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Discussion Starter #1
Hey guys, I know there is a whole section on treatments and sound proofing, but I like you all better :) I am wanting to build and install some panels in my room over winter, and am looking for some general info. Things like sizing, positioning, what areas to focus on first, etc. I am sure first reflection points should come first, but what type of panels should go there and how to I best find the points? Also, has anyone done anything really creative (DIY) with their treatments other than the printed covers?

I realize this is very vague, but this is pretty much all new to me. Any info, or links to check out for n00bs is appreciated.


Thanks!
Sean
 

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You're going to have to do some home work yourself. It's all there and easy to find. Sounds like you already know how to find the reflection points.

As for what type.. absorption for an easy setup and if you're speakers aren't great off axis.

If they are good off axis side walls getting combo panels is a great option. Absorb vocals and below and diffuse above. YOu can make your own. There's DIY BAD panels threads you can follow and slat combo diffusers using aluminum foil tape both over 1.5 to 2" ductboard/OC 703/rockwool. Frequency where diffusion ends and absorption begins is of course based on tape width and spacing all based on 1/4 wavelength.
 

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Discussion Starter #3
You're going to have to do some home work yourself. It's all there and easy to find. Sounds like you already know how to find the reflection points.

As for what type.. absorption for an easy setup and if you're speakers aren't great off axis.

If they are good off axis side walls getting combo panels is a great option. Absorb vocals and below and diffuse above. YOu can make your own. There's DIY BAD panels threads you can follow and slat combo diffusers using aluminum foil tape both over 1.5 to 2" ductboard/OC 703/rockwool. Frequency where diffusion ends and absorption begins is of course based on tape width and spacing all based on 1/4 wavelength.
I have tried, and I get lost quick. There is a LOT of info, and theory out there, and a lot of it is over my head. I know it helps tremendously if done right, which is why I want to get some in my room though.

I saw a demo of how to find the first reflection points once, but don't really remember it. I am sure I can figure that out easy enough, but even in that demo they vaguely talked about multiple methods. So, which method is the best?

How do I know if they are good or bad off axis?

After that you lose me pretty fast to be honest. I get there are different types of panels that do different things at different frequencies, but how do I know what type I need in my room and where to put them? After that I understood the materials, but that was about all I got out of that. I don't know anything about wavelengths for example.


Sean
 

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Here's how to find them.
http://realtraps.com/rfz.htm


You can just buy absorption panel here. You can also get the 703 or rockwool here as well and make them for half that price. http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24-x-48-x-2--1001.html

Look at my build thread below. The first few pics are of my old room with panels I made. Yours should be spaced similar once the mirror find the spots.

For off axis you need to see if the manufacturer has responses or measure your own. If you're not ready for that you can either just use absorption like above or just do combo panels anyway. Use absorption on rear behind your head no matter what.
 

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I'm about to make some diy acoustic panels sometime in the new year, I've already bought the Roxul rigid insulation. My panels are going to be 24 x 40 inches and 3 inches thick.

First some general guidelines. There's no solid rules you NEED to follow but these are some ideas.
1. Floyd Toole (IIRC) in his new book says about first reflection points - absorb everything or absorb nothing. If you absorb only a portion of the bandwidth at the first reflection points you will still get a reflection at low frequencies, all you are doing with thin absorption panels is sucking out the higher frequencies. This changes the tonal balance of the reflections and the overall tonal balance in the room. This is why he says absorb everything or absorb nothing. And it's VERY hard to absorb the entire bandwidth at the first reflection points. A different way to combat this issue is with very high directivity speakers. This type of speaker will (or should, depending on placement) severely limit the amount of reflections in the first place, then you can get by with absorbing nothing at the first reflection points.
2. I've seen it stated in several places that diffusion is more effective in larger rooms and that diffusors should be placed at least 10 feet from the listening position. I'm not sure how accurate this is but in small rooms it can be really hard to fit all the necessary diffusion and absorption so in a lot of cases it can be better to forget about diffusion and try to just fit the appropriate amount of absorption.
3. Tuned traps can be good but they are large and usually take up a lot of floor space - again good for large rooms but sometimes not so much for small rooms. Ethan Winer and several other manufacturers are not even offering any tuned trap options for sale anymore, instead focusing on smaller lightweight broadband absorption panels that can be hung and take up no floor space. The argument for this approach is that all rooms need a large amount of broadband absorption and if you have enough acoustic panels they will eventually be effective at lower frequencies as well. Of course you need a LOT of acoustic panels to be effective at low frequencies.

