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Discussion Starter #1
Should the walls be built out of an acoustic absorbing material on the bottom side halves and upper front side halves? And should the rear upper side halves and the rear upper half be built from a more reflective material for the surround speakers? Or should all the upper halves of the walls be more reflective?


Don
 

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The walls should be constructed with 1/2" drywall over 5/8" drywall. On both sides and the rear, the bottom portion of the walls should be covered with fabric over something like Johns-Manville Coated Insul-Shield Black. The size of "bottom portion" will depend upon the RT60 requirements of the room. The entire front wall is generally constructed with this floor to ceiling. Other factors in the room will determine additional needs.
 

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Discussion Starter #3
Hi Dennis,

Thank you for your help.


1. Is the Johns-Manville Coated Insul-Shield Black used in place of TS+ since I have read here that TS+ is now hard to obtain?


2. Is Johns-Manville Coated Insul-Shield Black something that can be purchased in most areas or am I going to have to special order this and have it shipped to me?


3. What does it cost?


I am going to be starting work on my HT in about 2 to 3 weeks and still need information on doing the walls. I will be converting a third bay garage into a HT. This room presently only measures 9'-8"X20'. The room is narrow and I can't afford to lose too much wall space. The outer wall is concrete block and the inner wall is a 2x4 wall with drywall on each side of it. What I planning on doing is (PLEASE let me know if you would do anything different or if this would work for me):


1. Outside Wall (the block wall) I was going to attach furring strips and place 1" thick Styrofoam sheets in-between. Over this I will place drywall and then I was going to carpet 3' or 4' of the lower wall. The upper part of the wall I was going to cover with GOM Fabric.


2. The back wall is also block, but it has an inner 2x4 wall that is sheet rocked. I was going to place another layer of sheet rock, then carpet on the lower part and GOM Fabric on the upper part.


3. The inner wall is a 2x4 wall that is sheet rocked on each side. Since I don't have a lot of room to work with I was going to put carpet and fabric as on the other walls, but on the opposite side of the wall (which is in the other garage) I would add another layer of sheetrock. If need be, I can also sandwich soundboard in-between the sheetrock layers on this wall.


4. The ceiling is presently about 8’-6†and is sheet rocked. I will be adding acoustic ceiling tiles directly to this.


It is very important that I keep as much sound in as possible as not to disturb the neighbors and naturally I also want good room acoustics.


I will be using tower front speakers on a 8†or 12†raised stage on each side of the screen and speakers mounted about two thirds back on the walls for the surrounds. I will also be adding a rear center for EX and may at a later time add two more surrounds on the upper back wall.


If you can, I would appreciate any advice you can provide me on my wall treatment.


Best Regards,

Don
 

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The J-M Coated Insul-Shield is the replacement for TS+


Carpet on the lower half of your walls will help only the high frequencies when, in a room of that size, you typcially need most your absorption at lower frequencies (250 to 500Hz).


The styrofoam is a good thermal insulator..a non player for acoustic absorption. Try a open cell product or a fiber product instead.
 

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Discussion Starter #5
Thanks again Dennis, your help is most appreciated.


I am still in the dark here to what I should do :confused:. I have been reading and searching here in the forum for some time now, but no other postings apply to my situation with having only inches to work with on their walls. You said I should use a "fiber product instead", are you referring to something like soundboard (the brown color, somewhat soft board at Home Depot)? Should I then cover this with drywall, and then use J-M Coated Insul-Shield on the lower part of the walls? How thick is J-M Coated Insul-Shield and will I need to bring out the upper wall with an additional layer of drywall so that the upper wall is the same thickest as the lower? Is the J-M Coated Insul-Shield easy to work with and cover with the GOM Fabric? On the lower walls does it even matter what I cover them with, GOM or carpet? Is GOM Fabric more absorbing on the lower frequencies then carpet?


I am sorry for all the questions, but I have not been able to get any feedback regarding doing the walls and I am hoping to start working on this in able 2 weeks. Everyone here has been very kind and helpful regarding all my other questions, but I have not seemed to been able to get any feedback how to go about sound proofing my walls and maintaining good room acoustics with only a few inches to work with on each side.


Best Regards,

Don
 

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From the inside of the room out:


GOM Fabric

1" J-M Coated Insul-shield Black.

1/2" dry wall

5/8" dry wall

firing strips and fiberglass insulation (1")

concrete or exterior wall.
 

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Discussion Starter #7
Thanks Dennis,


Are you referring too the rolled pink fiberglass insulation and does this come in 1" thickness, or would this be compressed as 1" in-between the walls?


I also am assuming you are referring to using 1" J-M Coated Insul-shield Black on the lower part of the wall and not the upper part. I am I correct here? If that is the case, then would I need to build out the upper part of the wall an additional 1" to match the lower wall?


Best Regards,

Don
 

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The 1" fiberglass between the concrete and backside of the drywall is similar to the J-M Insul-Shield (which you could use, btw), but it is not the typical pink batts.


