Need Help On Room Acoustics

[pdhanwada]

Budget: Small

Currently I want to experiment.

My room size 17 X13.

My speakers are not centrally aligned to the 13 ft wall but there is an eccentricity of about 1ft to the right.

On the Left side of the Projector screen I have a Tall rack containing all my equipment.

ALl my walls are Wall putty and smooth finish. Roof is too is pop/wall putty.

Floor was marble but right now covered with couple of carpets.

Recently I removed one piece of furniture which was near the first reflection point. Because of that I feel the room is bigger but I think the room acoustics have suffered.

Before I go with rockwool insulation or anykind of it. I want to experiment with anything that is cheap or available in the house.

In one of the post It was proposed to have a artificial plant in the room. I would use it at the first reflection point and see.

Another question. What would be cost of doing room treatment if we design it ourselves( I mean the material). We need carpenter anyway.

Is it nesscary to do the roof. It could cost more.

LEt me know your know thoughts

 

[venkatcr]

I would say insulation material would be roughly 200 Rupees per square feet. Add carpenter costs as well as you time. If you go to companies such as Anutone you are talking about 300 odd upwards.

Cheers

 

[micjak77]

Venkat I have a question, the room acoustic rate is calculated for a cubic feet or sq feet. Shouldnt it be cubic?

 

[venkatcr]

You calculate in cubic feet when you consider various thickness. But when you fix the thickness of the material, you go down to square feet. Companies mention various thicknesses and the price per square feet. Many companies do not even mention square feet. What they sell is a standard tile size, or the size of a predefined board of x feet by y feet by z thickness and a price for it. Yes, you can certainly convert that into Rupees per square feet.

Cheers

 

[pdhanwada]

venkatcr

If I look at the wall area then it is turning out to be 600 sq ft or are you talking about the carpet area of the room.

I feel 200 per sqft is on the high side let me know what material you have in mind. Also let me know how we should get it covered. I dont think Plywood is a good option.


If there is anybody in hyderabad who had got their room acoustics done then I can go visit them.

Thanks
Pandu

 

[venkatcr]

If I look at the wall area then it is turning out to be 600 sq ft or are you talking about the carpet area of the room.

I feel 200 per sqft is on the high side let me know what material you have in mind. Also let me know how we should get it covered. I dont think Plywood is a good option.

I was referring to the walls to be covered with sound absorbing material. You should look in the local market for exact prices. I was only mentioning a rough price range to give you a heads up on budget. BTW, sound absorbing material is not plywood. It is a combination of various material usually mixed with glasswool fiberglass, and other porous material. Alternatively companies such as Anutone make sound absorbing tiles or boards.

Cheers

 

[pdhanwada]

Venkatcr,


Thanks for your comments. I am trying to understand what is the most expensive portion of the wall panelling for sound absorbtion. It does not look like the absorbtion material. Panels which we are going to use to cover the insulation takes more money than anything else.

I was speaking to an architect, He suggested Gypsum board is a reasonable option to cover the insulation. What is your opinion. Do they reflect sound. If the sound passes thru them Then I guess we should be good.

Let me know which insulation is better if you have used with good results .

Thanks
Pandu

 

[venkatcr]

There are a nunber of threads that have discussed various materials in detail including costing. Please seach for them. In particular look for threads started by Santhol2 and Subash.

Cheers

 

[manishk13]

Just to add my 2 cents, I had called up Venkat sir (our moderator) for his kind advice about the broad strategy to treat the side walls and here is what I understood:

The main absorption needs to be done in line with 2 feet above and below of the tweeter. My tweeter is at roughly 3 feet high and Anutone absoptive boards come in 4 feet height. So I am leaving 1.5 feet from the floor and then putting the anutone absoption for 4 feet. So the line of the tweeter falls in the center at 3 feet and Anutone takes care 2 feet both above as welll as below

Rgds
Manish

 

[pdhanwada]

Question For Esanthol

How is your HT room after treatment. I guess you did not do the roof treatment.

My plan is to treat the side walls until the window height, the back(Behind the listener) wall not sure until what height. Leave the front(in front of the listener) wall as is. My front wall has a window right behind my projector screen. Let me know your opionion on the treatment related to the front wall.

