[lglura]

Volum reduction or sub across the couch, sorry but it is not an option.:nono:
I begin to understand how to build the room, i will describe it when I'm back from vacation, traveling tomorrow.
lgl:wave:

 

[Space]

You cannot turn down the volume?


It's your hearing your talking about losing...not if, but when.

 

[lglura]

You cannot turn down the volume?


It's your hearing your talking about losing...not if, but when.

Appreciate your concern Space, but the volum is not that loud.
:heehee:lgl

 

[Ted White]

So I assume the Holiday went OK?

 

[lglura]

I would not take up valuable headroom for that floor.

Hi Ted.
How much difference will 7 cm represent if I lower the floor, the room is 730x330x223 cm.
lgl

 

[Ted White]

Are you suggesting removing the concrete floor and re-pouring? I'm confused... sorry.

7cm isn't a lot of height to gain considering the work involved. Again, I'm probably misunderstanding

 

[lglura]

So I assume the Holiday went OK?

Yeah Ted, was a trip in France and the holiday went OK, and now i am ready to continue with my build.
lgl

 

[lglura]

Are you suggesting removing the concrete floor and re-pouring? I'm confused... sorry.

7cm isn't a lot of height to gain considering the work involved. Again, I'm probably misunderstanding

Sorry Ted, but I have problems to explain me properly, will try to be clearer.
I`m not removing the concrete floor and no re-pouring. The height between the concrete floor and roof beams are 230 cm. Between this I will build floating ceiling and floor, and the space is limited.
lgl

 

[Ted White]

Well ceiling height is always a desired thing. So I would see if you could avoid losing the 7cm

 

[patchesj]

Very interesting points on mass and isolated walls to absorb low bass... Out of curiosity, what *would* be an effective air gap/wall mass to absorb <45Hz? Are we talking 3x or 4x 5/8th drywall? something heavier??

 

[Ted White]

This can be calculated, but it's along the lines of a foor or two of airspace and 6-7 sheets of drywall on each side. Shocking, really

 

[patchesj]

This can be calculated, but it's along the lines of a foor or two of airspace and 6-7 sheets of drywall on each side. Shocking, really

Interesting. Would using MDF, concrete board, or some other high density material be of benefit? I would think that creating a sandwich of materials with varying densities would broaden the absorption properties of the wall.

 

[Ted White]

Not really. The resonance of the system is defined by the whole system, not the parts. Mass is mass. If well damped, there's no advantage to using dissimilar densities of mass in a leaf.

The LF resonance point calculation looks at:

Decoupled leaves?

Total Mass added

Absorption in cavity?

Air cavity depth (which is related to absorption).

 

[patchesj]

I wonder how much depth lgl has at the rear wall of his room? In my case the rear of the room backs up to a storage area. Creating a high mass floating wall (2x4s with single drywall on both sides filled with some high density material like sand OR 3-4 layers of 1" MDF, not tied to the side walls or ceiling??) in front of a 2' filled cavity (fiberglass or cotton?), with the final isolated double drywall behind that would create this low frequency absorber?

 

[Ted White]

Absorber is a term generally used to describe a treatment of sound remaining in the room. The sound we're describing has sufficient energy to enter (and leave) the room.

The object is to build partitions with as low of a resonance point as is practical.

Decouple the framing with a double stud wall.

Have as large a gap as possible between the two frames

Add absorption with standard R13 iberglass.

Add mass, generally double 5/8" drywall

These are the factors that lower that resonance point. Keep in mind that we're only able to significantly affect frequencies at 1.5X the resonance point and up. So if a wall had a resonance point of 60Hz, we're going to start to see a drop in performance at 90Hz and below.

Also your earlier question about a 45 Hz wall would be more along the lines of a 1' air cavity and 3-4 sheets of drywall. That's a guesstimate this morning.

 

[patchesj]

Now that I think about it, trying to absorb frequencies that low would be very difficult. My original concept was to allow a mass in the room to be "moved" by the pressure waves and try to dampen/translate the energy (a tuned mass damper??). And this is why I'm not a professional...

 

[Ted White]

I admire your thoughts and questions patchesj

 

[lglura]

Hello again. Thanks for all the feedback in this thread,
have finally realized that it is not possible to build the room completely soundproof.
Thanks to all the feedback I now know how to build the room.
I will build it as solid as it is possible within the limited space I have, walls and ceiling get 2x 1/2 " drywall and 1x 1/2" MDF and green glue between the layers. I come back with pictures to describe the build:bigsmile:

 

[patchesj]

Looking forward to the pictures!! Good luck and keep us informed. Out of curiosity (maybe I missed it in the thread), why 1/2" drywall, why 1 layer of MDF, and what will the sandwich look like (dry W, dry W, MDF? or MDF in the middle?).

Thanks

 

[lglura]

Looking forward to the pictures!! Good luck and keep us informed. Out of curiosity (maybe I missed it in the thread), why 1/2" drywall, why 1 layer of MDF, and what will the sandwich look like (dry W, dry W, MDF? or MDF in the middle?).

Thanks

Hi patshesj. It is drywall/drywall and MDF as the inner wall plate and i`ll use 1/2 " because it is the cheapest solution, 5/8" comes only in fire-plate design.
This is the type of MDF wall plates I`ll use
lgl