Dedicated home theatre

[rajesh srinivas]

Hi,
Everyone i am into designing and building my new Dedicated HT ,pics are enclosed for suggestions and feedbacks for the below following points.

1. Room size H 9'.8'X W 10'7" X D 21'10"
2. I have additional bathroom adjacent(behind) to the screen wall which has
a depth of 5'5" so if i break the partition wall the total depth of my ht room will be 21'10"+6"(partition wall)+5'.5"(width of bathroom = 27 feet
should i go for this size or if any one familiar with golden ratio can tell me if this room size is correct.
3. I have 2doors and a big window in ht room which i can close them fully with brick/cement ,or window is essential for air circulation???? if entire room has no door window few suggest to install duct exhaust fan?? if so what brand and what price we get.
4. Bathroom has 2 small window and a door which if used for ht will be covered fully by brick/cement.
4. HT walls(Front,side,back) thickness is 1.5 feet,so sound proofing should be that much better.
5. Since the ht room was already constructed ,Electricity cables connecting projector,a.v rack,a.c, will be laid at the back only since all the equipment are placed at the rear and cable for spot light will be laid through false ceiling.
6.Speaker cables for the mains,center,subwoofer will be laid running them at the bottom side wall which will be covered by floor carpet,laid corner to corner from the main speaker till the prime listening position.
7.Acoustics for absorbtion and for bass management will be done not for full room as i dont intend to deaden my room,will be covering only the 1st reflection points,(side wall,ceiling,all corner 4 walls from ground to ceiling for taming bass and 2 or 3 absorbtion panels on rear walls as per the below link.

corner bass traps will be done as per santy

http://www.hifivision.com/diy/40966-home-made-acoustic-panels.html

Where to Place Acoustic Treatment in a Home Theater

and

Cinema 651 Acoustic Treatments and building acoustic panels - Home Theater Forum and Systems - HomeTheaterShack.com

8. For acoustics will be using rigid fiberglass wool Twiga A grade 48 Kg/m3, 50 mm thick,size of panels 2x4x2in thick frame,covered with foam,cotton or jute breathable cloth,frame will be laid with 1in gap to the wall,
9.false ceiling will not be for entire ceiling because it can vibrate for low freq,but only at say about 1 or 1.5 feet from side/front/back walls,for placing the spot light i feel 1feet should be enough????
10.Need advice for the front screen i mean behind the screen should absorbtion panels be placed with diffuser i dont think diffuser panels are required since my ht room is huge,what material should be used for darkening the front wall,i feel black velvet of thick material will be great to cover the front and side walls if yes where do we get it and what price.
11. For ceiling what colour should i paint.
12. i have 2 shelves as can be seen in the pics,one at the rear will be using as a.v rack, and one in the front i have stuffed books for sound absorbtion or should i seal it of???
The above points will be my first step for which i will be only concentrating.firstly i will alter the room if required,then electricity cable layout,then false ceiling,audio will be diy,drivers are bought so at the time of making the boxes will also complete the acoustic panels,planning also for a 1feet hight stage below the screen to improve the looks.

i have read a lot about designing ht on net and also got inspired from hifi members who have there dedicated ht to name a few..hope i didnt miss others apologize
santhosh,santy,vinay,sams9s,manoj p,sash,mdharan,hydrovac,john,aloklala,cmsajith.

pics of my ht.sorry for the mess,as it needs cleaning,plus will be using the wood frames,pieces for ht.

thanks
rajesh

 

[raghupb]

Golden cuboid ratio is
0.618 : 1.000 : 1.618

You seem to have some antique furniture. Any plans of revival and incorporating them into the theatre?

Cheers,
Raghu

 

[rajesh srinivas]

Golden cuboid ratio is
0.618 : 1.000 : 1.618

You seem to have some antique furniture. Any plans of revival and incorporating them into the theatre?

Cheers,
Raghu

hi Raghupb,
I knew you would be the first to reply,coz i see in every other query/thread that is put in hifi you have your say i appreciate your talent..

coming to the Golden cuboid ratio...the calcuation for my setup is as under.

The Golden Ratio formular is 1.618 times ceiling height, that result gives width, then times 1.618 for that result for length.

my Height is 9.8x1.618 = 15.85 shld be the width wheras its 10.7
Length/depth will be 15.85 x 1.618 = 25.64 that shld be fine if i extend
my room to 27in.

only concern will the room width diff = 15.85-10.7 = 5feet will that be a concern or room acoustics will overcome it.

i do have plenty of antique furniture since the house belongs to parsi,what ever required like planks,furniture,wooden racks will be utilised for ht,so kept them in the room itself.