On the inside, on the three walls, you need to to place 1" blocking behind all mouldings, baseboards, casements, and trim in order to compensate for the fact the wall surface will be 1" out from the drywall. The blocking can also serve as the tacking surface for the fabric. On the upper portion of the wall, you can tack up 1" polyester batting and place the fabric over that. This will bring the upper wall out even with the lower wall.
 

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Discussion Starter #9
What form does the 1" fiberglass and the J-M Insul-Shield come in, 4'X8' sheets or what? Where can I obtain the Insul-Shield and is this fiberglass a type that can be obtained at somewhere like Home Depot?


Thanks Dennis, I apologize for all the questions.


Don
 

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Discussion Starter #11
Thanks Dennis,

Your help has always been appreciated :).


I posted this in another trend, but someone here may be able to answer my question since it is related to all of the above:


I was reading about the "Absorption Coefficients of Common Housing Materials" in the book "Cinema Source Home Design Handbook", it uses a scale of 1 to 0. The coefficient of 1, meaning it completely absorbs sound and coefficient of 0, meaning it completely reflects sound.


I was originally planning on using carpet halfway up the sides and back wall and use GOM fabric on the upper portions. However, the book shows the coefficient of carpet (low pile) as being .01 with 125Hz sound. According to this the coefficients of carpet are more reflective then window glass, which is .04 (small panes). This I don’t understand, does it mean that the carpet is almost totally reflective no matter what is even behind it? I would use the J-M Coated Insul-shield Black behind the carpet, but if the carpet were that reflective, then would the sound even reach the J-M Coated Insul-shield before it was reflected? Is there going to be a great difference in my room acoustics if I chose to use the carpet on the lower walls covering the Insul-shield, as opposed to GOM fabric covering the Insul-shield? BTW, I will still be using the GOM fabric on the upper walls.


The reason I ask is that we already had the colors pick out for our floor and lower wall carpets, and for the theater seats. I purchased the fabric for the seats based on the floor and lower wall carpets. I have the color chart for the GOM fabrics and it has no red that would come close for our chosen colors. I went back out today and tried finding another fabric for the theater seats that would be a match, but reds seem to be the hardest colors to match-up.


I want to thank everyone for all the kind help they have provided me to date. It is always a pleasure to know that there are so many good and helpful people in the world.


Don
 

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Don, Regardless of what "Cinema Source Home Design Handbook" says glass is more "reflective" than carpet.

Yes, low freq. will reach your Insul-shield thru the carpet.

There will be a minimal difference, in the low freq. absorption, if the Insul-shield is used in both cases.
 

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Discussion Starter #14
Quote:
Originally posted by Dennis Erskine
From the inside of the room out:


GOM Fabric

1" J-M Coated Insul-shield Black.

1/2" dry wall

5/8" dry wall

firing strips and fiberglass insulation (1")

concrete or exterior wall.
Hi Dennis,

What is the 1" fiberglass insulation you are referring too? I was unable to find anything at Home Depot or Lowe's that resembled this. Is this something that I need to obtain at the same places I will be purchasing the Insul-shield?


Thanks Dennis,


Don
 

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I would venture to guess that Dennis is talking about this stuff. I found this desc on the HD website (which I haven't had great success with). Anyhow, I'd be surprised if you couldn't find it with this description in hand.


>>>>>>

Rigid and semi-rigid foam panels - Provide the highest R-value per inch of common insulation types. They are relatively easy to work with and can be installed to cover wood framing members rather than fitting between them. The vapor barrier should be installed on the living space side of the insulation to shield against condensation soaking the fiberglass.


Four main types of rigid foam insulation aare: Types

Common Uses


Molded or Expanded

Polystyrene (Bead Board)

Exterior sheathing

Interior basement walls

Suspended ceiling panels

Siding backer board


Extruded Polystyrene

(Blue or Pink Board)

Exterior foundation

Wall sheathing

Interior above-grade applications


Polyurethane and

Polyisocyanurates

(Energy Shield)

Foil-faced for exterior wall sheathing

Vinyl-faced for beam ceilings

Impregnated-aspahlt for hot-mopped

roof applications


Semi-Rigid

Fiberglass Panels

Foundations below grade
 

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You DO NOT want to use foam panels unless you know exactly what you're doing. Most (not all) foam panels are closed cell construction and will give you little to no benefit. Also, "R" ratings speak to the thermal properties of an insulator. You're not interested in the "R" rating for acoustic products. A good "R" rating has no correlation to a product's acoustic properties.
 

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Discussion Starter #17
Thanks Dennis, but what is the 1" fiberglass insulation that you are referring too, and what size does it come in (4X8 sheets or what)? I have never seen this before so I don't know what to look for. I have not found this at Lowe's or Home Depot, is this something I need to obtain at the same place I will purchase the Insul-shield?


Thanks Dennis,


Don
 

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Dennis,


This was a very interesting thread. Once you have installed the Insul-Shield how do you install the fabric over it? Can you use any fabric or are their certain brands that you recommend?


Thanks!
 
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