Acoustical Treatments Master Thread - Page 311

Is the db-4-walls product in anyway acceptable for acoustical treatments? It's a dense rubber material that coats the walls for sound blocking.

Saw it recently at Lowes:

http://www.lowes.com/pd_336263-11580-DB-4-WALLS_0__?productId=3295396
http://db-4-walls.com/
Edited by MSutton - 12/31/12 at 7:47pm

^^ Looks to me like the EQ had more significant effect than the traps. I wonder how those plots would look with EQ applied but without the traps (and with another notch thrown in for the 90-100 Hz peak).

As for the db4 Walls, they claim 75% noise reduction. I'd say that translates to 12 dB attenuation, but at unspecified frequencies. As a comparison, MLV (mass loaded vinyl), 1/8" thick (1 lb/sqft), has an STC of 26. That would appear to be much better, but I have no way to compare these apples to those oranges.
Edited by Roger Dressler - 1/1/13 at 1:31am

I'm a sceptic (in re: db4). The manufacturer is making wild claims (75% 'unwanted' noise reduction) with absolutely nothing to back that claim up. For example, no accredited third party lab test results. It's a 1/4" thick product that Ms. Cutie can easily hold in place with two fingers (little mass), and costs $125 per sheet. Wow! It cannot be an absorber (1/4" and painted). Diaphragmatic? Nope. No weight given in any of the specifications. I suspect it is less effective than a second layer of drywall (or a second layer plus green glue) and far, far more expensive.

Here's a rule to follow: if a product claims acoustic or sound isolation benefits and the manufacturer cannot, or will not, supply third party test results, stay away. Also, for this type of application you are absolutely not interested in an STC value. You want to see the TL (transmission loss) values (which had to be obtained by the lab to come up with an STC).

I have in- wall speakers( floor standing sub) and my screen is mounted 3-4" off of the wall. Can I, should I treat the front wall? Will putting a treatment behind the screen but not the rest of the front wall do any good?

Thanks RT

Holy cow, +1! Very well said Dennis.

I'm very skeptical of most products that don't provide test results. This is my feeling regardless if we're talking decoupling mechanisms, assemblies, absorbers, etc.

Thought Id post this here instead of starting my own thread. I want to get some panels for my basement theater area. It has drop ceiling, carpet with thick padding, and drywall. Ive attached a rough picture of it from paint. I was thinking of putting two 2x2 panels from atsacoustics.com along the left wall and one 2x4 panels on the back wall above the couch. Would this likely help a lot? There currently isnt anything on the walls and I notice an echo so I was thinking panels would help.

FYI,

I have a closet that seems to have a thin drywall... and I get noise from my neighbor.

Since its a closet, I doesn't need to look nice.

I have been checking Green Glue from soundproof company and SheetBlok Sound Isolation Barrier from Auralex. I was thinking about Sheetblok from Auralex... by just applying this on top of my drywall...

Any suggestions on the simplest way to soundproof my closet.

Thanks in advance.

It would help somewhat, but 16 sq foot of absorption isn't really much, especially in a room that large. Anything is a start, but I would really recommend at least doubling that.

Thanks for the reply. Would I be alot better off getting two 2x4's for the side wall instead of the 2x2's? I was trying to make it aesthetically appealing as I could since the wife didnt really want any at all. So I know the side wall and back wall would be the only places I could put them, just wondering if its worth it. Most likely the other walls will never get anything. Its not a theater just a family room type thing with projector and stuff.

Hi all, I'm new to this forum and I have some questions as to how to effectively deal with my 24' x 24' room with a 10' ceiling. Everything I've read seems to indicate that a room of this dimension is a real problem and I guess that it's probably compounded by the fact that the seating is somewhat close to the middle(no choice, wife rules! LOL).

Do any of you have experience with a similar sized room or do you know of a link where I could get some info specific to my situation?

I am getting ready to do the acoustic treatments for the front wall of my theater that is currently under construction. My plan is to use Linacoustic acoustablanket for the front wall behind the speakers, and OC703 wedges in the corners for bass traps. My question is what is the recommended thickness for the Linacoustic I should be using? I've seen people in the theater construction threads use anywhere from 1" to 2", but I'm not sure which is correct.

Thanks

More absorption would definitely be worth it. You could always go with four 2x2s instead of two 2x4s.

We definitely understand the importance of what we call WAF (wife approval factor). Have you checked into things like custom Art Panels or nicer fabrics like the Guilford of Maine line? You can see examples of custom Art Panels here: http://gikacoustics.com/product/gik-artpanel-acoustic-panels/ and check out Guilford of Maine's colors here: http://gikacoustics.com/product/color-swatch-book/ (they also have EXCELLENT very high res photos of their fabrics on their website)


The dimensions would certainly cause some large bass response problems, though treatment would be similar regardless of the room. The only difference is you'll likely need stronger bass treatments (so corner traps, like soffit or tritraps/superchunks would be highly beneficial). Luckily though, the room is good size, so things like diffusion can easily be used for a good benefit.

