HT Room Acoustic - Suggestion

[mandark]

The story so far. It's been a while since I have been enjoying my AV purchase thanks to haisaikat, subhodeep and other members of this forum. As the next logical step I would like to have a dedicated HT room.

Room Size
10 ft x 11 ft x 10 ft (w x l x h)

Room Pictures:
Front

Back

Right

Left

Note:
The room would be used exclusively for HT purpose only.
The door on the left opens in library room.
The front speakers would be placed over the raised platform (5 inches high)
The room has vitrified tiles on the floor.

Room Setup:

A/V Equipments:
AVR: Denon 1911
Speakers: Front - Mordaunt Short Aviano 6, Center - Mordaunt Short Aviano 5, Rear - Mordaunt Short Aviano 1, Sub - Mordaunt Short Aviano 9
TV: Panasonic TH-P42ST30D
Blu-Ray Player: Panasonic DMP-BDT210

Budget:
1.0 - 1.2 Lacs (including acoustic & decor - excluding the sofa)


I seek guidance from the fellow members on the following:

1. Should the whole wall be treated or a portion (say running horizontal to the wall) would suffice. Should the front and the back walls be treated differently?

2. Is glasswool/rockwool preferred choice for acoustic insulation? Or Should one go for commercial boards such as - Anutone? Does glasswool/rockwool act as a diffuser or absorber?

3. What should be the thickness of the acoustic insulation material?

4. Are bass-traps necessary even after insulating the walls?

5. Is star ceiling feasible with acoustic treatment?


I would like to extend my thanks to neo9999 and aloklala for answering my questions.

 

[neo9999]

Hi Mandark,

I've answered your above queries.

Regarding my question about panels, how are you planning to put the rockwool material on the walls?

I was going to suggest to not use TV and use a projector screen but looks like you already purchased it as well made the enclosure for it..

Where do you plan to place the left rear speaker? I see the entrance door blocking the position. You need to place it slightly above ear level.

Neo

 

[manoj.p]

I would suggest keeping it simple.

For bass traps - build corner bass traps. Incidently in your case, the left and right surround are almost pointing at the front and left corners. So those bass traps will also take care of reflections from the surrounds.

For center speaker - Treat the back wall where the reflections from center will come. this will help in making the vocal's dialog clear.

For all other speakers and misc - do a mirror test and treat as necessary. don't do unnecessary treatment. It will make the room more dead.

also, on other hand, don't bother with 2" thick treatments. those won't help at all. You need at least 4" thick treatment to absorb anything worthwhile.

 

[Kittu]

Plan everything now for projector placement with screen and cables.

 

[mandark]

Regarding my question about panels, how are you planning to put the rockwool material on the walls?

I'm planning to use wood to make the frames (2 ft x 2 ft size blocks) to fill with the rockwool.

I was going to suggest to not use TV and use a projector screen but looks like you already purchased it as well made the enclosure for it..

Currently I don't have a plan to get a projector screen. But, I would love to keep an option for this. Any suggestion?

Where do you plan to place the left rear speaker? I see the entrance door blocking the position. You need to place it slightly above ear level.

Planning to place the left rear speaker on the left wall slightly above the door. However since it's way above ear level, I'm thinking about tilting it towards the listening position. Is this a good idea?

For center speaker - Treat the back wall where the reflections from center will come. this will help in making the vocal's dialog clear.

I plan on placing the center speaker in the enclosure below the TV. Should I treat the enclosure with the insulating material as well?

also, on other hand, don't bother with 2" thick treatments. those won't help at all. You need at least 4" thick treatment to absorb anything worthwhile.

Is 4" thick treatment required on all walls? This would really eat up a lot of room space Btw, what should be density of the insulating material?

 

[pdhanwada]

I'm planning to use wood to make the frames (2 ft x 2 ft size blocks) to fill with the rockwool.




Is 4" thick treatment required on all walls? This would really eat up a lot of room space Btw, what should be density of the insulating material?

Use plywood which is hard and strong to make the frames. Fill in with rockwool. Cover it with, Burlap/Jute then with Fabric. That way you are going to seal it better

I used 96Kg/per cu m rockwool to fill. It provides good dampening.

In the back two corners, Create triagular shape wedges from floor to roof. I used 12 mm plywood sheets to create the wedges. Then cut the rockwool into triangular shapes fill them in the bass traps.

I feel Bass traps are more important than the first reflection points.

Please go thru my thread which has all the details about how I did.

Thanks
Pandu

 

[pdhanwada]

My bass traps are big. I see your room size is small. At the max you can fit in a 92 x 52 screen size in the 10 foot wall. So you are left with around 12 inches on each side of the screen.

