New house construction - dedicated home theater room - initial questions

[John]

John,

I have used 4 inches glass wool from ground to 3 feet and thereafter 2 inches. About the loss of wall space please do not worry, my loss is much larger as i had knocked down my bathroom, sealed huge windows, the point is to achieve a great movie room, these losses are to small.

V.

Thanks Vinay, your tips are most useful. With my width of only 10', even if I lose 70 mm x 2 on each side, makes it almost 6" smaller. In effect, my plan of putting a love-seat in the front row might be a bit jeopardized. What size are these love seats?

What is the minimum glass wool thickness to be used for making it efficient?

I am waiting to look at the Chinese stuff before making a call.

Another reason I want to skip the Armstrong is I want to have a starfield ceiling later on; Just can't make holes in the Armstrong stuff later.

 

[manoj.p]

John,

Take a look at this site. http://www.bobgolds.com/AbsorptionCoefficients.htm

Check the density of GW you are using and thickness. You can only absorb max 46% of energy down to 125 hz. So, it won't absorb all.

If I were you, I would create corner bass traps for all the corners. That will pretty much take care of bass. Then at the reflection point, add all the diffusers. If you can't absorb the reflections, then diffuse them. That works out best. take a look at this post.http://www.hifivision.com/av-enhanc...-home-theater-diy-acoustics-5.html#post329015 Most will be applicable to your case as well.

 

[Alexkz]

hai guys,

Ones you are making a H T room should be Minimum 8feet hight, 16 feet length, and 10 feet width then only can acccomadate 10 to 12
screen size mi... 2m/1.5m , audio will be 5.1/7.1 for upgrde keep condut additional/cable
DVD, Booxe, or B/R with HDMI and projector ibnput also HDMI

Alexkz

 

[Sid_b]

Wow, just read thru the whole thread and I felt I have a lot of company of people obsessed with perfection. So glad I have a chance to interact, learn and share the experiences with so many like minded people. Can't thank hifivision enough.
John I salute your dedication T reach the final stages of living your dream. I can relate to you as I too have been thru something similar and have finally reached the stage of getting the ht room finally within grasp. But I have a few problems on which I seek members views and suggestions:
1. My room dimensions : 22'length, 10' width and 9' height. I have 2 6x5 windows on either side of the rectangular room. And one window which will fall behind the viewing screen.
2. This room will unfortunately not be a dedicated hT room now...but will still be a pvt living/ ht room.
3. I had no clue of the acoustics designing and the room is now at pop stage. The false ceiling with thermocol inserts on top is being done...awaiting the projector stand placement. All wirings are being done internally.
4. I am putting up the fenesta hardened double glazed windows but am yet to decide the thickness.

My queries are A. Will the windows (even with the thick glass) and thick Double curtains...are they going to help? B. how will the acoustics be effected...rather how much? I'm beginning to curse myself for not being a member here much much earlier!
Would appreciate all the help.
Thanks,

Sid

 

[vinay]

John,

The star field ceiling is not possible on acoustic tiles of Armstrong.

It will be better to get all the work done at one go because later to get things done will often be delayed beyond our imagination, if this is not enough, there also will be possibilities that the ideas will not come through. On the other hand to do some work later on may spoil or partly damage the interiors etc.

The recliners are huge in size be it the breadth or length, nothing short of a jumbo aircraft.

About the front row heading for a jeopardize, it is perfectly alright because if we try to put too many things in entertainment room then end results are likely to be compromised and so on.

V.

Thanks Vinay, your tips are most useful. With my width of only 10', even if I lose 70 mm x 2 on each side, makes it almost 6" smaller. In effect, my plan of putting a love-seat in the front row might be a bit jeopardized.

Another reason I want to skip the Armstrong is I want to have a starfield ceiling later on; Just can't make holes in the Armstrong stuff later.

 

[John]

Folks, construction of the house has again picked up after a lull due to issues with the contractor.

I am planning to proceed with acoustic treatment of the walls to begin with. Although I wanted to do ceiling + walls together, the budget is getting a bit tight for me as the rest of the house is also getting built and finished at the same time.

Nonetheless, I tried looking for local suppliers and returned with a blank.

Contacted Himalayan Acoustics. They are offering me Aphony Fibrette for the walls (3 walls - 2 side walls and rear wall), 20 mm thick at Rs 80/sq feet , including of freight and taxes.

For the ceiling, they are offering me black Aphony Fibrette 15 mm @ Rs 70/sq feet , including freight and taxes.

Can I do the walls now and ceiling later?

Do I have a cheaper alternative for walls an ceilings? Of comparable quality?

 

[manoj.p]

The better alternative would be NOT to do entire wall and ceiling. Instead, just treat the reflection points. You will end up saving on treatment material, YET it will be very effective acoustically.

 

[John]

The better alternative would be NOT to do entire wall and ceiling. Instead, just treat the reflection points. You will end up saving on treatment material, YET it will be very effective acoustically.

Thanks Manoj, like you mentioned in the earlier post, bass traps for all 4 corners and treat reflection points only? Which would cover all reflection points? And how best to treat it? Using something like Aphony Fibrette?