Close to middle doesn't necessarily mean middle. How close are you to the middle? The bass nulls caused by the middle of the room will NOT change regardless of treatment. The only thing that can change nulls due to position are moving, or changing the dimensions of the wall. Do you have a drawing of your room?


Thicker is better for absorbing lower frequencies. At roughly 800 Hz and above, they will both perform identically, but a 2" thickness will result in much more low end absorption. If bass absorption is needed, go with 2".

That makes sense, thank you for the quick answer.

Made a thread with some questions about acoustic treatments for my home theater room:

http://www.avsforum.com/t/1451756/help-with-acoustical-treatment-in-my-home-theater

If any of you guys had any suggestions or anything, I would really appreciate it.

Thanks for the response. The seating is positioned about 14' from the front wall and about 9.5' from the back, centered side to side. The front monitors are about 32" out from the front wall, side monitors about 1.5' out and the rear monitors are mounted to built in suspended shelving that hangs down from the cieling 30" and lines the back wall. The room itself is a detached garage that kind of doubles as a light duty workshop/theater with the theater aspect taking up most of the room and the workshop aspect relegated to the back wall with a workbench and pegboard for my tools as well as items like a Gun safe, small refridgerator/wine fridge on top of that and various tools like a table saw etc in the corner, again, all against the back wall. I'd supply you with a diagram but am not able to do that.

1st reflections don't seem too bad but I think I could definitely benefit with something on the ceiling. I've thought about Bass traps
but am not quite sure how to go about that on a DIY basis. I have access to some interesting material.......2" thick, dense foam with a unique thick fabric layer on one side that might aid in sound diffusion. It came from a Gym and was used as a floor mat for excersize. I'm not sure if it wouldn't be a bit of overkill but it might work well for doing some sort of DIY Bass trap.

Yes - you likely don't hear too much of a damaging effect from reflections since your room is 24' wide, but IMO if your speakers are still relatively close to a wall (within 2 meters) you will still likely experience some phasing type issues from reflections. The ceiling is, as you've pointed out, a bit bigger of an issue as it isn't nearly as tall.

There are a few threads here on building them. Superchunks offer good performance while taking up not as important of floor space (they go in the corners of the room)

Not sure about the material you've suggested though, its likely a very poor performer. Unfortunately, densities and a materials ability to compress really don't have too much to do with their absorbing qualities.

Thanks. It sounds as though my room might not be as difficult to tame as I have been led to believe. I will seek out those forums you mentioned and continue my edumacation quest.

Im having trouble hearing my center ch during movies & was wondering if ceiling treatments would help,Im getting old cant hear as well as I use to! My ceiling is painted OSD board,Ive got treatments in the room (side wall & bass trap treatments) would ceiling treatments help above LCR spks? thanks

I have a diffusion question for anyone with real world experience. Is there a minimum depth that we should be considering when buying or constructing diffusors? I am experimenting with diffusion in the back of my audio room and have several ideas floating around in my head...

1. I have a bunch of Auralex Mini Fusors that are 12" x 12" panels and roughly 6" in depth for the diffusor itself. The plan was to fill the cavity with OC703 and place them in array at the locations I have proposed.

2. I have seen other auralex products that are only 1" or 2" thick that are labeled as diffusors and have considered using them for ceiling reflection points or perhaps in place of the deeper mini fusors so they protrude in to the room less. I am not SET on using these products and am willing to fabricate or duplicate them on my own.

3. I have been browsing home improvement stores for items that can be used in place of commercial products. I have found some rigid fiberboard panels that is sold in 4' x 8' sheets and is in the form of a waveform. The difference between the high and low points is about 2" and I was considering cutting this material and placing it behind a fabric frame to allow the treatments to better blend in the room.

My question is really one of how effective can a diffusor be based on depth of the device and based on that answer are different depths better suited to use in different areas. i.e. ceiling versus rear wall...


Thanks in advance!

I've never had any type of acoustical treatments in any stereo or HT system I have ever had. Guess it would be a wise thing to have a few treatments before spending thousands on new components, subs, speakers, etc.

This is a general use room so I can't go insane with treatments, etc. Ceilings are 9', 24' wide and about 30-33' long. Lots of hard surfaces, pictures on wall, drywall, etc. Other than the curtains that I put down whenever watching or listening to the system the room has no treatments.

Suggestions welcome!

Yes, it is certainly not an impossible feat. Get to it!