You can make right triangular wedges of 12 X 12 X 17 inches size

http://www.hifivision.com/av-enhancers-room-acoustics/10892-need-help-room-acoustics.html

 

[neo9999]

Hi Mandark,

I'd believe you have a lot of suggestions to think about ...based on your room dimensions and your HT components specification, you need to take a final call. Also go through the various posts regarding acoustic treatments in this forum and you will get some more info. Besides, do some more research online reg. bass traps and acosutic treatment and you can decide better.

To answer your comments -

#I'm planning to use wood to make the frames (2 ft x 2 ft size blocks) to fill with the rockwool.
Neo: This is fine. I have used 1 metre X 0.5 metre frames to make the frames bigger It also works well in smaller sized rooms like yours and mine. Just make sure the depth of the panel is around 3.5 to 4 inches so that much rockwool goes in.
I have used 4 inch thickness on the wall opposite front speakers.

#Currently I don't have a plan to get a projector screen. But, I would love to keep an option for this. Any suggestion?
Neo: Believe me the enjoyment using a projector screen is different than using a TV. You can look out for various options depending on budget like Dalite (you need to find original), or Panaview or Liberty Grandview. I've taken a Grandview screen. And this depends on your projector throw parameter. So once you get a projector, you can take the next step.

#Planning to place the left rear speaker on the left wall slightly above the door. However since it's way above ear level, I'm thinking about tilting it towards the listening position. Is this a good idea?
Neo: This might not help giving the best surround, if you place above door height. I have the same situation and I fixed both speakers on the same wall but one of them placed just before the door entrance starts, at ear level.

#I plan on placing the center speaker in the enclosure below the TV. Should I treat the enclosure with the insulating material as well?
Neo: Yes it would be a good idea to treat the enclosure, depending upon how deep your enclosure is. If the speaker kind of juts out of the enclosure space need not worry, but if it will be placed inside deep then you will need to, probably mix of diffusers (using egg crates) also can help, or use plain rockwool treatment.

#Is 4" thick treatment required on all walls? This would really eat up a lot of room space Btw, what should be density of the insulating material?
Neo: In my opinion, 4" is not required on all walls, it depends on room dimensions too, and as per my understanding you need to have maximum thickness atleast opposite the front speakers, because that is the wall that would have max sound waves hitting and will require most absorption.

Looking at your room pics, one bass trap is sufficient I feel, if you are treating most of the walls and as Pandu mentioned, you can have one panel setup at one corner wall, in a triangular fashion. I'd suggest keep this bass trap at the top corner where your door is. Since I presume you wont be treating the door, implying that portion of your room is most untreated, it will help most by keeping bass trap on that corner.

Density of rockwool I've used is 32. you can use anywhere between 30-35.

You will need to think of options to cover the panel, because the rockwool shouldn't touch the outer cloth covering panel ideally, else you will be breathing that in the room. Covering with jute as pandu mentioned is one option, some folks have used tissue paper as well as thin ply like I've used. Just make sure the ply has holes in it, other wise there is no point , the sound waves need to hit the rockwool.

Hope this helps.

Neo

 

[manoj.p]

Is 4" thick treatment required on all walls? This would really eat up a lot of room space Btw, what should be density of the insulating material?

You don't need 4" thick treatment on all walls. But whatever treatment you do, if the thickness is less than 4" there is not much of lower frequencies absorbed. You need absorption for lower frequencies/mid-bass because these linger more compared to high frequencies. A 2" thickness will mostly absorb 100% upto only 500hz. and very less below that.

Refer to this link - http://www.bobgolds.com/AbsorptionCoefficients.htm It will give you idea how much each material will absorb.

I also agree with Padhu. Corner bass traps should be the first priority because the room is small. Next area is the back wall, from where center/front speakers will reflect. Since you are sitting so close to back wall, you will hear reflections at the same time as the speakers. That will muddy the front sound stage very badly. I would suggest moving the seating bit front by at least 2 ft. That will give some space between back wall and listening position. The surround will have better effect that way too.

Its not necessary to have the surround speakers at ear height. Surround speakers are there to provide ambiance. Having them above does not cause much difference. For movies, its in fact better to have the surrounds overhead. At movie theaters, the surround speakers are ALWAYS at the ceiling. all the movie tracks are mixed keeping this in mind.

 

[aakashr]

I would suggest keeping it simple.

For bass traps - build corner bass traps. Incidently in your case, the left and right surround are almost pointing at the front and left corners. So those bass traps will also take care of reflections from the surrounds.

For center speaker - Treat the back wall where the reflections from center will come. this will help in making the vocal's dialog clear.

For all other speakers and misc - do a mirror test and treat as necessary. don't do unnecessary treatment. It will make the room more dead.

also, on other hand, don't bother with 2" thick treatments. those won't help at all. You need at least 4" thick treatment to absorb anything worthwhile.

