or Connect
AVS › AVS Forum › Home Entertainment & Theater Builder › Dedicated Theater Design & Construction › Acoustical Treatments Master Thread
New Posts  All Forums:Forum Nav:

Acoustical Treatments Master Thread - Page 277

post #8281 of 10210
What's a good source for the demin or acoustic cotton material?
post #8282 of 10210
Quote:
Originally Posted by FOH View Post

What's a good source for the demin or acoustic cotton material?

http://www.bondedlogic.com/distributor-locator

Pretty ubiquitous, actually.
post #8283 of 10210
Quote:
Originally Posted by dragonleepenn View Post


It works just fine as a first reflection treatment for me. I'm suprised more people here are'nt using it, you'll fine that there is another company that sells a similar product,actually its the same denim material just different name and brand that sells it as a acoustical treatment. All the specs are the same.

Any ideas what the name is of the secondary company is that sells the ultratouch equivalent. Wonder if they sell it cheaper. Add acoustic to name of these materials and all of a sudden they are priced as gold!!!

I am kind of surprised of its limited use or recommendation around the forum. It is cotton for starters not half as nasty to work with. It is the thickness of a stud which can make it more flexible as a treatment in new theater construction.

Locally for me, it seems to be similar in price as OC. I guess it comes down to availability in your area.
post #8284 of 10210
Quote:
Originally Posted by orcarola25 View Post

Any ideas what the name is of the secondary company is that sells the ultratouch equivalent. Wonder if they sell it cheaper. Add acoustic to name of these materials and all of a sudden they are priced as gold!!!

I am kind of surprised of its limited use or recommendation around the forum. It is cotton for starters not half as nasty to work with. It is the thickness of a stud which can make it more flexible as a treatment in new theater construction.

Locally for me, it seems to be similar in price as OC. I guess it comes down to availability in your area.

This company has both products/one is sold as insulation the other is an acoustical material specific for such. Check out the sizes on both you can see the amount of product you get for each relative to purpose. You can check out the specs on both and compare. I selected wisely, the one sold as insulation, ultra touch. http://www.soundaway.com
post #8285 of 10210
Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!
post #8286 of 10210
Quote:
Originally Posted by Bullitt5094 View Post

Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!

Dont waste your time reading the thread - too much conflicting views.

I'd suggest Floyd Toole's book,, Sound Reproduction OR

http://www.avsforum.com/avs-vb/showthread.php?t=1267433
post #8287 of 10210
Hi all, I am in the process of re-disigning my HT room/basement. In the last couple of days, I decided to go with an AT screen and build a false wall with all three speakers going behind the screen. Althouhg I have read till my eyes hurt, I thought I should ask the following questions for absolute clarification:

1) From what I understand, in the case of a false wall/AT screen, the front wall MUST be acoustically treated. This is where I am uncertain: There are two different types of scoustic treatment available (a) the rigid insulation board from Johns Manville known as the JOHNS MANVILLE LINACOUSTIC Rigid Fiber Glass Plenum Liner Board and (b) the Linacoustic RC
Fiber Glass Duct Liner With Reinforced Coating System. Which is the right one to use?

2) Regardless of which one I end up using, is it correct to install the Linacoustic from floor to ceiling on the front wall (behind the false wall)?

3) Do I have to install the same Linacoustic on the side walls up to ear level only? Should I install floor to ceiling as on the front wall?

4) Should I move my subwoofer to behind the false wall (in one of the corners and next to the front speakers? I previously had it right next to the seating position.

Thanks,

atabea
post #8288 of 10210
Quote:
Originally Posted by Bullitt5094 View Post

Any way I can good some good basic Acoustic Treatment ideas for a dedicated Media Room without reading the 9+ years of posts in this tread? I'm not lazy, but I would like to finish my research before the house and room is finished in three months!

It is a lot to take in!! Here are a few articles we have done that might bring you up to speed.
http://www.gikacoustics.com/education.html
http://www.gikacoustics.com/news_081610.html

The following is a video (sorry English subtitles) of a room with and without treatment. It not only tests the room but also records music with and without treatment so you can hear the difference.
Hope that helps

http://www.gikacoustics.com/treated_video.html
post #8289 of 10210
Anybody?? I am really looking forward to getting this process completed and if the advice is to go ahead with acoustic insulation, then I want to start with that. I just need to know what is the right approach.

