My theater is 16' wide and 19' long. We have one sofa about 12' back and behind that is a 37" high wall which goes about 10' across (see way cool drawing).
Behind the theater is the rest of my finished basement which extends another 30' or so.

Speakers won't move, sub may.

I will treat the front corners (floor to ceiling) and lower right corner (37") with bass traps. Should I be concerned about the wall behind the sofa?

Bonus question. The SPeakers are AV123 X-Statik open baffle speakers (tweeter and mids). I haven't read much about treating rooms with these types of speakers.

Thoughts?

Front
____________
|.................|
|..SP......SP..|
|.................|
|............sub|
|...-Sofa--....|
|.................|
......._______| <-1/2 wall
|................................|
|................................|
|................................|
|................................|
|................................|
|................................|
|................................|
|................................|
|................................|
|................................|
-------------------------

I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.

Any update on this project? Pics?

I need something to copy.:)

This is a follow up and more info about the room I mentioned earlier.

In the planning stages for a new theater in a new house. Need some help and input for sound...

The new theater is already "built". The room is on the 2nd floor over a 3 car garage. Please see the pics, which includes a diagram of the rough space.

The floor space of the room is currently 19'4" wide (from the entry to the left wall)) and 20'6" long (from screen wall to rear). Because the current wall heights of the room are too low for what I want to do, I will be creating a "room within a room" effect, that will create some "unused" space that might be able to be used for sound absorption, but it will not be symmetrical.

All four walls will be 6'6" high and then begin angling at 45 degrees to a ceiling height of 11'2". By setting the wall height at 6'6" around the entire room, the room dimensions become 18'1" long and 16'1" wide. I'm including some pics. In the pics, where you see the boards taped to the wall, that is where the "false" wall height will be. The space behind those false walls is the unused space. On the screen and rear wall, I lose about 14" of floor space. On the left wall, I lose 3'3" of floor space. I plan on a 120" diagonal, non-acoustically transparent screen. I'll be running a 7.1 system. Infinite Baffle subwoofer that will have a large manifold opening the floor of my front stage and the manifold will actually be in my garage below the room. The manifold opening in the floor will span about 8' wide and will be centered in the front stage. Stand up floor speakers for L/R and each approximately 3' from the front wall and side walls. The center channel will rest on the stage floor and be aimed upwards.

I plan on using bass traps in all four corners, and either 2" acoustic foam or OC 703 at ear level and below. Perhaps do the bottom 2 feet of the 3 non-screen walls in 2 or more inches of OC 705 for even more evenly-distributed bass absorption. The room is carpeted. Will I need to put some sound absorption (either batting or 703 or 705) in the ceiling or on the slope walls going up to the ceiling? I can make the "inner" walls acoustically transparent and use the space behind the "inner" walls for sound absorption, but it won't be symmetrical. What are my other acoustic concerns for this room? I know angled walls are difficult to model...

Thanks in advance for the help guys... Todd

More pics...

Any update on this project? Pics?

I need something to copy.:)

I'm just getting the trim painted for the adjacent room and the door way sealed up. So, I have not yet started this phase of the project.

Due to a recent addition to the family, it is probably about a month away from being implemented.

Once I get a chance to get my theater build updated, I'll definitely post what I'm doing in there.

Sorry it's going to be so long, but having a new born in the house keeps you preoccupied.

:D

I still need to figure out if there's anything I can do regarding my LF sound isolation problem. ALL other frequencies - you can't hear a thing... But I might have an idea of where my flank is that's allowing the sound to permeate through the house. I just need to do a few more tests and then come up with a solution - which might actually mean taking up the carpet and floor from the room above the ceiling. :eek:

Todd, if you haven't done so already, I suggest you start your own theater build thread to help isolate your specific issues, and then direct a bunch of us over there. :) We're all here to help as we can.

More pics...

Ah. Now I see what you mean. I would definitely look into using an AT screen and placing the speakers behind the screen and use that space to help with acoustics and asthetics.

Well, I thought I'd just bring up the acoustics part here in this thread since angled walls aren't really covered much... There will be a separate build thread.

Well, I thought I'd just bring up the acoustics part here in this thread since angled walls aren't really covered much... There will be a separate build thread.

OH, I'm not saying you shouldn't have done that. I'm simply stating there sounds like there's more to this build than just the angled ceiling, that's all. :D

Anyone know where to buy corning 703 in the san francisco bay area?

I'd like to get 12 sheets or less of the 1". I saw one place in oakland that sold it, but it was still cheaper on ebay even with shipping....

Anyone know where to buy corning 703 in the san francisco bay area?

I'd like to get 12 sheets or less of the 1". I saw one place in oakland that sold it, but it was still cheaper on ebay even with shipping....
http://www.spi-co.com/

This may be a helpful idea.
In my many years of experience with both home a/v and reading questions regarding How-To info. I've come to realize that there are some patterns of reoccurring questions and responses. Obviously there is not a clear answer to all questions. And all the answers could be debatable in various degrees. But my point remains the same...
I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.
One outline (In like a sideways-tree structure) could address a more appropriate construction from the ground up.
Yet another outline could mirror this, for others who have a room they would like to improve on (as in, a retrofit theme).
And thirdly. A glossary of what the abbreviations and it's definitions would be. So that they can be linked directly when a product, term or abbreviation is mentioned in these outlines. So people who would like to get a basic knowledge of what is involved and how to begin, whey would have a better understanding of how much work it would entail. Then they may plan accordingly. As well as anyone at any given stage in their progress can refer to this to see if they have to step back, sideways or forward with their processes to identify their options for working around a basic/ 'common' acoustic concern.
Again. With most situations there are some general parallels in acoustic properties that must be addressed before step 2-3-4... and so on. This would help me as well as some beginner. And likely minimize excessive forum static/noise.
Your thoughts?
ew

This may be a helpful idea.
In my many years of experience with both home a/v and in reading questions regarding How-To info. I've come to realize that there are some patterns of reoccurring questions and responses. Obviously there is not a clear answer to all questions. And all the answers could be debatable in various degrees. But my point remains the same...
I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.
One outline (In like a sideways-tree structure) could address a more appropriate construction from the ground up.
Yet another outline could mirror this, for others who have a room they would like to improve on (as in, a retrofit theme).
And thirdly. A glossary of what the abbreviations and it's definitions would be. So that they can be linked directly when a product, term or abbreviation is mentioned in these outlines. Thereby people who would like to get a basic knowledge of what is involved, how to begin, and how much work it would entail for them to plan on a direction they may want to take with their ideas from there. And anyone at any stage in their progress can refer to this to see if they have to step back, sideways or forward with their processes and to identify other options for working around a basic/ 'common' acoustic concern.
Again. With most situations there are some general parallels in acoustic properties that must be addressed before step 2-3-4... and so on. This would help me as well as some beginner.
Your thoughts?
ew
Those here with the knowledge and experience who could put something like that together are professional consultants, with "professionals" meaning "they work for money." That they answer questions at all for free is greatly appreciated. I am afraid that you will need to research this material on your own - like the rest of us have - or step up and hire a pro.

Whats really interesting is that the more I learn, the more apt I am to hire a professional.

Maybe someday when my company takes off and I'm doing a redesign. :)

I agree with pepar; I just returned home from spi's KC location with a truckload (384sq.ft.) of 703. Friendly folks with great prices.

Regards,

Larry


http://www.spi-co.com/

I agree with pepar; I just returned home from spi's KC location with a truckload (384sq.ft.) of 703. Friendly folks with great prices.

