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Acoustical Treatments Master Thread - Page 319

post #9541 of 10188
Quote:
Originally Posted by Roger Dressler View Post

Tool's book states:

no need to guess - BEM simulation is quite sufficient via that of AFMG Reflex (free for 30-day trial): http://reflex.afmg.eu/index.php/rf-features-en.html
post #9542 of 10188
Quote:
Originally Posted by localhost127 View Post

im quite confused as to how their 15"x15" (9" depth) device offers bandwidth down to 125hz (which corresponds to wavelength of 9ft!). tongue.giftongue.giftongue.gif

where do their diffusion coefficients come from?

I wondered this as well - obviously the size limits this from being possible. It's also worth mentioning that the Model E boasts high diffusion coefficients at 125 Hz even though its polystyrene...I mean, can EPS really be reflective at 125 Hz? Maybe it can, I'm not sure honestly.

Quote:
Originally Posted by Nyal Mellor View Post

testing?

According to the product spec sheet, the absorption was tested in accordance with ISO standards but they did not list whether the diffusion coefficients were tested or calculated.
post #9543 of 10188
So this thread is from 2003 with 100 pages+ so I am guessing I probably should not have to read all of it. Anyone want to give me cliff notes or aware me ?

I'm looking to start a new construction theater (above 2.5 car garage) and I can control pretty much everything since I have not started yet. Construction starts in a few months. Is there a generally best practice process or product combo for sound treatment ?

What is ideal (based on high value) ? Is there a certain process or product I should be considering or planning for in a moderate middle class budget theater build ?
post #9544 of 10188
Quote:
Originally Posted by Mfusick View Post

So this thread is from 2003 with 100 pages+ so I am guessing I probably should not have to read all of it. Anyone want to give me cliff notes or aware me ?

I'm looking to start a new construction theater (above 2.5 car garage) and I can control pretty much everything since I have not started yet. Construction starts in a few months. Is there a generally best practice process or product combo for sound treatment ?

What is ideal (based on high value) ? Is there a certain process or product I should be considering or planning for in a moderate middle class budget theater build ?

You can read any one of the build threads in the Dedicated Theater Design forum to see the methods employed. Refer back to this thread if you have questions on specific methodology. Once you have a general idea of what you want to accomplish, start a thread with specific questions.

Beyond that, if you don't have the time to invest in research you can contact a design firm (eg Erskine Design is a popular firm here) that will lay out exactly what you need to do.

Tim
post #9545 of 10188
Think it is foolish not to invest in the time to read this thread. This thread is a convergence of best practices, science, and the invaluable experience of those who have designed and built their own home theaters. It includes the input of many design and audio professionals who graciously share the knowledge that earns them a living. Why would you not want to read it?

A cliff notes version would be akin to a fast food approach to home theater acoustics.
post #9546 of 10188
Quote:
Originally Posted by Willie View Post

Think it is foolish not to invest in the time to read this thread. This thread is a convergence of best practices, science, and the invaluable experience of those who have designed and built their own home theaters. It includes the input of many design and audio professionals who graciously share the knowledge that earns them a living. Why would you not want to read it?

A cliff notes version would be akin to a fast food approach to home theater acoustics.


I've been skimming and pretty much come to the same conclusion on my own.

I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.

Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????
post #9547 of 10188
Quote:
Originally Posted by Mfusick View Post

I've been skimming and pretty much come to the same conclusion on my own.

I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.

Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????

That could be a start, though a lot of people come into this thread with very specific questions and often times you won't know the context it's in. This thread is often jumped in for people to ask some simple questions instead of a whole host of where to start for a theater - for the latter you'd be better of with a dedicated thread when you've got the time.
As for best practices, some things differ by designers but there is a few things you'll want to look into, and that is reducing the reverberation and absorbing modes down to at least 125 Hz (roughly the cut off for male voice) to improve dialogue clarity, down lower than that if you want an accurate response for music. Many theaters employ a second subwoofer to 'fill in' dips in response. Treatment can be multipurpose (clouds with recessed lighting built in or risers with bass trapping built in) or can be hidden behind a wall of fabric. Often times the entire front wall is absorbed so that your surrounds don't reflect and come from the front of the room. Really there are a lot of things to address and we've hardly got information from you - how many speaker set up, what size do you have to work with, is isolation necessary, size of projector, etc etc..probably best for its own thread as there are a lot of things you'll address as you go along. You can read up on some of the general ideas here - most of it is geared towards a music room and not a theater, but the same principals apply: http://gikacoustics.com/acoustic-primer/ < start there and read the primer and you can go more indepth with the other articles and videos on the site.
Let me know if you have any specific questions!
post #9548 of 10188
Quote:
Originally Posted by Mfusick View Post

I've been skimming and pretty much come to the same conclusion on my own.