Is Door level treatment enough on the back wall.

Are Anutone boards needed across the wall. How about taking a ply and filling the space between wall and ply with glass wool and then wrapping fabric on the ply. I remember going thru your thread and you had done the same for portions of the wall and the remaining with the ANutone boards.

How much is the cost effectiveness for ply vs anutone boards. What was your fabric cost. How many sq ft did you do the treatment. What was the total cost excluding electrification. If you can break it up it would be great.

Can I call you. Need some help regarding the estimates and advice. PM me your #. Or I can call you .

Thanks
Pandu

 

[GeorgeO]

Praveen from Anutone suggested that leaving an untreated space of 300mm height from the floor was an optimal way to do wall treatment.

 

[venkatcr]

Re: Question For Esanthol

How much is the cost effectiveness for ply vs anutone boards. What was your fabric cost. How many sq ft did you do the treatment. What was the total cost excluding electrification. If you can break it up it would be great.

The sound absorption coefficient of some common material is as follows:

Plaster walls 0.01 - 0.03
Unpainted brickwork 0.02 - 0.05
Painted brickwork 0.01 - 0.02
3 mm plywood panel 0.01 - 0.02
6 mm cork sheet 0.1 - 0.2
6 mm porous rubber sheet 0.1 - 0.2
12 mm fiberboard on battens 0.3 - 0.4
25 mm wood wool cement on battens 0.6 - 0.07
50 mm slag wool or glass silk 0.8 - 0.9
12 mm acoustic belt 0.5 - 0.5
Hardwood 0.3
25 mm sprayed asbestos 0.6 - 0.7
100 mm mineral wool 0.65
Persons, each 2.0 - 5.0
Acoustic tiles 0.4 - 0.8

As you can see plywood's coefficient is very poor. The co-efficient must be as close to 1.0 as possible.

One of the cheapest ways of building a sound absorbing panel is to create a framework using MDF reapers with a chicken mesh at the back. Fill the frame with glass wool and cover the front with speaker cloth. Mount the panels on the wall or even simply lean it on the wall.

Cheers

 

[pdhanwada]

Venkatcr,

Thanks for your reply. WHy cant we fill in the fibre glass wool in between the wall and the plyboard. Does it not work. absorbtion is 1 %, what about reflection coeficient and the transparency coeficient.

All added together should make it 100% right.

Another question I have is should we need to do treatment till the roof height or 7ft is enough. I know it is subjective. What about the front wall.

I am planning to do back wall fully. My frontwall has a 4.5ft by 6ft window over which my Projection screen hangs.

Thanks
Pandu

 

[venkatcr]

WHy cant we fill in the fibre glass wool in between the wall and the plyboard. Does it not work. absorbtion is 1 %, what about reflection coeficient and the transparency coeficient. All added together should make it 100% right.

Where did you get the figure of 100% from? If you mount plywood, the sound hits that first and will get reflected immediately. So the point of putting glass wool behind the ply is no use. The panel should be covered with something that allows sound to go through to the glass wool. Ply is not the solution.

Another question I have is should we need to do treatment till the roof height or 7ft is enough. I know it is subjective. What about the front wall.

I am planning to do back wall fully. My frontwall has a 4.5ft by 6ft window over which my Projection screen hangs.

You have to cover what is called reflection points. There is a long thread where this has been discussed. Please search for that.

Cheers

 

[pdhanwada]

Where did you get the figure of 100% from? If you mount plywood, the sound hits that first and will get reflected immediately. So the point of putting glass wool behind the ply is no use. The panel should be covered with something that allows sound to go through to the glass wool. Ply is not the solution.



You have to cover what is called reflection points. There is a long thread where this has been discussed. Please search for that.

Cheers

Venkatcr,

I have gone thru the whole thread created by esanthol. If I understand correctly only the Anutone boards absorb it and rest of the ply reflects it. I guess this is done to keep the room not too much damped.

I also understand that the first reflection points are treated with Anutone boards. The plyboards are used for reflection. Then should we need to do plyboarding above the 5ft marker as my surface currently has Luppam finish and it is already reflecting.

LEt me know.