This will likely give an improvement if reflections from the ceiling are causing the problem, but it could just be the center channel as well. I would try different placements of your center channel to see if it changes anything and to make sure it isn't defective.

Something else to look into as well are floor reflections - if you have a hard floor, you might consider using a rug on the first reflection point on the ground.

With all that being said - first reflections on the ceiling are harmful and treating them is suggested. I just would rather not tell you it is the problem as it could be a few different things.

Yes! Depth of the diffusor will determine how low in frequency it diffuses to (but this also requires being farther away from it to gain the benefits). Likewise, the width of the wells will determine the high frequency cut-off of the diffusor.

I don't work for Auralex, but I'm quite sure I can confidently say yes - filling the cavity behind the T-Fusors with fiberglass will result in some low-mid to mid frequency absorption. It won't necessarily enhance the performance of the diffusors though (as in, it won't change the working frequencies of them)

The only product Auralex makes (that I'm aware of) labelled as a diffusor at a thin depth is the MetroFusor. It is slim at 2" of depth. While the product does work (I don't want to say that the product is a sham, as it isn't) it is VERY limited by the size. As I've stated above, depth of the diffusor determines how low the diffusor works. Diffusors 2" or thinner will not give you any considerable diffusion for anything other than very high frequencies. Building your own or purchasing MUCH thicker diffusors would be much more beneficial IMO.

Could you find a link to a similar product? I've never seen something like this sold in stores. Concave and convex shapes such as these are typically bad though, as they focus sound and typically don't offer great spacial diffusion.

Different depths are more beneficial in different places. To be general, you can be closer to a diffusor that only diffuses high frequencies than you can to a diffusor that diffuses mid and hi-mid frequencies. You usually don't want to be within a few feet of a wide performing diffusor.

Thanks GIK acoustics guy,my LRC spks are JTR triple 12s so my spks are pretty good!

The wood blocks in this appear to be 4x4 or 6x6. For some reason, mounting method perhaps - or by design, there are spaces between the blocks. Would those spaces enhance, decrease or have no effect at all on the diffusion properties?

That roofing design doesn't look to be calculated diffusion (it would be much too low in frequency to be useful at that distance and for that purpose in either case). It just seems to be an attractive ceiling with wood mounted at random depths. This will help scatter sound and will clean up the acoustics of a space like this, but wouldn't be of much benefit in a room where we need predictable and accurate results.

Also, the spaces between the wood will increase absorption a large amount which is something you typically want to avoid with diffusion. A good diffusor will diffuse as evenly as possible with as little absorption as possible.

More on diffusion here: http://gikacoustics.com/how-diffusion-works/

Thanks. I suppose with a large hard-surfaced space, absorption is important for creating an environment where conversation is easy and one doesn't have to raise one's voice to be heard.

So, calculating block lengths for 4x4, 6x6 and larger, where the ceiling is this high ... is useless for diffusion?

Jeff

It seems I should have been a bit more clear. If they were 6x6 blocks, these would diffuse ONLY quite low frequencies compared to a normal diffusor - and would need a LOT of space to work properly. Though, I didn't realize how high the ceiling is - I'm still (perhaps incorrectly) assuming you need to be further than that distance to get notable and useful diffusion. Also, calculating a grid this large would likely take insane amounts of time (though it isn't really clear how large of a grid this uses). You might want to hire a computational mathematician like my girlfriend to come up with methods to ease the calculation. This is the main reason I believe this isn't calculated and looks to be random. Which really is fine for the purpose, as it doesn't need to evenly diffuse at all, it mostly needs to absorb (which is what it's doing with the air spaces between the wood). Random still helps with scattering reflections and the spaces give good absorption, creating an easier conversational area, but doesn't equally diffuse sound and would not be very helpful in an environment other than where its at. Its better than a flat wall, yes, but to what extent would be quite difficult, if not impossible to know.

Edit: Its diffusion properties, if correctly calculated, would likely be akin to carpet's absorption properties. It is a good absorber but only at particular frequencies, and is a poor absorber otherwise. I'm assuming the same would be true of the diffusive properties of that ceiling.

So, then it is likely only aesthetic and "green" .. it is reclaimed wood ... and it absorbs.

Thanks for your insights.

Jeff

I have a question regarding ceiling treatments. I believe that I'm getting quite a bit of reflection from the ceiling from the center speaker. I have some 1" thick linacoustic and my plan was to build a frame 4' by 4' (out of 1" x 2" furring strips) and stretch some black ponte fabric (speaker grill fabric) over it. Then I was going to set the 1" linacoustic in the frame and hang it from the ceiling using hooks and eyes. I would not be covering the entire ceiling just the sections as determined by the mirror test. Does this make sense? I realize the ponte is not fire resistant but I would not be covering an entire wall or ceiling and there are not any lights on the ceiling, just wall sconces.