Thanks

atabea

[atabea;21260712]Hi all, I am in the process of re-disigning my HT room/basement. In the last couple of days, I decided to go with an AT screen and build a false wall with all three speakers going behind the screen. Althouhg I have read till my eyes hurt, I thought I should ask the following questions for absolute clarification:

1) From what I understand, in the case of a false wall/AT screen, the front wall MUST be acoustically treated. This is where I am uncertain: There are two different types of scoustic treatment available (a) the rigid insulation board from Johns Manville known as the JOHNS MANVILLE LINACOUSTIC Rigid Fiber Glass Plenum Liner Board and (b) the Linacoustic RC
Fiber Glass Duct Liner With Reinforced Coating System. Which is the right one to use?

2) Regardless of which one I end up using, is it correct to install the Linacoustic from floor to ceiling on the front wall (behind the false wall)?

3) Do I have to install the same Linacoustic on the side walls up to ear level only? Should I install floor to ceiling as on the front wall?

4) Should I move my subwoofer to behind the false wall (in one of the corners and next to the front speakers? I previously had it right next to the seating position.

Thanks,

atabea[/quote]
post #8290 of 10210
1) If you mean between these two (below), I'd take the second, based on better acoustic absorption numbers, which are listed towards the bottom of the two spec sheets (but I've seen a lot of builds use the first, really either will work):

http://www.specjm.com/files/pdf/AHS-329.pdf
http://www.specjm.com/files/pdf/AHS-156.pdf

2) Yes, I'd do floor to ceiling on the front wall.

3) There it starts getting tricky - that method seems to have fallen out of favor recently, and absorption / diffusion of just specific areas, based on acoustic measurements, is preferred. Many use the mirror method to determine locations, but a better approach is to measure first - since depending on the room and speakers, you might not need anything.

4) There is no answer that will suit all rooms, you'll need to experiment with different locations if the best audio performance is your #1 goal. On the other hand, if you're like most people with a false wall, aesthetics is part of the equation. I put my subs behind the screen, because they're too darn big for me to be happy with them anywhere else, I want that clean look. Better from an acoustics perspective would probably have been midpoint of non-opposing walls. But with a healthy dose of EQ, I've made it work well.
post #8291 of 10210
Thank you so much Brad! I now have a place to start--I will line the front wall with the Linacoustic roll and place the sub behind the wall ( I too like some aesthetics). I am not sure what the "mirror" method means or even how to "measure." I suppose I could just line the side walls and see how that sounds and if I don't like the sound I could always remove it.

Thanks again.

atabea


Quote:
Originally Posted by Brad Horstkotte View Post

1) If you mean between these two (below), I'd take the second, based on better acoustic absorption numbers, which are listed towards the bottom of the two spec sheets (but I've seen a lot of builds use the first, really either will work):

http://www.specjm.com/files/pdf/AHS-329.pdf
http://www.specjm.com/files/pdf/AHS-156.pdf

2) Yes, I'd do floor to ceiling on the front wall.

3) There it starts getting tricky - that method seems to have fallen out of favor recently, and absorption / diffusion of just specific areas, based on acoustic measurements, is preferred. Many use the mirror method to determine locations, but a better approach is to measure first - since depending on the room and speakers, you might not need anything.

4) There is no answer that will suit all rooms, you'll need to experiment with different locations if the best audio performance is your #1 goal. On the other hand, if you're like most people with a false wall, aesthetics is part of the equation. I put my subs behind the screen, because they're too darn big for me to be happy with them anywhere else, I want that clean look. Better from an acoustics perspective would probably have been midpoint of non-opposing walls. But with a healthy dose of EQ, I've made it work well.
post #8292 of 10210
Quote:
Originally Posted by atabea View Post

I am not sure what the "mirror" method means or even how to "measure."

