Pls help: Wall treatment- Continous anutone or alternate with ply ?

[manishk13]

Hi

I discussed this with Santosh the other day wherein for my HT room, I am currently planing to ALTERNATE between Anutone wall boards (for absorption) AND ply (for reflectrion). Height is 7 ft. So the idea is to have one anutone panel of 7 ft by 4 ft , then the next one of same dimension of ply (both covered by same fabric and backed by glasswool/synth). This way I get a combination of reflection and absorption. Please comment if this is better that having anutone throughout or not.

Some other points :

1. I am putting anutone celing tiles (backed by glasswool/synth) above it.
2. Back of the screen will be full anutone (no reflective ply). Is this ok?
3. Back wall (back of the seating) will also be full anutone (no reflective ply). Is this ok?
4. I have loft on left and right at 7 feet which I am covering with ply. Do I need anutone treatment on the closed wall behind the ply too or can i just leave it with ply ? Remember I am putting a combo of anutone and ply till 7 feet from the floor till loft. It is not possible to take down loft

Thanks
Manish

 

[cmsajith]

I am also doing my HT build and i will try to help you based on the information which i have gathered. Correct me if i am wrong.

As you said, its not required to treat the non reflecting surfaces. Having said that, you have to find out the surfaces which are reflecting (atleast 1st reflection points, provided enough absorption is there to reduce the secondary reflections).

As a general rule, the side walls treated for mid/high freqs at the reflection points and all the corners treated for low freq is required and it can be taken as a starting point or a reference point as most of the issues will be captured with this. Then based on the frequency bump or nulls, specific treatments are recommended.

Diffusion is not effective unless it has atleast 8-10ft distance to diffuse properly (even on using proper diffusers). So better you absorb all the first reflections. Also having absorbtion at the top portion which is not a reflection point (not sure about your speaker location) will not do anything.

The front wall should also be treated for mid/high freqs. As recommended by some acoustic panel designers, the back wall should be treated well for mid/high/low freqs as it is near to the listener. For HT, we can try using some diffusers at the backside of the side walls and the ends of the backwalls after the bass traps at the speaker level to get some scattered sound.

All the corners are to be treated for the low frequencies. Usually all the 8 corners of a room will have low freq boost. Use triangle shaped chunk bass traps or flat traps placed at the corners with space behind (2"- 4") or 2 flat traps placed one behind the other with space b/n them, from floor to ceiling. Usually the space behind the trap should be 1/4th of the length of the freq. This will allow the wave to pass the trap at its peak energy and absorb (when it goes in and goes out, because of the reflection from the wall). Chunk traps will be more effective as it has more material to absorb at various freqs. I have attached one pic which shows the bass accumulation inside a normal room (with Red areas with max energy).
Imageshack - bassq.png (sorry for the confusing pic)

Since you have a dedicated room, you can do the sound isolation also.

Hope you got some general idea about how to proceed.