Its 57 views till now for my thread you are the first to reply,awaiting also for the dedicated HT GURUS to pen their thoughts.

thanks
rajesh

 

[raghupb]

Rajesh,

Woke up early this morning to watch the Super Bowl (American football). Your post (actually the furniture) caught my attention while browsing during commercial breaks.

Coming to the golden cuboid, my gut feel tells me it is very important for unamplified large rooms; concert halls, king's durbar, etc.
With electronics and diffusers/absorbers, one should be able to overcome some of the ills of reflections in various room geometries.
You know this already. Good luck with the planning and implementation.

I am no expert nor do I have the opportunity for a dedicated HT; you will get better advice from folks who have actually built dedicated rooms.

Cheers,
Raghu

 

[rajesh srinivas]

Further to the pics posted and make things clear will explain pic by pic in detail.

1. 1st picture is taken from the entrance of the main door.
2. 2nd pic is right side view from the main door which shows the window and door leading to galary outside (exit)
3. 3rd pic is left side view where you can see 2 built in shelves one to the closet will be used for a/v rack,htpc,amps,bluray and the one far off at present stuffed with books/magazine to try if it can act well as a diffuser or else can seal it off need advice in this regard.
4. 4th pic is from screen side view where you can see the main entrance door,and also behind the window there is another door which leads to exit,feel like keeping one among 2 door to use for exit,or else will seal it off need suggestions.
5. 5th pic is the extra bathroom adjacent to the screen wall for extension again need advice for breaking the partition wall to make the ht room 27ft.
6. is the wall thickness 1.5 feet its a old building so the walls are thick.

thanks.
rajesh.

 

[Naturelover]

From what I have read, this 2:1 ratio is bad for sound. Maybe you could check this out on the net.
But, as raghu has pointed out, this may not affect the average listener so very much. Like the King's Durbar bit :lol:

Different sources give different ratios
IEC give following
8 12.8 19.2
9 13.5 21.5
10 16.0 24.0

Read on some other forum
1 : 1.14 : 1.39
1 : 1.28 : 1.54
1 : 1.60 : 2.33

Cardas (Fibonacci)
10 16.2 26.2

 

[raghupb]

Cardas rule is golden cuboid. Other ratios seem to match practical room geometry.

 

[rajesh srinivas]

hi nature love

is there any golden ratio which is close to my room dimension of

H 9'.8'X W 10'7" X D 21'10" or D 27ft

or just go for a depth of 27ft with acoustics.

r/s.

 

[rajesh srinivas]

Corner bass traps will be done as per santy (morderator) its a very good way
to make them,earlier link by him was for 1st reflection panels.

http://www.hifivision.com/av-enhancers-room-acoustics/54553-corner-bass-traps-diy-caution-picture-load.html

 

[rajesh srinivas]

251 views, only 4 replies so far from hifimembers,

where are the HT GURUS gone,feel dissapointed.

thanks
rajesh

 

[manoj.p]

Hi Rajesh,

I wouldn't worry about the room ratios if you plan to do room treatments. Yes, the room width is less and I like wider sound stage, but it is what it is. If you plan properly then you can take care of the audio issues very nicely.

Start with right speaker placement in the room and that can take care of main room modes. I suggest you read up some information about axial room modes. Since your room is square and if you get it pretty symmetrical, then you can predict room modes pretty accurately and take care of those through speaker and subwoofer placements.

Another point I would like to suggest - and this will make a huge impact to the audio in your room. Baffle wall. Since you have a long room, you can afford to lose few feet behind screen wall. Build a baffle wall, house your Left/Center/Right speakers in there. This will remove SBIR issues your room presents. As a bonus, you can use the space behind baffle wall for subwoofers and get yourself a kick-ass infinite baffle subwoofer.

If you have space behind, the best bass trap is to just pile up 2 ft thick insulation all over the back wall. You don't even have to take it out of covers etc. just pile it up and cover it. That will take care of all the standing waves. That's how I would do it. Smaller bass traps don't do much absorption.

Early reflections - don't worry about them from beginning. If you have speakers with wide dispersion and consistent off-axis response, then its better to leave early reflections alone. They actually aid in spreading the soundstage beyond your walls. You may want to tweak it later by building diffusers, if needed. You would want to absorb the cross reflections though. You can do that after your listening positions are finalized.

Then comes the seating - rule of thumb is place seating in such a way that listener's head comes at odd divisions, like 3rd, 5th of room length. Once you read about room modes, this rule of thumb will become quite clear.

