# Room treatment advice



## bkeeler10 (Mar 26, 2008)

Hi all,

I'm looking for advice on how to treat my room. A couple of years ago I thought I would be in a position to do this, but it didn't pan out. Now I think I will shortly be in a position to do it again. This room will be used for 2-channel music as well as home theater.

Last time I sought the advice of GIK Acoustics and Bryan Pape responded by suggesting some products they sell. This time around I am looking to DIY absorbers so that I can get the best result for the money I have allocated to spend on this portion of my room and system. Any diffusion products I will likely buy from GIK.

I've included an overhead drawing of the room (to scale) which incorporates much of what Bryan Pape suggested (with GIK product names) and adds a few extra ideas I have had. Also included are a few renderings of the room so you can get an idea of what I'm dealing with.

Is there any reason to believe that DIY absorbers and bass traps would be less effective than something purchased from a company like GIK? I see that Rockwool, for example, has acoustical properties similar to those of OC 703 and 705. What material does GIK use in their traps? I was reading in another forum about how a guy that had previously used a bunch of Roxul didn't experience the same benefit as a pair of what he called GIK Monotraps (?) produced in his studio. This did not make sense to me.

If I were to build bass traps using rock wool, what is the best material to face some of them with to avoid killing the high end too much? I figured I could add traps without facing and continue to measure RT60 in the room (I think REW does this?) until I got to where I wanted it to be, then face the remaining traps. What is the general recommendation for reverb time in a home theater/stereo listening room?

Anyway, any thoughts that you all might have in this regard (including Bryan if he is still lurking about!) would be much appreciated. Thanks.


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## robbo266317 (Sep 22, 2008)

You should be able to construct something comparable to a commercial product. As you are aware the covering needs to be the right material to allow it to work effectively. 
I am not sure what materials are available in your area, someone should be able to chime in and recommend something suitable.


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## bkeeler10 (Mar 26, 2008)

Right, they would need to be wrapped in an acoustically transparent material. I've read about people using fabrics from JoAnnes, which we do have around here. I'm sure I will be able to find something suitable.


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## hjones4841 (Jan 21, 2009)

A good quality burlap should be fine, but the smell may put you off for a while. Gilford of Maine is also popular, but more expensive.


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## Prof. (Oct 20, 2006)

Look for a material called Polyester Stretch or Polyester Interlok..It's quite cheap, looks nice and does the job..


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## bpape (Sep 14, 2006)

Anything breathable will be fine for covering things. We use ECOSE as the core for our products. While mineral wool is cheap and OK - it's a pain to work with and cut. We actually stopped even carrying it due to QC problems and people complaining about it chunking when trying to be cut.

Facing a panel is fine though understand that as you want to stop more and more, the membrane becomes more dense and more unpredictable as it starts to act as a damped membrane - which is not a bad thing - you just need to understand what it is and isn't going to do.

DIY can certainly save you money as long as you know what it's going to do and what you need it to do.

Bryan


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## bkeeler10 (Mar 26, 2008)

I forgot to mention that the floor is carpet, the ceiling is sheetrock and the walls are wood paneling on the bottom 3.5' or so, and sheetrock the rest of the way up.

Bryan, what do you think about the notion of QRD diffusors in the locations I noted on the first drawing (or are there better locations)? Also, do you think that the wall next to the left side surround needs absorption or is it okay to leave it bare?

What is the difference between the QRD diffusor and the Q7d diffusor to explain the large difference in cost?

Any recommendations on facing material?

Thanks again.


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## Todd Anderson (Jul 24, 2009)

They sell large (meaning very wide... 72") lengths of light-weight quilting fabric at JoAnne's... lots of different colors to choose from. It fits the bill and the extra width is really helpful. Also, I built some trap boxes that incorporated speaker fabric that I also bought at Jo Anne's. If you are interested, here's a build thread. You might get something out of looking at...

When you buy from JoAnnes, go with coupon in hand... I found that if you went to their website and searched for a store location... when you clicked on the store nearest to you on the resulting map, a printable coupon popped-up for 50% off.


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## Nyal Mellor (Feb 24, 2011)

You absolutely should measure your room as the first step before doing anything further on room treatments. 

Honestly without measuring you have no idea how bad your room is in various areas and therefore be able to formulate a proper plan of attack in terms of which areas to fix and in what order.

I co-authored this room measurement series with Ethan from RealTraps a whole back. It will tell you 'how to measure' but not really how to interpret. For that I suggest reviewing the [white paper I co-authored with Jeff of HdAcoustics. It will give you some targets to shoot for. The white paper is focused on two channel but most of the principles apply to home theater. At some point we will update the white paper to reflect our latest thinking, in particular the bass frequency response can be tightened.


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## bkeeler10 (Mar 26, 2008)

I did do some measuring a while back mostly to try to determine the best locations for subwoofers. I would have to go back and look for specifics but I do remember that I was not able to find a location for subs that would result in anything near flat response. I think the swings in the bottom 2-3 octaves were 20-30 dB depending on location, which is not uncommon in an untreated room as I understand it.

Now I have only done frequency response - I have not looked at waterfalls or RT60 or at any frequencies higher than about 200 Hz or so. The first thing I intend to do is sell some equipment to raise the funds necessary to get myself a proper measuring setup to use with REW and be ready to invest in room treatment materials.

I would be interested in reading your article.


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## Nyal Mellor (Feb 24, 2011)

Multiple seats and also a second row? You should definitely add one and better still three subs to even bass response.

REW is good and cheap, though not the simplest to use or the most stable with all computers. I like it though and it's what I use most when doing acoustic measurements.

The articles are linked to from my website www.acousticfrontiers.com/About-Us.html


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## bkeeler10 (Mar 26, 2008)

Thanks for the link.

I do have two subs. I am looking to revamp my entire system, and the new one will have two subs for sure. Three subs is not in the cards. My second row of seats will rarely be used, so I am not really concerned about them. They're right up against the wall anyway, so only people who like to get killed by bass would want to sit there . . .


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