Regards,

LarryThat's a bunch of 703 :D Just curious, what did you pay. I did finally find a place that charged $1.56/sqft.

People need to call first. The Denver SPI place didn't even sell OC

...I would like to recommend that someone with more time and knowledge put together a general (yet detailed) outline of the basics of how to build a "better" Home Theater room. Kind of like a bible in outline form.

It isn't quite what you've asked, but I tried to outline the links to all of the background material I used in making the decisions for my theater in my first couple posts in my theater build. Maybe it will help.

CJ

I know this is probably a real dumb questions for a lot of you, but I'm going to ask anyway. I've been reading a lot about OC 703 and Linacoustics and others in the forum. I was wondering if there was something comparable that I can just pick up at Home Depot or Lowes. Or something a little less costly. My space is approximately 24x17x8 and all this adds up. I'm building a theater, it doesn't have to be perfect, but I'd like it to be reasonably nice without blowing my budget. Anyone have any suggestions? I see that most people only go up about 3 feet with the fiberglass insulation, what do you recommend above that? Any help will be appreciated. I'll be honest, I don't know what I'm doing, I'm not real knowledgeable in acoustics, I didn't even think about the insulation when I started, but I'm determined to make a nice theater. Thanks in advance and I apologize if this question sucks.

David,

I'm almost ashamed to share; I paid $.85/sqft for the 703 (705 was $1.50/sqft). This is their standard price; they didn't have enough in stock, so i had to wait a week for the OC truck to come in.

Larry


That's a bunch of 703 :D Just curious, what did you pay. I did finally find a place that charged $1.56/sqft.

People need to call first. The Denver SPI place didn't even sell OC

David,

I'm almost ashamed to share; I paid $.85/sqft for the 703 (705 was $1.50/sqft). This is their standard price; they didn't have enough in stock, so i had to wait a week for the OC truck to come in.

Larry

Wow, that's a great price. The best I found around Austin was $1.30/sqft for the 703-plain, and $2.94/sqft for the 705-FRK. 705-plain was a little cheaper at $2.36sqft, but I needed the foil backed 705 for my bass traps.

703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.

OC 703 is 3pcf fiberglass, and the generic name for this is "Type 300." The US manufacturers of fiberglass are Knauf, Owens Corning, Johns Manville, and CertainTeed. 3pcf fiberglass from any of these manufacturers is acoustically equivalent.

Regards,
Terry

703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.

Ah yes, that's why I saw some different prices, but I was just thinking about the 2" boards I was looking at and got.

Ah yes, that's why I saw some different prices, but I was just thinking about the 2" boards I was looking at and got.
Different densities and different thicknesses all, I believe, in the 24" x 48" size. And, IIRC, it was cheaper to buy two 2" panels than one 4" panel.

Different densities and different thicknesses all, I believe, in the 24" x 48" size. And, IIRC, it was cheaper to buy two 2" panels than one 4" panel.

Yeah, I bought all 2" thick panels and doubled them up where I needed 4" thick panels, like for the bass traps in the corners especially.

Really, for how little I paid, plus my time, the sound improvement is quite dramatic. I'm glad I finally did it.

OC 703 is 3pcf fiberglass, and the generic name for this is "Type 300." The US manufacturers of fiberglass are Knauf, Owens Corning, Johns Manville, and CertainTeed. 3pcf fiberglass from any of these manufacturers is acoustically equivalent.

Regards,
Terry

Terry ... what would the JM 1" Linacoustic equivalent be from those other 3 manufacturers ? ... I am having a helluva time trying to find it in my market

Thanks

It seems one of the most popular size for acoustic panels is 2'x4'. I'm guessing, but I suspect it's because 703 (and eq.) comes in that size. I'm using Bonded Logic's UltraTouch which comes in 94" batts. Can someone comment on the value of using larger panels, i.e. 2'x6' or up to the full length, 94", other then aesthetics.

Terry ... what would the JM 1" Linacoustic equivalent be from those other 3 manufacturers ? ... I am having a helluva time trying to find it in my market

Thanks
Linacoustic is a trade name which JM uses to cover a range of their fiberglass duct liner products. The type usually used by forum members is Linacoustic RC (Reinforced Coating), which comes in rolls and has a dark color.

The RC part is kind of their "secret sauce," and JM doesn't like to give out a lot of specifics on this product, like its density. But density is found by simply dividing the weight of a roll by coverage area times thickness, and that makes this stuff 2.25 pcf. :) I wouldn't get hung up on 2.25 pcf vs. 3 pcf. From my own analysis, there's no significant difference in sound absorption between the two.

Can someone comment on the value of using larger panels, i.e. 2'x6' or up to the full length, 94", other then aesthetics.

The more total corner surface you cover, the better. Always. You can do this with multiple 2x4 foot panels, or with larger single panels. No difference.

--Ethan

The more total corner surface you cover, the better. Always. You can do this with multiple 2x4 foot panels, or with larger single panels. No difference.

--EthanThanks Ethan, I'm doing floor in the ceiling corners, I'm referring to first reflection points on the side walls. Would 2'x6' (or larger) be better then 2'x4'?

Thanks again for you help.

Thanks Ethan, I'm doing floor in the ceiling corners, I'm referring to first reflection points on the side walls. Would 2'x6' (or larger) be better then 2'x4'?

Thanks again for you help.
I sized mine to only cover the first reflection points of the L, C & R for all six of my seating positions. If further treatment is required to optimize RT60, it can be added.

Just my $.02.

I sized mine to only cover the first reflection points of the L, C & R for all six of my seating positions. If further treatment is required to optimize RT60, it can be added.

Just my $.02.I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?

I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?

Listening location height. So, if your ear level is between 40" and 60" from the floor, you want to build a panel that covers from say, 36" to 66" vertically to provide the most coverage.

There are also approaches where some engineers prefer to deaden EVERYTHING below the listener's ear level, and then use targeted reflection panels as you are speaking.

So, for us DYI'ers, we have to simply decide what direction we want to go in, and kinda hope we are going to get what we want in the end. Unless you want to spend lots of time doing your own room measurements, etc.

I have a relatively small room, with my entry on the same wall as the screen. I have decided to take the approach of deadening the entire front wall - including the door and behind the screen (I'm doing an AT screen for this reason). Then I'll take measurements and apply the rest of the room as I can.

I am not going to treat the entire lower part of my walls with absorbant materials due to the decor my wife and I want, and what we are willing to live with given our environment... Perfect? No, but it was either that, or hire an engineer to come in an design it all for us and work with us through the entire process, something we did not allocate budgeting for.

If I build another room, however, I will seek professional assistence outside of these forums and researching I did myself and some of the awesome professionals here who I have spoken with.

I hope this helps a little bit.

bty, I found my Low Frequency flank. It's a cold air return in my ceiling that vibrates like hell. I can't get at it from the basement now because of the floating ceiling, but since I'm tearing up the floor in that room above (going to hard wood instead of carpet) I'm going to rip up the floor to access and address that cold air return and try to address the vibrating wall that's right there as well. I also have acoustical floor matting (very, very dense) that I might put under the Hard wood for additional sound control... That's about the best I'm going to be able to do..

I'm sorry if my question isn't clear, but I'm not following. How big did you determine how big your reflection points were? I understand the mirror trick to discover where on the wall the reflection point would be, but what determines the vertical size of the panel?
The panel size and location are all a function of the locations of the speakers and the seats. Think in 3D. The mirror "trick" can define the outline on the panels, but I more or less used my skill at shooting pool. (The angle of the incidence = the angle of reflection.) Specifically, the vertical size of the panel is determined by the height of the speakers and the height of the listeners. If the speakers and the listeners are ALL ON THE SAME PLANE, then the panel will be pretty darn skinny in the vertical dimension.

