# Living Room HT set up...need acoustics advice



## A/V (Feb 5, 2014)

Hey guys,
I posted a while back looking for help on my room layout. I have now progressed to a 90% finished product.

Gear:
- Sony STR-DN1040 A/V Receiver
- Q Acoustics 2050i fronts, 2000Ci center (upright behind screen), 2010i rears (wall-mounted)
- SVS-PB2000 subwoofer (this thing is huge!). Plan is to get a second one asap.
- Sony BDPS4100 3D Blu ray player,
- Ben Q W1070 projector. (Gotta do something with that cord! But alas, we rent),
- 110" 16:9 DIY Spandex Acoustically Transparent Screen. 

Pics:

















































I need some advice with regards to some acoustic treatment. The WAF factor comes into play majorly with this one as it is the living room.

I plan on a mix of absorption and diffusion. Not sure where to incorporate diffusion, or whether it even needs it.

(Sitting in the main lounge) I currently plan a horizontal absorption panel behind our heads on the main lounge, an absorption panel on the right side near the dining room corner, and absorption panels behind the main speakers on the wall. Bass traps are not really an option unfortunately (unless you can make them pretty. :gulp. BTW, I usually throw a heavy blanket over the recliner on the left side closest to the speaker to help with some reflection/cancellation imbalance issues etc.

Thanks guys, I appreciate your help in advance.


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## bpape (Sep 14, 2006)

I would do a couple thicker as you can behind the seating since it's so close. Add 1 behind each front speaker to address boundary related phase interactions. After that, not sure if there's really any other place that you can without blocking the curtains that makes sense and is doable.


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## ajinfla (May 10, 2009)

I would do three things:
Elevate the mains off floor about 200-300mm +/- with small stands.
Make the rear wall (behind your seat/head) as diffusive as possible.
Ask Sony to rewrite their software not to boost the low end as much with their auto "room correction".

...and of course, tell us what it sounds like now.

cheers


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## phazewolf (Feb 5, 2012)

Correct me if I am wrong on this one but I would think with the seating that close to the rear wall that a defusing on the rear wall would be a bad idea. I thought you needed a few feet between you and the defusing otherwise you would have all kinds of phase issues.


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## bpape (Sep 14, 2006)

That's true depending on the lowest frequency the diffusion will function. For very very thin, high frequency only diffusion you can sit closer. Neither though is going to help with the bass buildup by the boundary.


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## ajinfla (May 10, 2009)

phazewolf said:


> Correct me if I am wrong on this one but I would think with the seating that close to the rear wall that a defusing on the rear wall would be a bad idea. I thought you needed a few feet between you and the defusing otherwise you would have all kinds of phase issues.


The diffusion will simply further randomize the incident reflections from behind the listener/ears. 
What "phase issues"?

cheers


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## ajinfla (May 10, 2009)

bpape said:


> That's true depending on the lowest frequency the diffusion will function.


Sorry Bryan, don't understand you here, what is true?



bpape said:


> For very very thin, high frequency only diffusion you can sit closer.


He's in a pretty tight space, not room for much of anything but "thin" .



bpape said:


> Neither though is going to help with the bass buildup by the boundary.


Indeed and that's why the Sony suggestion. EQ can certainly solve that for his rear seats, which appear to be the only relevant ones. But it seems like Sony doesn't help there.

cheers


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## bpape (Sep 14, 2006)

That's kind of the point. Tight space, thin diffusion, only deals probably in the kHz range so no help down low with any bass/mid buildup by the boundary. 

Have you ever sat within say a foot of a QRD diffuser that will work down to say 300hz? It's the oddest phasey kind of sound you'll hear and definitely not something I want to sit that close to. There is simply not enough space to allow the waves to spread. Think about putting a bucket an inch under a fire sprinkler head....

Turning down bass level does not help with boundary buildup or nasty quick broadband reflections.


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## phazewolf (Feb 5, 2012)

This puts it in better words then I ever could.

http://arqen.com/sound-diffusers/faq/#listening-distance


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## A/V (Feb 5, 2014)

Thanks for the great suggestions and discussion on this guys.

I also plan on doing REW on this room within the near future and will be able to provide more 'graphic' details.  Just need a decent sound card and microphone. This will help me see exactly what is going on in my room with the Sony bass boost hopefully.

As for diffusion and absorption behind our lounge, one thing I was concerned about if I used absorption only was a limited surround field. (Which I already have being so close the rear wall). I am not sure if I am correct, but too much absorption could reduce the 'atmosphere' that the surrounds are supposed to create?


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## ajinfla (May 10, 2009)

bpape said:


> Tight space, thin diffusion, only deals probably in the kHz range so no help down low with any bass/mid buildup by the boundary.


Diffusion for a (LF) pressure maxima??? Never heard of such a thing, much less suggested it.
The diffusion behind the listener, is simply to diffuse. Go figure.



bpape said:


> Have you ever sat within say a foot of a QRD diffuser that will work down to say 300hz?


