Need Acoustic Panel placement suggestion for this Room - AVS Forum
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post #1 of 21 Old 01-20-2013, 11:20 AM - Thread Starter
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I currently have a 3.0 Setup in my living room. I have already done everything necessary (placement, toe-in, cabling, room calibration[XT32] etc) as far as equipment is concerned, to make them sound their optimal. I have come to the point where I think it is the room more than anything else that needs to be treated to achieve the improvement in sound. I have already read through the forums regarding acoustic treatment and have visited all the links that are most commonly provided when anybody comes here asking for acoustic treatment suggestion. Unlike when I did my research for equipment, I haven't been able to clearly make an assessment as far as the placement of acoustic treatment is concerned. Since the treatment is more specific to the room, rather than a general rule of thumb, I have decided to reach out to the experienced people in the forum. I will try to provide as much detail as necessary on the room to be helpful in order to get a better understanding of the room.

The room is carpeted with an 8 foot concrete ceiling. The room dimensions are 20' X 9'. The distance between the TV/speakers to the listening position is 8'. The wall(of the closet) on the left side of the TV is layered with a mirror. The opening on the right side of the TV is the door to the balcony.

I am specifically looking for the placement of the acoustic treatment in this room. When I say that, I mean where exactly should, the panels be placed in the room. I would appreciate it, if the suggestions can stay specific to the placement and the kind of panels that are needed. I would like to politely appeal to not provide any links for further reading on the science behind acoustic treatment.
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post #2 of 21 Old 01-20-2013, 12:01 PM
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While lots of folks here have more experience with this than I do, and I'm sure there are at least a few who have enough experience to speak confidently on the subject, I suspect that the best advice you can get is not free, and would require some measurements in the room.

That said, I'd like to suggest that the first move I would make would be to slide the sofa away from the wall if possible, and treat the wall behind the sofa with something that at least resembles broadband absorption. I'd go for a double stack of OC703 or equivalent spaced another 2 or 4 inches off the wall (for total treatment depth of 6 to 8 inches).

The next thing I would consider is ceiling treatment, but I'm not sure that would be necessary or worth the trouble, once the front/rear flutter (I assume it's present) and SBIR issue on the rear wall were handled.

My hunch is that the generic response would be to treat the lateral reflections on the end walls of the room. That, IMO would be both difficult and counter-productive, especially given that you don't use surround channels.

Then I guess I'd re-run Audyssey. And as an aside, I'd be wishing I had a sub to allow XT32 to make then best use of.

Fred
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post #3 of 21 Old 01-21-2013, 09:48 AM - Thread Starter
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Thanks fred for your suggestion. Doesnt anything need to be placed behind the speakers too, on the back wall?
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post #4 of 21 Old 01-21-2013, 02:50 PM
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That's probably equally important.

I'd rather hear someone else's recommendation, though.
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post #5 of 21 Old 01-22-2013, 02:27 PM - Thread Starter
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Wow....I am hearing crickets....
..Guys?...........anyone....
rolleyes.gif
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post #6 of 21 Old 01-22-2013, 05:27 PM
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I'd start by pulling that television out of the stand. wink.gif
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post #7 of 21 Old 01-22-2013, 06:32 PM - Thread Starter
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Haha. Thanks mazeroth for figuring out the root cause. smile.gif
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post #8 of 21 Old 01-23-2013, 09:48 PM
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There are a number of things you can do. First, your the room will be hard to shape acoustically due to the design of the space. Second, there is an enormous amount of hard surfaces that architects love and acousticians hate. Since shaping the room acoustically, I would try to reduce the reverberation time in relation to the listening position. You'll have to calculate this or pay someone to do it. If you are good with math, then you can write a spreadsheet or program to help you calculate the room. I would aim for 400 ms. The calculation will determine how much "stuff" to put on the walls. Once that's figured out, then you figure out where to place "x" amount of stuff so it is appealing and will deliver the greatest impact relative to the listening position. No amount of automajik is going to compensate for the amount of reflective surfaces you have in that room. That's the scientific approach and the proper method to achieve results. If you are looking for quick and dirty results that may be hit or miss, treat the floor, behind the speakers, and behind the listener. If you get the right products, you can achieve better results using a thinner amount of material rather than 6 to 8 inches which is obtrusive. And...pull that couch away from the back wall.