Thanks
pandu

 

[ravidharap]

Hi all , I have done acoustic's for 2 high end recording suites. For home accoustics, low budgets, on walls,use glass wool of 50 mm thick , secured to a wall by 2"(inches) wide x 3 " height commercial grade ply wood, don't forget to do pest control of the same, docorate with a top of thick decorative fabric, &for flooring use thick carpet. And again one more way for very low end treatment of walls is put chicken mesh, paste earthen/ pottery diyas/ earthen lids or earthen pot covers , concave visible,as per random pattern on the walls, plaster the wall with pure mud, paint it as u wish, it will also save electricity.


Sent from my iPhone using Tapatalk

 

[pdhanwada]

Hi all , I have done acoustic's for 2 high end recording suites. For home accoustics, low budgets, on walls,use glass wool of 50 mm thick , secured to a wall by 2"(inches) wide x 3 " height commercial grade ply wood, don't forget to do pest control of the same, docorate with a top of thick decorative fabric, &for flooring use thick carpet. And again one more way for very low end treatment of walls is put chicken mesh, paste earthen/ pottery diyas/ earthen lids or earthen pot covers , concave visible,as per random pattern on the walls, plaster the wall with pure mud, paint it as u wish, it will also save electricity.


Sent from my iPhone using Tapatalk

Ravidhap,

You seem to be saying exactly the opposite of what venkatcr is saying. In the previous post he says, plyboard's reflect everything except the .1 %. What am i missing here.

Thanks
pandu

 

[venkatcr]

I have gone thru the whole thread created by esanthol. If I understand correctly only the Anutone boards absorb it and rest of the ply reflects it. I guess this is done to keep the room not too much damped.

You are getting confused between special boards made by Anutone and commercial plywood. Commercial plywood reflect sound and cannot be used in the front of a sound absorbing panel. If you really want to use it for some reason, you must drill holes in the ply at very close proximity to each other. Sound absorbing boards are covered in the front with special material.

Cheers

 

[cmsajith]

I think all are confused of what others are trying to say. I will try to put it clear (even though it was discussed several times in different threads before)

- Ply will reflect sound (not fully, but for the purpose in HT, we can consider it as 100% compared to others)
- Sound Absorbing panels will absorb sound based on its absorbing coefficient


There are 2 major things to consider while building a dedicated media room

- Sound Isolation (To be replaced with Room Treatment for Isolation) : To prevent any sound going outside the room and your house / To prevent any unwanted disturbances or noise from outside which will spoil the HT experience.

- Sound Absorption (To be replaced with Room Treatment for Sound Quality): To make the audio reproduction uniform through out the spectrum w/o any dips or peaks in any particular frequency range.

So based on the above requirements, as separate, the entire room has to be Sound Isolated, but at the same time the Sound Absorption also can be done through out the room or can be restricted to only where ever is required (overdoing the sound absorption will degrade the experience). So in simple terms, overdoing Sound Isolation is good or will not harm, but it will be reverse wrt Sound Absorption.

To make the room sound good not only requires the Sound Absorption, but at the same time Sound Diffusion also to a certain level to retain the liveliness of the sound. But choosing the correct treatments at the correct locations is the challenge in room treatment.

In most of the cases, treating the,
- Side walls and Ceiling with the medium density sound absorption panels (eg Anutone boards) / 2" glass wool at the 1st and 2nd reflection points (depends on the speaker position, eg: for a 3' floor stander, covering can be done from 1 ft above the ground with a height of 3')
- Same with the front wall (can be fully treated)
- Back wall with 4" if it is very near to the sitting position (can be fully treated)
- Diffusers can be used to reflect the sound in a particular direction or pattern to create the surround ambiance. But this will be effective only if the user is sitting atleast 8-10ft from the diffuser. Diffusers can be used at the back portion of the side walls after the 2nd reflection points and at the back walls (almost at the 2nd and 4th points if the back wall is equally divided into 5)

All the above will help in treating LowMid/Mid/High Mid/High frequencies only. You need to do special treatments (Absorption) for the low frequencies. All the wall joints are prone to low frequency accumulation especially the corners. You need to treat them with Bass Traps. Different type of Bass Traps are there with different effectiveness and aesthetics. Better would be Chunk Traps at all the corners and small Chunk traps at the mid point of all the joint surfaces.

