Effects of a large screen (85" inch)

[FrantzM]

Hi

About to receive (a month or so) a large screen, that will reside permanently on my front wall.
My system is for music and movies. I listen to music in 2-channel and am fussy about sound quality. on movies I have basic requirements and the movies itself fills the gap.

What should I expect from that large piece of very reflective material behind and between the LCR speakers. Currently I have 2 inch absorbers in 2/3 of the 12 feet wide from wall...
How to remediate?

Peace

 

[Frgirard]

The speakers are not omnidirectional over the bass.
A wall is a reflexive surface.
A screen between two speakers in certain condition can reduce the diffraction due to the speaker boxe.
2 inches is good for the decoration and unbalance the reproduction, 8 inches is the minimal value to treat the bass frequencies.

 

[FrantzM]

It is not the bass I am worried about.
Most speakers are actually omnidirectional in the bass.. It takes special drivers arrangement (dipolar among these) to change the directivity behavior n the bass, below 100 Hz ... Look at any directivity graph and you would see...
I am not worried about bass reproduction. The acoustic tiles are there for the upper register especially in movies when the surround and Atmos ceiling channels have part of their radiation toward the front walls.

 

[abdo123]

As long as the wall that the TV is on still has 20-30% surface area absorption and 20% diffusion it shouldn't be an issue.

 

[Frgirard]

Percentages without what: the air flow resistivity 8000 rayles , the thick 8" doesn't mean nothing.
The thick and the afr or gfr are link and co evolve together.
Acousticmodelling to make simulation.
http://www.acousticmodelling.com/porous.php


Effective diffusion starting at 700 hz needs a distance between wall and seat of 3 meters/ 9'.

 

[Chromatischism]

A picture would help. If your speakers are wide enough, and pulled forward, that helps. Absorption can then be used to the sides and top.

 

[FrantzM]

Percentages without what: the air flow resistivity 8000 rayles , the thick 8" doesn't mean nothing.
The thick and the afr or gfr are link and co evolve together.
Acousticmodelling to make simulation.
http://www.acousticmodelling.com/porous.php


Effective diffusion starting at 700 hz needs a distance between wall and seat of 3 meters/ 9'.

A picture would help. If your speakers are wide enough, and pulled forward, that helps. Absorption can then be used to the sides and top.

I am afraid you would ask ..

System being tidied-up .. The center speaker should be on the mount it is presently placed on the subwoofer while I am taking care of cables , etc ...

Screen is down for the picture but moves up.. More absorption behind the screen.. Nothing fancy. Same as what you see below. Room is 3.2 x 5.1 meters.
The projection screen goes up when I play music. Not in the way. However when the 85" inches will , it will be permanently mounted between the speakers. With the top of the speakers at the same height as the TV screen bottom. No more absorbption on top of the wall where you see the screen.
My worries are about music. I have found myself much les critical about those small sound details. If the FR is good, the SPL adequate, dialog comprehensible with no obvious distortions obvious defect or timing errors, sound effects present, sense of envelopment real, I am good... Happy on that side. I become then very critical about video... I did post about that. The PJ and screen are good but the LG CX OLED in my bedroom floors me in term of fidelity color accuracy and yes people HDR is a real thing, PJ can have serious ipact but I seat closer than I though, 2.7 meters from the screen, 85 inches is good enough (Thanks @DonH56 )
On Music different stories, I hear small flaws, care about them , etc.. Your audiophile story too, I guess

So my question : Should I worry?

And my setup's not worthy of being photographed.. You asked for pix however

 

[DonH56]

Gee, I got tagged, this is not a thread I would normally read... Ranks'a'rot, @FrantzM !

Disclaimer: I am not a speaker designer, nor claim to be an acoustics expert. Take comments FWIWFM.

The higher frequencies from conventional speakers are directional and those horns are not going to radiate significantly to the rear. The treatment on the front wall behind the speakers thus probably does the most for bass'ish and reflections from the back and side walls that makes its way to the front. How much sticking a big reflector in front of them affects the sound I could not say, but I have a similar situation and it does not seem to be a big deal. One thing I am doing is placing my TV (a tiny 65" OLED) on a shelf above my center speaker so it is about 18" ~ 24" from the front wall, which is heavily treated with absorbers (even more so than yours). That way I still get some benefit in the bass though the TV does have some impact. I also have deep (12") corner traps in the left and right front corners to help control room modes, and an angled absorber over my TV. Pix below. Bottom line: put the TV in and enjoy, chances are it won't do enough damage if any to worry about.

 

[amirm]

Hi Frantz. I could not tell what you meant by "screen." Do you mean a flat panel? If so, I would not worry about it too much. Front and back wall reflections fall in the category of "useless" reflections in that they don't help with spatial qualities as side walls can. As a result, they can be absorbed if your room is too live. If it is not, then it is not of huge importance.

In my speaker reviews I show the radiation to the typical back wall direction:

The terminology that is used is backward though. It is from the point of view of the speaker. So "rear wall" is the surface you are talking about. As you can barely see, it is that faint pink line that is lowest than all in this setup. Whether you take it away or not, it is not going to make hardly any difference to overall indirect sound power (other than bass).

 

[Chromatischism]

The terminology that is used is backward though. It is from the point of view of the speaker. So "rear wall" is the surface you are talking about. As you can barely see, it is that faint pink line that is lowest than all in this setup. Whether you take it away or not, it is not going to make hardly any difference to overall indirect sound power (other than bass).

Wow, I wish I had known this. I thought it was relative to the listener, so "front wall" was behind the speaker therefore stronger, and the "rear wall" was so much lower because it had so much travel and return distance!

 

[FrantzM]

Thanks People!