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post #9 of 21 Old 01-24-2013, 05:54 AM - Thread Starter
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For a start I already have four 2'x4' acoustic panels that have 2'' OC703. I would like to place them at the right spots to begin with, and add more (panels, traps, diffusers) as needed.
Should I start with 2 panels behind the speakers, and 2 behind the sofa (or 3 behind speakers and 1 behind sofa) ? At what height should I be hanging the ones behind the speakers and the ones behind the sofa?
As for pulling the couch away from the back wall, its going to reduce the viewing distance from the TV. How much away from the wall should it be moved, keeping that in consideration?
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post #10 of 21 Old 01-24-2013, 06:12 AM
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Great advice as you would expect from Shawn above.

I would likely start with panels at the reflection points (including the ceiling) and behind the LP as you've suggested., but it also depends on the problems you're actually having in the room. Do you hear an overemphasized low end? Is dialogue unclear? Are sounds too bright?

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post #11 of 21 Old 01-24-2013, 06:16 AM
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One of the easiest ways I've heard for acoustical treatments is to use a mirror with two people. Someone on here posted a video of how it was done. One person sit where they will view the tv, then the other person holds up a mirror on the wall in the location where the person sitting can see the reflection of the speaker. Then mark each spot with tape or something to note where you will hang your acoustic treatment.
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post #12 of 21 Old 01-24-2013, 06:24 AM - Thread Starter
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Quote:
Originally Posted by GIK Acoustics View Post

Great advice as you would expect from Shawn above.

I would likely start with panels at the reflection points (including the ceiling) and behind the LP as you've suggested., but it also depends on the problems you're actually having in the room. Do you hear an overemphasized low end? Is dialogue unclear? Are sounds too bright?

My goal is to obtain a more enveloping sound and improve dialogue clarity, fix the slightly recessed highs and have a tighter low end.
At what height should the panels be placed?
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post #13 of 21 Old 01-24-2013, 06:34 AM
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In most cases, for reflection point panels you'll want them centered around ear height.

The ones behind LP will obviously be a bit higher. Panels behind the mains, if you do those, would be best placed directly behind the speakers. If you're looking to tighten up the low end, I'd suggest getting some corner trapping, whether its typical panels straddling corners or even better, superchunks/tritraps in the corners.

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post #14 of 21 Old 01-24-2013, 06:46 AM - Thread Starter
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Thanks GIK for the tip on the panel height.
Do you think the mirror wall to the left of the TV is a major concern? Anything I need to do on that will hurt the aesthetics of the room.
Where in my room, do you think the corner traps can go, primarily?
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post #15 of 21 Old 01-24-2013, 08:25 AM
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Alexander is correct in that adding corner traps in this case will likely yield results. Since your side walls are uneven, not much use in trying to shape the lateral reflections unless the left side is causing uneven reflections compared to the right. In that case, I'd just add absorption on the left wall to kill it.

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post #16 of 21 Old 01-24-2013, 08:56 AM - Thread Starter
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OK. So far here is what I am planning on doing

1) Add two panels directly behind the fronts, centered to ear height.
2) Move the sofa to be 6 inches away from the back wall.
3) Add two panels on the back wall.
4) Add a bass trap on the upper 3d corner of the back wall and the mirror wall.
5) Add a panel at the first reflection point on the mirror wall. (Aesthetics permitting)

Is there any other place I need to add more panels?
Where exactly do I place the panels in point number 3 above? Do I place the panels directly facing the main speakers at a height (what height?). Or do they go facing in between the front speakers?


Edit : fixed wall confusion
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post #17 of 21 Old 01-24-2013, 11:07 AM
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Quote:
Originally Posted by enthusiast8 View Post

OK. So far here is what I am planning on doing

1) Add two panels directly behind the fronts, centered to ear height.
2) Move the sofa to be 6 inches away from the front wall.
3) Add two panels on the front wall.
4) Add a bass trap on the upper 3d corner of the front wall and the mirror wall.
5) Add a panel at the first reflection point on the mirror wall. (Aesthetics permitting)

Is there any other place I need to add more panels?
Where exactly do I place the panels in point number 3 above? Do I place the panels directly facing the main speakers at a height (what height?). Or do they go facing in between the front speakers?

