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Absorption or diffusion for rear wall 2.5ft from listening position

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Posted on October 3, 2011 at 03:49:00
hertzx
Audiophile

Posts: 32
Joined: April 12, 2011
Okay. I have this slightly problematic room. It is 15ft long and 12ft wide. I am forced to keep my speakers along the long wall due to some constraints. Hence my listening position (ear) is 2.5 ft away from the rear wall.

What kind of treatment is appropriate on the rear wall which so close to my ears ? If I do some treatment, what kind of improvements can I expect to the sound.

Diffussion panels?

Absorbtion panels?

Mixture of diffusion / absorbtion/bass panel ?

What size of a panel is required ?

Should they be on a stand (with some space between the panel and wall) for maximum benefit ?

Thanks
Hertz.

 

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RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 3, 2011 at 13:27:07
David Aiken
Audiophile

Posts: 5858
Location: Brisbane
Joined: September 25, 1999
Diffusion takes space in which to develop—sit too close and not only will you not get the full benefit of the diffusor but you may also get some unevenness of sound. How far you need to sit from a diffusor depends on the diffusor design but RPG mention a 10' distance in some documents on their website though they also seem to sell some diffusion products which allow closer distances. I'd say 2.5' is going to be too close for pretty much any diffusor so that means that absorption is your best choice.

With absorption, having some space—say a minimum of 4"—between the absorption material and the wall improves the efficiency of the absorber extending its absorption a little lower in frequency and increasing the amount of absorption.

I'd suggest as a minimum covering an area at least 2' high (4' would probably be better) and extending to either side of your head to about a foot or two past the rear wall first reflection points. Place the absorption at a height that places your ears around the middle of the absorption in the vertical plane.

What kind of improvements can you expect? Depends a lot on your gear, the rest of your room, and what kind of absorption you use on the rear wall and how much of it you use. There's too many variables for me to make a prediction. You don't say whether you have any other treatment in the room but unless there's something specifically related to your rear wall causing problems, treating that area isn't where I would start with room treatment. I'd start with bass trapping in the corners.


David Aiken

 

RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 3, 2011 at 19:47:14
hertzx
Audiophile

Posts: 32
Joined: April 12, 2011



Thanks David for the tips.

My speakers are the Blumenhofer fun17. Electronics is Plinius integrated amp and Arcam cd player.

http://www.blumenhofer-acoustics.com/Loudspeakers/SerieFun/Fun17/Fun17.html

I have a heavy two seater love sofa,two light chairs,three curtains, a carpet, two small bookshelfs. couple of flower pots etc..in the room.

What kind of bass trapping would you suggest ? This is a living room so want to keep it visually appealing too :-)

I was thinking of two bass traps (one each in the corners beside the speakers), and an absprbtion panel behind my head.

If you can suggest the exact models, it would be awesome!

 

RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 4, 2011 at 19:24:36
David Aiken
Audiophile

Posts: 5858
Location: Brisbane
Joined: September 25, 1999
I'm not familiar with your speakers and I have no idea of what products are available in India. I'm in Australia and the acoustic treatments I use are RealTraps Mondo Traps. both in corners for bass trapping and at first reflection points on the wall. The range here in Australia is much more limited than that in the US and I bought my RealTraps from the Australian distributor. Previously I was using DIY treatments so I'm not the best person person to make product recommendations. I can say the RealTraps Mondo Traps work extremely well in my room. I have no idea how they would work immediately behind my listening position because there's nothing directly behind my chair, I've got 3 metres to the rear wall, and the room is L shaped with the bend in the L behind and to my right so anything I did on the wall in the vicinity of the bend wouldn't give you any useful info about what to expect in your room.

Living rooms are awkward to treat if you're concerned about appearance. Acoustic treatments tend to look like acoustic treatments and most people don't want them in their living room. You could try hanging a quilt or a decorative rug on the wall as a feature rather than using proper acoustic treatments. It won't be as acoustically effective but it will do something and it won't look out of place in a living room. Another thing which can provide useful absorption is books and a bookcase full of books on the wall behind you could also work. I don't know how big the bookshelves you already have in the room are, or whether they actually have books in them, but if they do hold books, relocating them to the wall behind you may be beneficial.




If you match the colour of any treatments you use to the colour of your walls, they will be less visually intrusive and that may help a lot in a living room.


David Aiken

 

RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 6, 2011 at 10:47:29
mmlrot1
Audiophile

Posts: 89
Joined: June 10, 2011



I use ASC bass, midrange traps, GIK Monster bass traps and DIY bass trap underneath
sofa. All corners and mid positions have bass traps. The bass traps overhead work
extremely well. Mid range traps are spread 3' apart around the entire perimeter of the
room.

 

RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 18, 2011 at 05:25:55
hertzx
Audiophile

Posts: 32
Joined: April 12, 2011
Hey,

Regarding bass traps, I was thinking of stacking two megatraps from realtraps in one of the corners behind the speakers. Will this work ? Or do I need to place one each behind each speaker for these to be effective ?

 

RE: Absorption or diffusion for rear wall 2.5ft from listening position, posted on October 18, 2011 at 13:11:37
David Aiken
Audiophile

Posts: 5858
Location: Brisbane
Joined: September 25, 1999
With bass trapping the general rules are the more corners the better, so definitely 2 corners rather than 1 and preferably 4 corners rather than 2, and I'd say at least half the room height in each corner and floor to ceiling if possible. I use a MondoTrap in each corner in my room and that works fine for me with my speakers which are stand mount monitors, though I keep contemplating adding a bit more.


David Aiken

 

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