I have not.



bpape said:


> It's the oddest phasey kind of sound you'll hear and definitely not something I want to sit that close to. There is simply not enough space to allow the waves to spread. Think about putting a bucket an inch under a fire sprinkler head....


And this is positioned behind the ears, with MCH (as suggest for OP)? What is the physiological explanation?



bpape said:


> Turning down bass level does not help with boundary buildup


EQing (down) the amplitude peaks, at that boundary, when sitting at that boundary, absolutely will.



bpape said:


> ....or nasty quick broadband reflections.


That sounds scary...but we hear (sound) in front a lot better than behind. Obviously, some space is always nice, but I'm still not seeing A/Vs complaints about the sound

cheers


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## ajinfla (May 10, 2009)

phazewolf said:


> This puts it in better words then I ever could.
> 
> http://arqen.com/sound-diffusers/faq/#listening-distance


That's an ad. Absent psycho-acoustics. Any papers or links regarding this?
TIA

cheers


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## phazewolf (Feb 5, 2012)

Try this then it is from a book and you can read it all if you like says a lot of the same stuff the ad did. http://books.google.com/books?id=jY...+sit+too+close+to+a+diffuser&output=html_text


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## ajinfla (May 10, 2009)

phazewolf said:


> Try this then it is from a book and you can read it all if you like says a lot of the same stuff the ad did. http://books.google.com/books?id=jY...+sit+too+close+to+a+diffuser&output=html_text


Indeed. More words, no explanations or psycho-acoustic studies, nada. Probably some studio/LEDE types.
Maybe I should start running ads like that.
Well, we'll see what A/V wants to do I suppose.

cheers


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## phazewolf (Feb 5, 2012)

There are paper's out there that I have read but I am at work and the links are on a computer at home. It will take me time to find it as I have like 12000 pages book marked on all kinds of things and my memory is bad from a car accident and only gets worse.

If someone post a paper are you just going to rip that down as well? Have you done research on this post your research saying that you can be on top of a diffuser without issues as I would like to read it.


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## ajinfla (May 10, 2009)

phazewolf said:


> There are paper's out there that I have read but I am at work and the links are on a computer at home.


Shame on you posting at work!
I would greatly appreciate a link specific to perception of diffusion, especially from behind.



phazewolf said:


> It will take me time to find it as I have like 12000 pages book marked on all kinds of things and my memory is bad from a car accident and only gets worse.


Wow, that's a lot and sorry to hear that about the accident.



phazewolf said:


> If someone post a paper are you just going to rip that down as well?


No, I'm going to hopefully learn about something I'm fascinated with, which is the physiology and psychology of hearing.



phazewolf said:


> Have you done research on this post your research saying that you can be on top of a diffuser without issues as I would like to read it.


I am not aware of any research saying either, but you both are saying it's bad....and I'd like to know _why_. Unfortunately, an ad or book stating "because I said so" was less that satisfying for me.

cheers


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## phazewolf (Feb 5, 2012)

I will look more when I get home it is mostly if I recall shown the sound comes off a wall vs a difuser a wall has in a way a predicted response depending on the frequency to where a difuser with it's peaks and dips does all kinds of stuff to the phase of the sound waves that hit it and wile several feet away from it the effect can't be detected when your close to it it wreaks havoc.


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## A/V (Feb 5, 2014)

Any advice with regards to my post in post #10?

_As for diffusion and absorption behind our lounge, one thing I was concerned about if I used absorption only was a limited surround field. (Which I already have being so close the rear wall). I am not sure if I am correct, but too much absorption could reduce the 'atmosphere' that the surrounds are supposed to create?_


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## phazewolf (Feb 5, 2012)

I don't feel that it will hurt the sound field with placing a bass trap behind where you sit sense the speakers are mounted in the corners of the walls and don't need to use the wall like a dipole speaker.


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## phazewolf (Feb 5, 2012)

Just a quick thought but being that close to that wall is a issue that is hard to deal with but have you thought about moving the seat a foot away from the wall when you watch a movie and then push it back when your done? It costs nothing and easy to try. That wall will really make what your hearing very bass heavy and the best thing is getting away from it and you can't keep the seat away from a wall just pull it away when it's movie time and simply replace its location when your done.


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## A/V (Feb 5, 2014)

Thanks. I will give that a go. As it is, our ears are approximately about 550mm (21inches) off the rear wall. Is this enough to help with the bass pooling issue?


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## phazewolf (Feb 5, 2012)

Yes that helps the more the better but any helps. Try this move the couch out of the way and play something with lots of bass. Stand next to thus wall and then slowly move forward and listen to how the bass changes. When the bass sounds good place the seat there and see what you think.

Wile the spot may not be practical location wise it will help you understand what the room is doing and may give you ideas on things you can try. Sometimes just moving the speakers a bit can help out.