So to start out we need to figure out how much absorption is necessary. A general rule of thumb is that for thin absorbers you want to use a higher density insulation material. For absorbers that are thicker than 4 inches you want to use the less dense pink fluffy stuff. Here's a calculator to help decide which kind and how much. I can't vouch for the accuracy of this calculator but it seems reasonable.
http://www.acousticmodelling.com/porous.php

Next it's important to look at how placement and amount of panels affect things. We all know that insulation placed away from the walls absorbs to a lower frequency than the same amount of insulation flat up against the wall, so straddling corners can be a huge advantage. We also know that thicker panels absorb to a lower frequency than thinner panels. But what some people don't know is that covering a large portion of the room with thin panels can absorb to lower frequencies than expected. Here's a quick article that makes this point.
http://ethanwiner.com/density.html

And although all rooms should have at least a modest amount of acoustic panels there are options that work even better in the 0 - 80 hz range, namely multiple subwoofers. Multi subs have an averaging effect which makes the response in room better (flatter) than a single sub. There's even tools available to guide you in placement and settings for the multi subs if you want to get all scientifical instead of doing it by completely random trial and error.
http://andyc.diy-audio-engineering.org/mso/html/

And finally when you figure out what you want to do - and come to terms with the fact that at least some panel type broadband absorption is required in all rooms - its time to shop for a specific insulation product. Owens Corning 700 series rigid insulation is very effective, especially the FRK version which has the kraft paper and foil covering on one side. The FRK is better at lower frequency absorption than the non faced 700 series but obviously the foil face will reflect the high frequencies so it's no good for first reflection points unless you face the foil towards the wall. The problem with OC 700 series is that it's ridiculously expensive.

That's where Roxul comes in. They also have a wide variety of rigid insulation panels and they are much cheaper and just as effective. I'm not sure if they have a kraft paper and foil face in any of their products but this can be added, I actually have a huge roll of foil covered kraft paper that I will be gluing to my panels.

Here's absorption data for a variety of different types of rigid insulation. The type I bought is not shown here but it's fairly similar to Rockboard 80 - and I got it at a HUGE discount on kijiji from a seller that had too much after insulating his house.

Row 1 - Rockboard 40, 60 and 80
Row 2 - Comfortboard 80 and 110 (IIRC)
Row 3 - Comfortboard IS and Cavityrock MD (IIRC)
Row 4 - Safe and Sound
Bottom - several Owens Corning 700 series products

 

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I get there are different types of panels that do different things at different frequencies, but how do I know what type I need in my room and where to put them? After that I understood the materials, but that was about all I got out of that. I don't know anything about wavelengths for example.


Sean
For smaller rooms the consensus is moving toward using broadband absorption panels - as many as possible, and really nothing else. This is the way Ethan Winer and Realtraps are moving as well as many others.

Here's how to find them.
http://realtraps.com/rfz.htm


You can just buy absorption panel here. You can also get the 703 or rockwool here as well and make them for half that price. http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24-x-48-x-2--1001.html

Look at my build thread below. The first few pics are of my old room with panels I made. Yours should be spaced similar once the mirror find the spots.

For off axis you need to see if the manufacturer has responses or measure your own. If you're not ready for that you can either just use absorption like above or just do combo panels anyway. Use absorption on rear behind your head no matter what.
As I mentioned, it's not consensus or foregone conclusion that first reflection points should be treated at all.

And as far as buying the insulation material, ATS is quite expensive and shipping will be killer as these are large and heavy products. Do a search on kijiji and you can usually find this stuff at 1/2 price or less. And that's half price of what it would cost in home depot, not half price of ATS prices. And if that fails just buy it at home depot - my local Lowes and Home Depot both have rigid Roxul panels - one has Rockboard, the other has Comfortboard - basically the same thing if you check the absorption coefficients.
 

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For smaller rooms the consensus is moving toward using broadband absorption panels - as many as possible, and really nothing else. This is the way Ethan Winer and Realtraps are moving as well as many others.



As I mentioned, it's not consensus or foregone conclusion that first reflection points should be treated at all.

And as far as buying the insulation material, ATS is quite expensive and shipping will be killer as these are large and heavy products. Do a search on kijiji and you can usually find this stuff at 1/2 price or less. And that's half price of what it would cost in home depot, not half price of ATS prices. And if that fails just buy it at home depot - my local Lowes and Home Depot both have rigid Roxul panels - one has Rockboard, the other has Comfortboard - basically the same thing if you check the absorption coefficients.
He's a self proclaimed newb. So I was keeping it simple. The cheapest place to go it your local HVAC shop and get ductboard. But yes ROXUL works just fine. http://www.bobgolds.com/AbsorptionCoefficients.htm

ATS has the cheapest "ready to hang" that I know of even after shipping.

Yes Ethan is an abosrb only, while Erskine and who can argue with his results likes combo whenever possible.

http://www.certainteed.com/hvac-industrial-insulation/products/ultraduct-black-duct-board/

^^^cheapest out there.