Visualize the problem and the solution will come to you.

Good point on the plane of the speakers and the listeners. Thinking about how I was going about handling it, that's exactly what I was taking into account without actually pinning exactly what I was doing.

will and pepar - thanks for your patience and explanations, they have been very helpful.

Would 2'x6' (or larger) be better then 2'x4'?

Larger is usually better. It's not a single reflection point, of course, but an area. I suggest using a mirror to identify all places where either loudspeaker is visible. Then extend the area at least a foot in all directions. If the room is too live generally, you could go even larger.

--Ethan

Larger is usually better. It's not a single reflection point, of course, but an area. I suggest using a mirror to identify all places where either loudspeaker is visible. Then extend the area at least a foot in all directions. If the room is too live generally, you could go even larger.

--Ethan

Ya, I know in my case my room is very lively, but I'm not going to be totally sure what I have to do until I get the front wall and screen together. Then I'll measure and see where things stand. My guess is I"ll ahve to go pretty heavy on first and second reflection points, and I know I need some major base trapping, which is going to be VERY difficult in the front of the room due to how close everything is.

Actually, that's a question I have with regards to base traps. I'm going to be hard pressed to fit anything in the front of the room, other than my speaker stands which double as bass traps (can fill them with sand). With this being the case, would you suggest moving the subwoofer to the rear of the room where I'll have a couple of bass traps in the corners (I'm not sure what I'll have there at this point, I just know I will)?

Or should I just take measurements with the woofer in both places and see which comes out a little flatter and roll with that?

Because of this, would you also recommend against a second subwoofer?

My, what a disposition you have there; this was 2" thick 2' x 4' sheets... I'll remember NOT to include build pictures within this thread:rolleyes:

703 comes in a few different thicknesses. Just stating a square foot price without the thickness is like saying that my theater is 20 feet.

Here are some pictures of the UltraTouch Cotton attached to the walls with my specially fabricated acoustic panel attachment devices. ;) The corner traps are 33" across, 24" along the walls.
http://netlowdown.com/blogs/wp-content/uploads/2009/01/left-side-300x225.jpg http://netlowdown.com/blogs/wp-content/uploads/2009/01/right-side-300x225.jpg

Here is a view from the screen back through the theater and on into the pool room and bar area. I'm not sure what I should do if anything on the half wall and the small columns.
http://netlowdown.com/blogs/wp-content/uploads/2009/01/back-300x225.jpg

As an FYI, there is a new product (a couple actually) from Quest Acoustical Interiors (www.questai.com), ... no I don't work for them.

Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.

As an FYI, there is a new product (a couple actually) from Quest Acoustical Interiors (www.questai.com), ... no I don't work for them.

Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.
Thanks, but I could not find the Perf-Sorber. :o

I'm going to be hard pressed to fit anything in the front of the room

Wall-floor and wall-ceiling corners are just as good as wall-wall corners.

my speaker stands which double as bass traps (can fill them with sand).

A tube filled with sand is not a bass trap.

would you suggest moving the subwoofer to the rear of the room where I'll have a couple of bass traps in the corners

Sub location and bass trap location are not really related. If you can post a photo of your room I may be able to suggest something.

would you also recommend against a second subwoofer?

I do fine with one killer SVS sub and a huge amount of bass trapping, but some people are happy with two subs.

--Ethan

Wall-floor and wall-ceiling corners are just as good as wall-wall corners.



A tube filled with sand is not a bass trap.



Sub location and bass trap location are not really related. If you can post a photo of your room I may be able to suggest something.



I do fine with one killer SVS sub and a huge amount of bass trapping, but some people are happy with two subs.

--Ethan

I have family down your way, and I think we are going to visit sometime in April. I should try and see if I can make an appointment to come and visit you.

Here's a basic layout of my room:

http://farm4.static.flickr.com/3166/3012222934_10786b85c8_o.jpg


But, it is Tight around the screen and such. There's very little room in the front for bass traps.

Funny, I thought that a sand filled tube would suffice as partly a bass trap, but, I figured that something wasn't quite right about that. The two rear corners, again are going to be pretty tight, but I have more room to work with in those than in the front...

I might put 4" of 703 on the front wall instead of 2 just to help with the lower frequency absorbtion... Thoughts regarding that?

Or should I really take the time to take all the measurements of the room before doing anything?

Also, where those sconces are there are going to be 4 Cherry columns. They are wood, would mass loading the inside of them help absorb some of the low frequencies? They are not at the 1st and 2nd reflection points.

Thanks, but I could not find the Perf-Sorber
Call them. It may not be up on the website yet. Works very nicely.

I am hoping to make a theater in the upstairs room of a house. The roof slants into the room, creating an odd shape. I am unsure how to acoustically treat the room. Attached is a rough drawing of what I hope the front will look like...where should I put acoustic treatemnts? Should I put them on the slanted parts as well?

http://i177.photobucket.com/albums/w211/Phillyfan1138/newtheater.jpg

I thought that a sand filled tube would suffice as partly a bass trap, but, I figured that something wasn't quite right about that.

There's an article on the DIY TV Network site that shows how to make a "bass trap" from sand in a cardboard tube. That article is the laughing stock of the acoustics industry. I even wrote to them and explained (nicely), but they never replied and the article was still there the last time I checked.

I might put 4" of 703 on the front wall instead of 2 just to help with the lower frequency absorbtion.

Sure, that can only help. Especially if it's near wall-wall, wall-floor, and/or wall-ceiling corners.

They are wood, would mass loading the inside of them help absorb some of the low frequencies?

Not likely.

--Ethan

I previously explained my concrete bunker under the garage that I am currently working on. There is only one wall that is shared with the rest of the home, the other 3 walls are fully below ground level the only thing on the otherside of them is dirt.

If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls? Could I shove regular insulation in there, then some linacoustic (if it is needed?) and then fabric? Then I only have to drywall the top portion.

The one shared wall on the other side of the 8 inch concrete wall is 2X6 framed, and drywalled too.

Also, can anyone tell me if eggcarton shaped foam is a good idea to put on my sloped concrete ceiling?

Thanks,
Berk

If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls?

Drywall, cement, it's all the same - reflective. If you want the room to sound good what you really need are corner bass traps, plus absorbers at the side-wall and ceiling reflection points.

can anyone tell me if eggcarton shaped foam is a good idea to put on my sloped concrete ceiling?

It depends on the quality and thickness of the foam. Generally speaking, better treatments are made from rigid fiberglass.

--Ethan

Drywall, cement, it's all the same - reflective. If you want the room to sound good what you really need are corner bass traps, plus absorbers at the side-wall and ceiling reflection points.



It depends on the quality and thickness of the foam. Generally speaking, better treatments are made from rigid fiberglass.

--Ethan


So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?

Okay thanks, that will save me some time and money.

So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?

Okay thanks, that will save me some time and money.

Keep in mind that you want the room to be insulated for heat/ac as well as sound. Don't want to be sweating/freezing while you're watching movies.

If I'm not worried about sound isolation, only a good sounding room, wouldn't it also work to just not drywall the bottom 48" of all the walls? Could I shove regular insulation in there, then some linacoustic (if it is needed?) and then fabric? Then I only have to drywall the top portion.

The one shared wall on the other side of the 8 inch concrete wall is 2X6 framed, and drywalled too.
Thanks,
Berk

Are you going to have the room inspected by the city ? ( electrical etc ? )

Are you going to have the room inspected by the city ? ( electrical etc ? )

No, I'm not planning having inspections done.