I'm not afraid of doing the reading and research; the bigger concern was the beginning of this thread was 10 years ago. My concern was new products, technologies and practices might have developed after that time so I'm wondering if its outdated, or still viable. 10 years ago I was hanging out in the RPTV forum. Lol. Today I'm more into HTPCs but back when this thread started a PC couldn't even play 1080p video.

Its hard as a newb to figure out where the line is I should start. I was just looking for general advice on that regard. I guess I'll just read the thread backwards ????

http://www.avsforum.com/t/255432/acoustical-treatments-master-thread/5340#post_17390783

If you follow this Member's advice you will likely have achieved 80% of all that can be done. BasementBob is knowledgeable and experienced, and is the person responsible for the webpage chocked full of absorption coefficients.

If you want to push your theater to the pinnacle and have disposable income, the pros here can do it. If you are a DIYer and want to educate yourself enough to have a great sounding theater, then stay focused and do more research. Searching out BasementBob's posts are a good place to start.

And by the way, you might want to kill the lateral first reflections if your speakers have bad off axis response. But even the experts don't agree beyond that.

My $.02.

Jeff
post #9549 of 10188

I'm starting to think about the acoustic treatment of my theater room build.  I've put a query with some information about the room in my build thread.  I would welcome any advice you can offer over there.  I've read through a lot (I'll be the first to admit not all 9548 posts) and think I understand the basics of what to think about in treating a room.  But I hope to do a little better than basic at the end of the day; without needing to go way overboard!

 

The thread is here:

http://www.avsforum.com/t/1456093/diamante-build-in-dc/30#post_23363708

 

Thanks for your consideration.

post #9550 of 10188
I made some mid/high frequency acoustic panels and now I'm left with a 6 quantity of 2" 2'x4' Owens Corning 703 fiberglass. I am thinking of making 4 bass traps with the dimensions of 2'x2' and 6" thick which will be able to use up my remaining fiberglass. Will 6" thick suffice for bass trapping if I stagger then diagonally to the upper/lower wall corners as Ethan Winer does? Perhaps even only make then 4" thick so I can have an extra 2 bass traps? I do not want to buy any more fiberglass, I'm just trying to work with what I have left. I don't have room dimensions to give as these will be used in a future home and I just figure any bass trapping is better than nothing.

By the way, I just bought the fiberglass today and tested them in my room before I started building the frames. The difference these things made was quite remarkable, specifically the imaging. It's quite unfortunate acoustic panels are so elusive, unknown and impossible to demo. My parents were wondering what the hell I was doing when building these things outside.
Edited by brandon_k_w - 5/28/13 at 11:41pm
post #9551 of 10188

Pardon the cross-post.  I didn't seem to get much crossover into my build thread and there are some basic fundamentals I don't want to overlook as I get started with this part of my room build out.

 

PFU ScanSnap Manager 01PFU ScanSnap Manager 01

 

 

 

 

I would like to solicit opinions on acoustic treatment of my front wall assembly.  I've enclosed two schematics.  The first one is the top-down view that shows my front wall assembly consisting on a screen wall behind which is a wall to hold the speakers and behind that a couple of feet before getting to the foundation wall.  The "foundation wall" is not the bare concrete but will have 2 layers of 5/8" drywall attached to 2x4" framing (isolated from the ceiling with IB3 clips).

 

The screen wall will host an acoustically transparent screen and the rest of it will be covered with fabric (presumably as acoustically benign as possible).  Thus, except for the framing members and the frame of the screen, this wall is designed to be as acoustically transparent as possible.