Every one has different opinions. Best to do research and make your own.
 

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Yes Ethan is an abosrb only, while Erskine and who can argue with his results likes combo whenever possible.
It wasn't always that way, remember this famous article? http://ethanwiner.com/basstrap.html

As far as I know that was where Winer started but now that article has this preface:
"Please understand that the bass traps described in this article are an older design intended mainly for larger rooms. For rooms smaller than 30 by 20 feet you'll do better with broadband bass traps made from thick rigid fiberglass placed in the room corners, with more on the front and rear walls if possible. Small rooms have peaks and nulls at all frequencies, so broadband absorption is better than the tuned traps shown in this article. This is described in my Acoustics FAQ linked above."

Regardless, it doesn't get much easier than diy'ing a bunch of broadband panels based on rigid insulation. There are a ton of different types of room treatments but using a lot of broadband panels is probably most effective and least effort and takes up zero floor space if you hang them all preferably straddling wall/ceiling junction. You just have to make sure to face them with foil or similar to reflect the high frequencies or the room will be way too dead.
 

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@Broke EF
what is your setup? Surround iirc?
In that case, vaguely speaking, balanced absorption is your primary goal, since that will improve imaging, soundstage and envelopment greatly. And corner basstrapping.
Do you know how and can you make REW measurements of your fronts and center (each separately). Graphs I am interested in are ETC in Impulse response and T30 in RT60 tab. Room dimensions would help too. Oh and generate waterfall for bass, up to 200 Hz. :cool:
 

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Guys he said he's a newbie. If interested Here's all the info on subs including measuring setup etc. This is much more effective than bass traps which only get into the upper bass unless you go riser traps etc.

http://www.avsforum.com/forum/155-diy-speakers-subs/2566897-compilation-multiple-sub-setup-info.html

That said..keep it simple.. go absorption. Or just diy or buy bad panels.
Everyone was noob once. But one day they discovered avsforum.
Btw, regarding subwooferage, OP has got that pretty much covered. ;)
 

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Guys he said he's a newbie. If interested Here's all the info on subs including measuring setup etc. This is much more effective than bass traps which only get into the upper bass unless you go riser traps etc.

http://www.avsforum.com/forum/155-diy-speakers-subs/2566897-compilation-multiple-sub-setup-info.html

That said..keep it simple.. go absorption. Or just diy or buy bad panels.
While it's true that multi subs are more effective than any (reasonably sized) room treatment option for evening out the bass, multi subs are only effective up to the sub crossover, which is usually 80 hz. In small rooms it's not uncommon to have more problems above 80 hz than below 80 hz so you still need to do something about the above 80 hz modes and other assorted room related issues.

Another solution to all this is to sit ultra nearfield (like almost headphones close to the speakers). In that case you get a lot more direct sound and a lot less reflected sound.
 

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FYI
for 703 purchases, I found buyinsulationproducts.com.
a 6 pack of 2" ended, with shipping, was about $35 less than when I bought it thru amazon from ATS.
significant % savings.
YMMV

Reading extensively at realtraps, Acoustic Fields, the treatment thread (s) here at AVS, Gearsluts, Audioholics, HTS, you tube videos, , yes , it's ALOT!
Re-reading the "right stuff" input you've already received here is a great distillation of the essence/basics you'll want to address.

for my own info base / refresher, @ diy speaker guy nails it!

FTR most of my panels are 5" thick, 3" Roxul laid over 2" 703. I wanted to take advantage of the rigidity of the 703 to reduce the use of plywood in a panel so I might be able to have more surface area exposed on the sides/edges.
Probably not hugely significant amount of "extra" area but as a no big rush DIY project I felt challenged to innovate/ implement that design factor.
For esthetics I also used plastic outside drywall corners on my top corners. It anchors the "sandwich" to the base frame. It also gives me a better/ smoother look when wrapping my fabric. made it a bit easier without "crushing the corners.

I've used no printed fabric "movie' related items for covering as I went for invisibility when the lights go out. I really don't have many "favorites"
my single most favorite, if I were to follow up on it, is the Monolith, from 2001 as seen in the crater.
Well I don't have the crater but I do have a "few" largish rectangular silent (and silencing) monoliths hanging around on the side walls, the front ceiling, the front wall , the rear wall and my 40 ft^2 for my SCATMOS array,
subliminally, the monolith has given me the message. . .

I have a few pics of the process of my building, maybe they will, with all the other info, make some sense for you.
 

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Discussion Starter #14
WOW, OK this is a lot of info to digest (still at work) but I will chew through it as I can this weekend. A couple things I saw that I can answer to help keep things moving.