Here's a description of the "mirror trick", which is used to locate approximate locations of "first reflection points" - the locations on the walls where sound will bounce off, on its way from each of the speakers to each of the listening positions (seats). Those reflections are one of the main things being addressed by the addition of absorption.

http://www.auralex.com/auralex_acous...mirrortest.asp

Measurement (ETC measurement mentioned in that definition above) means measure using a microphone attached to a PC, using acoustic analysis software such as REW (Room EQ Wizard - free). It can tell you (a) do you have a problem that needs treatment; and (b) after treatment, have you addressed that problem.
post #8293 of 10210
atabea,
please take a moment to read this thread:
http://www.avsforum.com/avs-vb/showthread.php?t=1372192

it's a long one - but it is important to understand that if one is utilizing absorption to attenuate early, high-gain specular reflections (as you are doing at the sidewall reflection points and elsewhere), it is vital to use a sufficient broadband absorber to fully attenuate the specular reflection ... vs using thin absorption to simply filter or EQ the band of which has the least energy content to begin with....

measurements are generally required to verify an existing problem as well as for confirmation once the absorber has been placed ... and this can be done with the ETC response as part of the free software measuring suite: Room EQ Wizard.

you'll notice that some of the theater experts here may recommend 'diffusion', or may say that their choice of absorption/diffusion/hybrid depends on the polar axis of the speaker - but i have yet to see anyone elaborate as to how such decisions are made or what types of 'polar responses' of the speakers dictate their choices.

there is also the issue of diffusers being effective only in the mid or HF band of the specular region, which is essentially the same effect as applying thin absorption which does not address the full specular reflection with attention to the lower band where the bulk of the energy content is and the wavelengths are longest.

specular energy is energy that can be modeled like light - hence the mirror trick described by Brad above is a crude way of determining what large surfaces or boundaries may have energy incident from the speaker. eg, if you sit in your listening position and have a friend hold up a mirror on the sidewall, and move it until you can see a speaker's acoustic center in the mirror, then that is a geometric reflection point that may be a candidate for absorption. you look for the acoustic center of the speaker, NOT the tweeter, as the acoustic center has the bulk of the energy content of which the absorber must be sufficient to attenuate. the tweeter contains the wavelengths with the least energy content, so they are not as difficult to attenuate.

of course, the mirror only gives you crude approximations on large boundaries. it does not provide you with detail of the time arrival of the specular energy, its gain (with respect to the original signal), nor the performance of the absorber once it has been placed to verify the proper attenuation of the specular reflection. it's a crude tool but it can help the novice understand how specular energy behaves within a small acoustical space. just understand the limitations.
post #8294 of 10210
There are two inch products that will get down to the Schroder frequency. (For example -- Class A --- 125Hz - .73, 250Hz - .95, 500Hz - 1.17, 1000Hz - 1.16, 4000Hz - 1.13) and 2" products that won't eat your HF (for example 125Hz@.66 and 4000Hz@.18). However, the underlying, oft ignored component in all of this is the failure to recognize you have a wall behind these treatments and the wall itself contributes to the room acoustics (it has an impedance, it has absorption characteristics) and you really don't have just a piece of something, you in fact have a composite, and that composite behaves as a different material...not the sum of all the materials. So, if you get "whacked" by a CDO (OCD in alphabetical order), well don't get cornfused with big words.

Path differences (hence phase differences) and absorption by frequency in air over distance is easily calculated. Where both absorption and diffusion is called for "PerfSorberLR.pdf" illustrates a product in that domain.

If you look at "good off axis", as you measure off axis, a well behaved speaker will resemble this plot. Note as the frequencies roll off as you move off axis, the plot has the same shape. This would likely call for diffusion. If you look at "bad off axis", you'll see the behavior of a less than well behaved speaker. This speaker would call for absorption ... you really don't want the poor frequency response (off axis) of this speaker redirected, reflected or otherwise injected into the listening positions of the room.
LL
LL

 

PerfSorberLR.pdf 237.13671875k . file
post #8295 of 10210
Quote:
Originally Posted by Dennis Erskine View Post

There are two inch products that will get down to the Schroder frequency. (For example -- Class A --- 125Hz - .73, 250Hz - .95, 500Hz - 1.17, 1000Hz - 1.16, 4000Hz - 1.13) and 2" products that won't eat your HF (for example 125Hz@.66 and 4000Hz@.18).

Quote:
Originally Posted by Dennis Erskine View Post

attached file:

Quote:


ISO 17497-1:2004
Acoustics -- Sound-scattering properties of surfaces -- Part 1: Measurement of the random-incidence scattering coefficient in a reverberation room

yes, and when interpreting such values, one needs to understand that random incidence (reverberant/diffuse-field) does not exist in a small acoustical place - and one needs to be accounting for angle of incidence.

Quote:


"The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. Normal incidence absorption coefficients are percentages. The two are often confused in the literature. A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."
post #8296 of 10210
Quote:


"The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. Normal incidence absorption coefficients are percentages. The two are often confused in the literature. A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material."