 

The speaker wall will just host a few studs to screw my in-wall speakers to.  Each of the speaker bays will have OSB or plywood backers and be filled with fluffy pink stuff to a manufacturer's recommendation of 2.0-2.5 cu. ft. volume.  There will be drywall from side to side and from the top of the speaker cavities to the bottom of the speaker cavities.  The tops and bottoms of the wall will be open between the screen wall and the foundation wall.

 

My understanding is that a good place to start acoustically for reflection control is to put Linacoustic on the "front wall".  And I also believe that there is some consensus that a bunch of loose-fill fiberglass in the "corners" is a good start for bass-trapping.  

 

My initial thoughts would be to fill the majority of the space between the speaker wall and the foundation wall with a bunch of fluffy pink fiberglass.  It would seem that this would offer a good start to bass trapping in the front corners of the room.  My assumption is that the corners of the foundation wall are the "corners" I should be treating and not the intersection between the screen wall the the side foundation walls?  Since the screen wall is supposed to be acoustically transparent, it would seem that I could just ignore it for acoustic treatment purposes.

 

My question now becomes what is the "front wall" that is typically treated with Linacoustic?  I'm actually off to the supplier to pick up some 1" and 2" Linacoustic right now.  I would assume that the Linacoustic would be attached to the drywall of the speaker wall.  Is there a need to put any Linacoustic along the foundation wall - either at the tops or bottoms to cover the areas not protected by the speaker wall drywall and its Linacoustic covering, or the whole foundation walll?

 

Any other thoughts for acoustic treatments would be appreciated.

post #9552 of 10188
Quote:
Originally Posted by brandon_k_w View Post

I made some mid/high frequency acoustic panels and now I'm left with a 6 quantity of 2" 2'x4' Owens Corning 703 fiberglass. I am thinking of making 4 bass traps with the dimensions of 2'x2' and 6" thick which will be able to use up my remaining fiberglass. Will 6" thick suffice for bass trapping if I stagger then diagonally to the upper/lower wall corners as Ethan Winer does? Perhaps even only make then 4" thick so I can have an extra 2 bass traps? I do not want to buy any more fiberglass, I'm just trying to work with what I have left. I don't have room dimensions to give as these will be used in a future home and I just figure any bass trapping is better than nothing.

By the way, I just bought the fiberglass today and tested them in my room before I started building the frames. The difference these things made was quite remarkable, specifically the imaging. It's quite unfortunate acoustic panels are so elusive, unknown and impossible to demo. My parents were wondering what the hell I was doing when building these things outside.

It depends really on how low you need to trap. 4" traps in the corners will work well down to 100 Hz in corners. 6" traps would get you close down to 80 Hz in the corners.

Quote:
Originally Posted by RossoDiamante View Post


I would like to solicit opinions on acoustic treatment of my front wall assembly.  I've enclosed two schematics.  The first one is the top-down view that shows my front wall assembly consisting on a screen wall behind which is a wall to hold the speakers and behind that a couple of feet before getting to the foundation wall.  The "foundation wall" is not the bare concrete but will have 2 layers of 5/8" drywall attached to 2x4" framing (isolated from the ceiling with IB3 clips).



 



The screen wall will host an acoustically transparent screen and the rest of it will be covered with fabric (presumably as acoustically benign as possible).  Thus, except for the framing members and the frame of the screen, this wall is designed to be as acoustically transparent as possible.



 



The speaker wall will just host a few studs to screw my in-wall speakers to.  Each of the speaker bays will have OSB or plywood backers and be filled with fluffy pink stuff to a manufacturer's recommendation of 2.0-2.5 cu. ft. volume.  There will be drywall from side to side and from the top of the speaker cavities to the bottom of the speaker cavities.  The tops and bottoms of the wall will be open between the screen wall and the foundation wall.



 



My understanding is that a good place to start acoustically for reflection control is to put Linacoustic on the "front wall".  And I also believe that there is some consensus that a bunch of loose-fill fiberglass in the "corners" is a good start for bass-trapping.  



 



My initial thoughts would be to fill the majority of the space between the speaker wall and the foundation wall with a bunch of fluffy pink fiberglass.  It would seem that this would offer a good start to bass trapping in the front corners of the room.  My assumption is that the corners of the foundation wall are the "corners" I should be treating and not the intersection between the screen wall the the side foundation walls?  Since the screen wall is supposed to be acoustically transparent, it would seem that I could just ignore it for acoustic treatment purposes.