Keep in mind that you want the room to be insulated for heat/ac as well as sound. Don't want to be sweating/freezing while you're watching movies.

I'm definitely going to insulate still, but I'm thinking of saving the bother of putting drywall on top of the insulation, only to add more insulation for accoustics.

So if drywall and cement are both reflective, there is no benefit to drywall the areas that will be covered up with treatments anyways?

Yes, assuming you mean using Liquid Nails etc to glue drywall flat onto the cement. In that case it's bunch of work for no acoustic gain. But making a new stud wall inside the cement wall can help (a little) with acoustics, and that can add thermal insulation too as eugovector said.

--Ethan

Yes, assuming you mean using Liquid Nails etc to glue drywall flat onto the cement. In that case it's bunch of work for no acoustic gain. But making a new stud wall inside the cement wall can help (a little) with acoustics, and that can add thermal insulation too as eugovector said.

--Ethan

No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.

I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.

No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.

I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.
Resale value?

No, I have a 4 concrete walls that I've framed a new stud walls inside which will be fully insulated.

I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.

I guess in theory you could, but you are only going to be saving maybe $100-150 on a several $1000's build. IMO, it's not worth saving in this case. Build a studded wall inside the concrete walls, and decouple that wall. Put Drywall on the whole thing, and then go from there. It'll be the best bang for the buck.

When I did this, I actually glued insulation onto my concrete walls, to help with both environmental and acoustics. Whether or not it made a difference acoustically, I have no idea.

I am asking if it is okay to drywall only the top half of the walls and put fabric wrapped linacoustic (without drywall) on the bottom 48"? My thought is, what is the point of putting drywall on the bottom 48" if I'm going to cover it with accoustical treatment anyway? I'm not concerned about sound isolation.

In that case you'll do well to pack the entire space behind the drywall with fluffy fiberglass. Leaving off the bottom sheet rock will help a lot acoustically, because that gives substantial bass trapping along all the wall-floor corners. I agree with pepar about resale value, though maybe the next owner will want a good sounding room too?

--Ethan

Those here with the knowledge and experience who could put something like that together are professional consultants, with "professionals" meaning "they work for money." That they answer questions at all for free is greatly appreciated. I am afraid that you will need to research this material on your own - like the rest of us have - or step up and hire a pro.

Thanks Pepar for your response. But I feel you have misinterpreted my message a little. It would not intend to weaken the consumer/client relations. I think it would enrich it.

I am in the A/V retail sales industry. And I have been for years. I see with both a consumer-client point of view (it's my hobby) AS WELL as the sales side of things. I always appreciate a more knowledgeable client when I meet one. It makes for a better level of communication. Even if they have the basics down... just a little. I can better understand their motives and interests. It also makes their efforts easier, as well. Since this is a technology based language. It seems obvious to me that one must understand the basics before they can communicate with a more experienced individual.

Often times, a client may not have the full or correct information from what they have learned. But that's OK if they have not executed that idea yet. After talking with a professional, they will be more aware and appreciative of their help and knowledge. They will realize that there is a whole lot more to know. When the client has taken the initiative to attain some knowledge on their own. They then realize it can't be done on their own if they want to do it right and/or done in a reasonable amount of time.

With the intent of this "outline- a/v bible", most of these basics can be covered. This should minimize a level of forum redundancy and advance beginners to intermediate in little time.

no?

Thanks Pepar for your response. But I feel you have misinterpreted my message a little. It would not intend to weaken the consumer/client relations. I think it would enrich it.

I am in the A/V retail sales industry. And I have been for years. I see with both a consumer-client point of view (it's my hobby) AS WELL as the sales side of things. I always appreciate a more knowledgeable client when I meet one. It makes for a better level of communication. Even if they have the basics down... just a little. I can better understand their motives and interests. It also makes their efforts easier, as well. Since this is a technology based language. It seems obvious to me that one must understand the basics before they can communicate with a more experienced individual.

Often times, a client may not have the full or correct information from what they have learned. But that's OK if they have not executed that idea yet. After talking with a professional, they will be more aware and appreciative of their help and knowledge. They will realize that there is a whole lot more to know. When the client has taken the initiative to attain some knowledge on their own. They then realize it can't be done on their own if they want to do it right and/or done in a reasonable amount of time.

With the intent of this "outline- a/v bible", most of these basics can be covered. This should minimize a level of forum redundancy and advance beginners to intermediate in little time.

no?
Nice thoughts, but it would still be a lot of work on a complex subject with many aspects that lack 100% consensus . . with no immediate . . and perhaps simply no . . return.

You're in marketing, aren't you? ;)

Where is a great place to get rigid fiberglass so I may make my own panels? Also are foam panels bad to use?

Perf-Sorber is a combination absorber/diffuser in a single fiberglass panel. An excellent early reflection point product speakers with good off axis response. Also, a good choice around surround speakers. The other (I forget their trade name) is a product with very good absorption down to 150Hz.

So, I was thinking about trying these, or maybe just a plain old absorption panel, at my side reflection points. However, my room has a 6" ledge and then a window about 4' up the wall. The right side wall has no similar constraints. How would I position a panel on this wall?

Here are some photos (see particularly the last one of the bunch):
http://www.avsforum.com/avs-vb/showpost.php?p=15699533&postcount=2825

Thanks!

Nice thoughts, but it would still be a lot of work on a complex subject with many aspects that lack 100% consensus . . with no immediate . . and perhaps simply no . . return.

You're in marketing, aren't you? ;)

Perhaps you are right. There are a lot of good books out there to begin with, as well.

p.s. no. I'm not in marketing. :)
p.s. I've been reading the latest posts. I just would like to throw this out.
If anyone is thinking of putting up a lot of sound treatment on the walls. Be careful of what type of material you use to keep the maintenance low. Mainly mold. For instance. If you live in a humid place and you want to put up something like cotton in a basement wall, consider your options first. You also might want to keep this spider free, too.
ew

Where is a great place to get rigid fiberglass so I may make my own panels? Also are foam panels bad to use?

Here's where I got mine in Dallas: http://www.spi-co.com/index.html

And guess what...they have a location in Omaha: SPI (Specialty Products and Insulation Co.)

5010 I Street
Omaha, NE***68117
402-827-3880
402-827-3882 FAX
omaha@spi-co.com

Great, friendly folks to deal with at my location. I bought 1 1/2" 3# ridgid panels for about $90.00/case (16-2x4 sheets). Worked like a champ.

Anyone have a good place to buy Guilford of Maine fabric?

I have some GIK panels that need to be recovered in a new color.

thanks

In that case you'll do well to pack the entire space behind the drywall with fluffy fiberglass. Leaving off the bottom sheet rock will help a lot acoustically, because that gives substantial bass trapping along all the wall-floor corners. I agree with pepar about resale value, though maybe the next owner will want a good sounding room too?

--Ethan

Thanks Ethan,

I'm more interested in the accoustic results than the resale value, but I'm not sure how anyone would notice that there isn't any sheetrock behind the bottom section if the fluffy fiberglass is covered with fabric wrapped rigid fibreglass panels. What do you think about using painted Tectum board for the bottom section instead of the rigid fibreglass? It would still be on top of the fluffy fibreglass.

Thanks for your input.

Anyone have a good place to buy Guilford of Maine fabric?

I have some GIK panels that need to be recovered in a new color.

thanks
The best price I had found when I built my treatments is here (http://www.silentsource.com/index.html). Every online seller that I found was very "proud" of this product (read: it ain't cheap), but it works and has safety aspects that stuff from the local fabric shop lacks.

