Room Acoustics treatment for electrostatics

Hi George,

I was in Home depot today looking at the wood. They had a rough grade of 2x2 pine at around $1.97 a board and a higher grade with no knots or defects that was had square edges and a better finish.

It was a little more pricey at $5.00 and change. When , I do go to do this , I will have a better look around. I will definately buy a good sander for a quality finished look. If you made the skyline 2x4 , it would be perfect behind a set of ML'S.Glad you liked the links.

I thought this would interest you guy's as well http://www.canuckaudiomart.com/forum/viewtopic.php?f=21&t=8520
Cheers, Greg

Note that diffusion, while better than an untreated wall, will still reflect back through the panel and cause serious comb filtering.
If the diffusion can angle the reflections away front the panel then all the better. But by definition, most diffusion has specular reflections that would inevitably come back at the panel.

For rear speakers, this is a good thing, and I use some Abfussors (absorbers with diffusion gratings on the front) behind my rear channel Sequels. And that’s great for creating an enveloping ambiance in the rear.

For the front channels, absorption yields a more cohesive sound. And my front wall and most of the side walls are totally covered in absorbers.

Also, diffusion does nothing to help the dipole cancelation at frequencies below 250hz. So if realy, really stuck on wanting to do the diffusion thing behind your speakers, please consider using an abfusor product like the Real Traps Diffusor

Jimna said:

isnt the basis of a diffusor to reflect not absorb? thats my understanding, so the painted/not paint makes no difference right?

i do know that most of the difussors for sale online are plastic which has no absorption at all.

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I think JonFo's link talks about this, and that comb filtering is mostly in the mid and upper frequencies something bare wood is good at (see churches and auditoriums). I suspect that a lightly sealed/stained bare soft wood diffuser will absorb some sound, maybe not the extreme amount found in a absorber panel. I also suspect that the plastic version of the Skyline diffuser absorbs even less than the wood version. We are talking much smaller amounts and differences than the basic predominant character of diffusion going on.

http://www.realtraps.com/diffusor.htm

When placed on the rear wall behind the listening position the RealTraps Diffusor scatters mid and high frequencies, while low frequencies pass through the reflecting well membranes to be absorbed by rigid fiberglass behind.

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I like the look of those RealTraps, and that they do a double duty.

The wall I built behind my speakers was meant to address dipole cancellation at frequencies 500 to 250hz and to scatter higher frequencies. I recently modified my 1/4 round corner trap to cover the area lower in frequency. It was very seat of the pants, I think I got lucky.

kach22i said:

I think JonFo's link talks about this, and that comb filtering is mostly in the mid and upper frequencies something bare wood is good at (see churches and auditoriums). I suspect that a lightly sealed/stained bare soft wood diffuser will absorb some sound, maybe not the extreme amount found in a absorber panel. I also suspect that the plastic version of the Skyline diffuser absorbs even less than the wood version. We are talking much smaller amounts and differences than the basic predominant character of diffusion going on.

http://www.realtraps.com/diffusor.htm

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yes very true. im not as familiar with realtraps products as i am the standard tradition diffusion types. but i dont believe plastic has any absorption at all does it? i looked into the plastic types and all the vendor say their products are not for absorbtion.

i did just get a new table saw for a xmas gift from dad, might be time to try my own skyline diffusor!

Jimna said:

i did just get a new table saw for a xmas gift from dad, might be time to try my own skyline diffusor!

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As much as I admire the science and math behind Skylines, I'd personally lean toward a more artistic approach. Perhaps a compromise or fusion of art and science.

http://www.flowerseast.com/Originals_Exhibitions_Large.asp?Exhibition=05EP&OL=5


http://thediplomat.fandm.edu/article/187


http://www.box-central.com/woodcarving.htm



http://fineartamerica.com/featured/the-flesh-of-the-evening-evan-leutzinger.html

George, even if not 'scientifically' validated, I have great admiration for artistic designs, such as the last one you listed. That would actually do pretty well in any room as a specular diffuser.

agreed i love the artistic approach too, but art isnt as easy to replicate....but I follow directions like a motha. an artist im not, a DIYer i am.


JonFo, do you ave diffusion in your room? if so what kind? and what have your diffusion experiences been, good or bad?

Jimna said:

agreed i love the artistic approach too, but art isnt as easy to replicate....but I follow directions like a motha. an artist im not, a DIYer i am.


JonFo, do you ave diffusion in your room? if so what kind? and what have your diffusion experiences been, good or bad?

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I use diffusion in the rear of the room. this helps in creating an enveloping soundfield in the rear of the room.

for Surround speakers that sit behind the listner, some diffusion helps spread out the rear-wave sound and distribute it, rather than abosrb it. this maintains a perception of a wide soundfield behind the listener, rather than a pinpoint on the speaker itself.

As you can see in this picture of the rear of the room, the tratments are:

Far left corner - two Realtraps Mondo bass traps stacked on top of each other
behind the left Sequel - a realTrap Abfusor
between the sequels - 4x RPG Skyline diffusors
the right side symmetrically repeats.

Bernard suggested to me in the members systems section to take the tube traps in the corners of the room behind my speakers and place them directly behind the speakers with the absorbtive side of the ASC trap facing the speaker to absorb the rear wave. This was the tip of the year!!

The differences were clearly audible switching back and forth, having the tube traps in the corners - reflective side facing the room vs the tube traps as suggested by Bernard with the absorbive side of the trap facing the speakers, directly behind each speaker.