Better way to say it "Look at the sabins per unit".
post #8297 of 10210
Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.

atabea
post #8298 of 10210
Quote:
Originally Posted by atabea View Post

Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.

atabea

LOL. You didn't think you could just "splash around in the puddle" now did you?
Gonna have to get wet on this topic....soppy drenching wet I say!
post #8299 of 10210
Quote:


yes, and when interpreting such values, one needs to understand that random incidence (reverberant/diffuse-field) does not exist in a small acoustical place - and one needs to be accounting for angle of incidence.

Yeah. So. You think I need to know that?

A reverberant field does exist in a small room ... just not a fully random homogeneous one. Any suggestion that an item tested under standard lab conditions is not appropriate, or won't work in a small room is just arm waving.

Quote:


Wow! the terminology and language in general is so far beyond me that I think I need a physics/electronics class or something to even begin to understand what you guys are saying.

Hah! Think that's a new language...sit on an ISO or (particularly) an ITU working party...now there's a whole new lexicon and set of rules.

If you'll note, Atabea, as is typical, the response didn't add anything to the conversation; but, was strictly an effort to be overly critical (and perhaps to impress people). The language changes after you put down the slide rule, get out of the office, and actually build (and measure) a hundred or so rooms. The language usually becomes monosyllable and much better understood by all.

So, to cut through the krap ... most enthusiats do not have the predictive tools (or need) to model coefficients vs percentage, non-incident vs random incident (basic geometry). This is supposed to be fun?! The basic point is just slapping a piece of fiberglass on early reflection points may not be the best approach. If you don't care to invest several months of time, don't have the budget (or desire) to purchase acoustic measurement equipment or hire a "professional", there are a few things you can do. One is to buy a couple of absorption panels and perhaps a couple of hybrid panels (like and absorber/diffuser) and place them on the side walls between your seating location and the speakers ... move them, swap them out, until it begins to sound better (one key metric is the dialog is understandable, another is you don't have to keep adjusting the volume between loud scenes and quiet scenes...and then continue the process until you're happy with your room. Splitting hairs is never productive when the low hanging fruit is the first priority.

If you want to take it further than that, you can read Floyd Toole's book "Sound Reproduction", you can take an HAA (www.homeacoustics.net) class, or you can go all in and spend several months collecting approaches, opinions, reading, and gaining an understanding of what "stuff" does to sound in a small room. Or, you can spend the bucks and hire Floyd!

I think you got a pretty reasonable answer about mirror points. Yup, there are a lot of them but keep the low hanging fruit in mind, address the big stuff first, and over time nail the nits.
post #8300 of 10210
Quote:
Originally Posted by Dennis Erskine View Post

Yeah. So. You think I need to know that?

sure. far too often are such coefficient values presented on this forum without anyone taking the time to explain or understand how they were obtained and how they may or may not be relevant to the rooms most of us here are constrained to.

it should also be pointed out you provided data to a complete novice, of which no explanation of what those values meant. far too often we have people assuming those values are 'percentages' - and may make the misunderstanding. the statement was made to address any possible misconceptions the user or any other passive reader may have regarding such test facilities and standards. i'd love to hear you try and spin how you feel this is somehow "not relevant" considering this is the "acoustical treatment master thread"...


Quote:
Originally Posted by Dennis Erskine View Post

A reverberant field does exist in a small room ... just not a fully random homogeneous one.


that is a contradictory statement. how can it be a reverberant field if the energy flow is not equal/homogeneous in all directions? there is no reverberant soundfield for the frequencies relevant to small acoustical spaces - and what little exists in the higher frequencies in itself is lower than the noise floor.


Quote:
Originally Posted by Dennis Erskine View Post

Any suggestion that an item tested under standard lab conditions is not appropriate, or won't work in a small room is just arm waving.

it's not that it isn't appropriate - just that one needs to understand how such values may or may not be directly relevant to how the unit performs in their room. i find it slightly odd you consider such commentary as 'arm waving' ... it's quite applicable knowledge - especially when we have so many people on this subforum quoting Bob Gold's absorption coefficient page without somuch as reading the 2nd paragraph.

specular reflections dominate small acoustical spaces, and sidewall treatment properties can change dramatically with angle of incidence.