Anyone have a good place to buy Guilford of Maine fabric?

I have some GIK panels that need to be recovered in a new color.

thanks

GIK sells GOM fabric separately from the panels for about $15 per yard which seems to be the standard price.

GIK sells GOM fabric separately from the panels for about $15 per yard which seems to be the standard price.
I'm pretty sure that I paid substantially less at the place I linked, but that was some years ago. The poster should compare prices for himself.

Looks like the same price, these days. I'd love to find a lower priced source, too, since I have some substantial areas to cover but have held off due to the price.

To continue where I left off, I have thought of way to keep the height the same. I could use some string, thread, or line with some push pins on each wall to the side of the seats using a level to check it was correct then mark have correct height to measure at. I could also mark using some tape or marker on the string or line to mark exactly where the RS meter would be for each test.

I have some questions first.

Do I wait until I have my left corner treated same as the right before I check these panels at different locations? I'm worried that it will make my measurements more difficult to look at. I have an idea of what the left corner not having the additional trap will cause, so should I just start with the panels and keep that in mind when looking at results? I am aware of what modes this effects.

I have another Pillar trap for the left corner and another pair of GIK 244's on the way also so I am wondering if I should just wait to measure when I have these also.

Another thing I am concerned with is that if I am moving my speakers out to the center of the room that is going to be a problem I would think having my screen area left untreated. Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?

http://farm4.static.flickr.com/3392/3179405244_4fd8461d60_o.jpg

Still at it. Here are the left and right speaker measurements again.

http://farm4.static.flickr.com/3095/3256111006_23b11a5d1e_o.jpg

http://farm4.static.flickr.com/3467/3255281879_a9026966ed_o.jpg

http://farm4.static.flickr.com/3307/3255283083_2c50fe65d3_o.jpg

http://farm4.static.flickr.com/3392/3255284415_e8824b2b52_o.jpg

What do you think about using painted Tectum board for the bottom section instead of the rigid fibreglass? It would still be on top of the fluffy fibreglass.

Sure, or homasote etc works well too and can be painted. Bass goes right through into the fiberglass behind.

--Ethan

Sure, or homasote etc works well too and can be painted. Bass goes right through into the fiberglass behind.

--Ethan


So, just fibreglass in between the studs and painted homesote or tectum on top of that will give me better bass control that covering with sheetrock?

If I did that along the bottom 48" of all walls, and sheetrocked the top, would that be a good balance of absorbtion and reflection?

Do you have any before and after H20 plots to show diff in decay time?
I'm also looking at adding panels and am interested in others results, compared to this chart from Rives site http://www.positive-feedback.com/Issue12/rives2.htm
http://www.positive-feedback.com/Issue12/images/RT-60.gif

After having my theater for 5 years now, I finally got around to analyzing first reflection points and building/mounting acoustic panels. I used 2" thick OC 703 with 2" air gaps for the acoustic panels. I also used 4" thick OC 705 for several corner bass traps. The improvement in the audio is amazing. I've only auditioned a few movie scenes so far, but the difference is tremendous. Even my girlfriend (she's not a video/audiophile) thought the asteroid chase scene in Star Wars Episode II was incredible sounding. :)

Here are some panels on one wall:

http://www.samos.org/Theater/DSC02880-.jpg

I mounted 4 on the ceiling in front the projector. You can also see a bass trap at the ceiling, as well as part of an acoustic panel to the right of the component cabinet.

http://www.samos.org/Theater/DSC02885-.jpg

There are bass traps in the front corners of the room and along the right side at the ceiling. This was before the acoustic panels were installed, and all mounting hardware has been painted black as well, so it's no longer visible.

http://www.samos.org/Theater/TheaterBackView600.jpg

It was a much longer task than I anticipated, but I'm so glad I finally did it.

So, just fibreglass in between the studs and painted homesote or tectum on top of that will give me better bass control that covering with sheetrock?

Yes.

If I did that along the bottom 48" of all walls, and sheetrocked the top, would that be a good balance of absorbtion and reflection?

Hard to say without seeing the rest of the room. Most HT rooms benefit from more absorption than less. So if it were me I'd have bass traps in the upper corners of the walls too.

--Ethan

I am need of some help I am not sure if I calculated my first reflection surface correctly and I may need to move my light positions. I have a small room 15’ (false wall) x 12’ 4”. I am borrowing the Arthouse design alternating wood panels 2’ 2” x 4’ and OC 703 same with 3.5" gap. I will treat behind the screen with linacoustic. I calculated my first reflection surface using info on Ethan’s website at around 1’ 9”.

Speakers are about 1’ 5” from the wall.
Offset I am about 6’ from the same wall
I estimated the distance from the speaker to me ear at 8’. My stage is about 9’ from false wall.

If I estimated correct I only have about 1’ of OC in front of the stage before the wood panel starts. Do I need to shift me center wall light back another 1'? In attached Picture lines indicate light placement and center of wood panel. Thanks for your help in advance I was hoping to wire this weekend.

I am need of some help I am not sure if I calculated my first reflection surface correctly and I may need to move my light positions. I have a small room 15’ (false wall) x 12’ 4”. I am borrowing the Arthouse design alternating wood panels 2’ 2” x 4’ and OC 703 same with 3.5" gap. I will treat behind the screen with linacoustic. I calculated my first reflection surface using info on Ethan’s website at around 1’ 9”.

Speakers are about 1’ 5” from the wall.
Offset I am about 6’ from the same wall
I estimated the distance from the speaker to me ear at 8’. My stage is about 9’ from false wall.

If I estimated correct I only have about 1’ of OC in front of the stage before the wood panel starts. Do I need to shift me center wall light back another 1'? In attached Picture lines indicate light placement and center of wood panel. Thanks for your help in advance I was hoping to wire this weekend.

Is the room built? If so, use the mirror method to find your first reflection points.

No it is just framed out.

[qutoe]Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?[/quote]
The primary purpose for near field measurements is to measure the speaker's performance eliminating room interactions. To determine the impact of room treatments, you should be measuring (and listening) from the seating locations.

Thanks Dennis. I will be getting some mineral wool for the back wall and probobly some more bass traps for the side walls. I would then have a total of 6 for the side walls not counting the one on the door already. My projector conked out so until we get the new one I will be moving the front left and right speakers away from the walls further now. That 84Hz second order width mode and the 85Hz first order length mode are a pain to deal with.

I've read for days concerning various DIY bass traps. Tubes, resonating panels, Helmholtz resonators, and all manner of rigid fiberglass designs with and without air gaps and with and without limp mass membranes and reflective materials. For present purposes I am interested in quick and dirty bass absorption with no regard for aesthetics or other frequencies. Rolls of insulation stacked in the corner are said to be useful.

It seems, generally, that the effectiveness of fiberglass products increases with increasing density. Owens Corning Atticat isa loose fiberglass insulation that comes packaged in stackable plastic bags having dimensions of about 9"X 20"x 38" (about 4 cubic feet of volume). The weight is about 35lbs. Therefore, as packaged, it has a density of about 9 pcf. Rolls and other forms of fiberglass are far less dense. With OC 705 having a density of about 5 pcf, would we not expect Atticat to be a bit more effective at bass absorption than OC 705 per unit volume?

I don't find any mention of anyone trying to use this product as a bass absorber. I'm gonna try it, but before I do, perhaps someone out there can tell me that it doesn't work or why it won't work.