I would add a bit more bass trapping if you have concerns with dialogue intelligibility. Wall/ceiling corners can be a good place to trap if you don't have much floor space available. Any wall/wall corner possible should be used (around your area of the room)
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Originally Posted by enthusiast8 View Post

Where exactly do I place the panels in point number 3 above? Do I place the panels directly facing the main speakers at a height (what height?). Or do they go facing in between the front speakers?

You're misunderstanding (Actually, I should say we're miscommunicating)

Front wall = wall you're facing (the one with the TV on it)
Back wall = wall behind your head that you can not see whilst sitting on the couch.

My prior suggestions are using these definitions and can be repeated again to answer your questions
Quote:
Originally Posted by GIK Acoustics View Post

In most cases, for reflection point panels you'll want them centered around ear height.

The ones behind LP will obviously be a bit higher. Panels behind the mains, if you do those, would be best placed directly behind the speakers. If you're looking to tighten up the low end, I'd suggest getting some corner trapping, whether its typical panels straddling corners or even better, superchunks/tritraps in the corners.

When I say "behind the speakers" I mean in between the speakers and the front wall, at speaker height. This will address SBIR (you can read about SBIR here: http://gikacoustics.com/speaker-boundary-interference-response-sbir/ )

If your concern was reflections instead of SBIR (this will depend on how wide your speakers disperse) then you would have them at your reflection points on the front wall instead (or both if you were concerned with both SBIR and reflections)

Hopefully that makes a bit more sense now.

Alexander Reynolds
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post #18 of 21 Old 01-24-2013, 02:18 PM - Thread Starter
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Thanks Alexander for the clarification.
Maybe I missed this from your suggestions, but where should I be placing the panels on the back wall? Meaning, at what height? Should they be directly opposite to the panels on the front wall? Or should they be facing the space between the panels on the front wall?
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post #19 of 21 Old 01-25-2013, 02:09 PM
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Quote:
Originally Posted by enthusiast8 View Post

Thanks Alexander for the clarification.
Maybe I missed this from your suggestions, but where should I be placing the panels on the back wall? Meaning, at what height? Should they be directly opposite to the panels on the front wall? Or should they be facing the space between the panels on the front wall?

You would want them close to ear height, likely right at the height of the couch/sofa. I would say along the entire couch for a length/position, since you want to absorb those close reflections for any seating position.

Alexander Reynolds
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post #20 of 21 Old 02-03-2013, 12:03 AM
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Quote:
Originally Posted by enthusiast8 View Post

Thanks Alexander for the clarification.
Maybe I missed this from your suggestions, but where should I be placing the panels on the back wall? Meaning, at what height? Should they be directly opposite to the panels on the front wall? Or should they be facing the space between the panels on the front wall?

If you could provide pictures and or a sketch of your space this would help tremendously in regards to placement assistance.
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post #21 of 21 Old 02-03-2013, 05:03 AM
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Originally Posted by SierraMikeBravo View Post

There are a number of things you can do. First, your the room will be hard to shape acoustically due to the design of the space. Second, there is an enormous amount of hard surfaces that architects love and acousticians hate. Since shaping the room acoustically, I would try to reduce the reverberation time in relation to the listening position. You'll have to calculate this or pay someone to do it. If you are good with math, then you can write a spreadsheet or program to help you calculate the room. I would aim for 400 ms. The calculation will determine how much "stuff" to put on the walls. Once that's figured out, then you figure out where to place "x" amount of stuff so it is appealing and will deliver the greatest impact relative to the listening position.


in typical residential sized rooms, we do not apply absorption "statistically" and RTxx isn't valid as the pre-requisites for the calculations to be valid are not satisfied. eg, we do not focus on a % of how much absorption to add to the room to bring down the reverberation time.

small rooms (acoustically) deal with local areas of variable pressure with respect to the ambient noise floor. modal distribution and focused indirect specular reflections. the latter of which can be discretely identified via their incident boundary and absorption (or othre treatment of choice) and be placed to address that particular destructive indirect signal.
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