I am eating crow, Jon Fo and others who said absorbing the rear wave is the way to go are correct.The differences in absorbing the rear wave was better clarity, I have to tell you I couldn't beleive it.I used various disc. On Queen - The Game ( mobile fidelity ) on another one bites the dust there are sounds going side to side and up and down within the soundstage. Absorbing the rear wave specified way more on these sounds and pinpointed them moving around more clearly and in a whole new detail. I also find much greater ambience than before, more of you are there compared to listening to a stereo system.

I am presently listening to Peter Gabriel - Scratch My Back There is orchestral accompiant on the whole disc.It's amazing with the traps behind the speakers. To me , it's as if the sound was blurred before or smeared. It was an ear opener switching back and forth between the 2 trap positions.I will ad new pictures to my system pictures when time permits to reflect the change.

Once again, Bernard , I can't thank you enough and it didn't cost anything.

Cheers, Greg

MOON said:

I am eating crow, Jon Fo and others who said absorbing the rear wave is the way to go are correct.The differences in absorbing the rear wave was better clarity, I have to tell you I couldn't beleive it.

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Thanks, Greg. Jonfo and I, among others, have been preaching this for years. Glad it worked for you. Ultimately, I suppose some of it is subjective. Some people like the "ambiance" of interfering reflections because that is what they have grown accustomed to or because that is "supposed" to be one of the "benefits" of ESL speakers. They simply don't realize, in my opinion, the huge gains in clarity, imaging, and soundstaging that come with minimizing obstructive reflections and listening only to the front wave of the speaker (which is the way the signal was intended to be transmitted to your ears). Unless you can increase the time-delay of rear wave reflections by having a large enough room, and having the speakers far enough from the front wall, then absorption behind ESL's really is the way to go.

Jeff said it a long time ago, if you want to hear what your speakers really sound like take them outside and play them. I believe thats the sound we should all strive for in our rooms. I guess hearing is believing but we should all strive for that roomless sound. Glad you have tried this, and Bernard recommended it.

:highfive:

Room treatments, one of the best upgrades you can do to improve your sound! Big fan!

Thanks for all the replies everyone!

I am just about ready to purchase some material and i have a question.

I see some models that are made with different thicknesses. Why is that? Is it because louder systems need thicker panels?

My system is never played loud so would I be ok wth the thinner stuff (saving me $$$$)?

Thanks again!

Peter_Klim said:

I see some models that are made with different thicknesses. Why is that? Is it because louder systems need thicker panels?

Thanks again!

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Wavelengths of the different frequencies require more or less absorption material, that is why corner bass traps (longest wavelengths) require the greatest amount of 'thickness' and first angle reflections less (higher freq)

In that case, should I get different thicknesses and use them all? I see 3", 2" and < 2"

Usually the ones manufactured by GIK, Real Traps and ATS are either 2" or 4" thick.

Peter, before you go and spend hundreds of dollars or more on acoustic treatment, do some research and learn about how they are manufactured and what the purposes are of the different kinds, as well as what the suggested placement patterns are. Different types of traps have specific purposes -- bass traps go in the corners to absorb excess low frequencies. Thinner traps go on the side walls to absorb first reflections, which tend to be higher frequencies. If you want to absorb some or all of the back wave of your speakers, you will need a panel that can evenly absorb from about 200 Hz. all the way up to 20,000 hz., which is the frequency range emitted by the ESL panel.


There is a ton of information out there, so no need to shoot from the hip on such an important (and costly) part of your system. Check out Ethan's site at realtraps.com. He has a ton of helpful information on his site. You can even call him or the guys at GIK to get some specific ideas of how best to treat your particular room. Good luck with it. I think the time, effort, and money spent on acoustic treatment is probably the biggest bang for the buck you can get in the sound quality of your system.

Peter_Klim said:

In that case, should I get different thicknesses and use them all? I see 3", 2" and < 2"

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Peter, as Rich said, do some research as he suggested.

FWIW, it is generally accepted that one treats corner bass loading issues and first point of reflection first. Treatment of 'back wave' is generally dealt with absorption and or diffusion depending on distance from wall (closer to the wall the more absoption, further away more diffussion), again room demensions, etc all play a part.

In so far as 4" of absorption for corner bass traps I would consider that to be a min and only when 'air' is behind the trap thus effectively dbl it's absortion (4in....4out)

Thanks guys, for the tip that in making to sure to research before spending my $$$.

So, I did some reading at the GIK site. It stated what I already knew:

"Don't put your seating right against a wall, back or side. This is the worst place in any room for smooth frequency response."

Unfortunately for my small room, I'm pretty close to the wall. The back of my couch is approximately 3 feet from the back wall. there is nothing i can do but move the ReQuests closer to the front wall, which I don't think is a good idea ( the back of the ReQuest's stators are about 4' from the wall). If i recline the couch out, my feet almost touch the stereo rack, which is almost touching the ReQuest. Above my feet is the turntable wall mount (I'll post pics when I get home) so you see there is not much room...in my room.

What would be the best thing to do as far as treatment for that back wall? Lay it heaving with acoustic panels? What kind?

Is there much, if any, noticeable difference between to acoustic panels where one has a NRC rating of 1 and another of 0.8?

ATS makes it in regular fabric (1 NRC) and in suede (0.8 NRC).

I also want to get a few where you can choose to have a photo dyed onto it. That doesn't decrease the absorption on it, does it?