Thanks

I've read for days concerning various DIY bass traps. Tubes, resonating panels, Helmholtz resonators, and all manner of rigid fiberglass designs with and without air gaps and with and without limp mass membranes and reflective materials. For present purposes I am interested in quick and dirty bass absorption with no regard for aesthetics or other frequencies. Rolls of insulation stacked in the corner are said to be useful.

It seems, generally, that the effectiveness of fiberglass products increases with increasing density. Owens Corning Atticat isa loose fiberglass insulation that comes packaged in stackable plastic bags having dimensions of about 9"X 20"x 38" (about 4 cubic feet of volume). The weight is about 35lbs. Therefore, as packaged, it has a density of about 9 pcf. Rolls and other forms of fiberglass are far less dense. With OC 705 having a density of about 5 pcf, would we not expect Atticat to be a bit more effective at bass absorption than OC 705 per unit volume?

It should work, but how well compared to other fiberglass densities? I don't know.

You see, absorption is a function of material acoustic resistivity, thickness, and frequency. Acoustic resistivity increases with density. For fiberglass, it increases reasonably linearly from the data we have - up to 6 pcf. But I don't know above this point. I have no measured data. Mineral wool, on the other hand, shoots up pretty fast in resistivity (non-linearly) above roughly 5 pcf.

For any given frequency, there is an optimum region of porous absorber resistivity and thickness. If you are too far from this region, the absorption will not be maximum. This is known from a ton of empirical data analyzed back in the 80's.

Fortunately, the region is fairly broad. So if your are off some from the optimum, the absorber will still work very well.

That's about all the detail I can give before the subject gets pretty technical and ugly! :D

Regards,
Terry

Terry, thank you. I shall try this and report my qualitative observations for whatever they might be worth.

Doug

I did some searching for "Roxul", "Safe n Sound", "Roxul AND Soffits" and didn't quite find what I was looking for, so...

Using the following picture as a loose guide, I'm planning on building soffits along the sides of my theater. I was planning on simply building a skeleton, fill it with Safe n' Sound and basically wrapping it in GOM (or a suitable budget-friendly replacement).

http://i167.photobucket.com/albums/u129/dc_pilgrim/soffit.jpg

My soffits will be 10 x 24-ish, so I plan on using 3 layers of 3" Safe n Sound. These will be down the sides of the theater. I plan on building some panels for first reflections and for around the screen, likely using the OC-703 if I can find it. I've compared values for Safe n Sound vs 3-inch 703 (plain) on this (http://www.bobgolds.com/AbsorptionCoefficients.htm) site. They seem very comparable... when you don't really know what you're reading :rolleyes:

My main question is, the chunk between the insulation and light tray appears to be solid, and I've seen it as solid in nearly every soffit I've seen on here. Does it have to be solid or can that be just fabric too?

So... Is this a completely horrible idea? Keeping in mind I'm going from nothing to some SnS soffits and first reflection/screen-wall treatments.

I am way back on page 5 of this thread and am planning a build of my own. Can someone help me along by explaining what RT60 refers to.

I am way back on page 5 of this thread and am planning a build of my own. Can someone help me along by explaining what RT60 refers to.
Google is your friend - first link (http://www.google.com/search?hl=en&client=firefox-a&rls=org.mozilla:en-US:official&hs=dC7&defl=en&q=define:RT60&ei=MleSSbjLDonOtQOph7CkCw&sa=X&oi=glossary_definition&ct=title) in the list.

There are many others. Search string was: What is RT60.

Google is your friend - first link (http://www.google.com/search?hl=en&client=firefox-a&rls=org.mozilla:en-US:official&hs=dC7&defl=en&q=define:RT60&ei=MleSSbjLDonOtQOph7CkCw&sa=X&oi=glossary_definition&ct=title) in the list.

There are many others. Search string was: What is RT60.

I had may head so wrapped around this whole accustical thing, I forgot Google was my friend. Thanks:)

Hello,
I need some help with accoustic treatments. I know that waiting until the room is complete is probably not the best thing to do but since I'm a few days from carpet install I hope I'm not to late. I have a "multi purpose" room that is 19.5 X 46. Although it is one big open room it is basically cut in half with one side being a bar and the other side being a 120" screen with projector and 5.1 layout. The room has 2 entrances that do not have doors on them and one bulk head that runs the 46 feet length of the room. The area around the bar is tile, the area of the screen is to be carpet. All of the walls are painted drywall. I have a rough layout document that I can post if it helps. My goal is to be able to tame some of the echo and get the most out of my speakers and equipment using the layout and design of the current room. My question is where do I start?

Hello,
I need some help with accoustic treatments. I know that waiting until the room is complete is probably not the best thing to do but since I'm a few days from carpet install I hope I'm not to late. I have a "multi purpose" room that is 19.5 X 46. Although it is one big open room it is basically cut in half with one side being a bar and the other side being a 120" screen with projector and 5.1 layout. The room has 2 entrances that do not have doors on them and one bulk head that runs the 46 feet length of the room. The area around the bar is tile, the area of the screen is to be carpet. All of the walls are painted drywall. I have a rough layout document that I can post if it helps. My goal is to be able to tame some of the echo and get the most out of my speakers and equipment using the layout and design of the current room. My question is where do I start?

Start with trying to treat the front corners, then think about treating the first reflection points as well.

where do I start?

Steve gave you good advice. Much more here:

RealTraps Articles (http://www.realtraps.com/articles.htm)
RealTraps Videos (http://www.realtraps.com/videos.htm)

--Ethan

I am hoping to make a theater in the upstairs room of a house. The roof slants into the room, creating an odd shape. I am unsure how to acoustically treat the room. Attached is a rough drawing of what I hope the front will look like...where should I put acoustic treatemnts? Should I put them on the slanted parts as well?

http://i177.photobucket.com/albums/w211/Phillyfan1138/newtheater.jpg

I have nearly the exact setup as you are planning. My difference being I have smaller speakers which are wall mounted.

This setup not only presents some acoustical challenges, but some light reflection challenges as well. The screen will reflect a significant amount of light on the ceilings and walls. I just received some triple black velvet from syfabrics that does amazing things for light control. VERY impressive stuff.

So, not to hijack your request for info, but this may serve both our purposes:

I have not yet permanently mounted the velvet on the walls/ceilings. I understand that velvet is not optimum for acoustic treatments. However, I was thinking about using this as a covering fabric over some diy acoustic panels. As you can see in the the above picture, 2" thick panels would really push intruding in the viewing area(see sloped ceiling area).

Would 1 to 1.5 inch thick panels with velvet cover offer any noticable improvement worth the money? I believe the general opinion is some treatment is better than nothing. However, I haven't seen this shape of a room addressed very often, if at all. I'm not looking for a definative answer, just some added opinions before I justify spending the cash on the OC703.

I got noticable improvement after putting bass traps in place and lining the front wall with 1" Linacoustic.

I've taken some measurements and am looking for some advice on the next steps.

After reading the recent discussion about not treating first reflection points, I'm not sure whether that is desirable or necessary.

Can you look at my measurements and give me some advice?

Thanks in advance,
Eric

Link to my thread:
http://www.avsforum.com/avs-vb/showthread.php?p=15820097&posted=1#post15820097

Eric,
After doing it in my own room, I would put up an additional layer of linacoustic on your screen wall.

My wife didn't hear as much improvement as I did but she did notice.

I got noticable improvement after putting bass traps in place and lining the front wall with 1" Linacoustic.

I've taken some measurements and am looking for some advice on the next steps.

After reading the recent discussion about not treating first reflection points, I'm not sure whether that is desirable or necessary.