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## A/V (Feb 5, 2014)

Thanks phazewolf. I will try that.

@ ajinfla: Regarding elevating the front main speakers, what would raising them help with?


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## phazewolf (Feb 5, 2012)

You want the tweeters at the same height as your ears. So if the tweeters are at say 28" and your head sits at 38" you would want to move the height of the mains up 10" 

As for the mains and bass the more you move them off the front wall the less the bass will be reinforced.


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## A/V (Feb 5, 2014)

This is currently my heights setup. The tweeters are currently 75mm below my ear height. So yes they could definitely come up a bit I think.


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## phazewolf (Feb 5, 2012)

Yes they could use some extra height for sure. Try using something to lift them up and see if you like how they sound. Can't hurt to try.


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## A/V (Feb 5, 2014)

This is my current floor layout. The speaker placement is not ideal but I wanted the mains behind the A/T screen. Although I think the bass definition has disappeared since being relocated to the corner of the room. I think I will have to revert back the way it was with the L/R outside the screen, and the sub moved inside the L speaker.


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## phazewolf (Feb 5, 2012)

Try leaving the speakers where they are at place the sub where you sit and crawl around the room until you find the bass your looking for.


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## A/V (Feb 5, 2014)

Unfortunately I am very limited in where I can put the sub because it is so huge! They are really my only two options I think.


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## phazewolf (Feb 5, 2012)

Then try both places and see which one sounds best. Have you checked to see if the avr set the gain correctly on the sub? Some set up very hot I have seen a few Sony do that.


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## A/V (Feb 5, 2014)

Hey guys. I finally did a REW on my room. I can email you the file if you'd like but here it is:

15-500Hz:









15-500 Waterfall









This has given me a lot of information. Hopefully you can help me interpret it a little more.


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## ajinfla (May 10, 2009)

Wow, you gentlemen were busy last night.
Hi A/V, how does it currently sound to you, in terms of bass, dialog clarity, "immersion" with the surrounds, etc when watching movies? Do you listen in stereo as well? Sound?
Is the graph above at the LP, 21" off the wall?
Doesn't look too bad, although the peaking between 30-50hz could be reduced a bit. Your Sony doesn't allow "manual" EQ correct?

cheers


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## A/V (Feb 5, 2014)

At low volumes it doesn't sound too bad. But as soon as you start pushing near reference, it starts to get very peaky and confusing in terms of ease of listening. I usually turn it down and everything starts to sound more balanced then. Dialogue clarity is great, immersion with the surrounds is very good too. Yes the measure ments are taken at the listening position. The Sony doesn't have much of a manual eq. Just bass/treble.

As far as music goes, I listen to Spotify mainly due to their massive library and convenience. I listen at 320kb/s and it sounds good but not amazing. Some songs sound worse than others and this could be just down to a lower bitrate or the actual recording so it is hard to tell when using streaming services. Live music usually sounds the best.

I am using the cal mic that came with my AV receiver for the test, and it was taken in my listening position pointed towards the screen. I was running the test through both front L and R speakers and the subwoofer. My test was for room acoustics to see what frequencies are interfering with a tight clean sound.

The room mode at 55 Hz is a bad one and decays hardly at all over even 1500ms! The full range it goes pretty comb filtery (when no smoothing is applied). I am thinking that some basic rules of room treatment like first reflections and bass traps may be a good place to start.

I have attached the mdat file for you to have a better look at the full analysis.


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## bpape (Sep 14, 2006)

You can use a damped membrane on the absorption to limit the mid/high absorption while still grabbing the energy down lower. The more mass the membrane has, the lower in frequency it will cut off.


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## phazewolf (Feb 5, 2012)

Been wanting to ask this for sometime how close can you sit to a membrane style trap? No odd effects from being close to it?


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## bpape (Sep 14, 2006)

Should be no problem. Not much different in the mids and highs as sitting close to a wall. I'm talking about limp damped membranes here - not sealed tuned membranes.


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## phazewolf (Feb 5, 2012)

Thanks just trying to learn more.


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## A/V (Feb 5, 2014)

Sorry guys...damped membranes?


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## ajinfla (May 10, 2009)

A/V said:


> At low volumes it doesn't sound too bad. But as soon as you start pushing near reference, it starts to get very peaky and confusing in terms of ease of listening.


Have you heard those speakers stay clean at similar levels in other systems/rooms?



A/V said:


> Dialogue clarity is great, immersion with the surrounds is very good too.


Great. So maybe just the bass droning a bit (and the high level issues)?



A/V said:


> Yes the measure ments are taken at the listening position. The Sony doesn't have much of a manual eq. Just bass/treble.


That's unfortunate. Can you do a measurement with the sub off? What about the possibility of raising the mains a few inches?



A/V said:


> I am thinking that some basic rules of room treatment like first reflections and bass traps may be a good place to start.


Let's just say there is not unanimity on those "rules".

cheers


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