To reduce the overall expenditure,

- If Sound Isolation is not a major criteria, use only the Sound Absorption where ever required with the remaining portion as exposed walls.

- If you look for both, do the Isolation only to the portions where Sound Absorption is not done and do the absorption with absorption panels with glass wool packing (helps in Isolation and absorption of some low frequencies also) at the backside. The Sound Isolation for the non absorbing area can be done by 19mm Ply fixed on top of 2x2 frames (to replace the bare walls) with glass wool packing at the backside so that the room will have the necessary absorption and the liveliness and the Isolation. If glass wool backing with a 2"gap from the wall will be more effective in its job.

Hope this will give you a starting point.

 

[pdhanwada]

Sajith,

Thanks for your detailed reply.

I think all are confused of what others are trying to say. I will try to put it clear (even though it was discussed several times in different threads before)

- Ply will reflect sound (not fully, but for the purpose in HT, we can consider it as 100% compared to others)
- Sound Absorbing panels will absorb sound based on its absorbing coefficient


There are 2 major things to consider while building a dedicated media room

- Sound Isolation (To be replaced with Room Treatment for Isolation) : To prevent any sound going outside the room and your house / To prevent any unwanted disturbances or noise from outside which will spoil the HT experience..

My HT room is on the penthouse. I dont need sound isolation.

- Sound Absorption (To be replaced with Room Treatment for Sound Quality): To make the audio reproduction uniform through out the spectrum w/o any dips or peaks in any particular frequency range.

So based on the above requirements, as separate, the entire room has to be Sound Isolated, but at the same time the Sound Absorption also can be done through out the room or can be restricted to only where ever is required (overdoing the sound absorption will degrade the experience). So in simple terms, overdoing Sound Isolation is good or will not harm, but it will be reverse wrt Sound Absorption..

Currently My room is finished with Smooth Wall putty meaning it will reflect sound. By treating with Anutone panels until 4ft height should solve the problem with respect to side walls. My ceiling is finished with smooth pop and wall putty. How essential is to do that. May be can we create a 4 ft band in the center of the ceiling parallel to the line of speakers such that first reflection points are handled.
With respect to Back and front walls should we need to do full walls?.

To make the room sound good not only requires the Sound Absorption, but at the same time Sound Diffusion also to a certain level to retain the liveliness of the sound. But choosing the correct treatments at the correct locations is the challenge in room treatment.



In most of the cases, treating the,
- Side walls and Ceiling with the medium density sound absorption panels (eg Anutone boards) / 2" glass wool at the 1st and 2nd reflection points (depends on the speaker position, eg: for a 3' floor stander, covering can be done from 1 ft above the ground with a height of 3')
- Same with the front wall (can be fully treated)
- Back wall with 4" if it is very near to the sitting position (can be fully treated)
- Diffusers can be used to reflect the sound in a particular direction or pattern to create the surround ambiance. But this will be effective only if the user is sitting atleast 8-10ft from the diffuser. Diffusers can be used at the back portion of the side walls after the 2nd reflection points and at the back walls (almost at the 2nd and 4th points if the back wall is equally divided into 5).

Where do we find sound diffusers or do we make them.

All the above will help in treating LowMid/Mid/High Mid/High frequencies only. You need to do special treatments (Absorption) for the low frequencies. All the wall joints are prone to low frequency accumulation especially the corners. You need to treat them with Bass Traps. Different type of Bass Traps are there with different effectiveness and aesthetics. Better would be Chunk Traps at all the corners and small Chunk traps at the mid point of all the joint surfaces.

I have seen in the web
To reduce the overall expenditure,

- If Sound Isolation is not a major criteria, use only the Sound Absorption where ever required with the remaining portion as exposed walls.

- If you look for both, do the Isolation only to the portions where Sound Absorption is not done and do the absorption with absorption panels with glass wool packing (helps in Isolation and absorption of some low frequencies also) at the backside. The Sound Isolation for the non absorbing area can be done by 19mm Ply fixed on top of 2x2 frames (to replace the bare walls) with glass wool packing at the backside so that the room will have the necessary absorption and the liveliness and the Isolation. If glass wool backing with a 2"gap from the wall will be more effective in its job.

Hope this will give you a starting point.