Can you look at my measurements and give me some advice?

Thanks in advance,
Eric

Link to my thread:
http://www.avsforum.com/avs-vb/showthread.php?p=15820097&posted=1#post15820097

I would recommend a minimum use of 3", but my front wall has over 5". You will want to look at the waterfall tab or spectral decay in REW to observe the improvements in decay time. The different response should ring out more evenly if the treatment is helping the way we want it to. RT60 is not valid for small rooms, but it is interesting to try and figure out how the measurements are generated. Kudos for giving that a try. I think some of us are still stuck reading those articles from the late 90's.

Treating first reflection points is always desirable in home theater.

RT60 is not valid for small rooms, ...

It is at all but the lowest frequencies. Floyd Toole's statement is an oversimplification which gets people's attention at conferences. Presumably, it is meant to goose us acousticians into doing more research on residential-sized rooms instead of just concert halls and churches. But the truth is not black and white.

I and others measure very nice, smooth reverberation decays at 500 Hz and above in small rooms. For some rooms, the 250 Hz octave band is not as good, and in general, the 125 Hz octave band is dodgy.

Linearity of scale is a fundamental principle of acoustics. It's what allows us to build scale models of rooms and obtain meaningful acoustical measurements*. All you do is scale the frequencies accordingly. A reverberant sound field at 400 Hz in a 100 foot space translates to an equally reverberant sound field in a 20 foot space at 2 kHz.

Regards,
Terry

* There is an air absorption effect at high frequencies which does not scale. But this is easily adjusted for.

I beleave that we are not all in agreement with that in other parts of the world, but please don't quote me on that. :)

After following this thread and gathered very good informations from the experts, I added sound absorption in our HT and my next project will be adding bass trap for the front corners, I am glad I did this and very happy with improvement, Before, my wife hate to watch with me because I have to crank up the volume but now she loves it I told her I've been using same level of volume eversince I put this up and she can't believed the improvement. The only stopping me for the bass trap in the corner is if I needed to build a false wall, If I can find a way of putting a bass trap in the corner without building a false wall to hide it that would be great. My Room is just 13x22x7.5

I am open to suggestions you guys can give base from what I have now. Thanks

http://i568.photobucket.com/albums/ss130/rutlian/IMG_2019.jpg
http://i568.photobucket.com/albums/ss130/rutlian/IMG_2020.jpg
http://i568.photobucket.com/albums/ss130/rutlian/IMG_2021.jpg
http://i568.photobucket.com/albums/ss130/rutlian/IMG_2022.jpg
http://i568.photobucket.com/albums/ss130/rutlian/IMG_2024.jpg


After watching a few movies WOW what really an improvement, before I could not differentiate the sounds coming from my main L/R fronts
now it is very clear and it sounds is more solid and much much better.

OK, this seems straightforward from searching AVS and studying theater wall treatment...

FRONT WALL: Acoustical treatment (1" Insul-Shield) floor-to-ceiling.
CEILING: No acoustical treatment - none, nada.
FLOOR: Thick, plush carpet is fine.

But here's where it gets confusing, and I need help...

SIDEWALLS
A) Acoustical treatment (1" Insul-Shield) from floor to ear-height (44"), with 16oz polyester batting above.
--or--
B) Acoustical treatment (1" Insul-Shield) from floor-to-ceiling on all 1st reflective surfaces.

These 2 theories seem to contradict each other. So which is it?


BTW, for those searching for Insul-Shield type product, here are the substitutes which seem to have identical acoustical absorption ratings:

Owens Corning Select Sound Black Acoustic Board
Owens Corning Fiberglas 703 Series duct insulation.
Johns Manville Insul-Shield
Johns Manville Linacoustic Permacoate rolls.
Certainteed Certpro Acoustaboard Black
Knauf Duct board EI-475
Knauf Duct liner EM

...personally, I found the Knauf EI-475 easiest to find (4' x 10' sheets @ $40) from a general heating and air conditioning company.




For 18 hertz to 100 hertz standing wave controll you want sonotubes cut to X length depending on offending frequency with a crappy five dollar subwoofer at one end that absorbs standing waves via woofer movement.

NOTE.
The crappy five dollar subwoofer does NOT have any wires going to it.

Its a perfect Hemholtz resonator thats way above any competing products for base absorption in the 18 hertz to 100 hertz ranges.

HELP: My workers are just about to finish framing a bulkhead we've applied to my ceiling. I'm wondering if there might be a decent opportunity here to apply some acoustic absorption in the portion of the bulk head running along the top of the screen wall. (I'm hoping to tame a bit of bass bloat, ideally, but otherwise I would hope this would do something beneficial).

The bulkhead portion above the screen is 12 foot 9 inches long, 24 inches wide and 6 inches thick from the ceiling. I wonder if we can make a frame that shape and, since I'm going to cover the entire bulkhead with fabric, just fit some sort of acoustic material in the portion over the screen.

Any suggestions? Here are to depictions of my screen wall, looking up so you can see the bulkhead that is being built from the ceiling. In the second image I've indicated a sort of frame idea (to be covered in fabric) in the bulkhead in front of the screen:

http://img134.imageshack.us/img134/3108/1avroomlookingupnf9.jpg (http://imageshack.us)
http://img134.imageshack.us/img134/1avroomlookingupnf9.jpg/1/w1024.png (http://g.imageshack.us/img134/1avroomlookingupnf9.jpg/1/)

With the bulkhead trap indicated above the screen:

http://img16.imageshack.us/img16/4104/2avroombulkheadtraprv9.jpg (http://imageshack.us)
http://img16.imageshack.us/img16/2avroombulkheadtraprv9.jpg/1/w1024.png (http://g.imageshack.us/img16/2avroombulkheadtraprv9.jpg/1/)

HELP: My workers are just about to finish framing a bulkhead we've applied to my ceiling. I'm wondering if there might be a decent opportunity here to apply some acoustic absorption in the portion of the bulk head running along the top of the screen wall. (I'm hoping to tame a bit of bass bloat, ideally, but otherwise I would hope this would do something beneficial).

The bulkhead portion above the screen is 12 foot 9 inches long, 24 inches wide and 6 inches thick from the ceiling. I wonder if we can make a frame that shape and, since I'm going to cover the entire bulkhead with fabric, just fit some sort of acoustic material in the portion over the screen.

Any suggestions? Here are to depictions of my screen wall, looking up so you can see the bulkhead that is being built from the ceiling. In the second image I've indicated a sort of frame idea (to be covered in fabric) in the bulkhead in front of the screen:

http://img134.imageshack.us/img134/3108/1avroomlookingupnf9.jpg (http://imageshack.us)
http://img134.imageshack.us/img134/1avroomlookingupnf9.jpg/1/w1024.png (http://g.imageshack.us/img134/1avroomlookingupnf9.jpg/1/)

With the bulkhead trap indicated above the screen:

http://img16.imageshack.us/img16/4104/2avroombulkheadtraprv9.jpg (http://imageshack.us)
http://img16.imageshack.us/img16/2avroombulkheadtraprv9.jpg/1/w1024.png (http://g.imageshack.us/img16/2avroombulkheadtraprv9.jpg/1/)

Since it is an area you are concerned about possible bass build up, that area should be very well constucted espicially for the subwoofer. I might check unless you already did. What to do with the area above the screen? I personally would attempt at placing some regular insulation up there, then something rigid under that so as to support the absorption above and keep it from being lumpy. After some sturdy support bracing under the rigid absorption (not overdone) you could place the fabric over the area however you needed for the hidden treatment.