One question - are you planning to have ceiling speakers for Atmos or DTS:X? Any POP plans for ceiling?

 

[rajesh srinivas]

I wouldn't worry about the room ratios if you plan to do room treatments. Yes, the room width is less and I like wider sound stage, but it is what it is. If you plan properly then you can take care of the audio issues very nicely.

yes since the room is already constructed we cant do much about the result from golden ratio,given a fixed dimension proper planning is required as you say.

Start with right speaker placement in the room and that can take care of main room modes. I suggest you read up some information about axial room modes. Since your room is square and if you get it pretty symmetrical, then you can predict room modes pretty accurately and take care of those through speaker and subwoofer placements

.

i read about axial room modes and did the calculation as below but dont know how to implement them and correct the room with these result.

Axial Modes - Involve Two Parallel Surfaces - opposite walls, or the floor and ceiling. These are the strongest modes.

Length Width Height
Mode Frequency Mode Frequency Mode Frequency
1 0 0 20.92592593 0 1 0 52.80373832 0 0 1 57.65306122
2 0 0 41.85185185 0 2 0 105.6074766 0 0 2 115.3061224
3 0 0 62.77777778 0 3 0 158.411215 0 0 3 172.9591837
4 0 0 83.7037037 0 4 0 211.2149533 0 0 4 230.6122449
5 0 0 104.6296296 0 5 0 264.0186916 0 0 5 288.2653061
6 0 0 125.5555556 0 6 0 316.8224299 0 0 6 345.9183673
7 0 0 146.4814815 0 7 0 369.6261682 0 0 7 403.5714286
8 0 0 167.4074074 0 8 0 422.4299065 0 0 8 461.2244898
9 0 0 188.3333333 0 9 0 475.2336449 0 0 9 518.877551

my room is rectangular (10.7x27),i will placing the speakers and sub at best possible position,L & R will be placed say 1/2 or 1ft away from back/side walls,and sub at the center,hope by this the room modes can be corrected.
how does all the four corner bass traps help in controlling bass freq,say if i use 4inch thick insulation.

Another point I would like to suggest - and this will make a huge impact to the audio in your room. Baffle wall. Since you have a long room, you can afford to lose few feet behind screen wall. Build a baffle wall, house your Left/Center/Right speakers in there. This will remove SBIR issues your room presents. As a bonus, you can use the space behind baffle wall for subwoofers and get yourself a kick-ass infinite baffle subwoofer.

if you have space behind, the best bass trap is to just pile up 2 ft thick insulation all over the back wall. You don't even have to take it out of covers etc. just pile it up and cover it. That will take care of all the standing waves. That's how I would do it. Smaller bass traps don't do much absorption.

Its a good suggestion,but whats the difference between placing the LCR in front or behind the screen as you say the SBIR issue will be resolved,but for
that i should buy a transperent screen and cover the entire wall with 24ft insulation for a price.am i right....??? i already have 12inch peerless sub as in my profile picture dont want to invest for a infinite baffle subwoofer since lot of things to buy and get things finished.

Early reflections - don't worry about them from beginning. If you have speakers with wide dispersion and consistent off-axis response, then its better to leave early reflections alone. They actually aid in spreading the soundstage beyond your walls. You may want to tweak it later by building diffusers, if needed. You would want to absorb the cross reflections though. You can do that after your listening positions are finalized.

for LCR i have already acquired the drivers they are from peerless.
peerless drivers are
1. tweeter 1inch silk dome-TL26SG
2. mid range paper cone 5.25inch- m16nh
3. mid woofer 6.5inch- k16ki (keevler)

Similar build as done by one of our hifimember as below link
http://www.hifivision.com/diy/59106-home-made-5-1-channel-speakers.html

The original design is taken from Clear wave as in this link but box calculated
as per peerless T/S specs.

4T SE main speakers:
4T SE main speakers (pair-- full kit) - accuton high end


4CC SE center channel speaker:
4CC SE center channel speaker (full kit) - accuton high end

One question - are you planning to have ceiling speakers for Atmos or DTS:X? Any POP plans for ceiling?

in future yes,but at present 7.1 ch. for false ceiling yes will go for pop but only at the corners as in the link for installation of spot light and for better ht ambience/looks.

http://i65.tinypic.com/k3kpw3.jpg


thanks for all the valuable suggestions you have given,first will go ahead now with breaking the partition wall to extend the depth 27ft,side by side will build the speaker boxes,will keep you update about the progress and if any help will ask you.

thanks
rajesh

 

[sdurani]

These are the strongest modes.

