. The way the walls and ceiling connect to other parts of the structure is another way you can change the movement of sound through the house. What can you tell us about these aspects of the design?"

Hey Fred................I am the brother.
Let me try to make things clearer so that we could all make this project work.

In both floor plans, you can see the shape of the room. All walls that area visible here are made of clay bricks with concrete plaster on both sides. All of these walls will stay in their place and we will be applying a new wall, to put it simple, on top of the one already built.
This new wall will be made of, wooden studs 2"x4", separated at 24" or less, depends on the length of the wall. On top of that we will be applying a layer of plywood boards 3/4" thick. In between the plywood board and the existing wall, we will put some pink stuff as filling or fiber glass boards.
After this, we are thinking of applying some gypsum boards 1/4" all the way from ground level to ear level, to help buffer the sound. Finally we will add the fabric to give it the nice black look to it and help the sound buffering.
(Not sure that buffer is the correct term. jejejejejeje)

The roof will be handled the same way, wooden studs 2"x4", spaced out about 12", with the plywood boards 1/2" and fabric applied to it. The stage area will be handled the same way, but we are adding the stage once we get started with the walls and roof.

Basically, the joints are plywood with plywood. We are thinking of filling the joints with some type of elastomeric product that will help seal off the joints on the walls and roof.

Hope this helps to clear things.

JOINTS: All joints will be plywood boards with plywood boards, which we are thinking of sealing off with an elastomeric product. (Rubber type sealant, normally used to seal off window corners and such)

I don't know enough about the building codes and so on in Panama, but I would be interested in using larger lumber for the walls and ceiling. If you are trying to minimize the sound transmitted through the structure, the best thing you can do is make it heavier. That means the best is several layers of wood or gypsum - I will use three in my theater - one wood and two gypsum. The second thing to do is to disconnect the room from the rest of the house. You can build walls that don't touch the brick walls, and then build a ceiling on top of the new wooden walls. If this in not possible, you can find small rubber and metal clips - like these http://www.soundproofingcompany.com/soundproofing-products/soundproofing-clips/ - that can allow you to connect the structures, like the ceiling to the floor above, without transmitting as much sound. The fiberglass inside the walls and ceiling will help, but these first two things are the most important. Another thing that is very important is making no holes through the wall. Places where you cut open the wall to install lights or air vents should be very carefully sealed. The acoustic caulk can be an important part of this process, but so can putty pads - depending on what exactly you do. http://www.soundproofingcompany.com/soundproofing-products/soundproofing-accessories/putty-pads/

I know you want the room to be as large as possible, and that's fine, but if soundproofing is a goal, you should make it a few inches smaller so that the walls can be disconnected and thick and heavy.

I hope that helps,

Fred

Hey Fred,

We are not so worried in minimizing the sound transmitted through the walls if this doesn't have an effect over the sound quality. Since the building is made up of concrete walls and slabs and we only have 1 neighbor across a hall, it won't affect us if sound is heard from outside the room. But we are really interested in having the best sound quality inside the room, which brings me to the next set of questions.
Taking this into account, do your recommendations stick on separating the new wall structure from the existing one?
What type of sealant could we use in the joints for the walls and ceiling of the new structure?

Regards,

JDCM

Let's be clear about the different things we may be talking about. There are two different reasons to talk about sound - one is what I thought was most important - keeping sound from moving through the walls. We might call this soundproofing, or sound isolation. The other thing about sound is the quality of the sound environment inside the room - this is related to isolation, because sounds from outside can spoil the sound inside the room. But generally, we deal with the acoustic quality of the room by absorbing, reflecting, and diffusing the sound as it moves within the theater space.

My first recommendation is to make sure the theater is a quiet as possible.

The walls and ceiling construction will have only a very small impact on the sound quality of the room. If you are serious about making the acoustics as good as possible, the only way to know what to do before you build and listen and measure it is to have a professional model it and determine what exactly you should do. For most of us here, we instead measure the frequency response and the decay and impulse response after we have the room built, and use that information to adjust the positions of the speakers, the EQ in the processor, and to help us figure out where to put any absorbers, or reflectors, or diffusors or bass traps. Concrete walls will reflect slightly more sound than drywall alone, but no wall surface will remove the need for these optimization processes. If you examine closely enough, you will find small differences in the acoustic performance of every wall construction type or technique - stud spacing, drywall weight, number of screws, etc - but in my opinion the difference is not important.

With that said, it doesn't seem to me to matter how you build the walls, as long as the room is as quiet as you need. If you want to seal the corners with something better than drywall mud, acoustic sealant is probably the best choice. http://www.soundproofingcompany.com/soundproofing-products/soundproofing-accessories/silenseal-acoustical-sealant/ you can get it lots of places, but probably not local. If not that, a caulk that will not harden is the next best choice. I used some of this: http://www.dap.com/product_details.aspx?product_id=4

You can get opinions from other people that might be different, but this is my opinion.

exactly.

Those all (except the adhesive) look good to me.