 

[manoj.p]

John,

yes, exactly like that. Get a friend and do the mirror check for reflection points on all the walls, mark those. Then perform the room treatments. I would make them enough wide and tall to capture most reflections and atleast 3 to 4 inch deep. Any rockwool, rigid fiberglass insulation covered with acoustic cloth will do. Does not have to be very fancy room treatment. You can do the same thing on the ceiling. Also, you can leave the gap between insulation and wall/ceiling (make sure both the sides of insulation have acoustic cloth) and you can use half insulation thickness. For example, if you leave gap of 2" between ceiling and use 2" insulation, then effectively, you are getting 4" thick insulation. Google Air gap mount for treatments.

HTH.
Update: Another alternative to absorption is diffusion, atleast for reflection points. If you can't absorb, diffuse them.

 

[John]

John,

yes, exactly like that. Get a friend and do the mirror check for reflection points on all the walls, mark those. Then perform the room treatments. I would make them enough wide and tall to capture most reflections and atleast 3 to 4 inch deep. Any rockwool, rigid fiberglass insulation covered with acoustic cloth will do. Does not have to be very fancy room treatment. You can do the same thing on the ceiling. Also, you can leave the gap between insulation and wall/ceiling (make sure both the sides of insulation have acoustic cloth) and you can use half insulation thickness. For example, if you leave gap of 2" between ceiling and use 2" insulation, then effectively, you are getting 4" thick insulation. Google Air gap mount for treatments.

HTH.
Update: Another alternative to absorption is diffusion, atleast for reflection points. If you can't absorb, diffuse them.

Thanks Manoj,

I am quoting from your other most useful post regarding the "reflection test." And posting few more questions, which I hope you will be able to respond to.

1) Where can I get Rockwool or rigid fiberglass? I am not able to get them locally. What are the alternatives?

2) Where can I get acoustic cloth?

You need bass traps for subwoofer. Those usually go in the corners of the room, where two surfaces meet each other. Check some threads here and at google to find more info.

for main speakers, if you want to treat, there is a simle mirror test to determine the reflection points. Have a friend sit in the listening position, and then you, holding a small mirror in hand (flat, facing the room). Start from the back of the room on the left side of the wall. Start walking slowly towards the front of the room. At some point, your friend will see the reflection of right speaker in the mirror. Mark that position. You would want to put an absorber here. That will take care of the reflection of the right speaker on the left wall. Keep walking slowly towards the front and next your friend will see is the reflection of center speaker. We will talk about this later. Keep going and your friend will the reflection of left speaker. Now, you have two choices here - You can put absorber, but it will make the room quite dead. Instead, if you put diffuser here, it will diffuse the sound and a straight reflection will not occur coming from there and won't interfere as much coming from the left speaker.
Repeat the above with the right wall. This way, you will have taken care of the left and right speaker reflections and made sure that right speaker sound is coming from right only and vice-a-versa.

About center speaker - whether to treat with absorber or diffuser is your choice. You can even leave it alone because, if the center is exactly in the center, then the reflections from left and right will be same and pretty much cancel each other. If the room is not square and you don't like the sound, then measure and decide.

The above will get you pretty much covered from the audio wise. You can offcourse, get the measuring tool out and measure the room response to do more tweaks.

1) Manoj, the mirror test, I have to walk with the mirror facing the front, right?
2) How do I mark the spots for the ceiling?

Thanks in advance.

 

[manoj.p]

Thanks Manoj,

I am quoting from your other most useful post regarding the "reflection test." And posting few more questions, which I hope you will be able to respond to.

1) Where can I get Rockwool or rigid fiberglass? I am not able to get them locally. What are the alternatives?

Rockwool/Rigid Fiberglass is nothing but insulation material. You can find it with contractors installing heating/Air conditioning for commercial buildings. Especially wrapping around the ducts. They may have different names/brands in India.

2) Where can I get acoustic cloth?

Acoustic cloth is any cloth that sound can pass through. A simple test is to blow the air through it. If you can feel the air on other side, then its acoustically transparent. You need the sound to go through cloth to the rigid fiberglass.

1) Manoj, the mirror test, I have to walk with the mirror facing the front, right?

You need to walk with mirror facing the other wall. for example, if you are trying to find the reflections on left wall, then the front of the mirror should be facing right wall.

2) How do I mark the spots for the ceiling?

you need to make a handle of something for mirror, so you could place the back of mirror to ceiling, facing down and then move across the front. Use either a chalk to mark the location of reflection points approximately. You will be covering those points in the size of 2ft x 4ft anyways, so need not be very precise.

Thanks in advance.

You're welcome.