Surround sound system (7.X)
Room is about 11 feet wide, 22 feet long, and 8 feet tall (Not a sealed room)
I do have REW and a UMIK-1, so I can sweep whatever and post the results, just tell me what is needed.

Here is the latest response of my subs.



I will check back in later when I had a chance to read everything. Thanks for everything so far, keep it coming!


Sean
 

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Check out the diffusion panels documented on Arqen.com - I think bwaslo has built them and had positive reviews
 

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Crazy complicated subject. Building them is easy, knowing what to build and how to use them is the challenge.

What about a situation with an asymmetrical room?

My room has basically no 1st reflection points. The left speaker is up against a wall, the right has no wall parallel to it at all (bay window)...
 

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Crazy complicated subject. Building them is easy, knowing what to build and how to use them is the challenge.

What about a situation with an asymmetrical room?

My room has basically no 1st reflection points. The left speaker is up against a wall, the right has no wall parallel to it at all (bay window)...
Your left wall, ceiling, floor, back wall...are all first reflection points. Bay window also reflects sound, but since its thinner it also lets sound bleed out more.
Treating left wall is priority, since left speaker is very close to it. But in general, in asymmetrical situations, unless you want to go really crazy with room treatment, I find DSP necessary for good and easy results without too much complication.
 

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Crazy complicated subject. Building them is easy, knowing what to build and how to use them is the challenge.
It's only complicated if you want it to be. Small rooms really don't allow for a whole lot of complication, there's simply no room for it.

For example, in my situation I'm treating a room that's roughly 11 x 14 x 8, it's small and acoustically horrible.

I'm going to start with 10 panels, each with rigid Roxul with dimensions of 24 x 40 x 3 inches thick. These will straddle basically all of my ceiling/wall junctions all around the room. They will all have kraft paper and foil facing to lower the absorption frequency and reflect the highs back into the room. And this is just the bare minimum starting point.

If that's not enough (and I don't expect it to be enough) I can then move on to replace the double wide closet door with a large acoustic panel of the same materials. This one might not have the foil facing, as it's in the right spot and the closet is deep enough to absorb full bandwidth across 1/2 the back wall area (it's a big door).

If that's still not enough, or if I have lingering slap echo problems between the bare walls I can then start adding flat panels directly on to the wall.

The one area in the room that I'm not considering treating is the first reflection points and the floor - there's not a lot you can do about the floor. Everything else is fair game if needed.

The amount of panels that I'm considering using doesn't leave a lot of wall area open for much diffusion or anything else, even though none of the broadband acoustic panels take up any floor space.

What about a situation with an asymmetrical room?

My room has basically no 1st reflection points. The left speaker is up against a wall, the right has no wall parallel to it at all (bay window)...
First reflection points are first reflection points. No matter how oddly shaped your room is you have first reflection points. If you put a mirror on the wall and can see the drivers from your listening position you are in the direct line of the first reflection points. If you can't see the drivers you are not directly in line but they still exist.

In your case it's almost the worst of all worlds. Placing the speaker tight to a wall can be good - it moves the Allison effect boundary bounce null very high in frequency - but if you are going to use this you should have both speakers against a wall. Otherwise you have horrendously different frequency response and spl levels from each speaker AND the Allison effect boundary bounce null is at very different frequencies for each speaker. The listening area and speaker placement should be as symmetrical as possible in the horizontal plane.

In this case it might be worth it to put a thick broadband absorber panel at the first reflection point of the speaker that's against the wall. The first reflection point would be directly in front of the speaker. That will get the frequency response of both speakers a bit closer and might partially or completely eliminate the boundary bounce null for that wall for that speaker.
 

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Yea I know there are reflections but the right speaker hits a window that aims away (behind) the seating and neither hit the ceiling before seating (coaxial but sitting 6-7ish feet away).

Really the only 1st reflections are the floor and the left speaker. I thought of putting a nice large panel next to the left. It's actually in a corner and can cover one of the double doors right besides it in a big pannel.
 

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Yea I know there are reflections but the right speaker hits a window that aims away (behind) the seating and neither hit the ceiling before seating (coaxial but sitting 6-7ish feet away).

Really the only 1st reflections are the floor and the left speaker. I thought of putting a nice large panel next to the left. It's actually in a corner and can cover one of the double doors right besides it in a big pannel.
Did you use mirror trick to confirm?
Btw, both left and right speakers hit both left and right wall...therefore...in non ideal situation depending on room dimensions...someone might need two acoustic panels on each wall.
What do you mean by coaxial? I sit 2 feet from speakers and they still hit ceiling and floor reflection. Unless you have a ribbon tweeter. (and if it hits floor, it hits ceiling too)
 
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