 



My question now becomes what is the "front wall" that is typically treated with Linacoustic?  I'm actually off to the supplier to pick up some 1" and 2" Linacoustic right now.  I would assume that the Linacoustic would be attached to the drywall of the speaker wall.  Is there a need to put any Linacoustic along the foundation wall - either at the tops or bottoms to cover the areas not protected by the speaker wall drywall and its Linacoustic covering, or the whole foundation walll?



 



Any other thoughts for acoustic treatments would be appreciated.



You've definitely understood most of the concepts. The biggest thing to note is the reason for the thin trapping on front wall is mostly just to deaden any reflections coming from your surrounds. So a basic concept to think of is if the reflection is obscured by wood or speaker or something then absorption there wouldn't really make an impact on high frequencies as they'll already be scattered. However, all other areas where direct reflections can come in would be where you would line with Linacoustic. If its possible, I recommend doing 2" everywhere and not using 1" to get absorption lower in frequency. Also, the pink fluffy idea would work well. I think your plan so far looks good.
post #9553 of 10188
Someone mentioned to me that if you 'laminate' insulation in the middle with a layer of alu foil it will improve dampening in the bass range. Is this correct? Any other issues with it?
post #9554 of 10188
I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.
post #9555 of 10188
Quote:
Originally Posted by LeBon View Post

I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.

ok, that's understandable if used inside the room. Inside the walls there's no need to reduce absorption of anything.

So... is it just a shift, or is bass dampening improved? Anyone?
post #9556 of 10188
Quote:
Originally Posted by GIK Acoustics View Post


Also, the pink fluffy idea would work well. I think your plan so far looks good.

 

Would the pink fluffy stuff be "configuration" dependent?  In other words in that trapezoidal space between the speaker wall and the foundation wall, given a fixed volume of fluffly pink stuff, would it make a difference if I put a column of insulation floor to ceiling in each of the lateral corners vs. just laying all of that insulation flat on the floor and piling it up as high as it would go given the same volume?  And for sake of argument, assuming I'm using 15" wide insulation, would it make a difference if I made a pile X inches high by putting two "rows" of this 15" insulation butting against each other parallel on the floor vs. taking the same volume of insulation and piling it 2X inches high in one single 15" wide stack against the back foundation wall?

Are my results going to be more dependent upon the actual placement of the insulation or the overall volume?

post #9557 of 10188
Quote:
Originally Posted by Nightlord View Post

...Inside the walls there's no need to reduce absorption of anything.

Actually, the idea is to avoid excessive dampening of the higher frequencies in the room, while absorbing low frequencies. It is an "acoustic" treatment, not a "soudproofing" measure.
post #9558 of 10188
Thanks. It improves bass dampening relative to high frequencies but it does not improve dampening per se.
post #9559 of 10188
I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?

Also, what is the purpose of the stage?
post #9560 of 10188
Quote:
Originally Posted by rabident View Post

I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?

If the screen is acoustically transparent, no. If it is not acoustically transparent, then it does make that big acoustically reflective surface even bigger (surround sound bounces off it), and also makes it harder to place L/C/R speakers.
Quote:
Originally Posted by rabident View Post

Also, what is the purpose of the stage?

Cosmetic
post #9561 of 10188
Quote:
Originally Posted by rabident View Post

I've been going to IMAX a lot. I like the really big screen. Are there any acoustic downsides to having a screen that takes up the whole front wall?

Yes I love that huge screen am looking to do the same but you need acoustically transparent screen! Elite screen pro 4K
post #9562 of 10188
Quote:
Originally Posted by Nightlord View Post

Someone mentioned to me that if you 'laminate' insulation in the middle with a layer of alu foil it will improve dampening in the bass range. Is this correct? Any other issues with it?

It doesn't need to be in the 'middle' - it can be on any side. And yes, this gives a slight membrane effect which can enhance low frequency absorption (not by a lot, but it's shown a difference in tests I've seen so...). And I'm not sure if you'd just use plain aluminum foil, the main foil facing that comes on some fiberglass is certainly different than regular foil. You'd want to look for that FRK/FSK facing that is used on the insulation. You can buy it separately.