 

[ranjeetrain]

Re: Dedicated Home Theatre - Foundation Time

1. One is the kind who, without your permission, start 'mis-handling' your equipment. I usually keep my speakers covered with a special cloth cover that I have got stitched. I had a guest who, first of all had no idea about speakers. This guy just rips open my speaker covers as he wanted to look at the speakers. Then there are people who remove the speaker cables and peek at the brand and model name. They put their heads into the shelves to read the brand and model numbers. When you answer their question and tell them hesitatingly that your amp generates 100 watts per channel, you will hear an instant scream. 'What? 100 watts? And you spent so much? My Sony generate 2000 watts and I paid just 2,500!! You have been cheated, man! You must take the system back and ask for a replacement.'

2. The second is the 'half baked' knowledge types. These people want to 'audition' your system, start pressing buttons on the system or remote, and then loudly pass comments on how their 'inexpensive' system sounds much better. "These systems are for people like Venkat who have nothing else to do", is their regular comment. "If I want to see a movie I will go to a cinema hall."

3. The third, and the ones I fear the most, are the ones who become bolder with the number of drinks they have. I had a 'guest', who after a few drinks, leaned on my rack and placed his shoe horned feet on one of the shelves. There was a loud thud and the shelf came tumbling down. Fortunately I dived and saved the day before any damage happened.

I nearly fell off my chair LMAO reading that! :lol:

Well, Venkat, you need to suppress the urge to show off your system to all and sundry. No disrespect meant to your guests, but the people who don't understand the importance/value of the stuff you are showing them should not be on your guest list

I get upset when someone fiddles with my system. So I only let my close friends operate my system whom I can clearly ask to "keep their a$$ off" from things I don't want them to touch. With not so close friends, it become a tad tricky. Specially, if you are soft spoken person. You don't want to tell them clearly that you are not liking it, and they won't take the hint.

I have my own stories but don't wanna hijack this thread.

@all, sorry about the OT.

 

[vinay]

John,

The fabric can be easily sourced from wholesalers who sell inner/outer accessories for purse, lap top and other bags, shoes. The fabric is available in dozen colors and is acoustically transparent.

I have used this fabric and it is beyond excellent.

V.

Acoustic cloth is any cloth that sound can pass through. A simple test is to blow the air through it. If you can feel the air on other side, then its acoustically transparent. You need the sound to go through cloth to the rigid fiberglass.

 

[John]

Guys,

I have looked up a wood wool manufacturer. Balaji Wood Wool Insulation-INDIA - Home

Has anyone used this kind of stuff?

The density is supposed to be 400 kg/m3 or so..

 

[John]

I am thinking of going with wood wool for wall treatment. I have marked out the reflections points. The wood wool I am looking at is 4' x 2' x 25 mm; will that suffice per reflection point? Or should I put it the entire 8 feet height, i.e., 2 pieces of 4'?

 

[manoj.p]

That material looks good as sound barrier, not sure if it is effective at sound absorption.

In any case, 1 inch thick material won't absorb much. It will be more effective to diffuse it. Get a diffuser instead.

 

[vinay]

John,

I too had a lot of problems with contractors during the making of my Mini Theater, fortunately i was clear from day one that i will not take anything which is wrong therefore the making got delayed often therefore it took a extremely long time to complete the Theater. The take away lesson has been simple that do not settle for anything less then what was planned and be open to alter if the need be, even if that means some loss of money but eventually such losses may be beneficial many a times.

If the budget is getting tight it will be way better to slow down or pause the making of room while it would be always great to plan all sort of expenses in advance with a good amount for grace towards unforeseen.

V.

Folks, construction of the house has again picked up after a lull due to issues with the contractor.

I am planning to proceed with acoustic treatment of the walls to begin with. Although I wanted to do ceiling + walls together, the budget is getting a bit tight for me as the rest of the house is also getting built and finished at the same time.

 

[John]

Hi guys,

I am in a fix about getting the acoustic panels made of wood wool. The supplier said the minimum density is 400 kg /m3; isn't it too much and will deaden all the music?

Alternatively, I am thinking of getting stuff from bajaao.com

Experts please guide me.

Thanks in advance.

 

[sharadgaur]

Hi John,

I would suggest that you look for something other than the wood wool boards mentioned (400 kg/m ?). A guide such as http://www.bobgolds.com/AbsorptionCoefficients.htm would give you a good idea. You can make 2 inch fiberglass/rockwool panels yourself or can go for acoustic panels from Anutone. Moreover a room becomes dead only if excessive AREA is treated with acoustics. So, just placing high absorbent panels at reflection points will no cause this problem.

 

[John]

Hi John,

I would suggest that you look for something other than the wood wool boards mentioned (400 kg/m ?). A guide such as http://www.bobgolds.com/AbsorptionCoefficients.htm would give you a good idea. You can make 2 inch fiberglass/rockwool panels yourself or can go for acoustic panels from Anutone. Moreover a room becomes dead only if excessive AREA is treated with acoustics. So, just placing high absorbent panels at reflection points will no cause this problem.

Thanks Sharadgaur, I also thought the sound would become too dead with so dense wood wool, so I have cancelled that plan. Rockwool is not available where I live and fiberglass is also not readily available, but I still have a chance of getting it.

In the meantime, I need to make a door for the room. I am making 2 panels for the door made with plywood. How should I treat the door (acoustically)?