Width
Frequency
52.80373832

Height
Frequency
57.65306122

sub at the center,hope by this the room modes can be corrected.

Sub at the centre of room width will cancel the 1st width mode at 52Hz. If you can raise the sub to the centre of room height, you can also cancel the 1st height mode at 57Hz. When you cancel a mode, all the peaks & dips caused by that mode will be cancelled as well.

 

[rajesh srinivas]

Sub at the centre of room width will cancel the 1st width mode at 52Hz. If you can raise the sub to the centre of room height, you can also cancel the 1st height mode at 57Hz. When you cancel a mode, all the peaks & dips caused by that mode will be cancelled as well.

thanks sdurani,

cancelling the 1st room mode at 52hz is fine since sub will be placed at that point,how can we raise the height of sub to the centre since screen will be placed,provided if you have a transparent screen which is costly,and do the way manoj told me to build baffle wall.

going for a baffle wall will be not a problem since i have sufficient depth,i feel the cost of buying insolation 2ft (24inch) thick will be huge.

how effective will be the 4 corner bass traps (ground to ceiling) say 4 to 6 inches???

r/s.

 

[sdurani]

how can we raise the height of sub to the centre since screen will be placed,provided if you have a transparent screen which is costly,and do the way manoj told me to build baffle wall.

Centre of room width & height doesn't necessarily mean the front wall. Place the sub on a sturdy stand at the middle of the back wall. As long as you cross over at 80Hz or below, the sub won't be localizable.

 

[rajesh srinivas]

correction to my earlier mesg.

but for
that i should buy a transperent screen and cover the entire wall with 24ft insulation

the insulation which can be placed behind the screen if baffle wall method is used is 2ft (24inch)

1. tweeter 1inch silk dome-TL26SG

the diameter of TL26SG IS 4INCH.

thanks
r/s

 

[manoj.p]

Rajesh,

I meant baffle wall on the front and 2ft insulation (if you can afford) on the back wall. This you don't have to do right away or during build. You can add the absorption on back wall later or when you have money.

Yes, baffle wall means using a transparent screen. Sorry, should have asked about your budget first though. Not sure about prices in India, but I got my transparent screen from SeymourAV. They have a DIY material option which is fairly cheap. Another factor with baffle wall is - you need to place around 1" or so absorption on it. It will also add to the cost.

About infinite baffle subwoofer and baffle wall, these are two separate things. We can combine them to be cost effective. But if you already have a subwoofer, then you can use it with baffle wall arrangement still. As long as you can still place your sub(s) at right locations as Sanjay suggested, then no need to worry about it.

See what you can fit in your budget and go in steps with it. I have done multiple iterations myself so can understand.

 

[rajesh srinivas]

Centre of room width & height doesn't necessarily mean the front wall. Place the sub on a sturdy stand at the middle of the back wall. As long as you cross over at 80Hz or below, the sub won't be localizable.

The 12inch sub box is very heavy plus I have entrance door at the center of back wall,how about adding similar 2nd sub at the rear wall??
So that there will be uniform bass all over the room which can inturn can overcome the room boom and even out the bass at all the 4 corners.
Correct me if am wrong.

R/s

 

[sdurani]

If you can't raise the sub or put it at the middle of the back wall, then stick to your original plan of putting the sub on the floor at the centre of the front wall.

BTW, if I had your room, I would turn the entire set-up 90 degrees, so that front-to-back length would be 10.7 feet and room width would be 21 feet. This will allow you to spread your front speakers apart and have a nice wide soundstage.

 

[rajesh srinivas]

If you can't raise the sub or put it at the middle of the back wall, then stick to your original plan of putting the sub on the floor at the centre of the front wall.

BTW, if I had your room, I would turn the entire set-up 90 degrees, so that front-to-back length would be 10.7 feet and room width would be 21 feet. This will allow you to spread your front speakers apart and have a nice wide soundstage.

But 10.7 feet depth will be to less for video part,esp..if you are using screen size of say 120in to 130in.audio part it will be fantastic but i feel 21ft gap for the L & R speaker will be too much of separation,and it will not form a v design to the listeners position.

i will initially place the sub in the front wall at the center,and lcr,surround at their right places then break in,listen to them for few days then do the tweaking/room correction acoustically and also go for the baffle wall as suggested by manoj when things get settled.

one help/answer from you -- should i go in for the 27ft room depth or 21 would be good enough,and also can i provide 2 doors one for enterance and 1 for exit,i am going to seal all the other doors and windows though to make the room sound proof.

what type of acoustic material/thickness should be placed on the door to make it sound proof as well as absorbtion/difussion.

thanks
r/s