Quote:
Originally Posted by LeBon View Post

I'll be using 2 layers of 1 inch Linacoustic with 3 mil. plastic film in between. M understanding is that the purpose of the plastic film is to reduce absorption of higher frequencies.

The high frequencies would already be absorbed by the time it got to the middle of the panel so this wouldn't be the best plan. You'd want the 3 mil between the fabric and the insulation to block off some high frequency absorption. However, it is also worth noting that 3mil is likely much too thin to really block any significant high frequency absorption. 6 mil is borderline, somewhere around 10mil is where I'd look if I wanted high frequencies reflected.

Quote:
Originally Posted by RossoDiamante View Post

Would the pink fluffy stuff be "configuration" dependent?  In other words in that trapezoidal space between the speaker wall and the foundation wall, given a fixed volume of fluffly pink stuff, would it make a difference if I put a column of insulation floor to ceiling in each of the lateral corners vs. just laying all of that insulation flat on the floor and piling it up as high as it would go given the same volume?  And for sake of argument, assuming I'm using 15" wide insulation, would it make a difference if I made a pile X inches high by putting two "rows" of this 15" insulation butting against each other parallel on the floor vs. taking the same volume of insulation and piling it 2X inches high in one single 15" wide stack against the back foundation wall?


Are my results going to be more dependent upon the actual placement of the insulation or the overall volume?

You don't want it to be compressed but you aren't describing that. I don't think the orientation of the fibers would have a huge impact - I'm sure there is a difference, but I'm afraid I've never seen testing to confirm one way or the other.
post #9563 of 10188
What do you think of vicoustic http://www.vicoustic.com/vn/Musicbroadcast/default.asp

Their panels look great!
post #9564 of 10188
As 90 degree corners in a rectangular room are bad for bass, will there be an advantage to build a room in a shape of an elongated octagon (rectangular with 4 corners cut)?
post #9565 of 10188
I think most fill the corner with the triangle bass traps but I'd be curious to know the answer too.
post #9566 of 10188
Quote:
Originally Posted by Skylinestar View Post

As 90 degree corners in a rectangular room are bad for bass, will there be an advantage to build a room in a shape of an elongated octagon (rectangular with 4 corners cut)?

Quote:
Originally Posted by Mfusick View Post

I think most fill the corner with the triangle bass traps but I'd be curious to know the answer too.

wink.gif Bad for bass = good for trapping bass. The whole "gang" is there, so why not use that to advantage instead of building a room where the modes are dispersed and impossible to corral? Sorry for mixing metaphors!

post #9567 of 10188
For the front - best use the corners for the subs. In the front you want to kill off as little bass as possible (= very stiff walls), and once the first wavefront has passed by, you want to kill all you can.

I'm not expecting everyone to agree on this. biggrin.gif
post #9568 of 10188
Quote:
Originally Posted by pepar View Post


wink.gif Bad for bass = good for trapping bass. The whole "gang" is there, so why not use that to advantage instead of building a room where the modes are dispersed and impossible to corral? Sorry for mixing metaphors!

+1 - by cutting off the corners you're not changing the amount of bass in the room, you're just getting rid of a good area to absorb it.
post #9569 of 10188
Quote:
Originally Posted by Nightlord View Post

For the front - best use the corners for the subs. In the front you want to kill off as little bass as possible (= very stiff walls), and once the first wavefront has passed by, you want to kill all you can.

I'm not expecting everyone to agree on this. biggrin.gif

Below the Schroeder frequency, room mode range, I don't thing there is a "front" or for that matter a "rear" to the room. So bass should be trapped anywhere one has the space to place traps. At this time I have SSC-style bass traps only in the front of the room; it sounds stunning. If I ever get a round tuit, I will add some more in the rear.

Jeff
post #9570 of 10188
If you trap all the energy radiating from the subwoofer and backwards into the wall, you loose a huge portion of it's entire power. Given the short distance, that bounce is not problematic, rather beneficial. You want as strong bass as possible for first wave and then as little as possible later. ( 1/8th wavelength @ 80Hz is about half a meter, that's nor a problem to get a subwoofer element within half a meter of both back and side walls ).

(Normal) measurements might not be able to tell the methods apart, but ear will.
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