Hi Manoj,

I have a similar request........need to do some basic acoustic work for my dedicated HT room. They room has is all done up.........should have also included some basic acoustics right from the beginning but did not. If I give you details of my HT, would you be able to help?

Thanks

 

[pdhanwada]

Hi Manoj,

I have a similar request........need to do some basic acoustic work for my dedicated HT room. They room has is all done up.........should have also included some basic acoustics right from the beginning but did not. If I give you details of my HT, would you be able to help?

Thanks

I agree with manoj's suggestion. 2 inch thickness planks will not help much.
4 inches is needed.

Also more important are bass traps. If using rockwool try 64 Kg/per cu m or 96 kg/cu m.

Please go thru my thread it has all the details mentioned in the previous post.

 

[manoj.p]

Hi Manoj,

I have a similar request........need to do some basic acoustic work for my dedicated HT room. They room has is all done up.........should have also included some basic acoustics right from the beginning but did not. If I give you details of my HT, would you be able to help?

Thanks

sure. Thats why we all are here for.

 

[mandark]

@pdhanwada: I followed your thread and it was very informative.

I contacted Anutone and was referred to an acoustic dealer in Kolkata. However, the price was beyond me. He was offering acoustic panel @ Rs. 3000 - Rs. 3500 sq. meter.

I've decided to stick with rockwool. The plan for room treatment is as follows:

Front - 3 inches thick - area measuring 5ft x 7ft (h x w)
Left - 3.5 inches thick - area measuring 5ft x 6ft (h x w), will cover the door.
Right - 3.5 inches thick - area measuring 5ft x 6ft (h x w)
Back - 4 inches thick - area measuring 5ft x 7ft (h x w), will partially cover the door.
Ceiling - 3 inches thick - area measuring 5ft x 6ft (w x l)
Floor - Thick carpet

After the above arrangement do I still need bass-trap? Do bass-traps need to be placed in pair? Due to the position of my door, I can place only one on the right wall.

My carpenter will be using gypsum boards for false ceiling. Will the gypsum boards be able to take the weight of rockwool and the fabric?

Since bottom 1ft and top 2ft of the wall will not be treated with rockwool, what can I place in the ply frames so that they do not remain hollow?

 

[Hari Iyer]

Download the THX suggested recommendations from the internet for your home.

 

[pdhanwada]

@pdhanwada: I followed your thread and it was very informative.

I contacted Anutone and was referred to an acoustic dealer in Kolkata. However, the price was beyond me. He was offering acoustic panel @ Rs. 3000 - Rs. 3500 sq. meter.

I've decided to stick with rockwool. The plan for room treatment is as follows:

Front - 3 inches thick - area measuring 5ft x 7ft (h x w)
Left - 3.5 inches thick - area measuring 5ft x 6ft (h x w), will cover the door.
Right - 3.5 inches thick - area measuring 5ft x 6ft (h x w)
Back - 4 inches thick - area measuring 5ft x 7ft (h x w), will partially cover the door.
Ceiling - 3 inches thick - area measuring 5ft x 6ft (w x l)
Floor - Thick carpet

Rockwool slabs come in 2 in thickness. Either you use 2 inch thick or 4 inch thick.

If you are doing false celing with gypsum board. You need to do seperate frame work for Rockwool, as it is heavy, and gypsum cannot hold it.

After the above arrangement do I still need bass-trap? Do bass-traps need to be placed in pair? Due to the position of my door, I can place only one on the right wall.

My take is Bass traps are more important to control Bass. It balances the bass out very much.

My carpenter will be using gypsum boards for false ceiling. Will the gypsum boards be able to take the weight of rockwool and the fabric?

Since bottom 1ft and top 2ft of the wall will not be treated with rockwool, what can I place in the ply frames so that they do not remain hollow?

Aesthetic sense I cannot comment. You can do whatever you want.

 

[vinay]

I am pleased to see pictures of the making of your dedicated entertainment room, congratulations.

The flooring should ideally be carpeted for such a wonderful room. The star ceiling lights will not interfere with acoustics.treatment.

V.

 

[vinay]

Neo, is perfectly right that a projector is the best way to watch movies, all the more if it is a dedicated entertainment room.

If you have bought the TV already then you can shift it to other room and abandon the enclosure which you have made. In my case i had to abandon several things to get it right during the making of my Mini Theater, hard decisions are a must after all such rooms are made once in a life time.

V.

Hi Mandark,
I was going to suggest to not use TV and use a projector screen but looks like you already purchased it as well made the enclosure for it..
Neo

 

[manoj.p]

Since bottom 1ft and top 2ft of the wall will not be treated with rockwool, what can I place in the ply frames so that they do not remain hollow?

Create a frame with clothes wrapped and install it there. Wall will look complete. Choose different color and you can have a very appealing room decor.