Quote:
Originally Posted by Dennis Erskine View Post

If you'll note, Atabea, as is typical, the response didn't add anything to the conversation; but, was strictly an effort to be overly critical (and perhaps to impress people). The language changes after you put down the slide rule, get out of the office, and actually build (and measure) a hundred or so rooms. The language usually becomes monosyllable and much better understood by all.

if i wanted to impress people, id mimic your signature.

im here to discuss and learn acoustics, not market a company and sell rooms, room designs, products, etc.

back to the product, is there a particular reason why the scattering coefficient was used and diffusion coefficient was omitted/not tested in the perf-sorber product data sheet?
post #8301 of 10210
This ought to be interesting. Mr. Pink Fluffy vs. Dennis (someone considered to be an expert in the field)....
post #8302 of 10210
Quote:
Originally Posted by localhost127 View Post

if i wanted to impress people, id mimic your signature.

im here to discuss and learn acoustics, not market a company and sell rooms, room designs, products, etc.

Yawn.....no need for the aggressive attitude, I dont understand why you persist with it in almost every post

Dennis has provided almost unlimited advice, free of charge to many, many builds....some respect of his position both within the industry and within AVS would be appreciated

His work speaks for itself, a more constructive dialogue would be appreciated
post #8303 of 10210
Yeah, arguing about absorption. Look at the brigh side - waay better then arguing about cables!
Speaking of which, has the ISO standard calculating absorption/scattering coefficients been already revised, based mr. Sauro's research? We need our sabins to be correct for our models! (or not really, fudging is fun)
post #8304 of 10210
Quote:
Originally Posted by nickbuol View Post

This ought to be interesting. Mr. Pink Fluffy

did you build your porous corner LF traps as of yet? working out for you?

it's clear from your 'jab' at me you likely did not go with a lower flow-resistivity material.
post #8305 of 10210
This point has been made before - not everybody has space for bass traps, and even less people have space for the pink fluffy kind.
post #8306 of 10210
Quote:
Originally Posted by pepar View Post

This point has been made before - not everybody has space for bass traps,

...

Quote:
Originally Posted by nickbuol View Post

I found some mineral wool today while out and about over lunch, but I couldn't find out if it would work for super chunk bass traps

Quote:
Originally Posted by nickbuol View Post

Personally, I'm going with straight up, known to work, 703 panels and super chunk bass traps. They work for sure, and I've not afraid to build them.

this is the acoustical treatments master thread. if they have design constraints of which they are not able to apply a treatment, then why does it matter in this thread?
post #8307 of 10210
Quit taking differing opinions personally.
post #8308 of 10210
Reverberant Field = The area, away from a sound source, where reverberation is louder than the direct sound from the sound source. Fully random, homogeneous reverberent field is a subset of reverberant field.

I suggest Architectural Acoustics (M. David Egan) or Salford University.

Let us also remember that people who sell things, are evil, wicked, greedy, and always self centered and self serving. To get even with these evil peddlers, let's all agree to buy absolutely nothing from anybody until, let's say, January 31st of 2012.
post #8309 of 10210
Quote:
Originally Posted by Dennis Erskine View Post

Reverberant Field = The area, away from a sound source, where reverberation is louder than the direct sound from the sound source. Fully random, homogeneous reverberent field is a subset of reverberant field.

I suggest Architectural Acoustics (M. David Egan) or Salford University.

Quote:
Originally Posted by Dennis Erskine View Post

A reverberant field does exist in a small room ... just not a fully random homogeneous one.

i'm sorry - but while your definition of 'reverberant field' is indeed true, it does not provide objectivity to the fact that such reverberant field still does not develop in a small acoustical space. there is no critical distance in a small acoustical space. there is no point where the reverberation is louder than the direct source in a small acoustical space.

your recommendation for literature is for large acoustical spaces ... easily confused and the very reason i continue to bring up such a topic - people mixing terminology, statistical calculations (RT60), and physics of large acoustical spaces with that of small acoustical spaces which are not applicable, and of which many here are constrained to.
post #8310 of 10210
You need to get into more small rooms (start with a shower stall).
In re Egan ... correct. It was suggested I do such a book as a PhD project; but, I'll leave it an eager student.
New Posts  All Forums:Forum Nav:
  Return Home
AVS › AVS Forum › Home Entertainment & Theater Builder › Dedicated Theater Design & Construction › Acoustical Treatments Master Thread