Sorry to be so off topic but I've just moved into a house that has an awful acoustic environment for loud kids that are easily exciteable. I'd like to absorb some of this mess before it reaches my poor brain. My question is if there is anything I can just make home made that has a 100% or near 100% absorption that also won't look like a complete mess?

I realize I could just tell them to shut up.

Thanks. Please. ;)

Sorry to be so off topic but I've just moved into a house that has an awful acoustic environment for loud kids that are easily exciteable. I'd like to absorb some of this mess before it reaches my poor brain. My question is if there is anything I can just make home made that has a 100% or near 100% absorption that also won't look like a complete mess?

I realize I could just tell them to shut up.

Thanks. Please. ;)

Are you trying to stop the sound from echoing when they are yelling in the same room as you or ...

are you trying to create a room for them that they can yell away in and you cant hear them in the rest of the house ?

If it is the first then there are lots of examples of DIY acoustic panels in this forum ... just do a search

If it is the latter then visit www.soundproofingcompany.com and read the articles in the library

A little of both actually. This house echos like crazy and I'd like to treat all the hotspots. I'll look into that link and do a search thanks.

earplugs

CJ

What would one say my RT60 is? There is alot of trapping in the room.

Perhaps too much. :(

Looks like this was measured with Room EQ Wizard, which actually does a good job in calculating RT60. The reverberation times should ideally be the same over frequency, at least down to 200 Hz. The EBU recommends to within 0.05 seconds. When they are not, and there is more reverb at high frequencies, the subjective impression can be of a "too live" high end, or a "too dead" low end.

Regards,
Terry

Terry Montlick,

Can you give any comment on my question about possibly employing acoustic absorption above the screen (as in the room sketches I supplied above)?

I'm trying to figure out if it will be worth the hassle (any benefit), and I am at that critical part of construction so I have to make the decision.

Thanks.

I have a large living room, the dimensions are approximately 20 feet by 25 feet. The ceilings are vaulted, and approximately 15 feet tall at the top. My dining room is directly attached to the back of the room and open, so it extends another 12 feet, and is around 15 feet wide. All of the flooring is porcelain tile. The walls are covered with wood paneling that has been painted over. The ceiling is sheetrock.

As you can see, all of these factors contribute to a very live, reverberant space. I just purchased this house recently, and before I moved any furniture in, it was pretty much an echo chamber in my living room. Now, with furniture and a rug, it is slightly better, but still way too reverberant for serious music/movies listening.

I was thinking about purchasing some acoustic panels, these actually: http://www.atsacoustics.com/item--ATS-Acoustic-Panel-24x48x4--1008.html

I was going to purchase 6 of them, but is that even enough to make a difference in such a large room? Their 'calculator' says I need approximately 75 of them, but I figure that is for a veritable anechoic chamber.

Will 6 of these panels make an easy to hear difference, or am I better off spending my money on something else?

Perhaps too much. :(

Looks like this was measured with Room EQ Wizard, which actually does a good job in calculating RT60. The reverberation times should ideally be the same over frequency, at least down to 200 Hz. The EBU recommends to within 0.05 seconds. When they are not, and there is more reverb at high frequencies, the subjective impression can be of a "too live" high end, or a "too dead" low end.

Regards,
Terry

You answered my post before I could delete it and it wasn't there very long.:cool: I had my speaker ports plugged on accident and I'm not sure how this would have effected the results. I will try again this morning. My mic clips because of the reflections off the back of my couch. I will try and see if I can get one without it clipping. These are without the front wall treated for which I ordered some OC 705 2" to cover it with.

Here are some mesurements of my progress. I calibrated levels with my THX optimizer, then I turned down the level on my pre/pro to an 80dB target in REW. There was a thin blanket behind the mic, and no clipping this time. At an 85dB target REW said I had .01 headroom. The subwoofer level on my Outlaw was: subwoofer -3 and the other speakers were -3 to -2. It's a bypass multichannel input with the internal 80Hz crossover set to on. Measurements are 0Hz - 2000Hz 1 sweep at 256K. The levels matched so I used the calibration of the soundcard using my external source. The Helmholtz Resonator in the back of my room was converted to a broadband bass trap and the corners have insulation. The back of the rooms ceiling has no insulation exluding the insulation in the tiles. The traps in the back are 1/4 full each from the corners.

Left channel decay

(Treatments in this area are...GIK Pillar Trap, 3 GIK 244's, a 2" panel, GIK Monster Trap, lower and upper walls corner trapping with light or thick insulation, upper ceiling 2" pink inside tiles and Quiet Batt above that.2" panels cover the front wall stage.)

http://farm4.static.flickr.com/3336/3294417253_de3649a1db_o.jpg

Right channel decay.

(Treatments in this area are...GIK Pillar Trap, 3 GIK 244's, a 2" panel, GIK Monster Trap, lower and upper walls corner trapping with light or thick insulation, upper ceiling 2" pink inside tiles and Quiet Batt above that. 2" panels cover the front wall stage.)

Right channel decay
http://farm4.static.flickr.com/3336/3294417253_de3649a1db_o.jpg

Center channel decay

The speaker is sitting on a subwoofer with concrete tiles under it between the left and right channels. All speakers including the center channel are the same model at this time. There is no absorbtion on the front wall behind where the screen will be right now.

http://farm4.static.flickr.com/3595/3295241216_889abab450_o.jpg

Right surround decay

(treamtents in this area are a large broadband bass trap under it, small corner trapping with Rockwool 60 above that next to the speaker, and the ceiling tiles. There is concrete laying under the speaker and on the large broadband bass trap that it sits on. Subwoofer nearby is decoupled from the stage now with a hole inside the stage sitting on concrete tiles surrounded by insulation. Walls behind and to the side of the speaker are bare.

http://farm4.static.flickr.com/3343/3294418891_e6cbdf6f18_o.jpg

Left surround decay

(treamtents in this area are a large broadband bass trap under it, small corner trapping with Rockwool 60 above that next to the speaker, and the ceiling tiles. There is concrete laying under the speaker and on the large broadband bass trap that it sits on. Subwoofer nearby is decoupled from the stage now with a hole inside the stage sitting on concrete tiles surrounded by insulation. The wall behind and to the side of the speaker are bare. There is a hollow core steel door with 4" traps on it nearby.

http://farm4.static.flickr.com/3618/3294419871_712b69ea4b_o.jpg

RT60 of all speakers. I am aware this isn't how to measure RT60 but it's interesting to look at in this case. My left surround measures a higher RT60, the worst looking response I have of all speakers.

Red = Left
Blue = Center
Green = Right

(I always use those colors now)

Surround left = orange
Surround right = purple

(these look like good colors to use???)

http://farm4.static.flickr.com/3443/3295240408_db6f7114b2_o.jpg

Any interpretations of these results? These RT60 measurements are sort-of accrurate?:confused:

Edit: There is also corner trapping with Rockwool 60 behind the Pillar traps.

Terry Montlick,

Can you give any comment on my question about possibly employing acoustic absorption above the screen (as in the room sketches I supplied above)?

I'm trying to figure out if it will be worth the hassle (any benefit), and I am at that critical part of construction so I have to make the decision.

Thanks.
In general, absorption at or near the front is good. In general, bass absorption, as afforded by a thick absorber placed in a corner, is good (though SteveMo's recently posted RT60 times from REW appear to show too much LF absorption).

As to whether it is good for your specific room with a reasonable degree of certainty, I don't know. There is a ton of additional detail required, and even then, it can take me hours to come up with an evaluation/diagnosis/treatment plan. Sorry that there is no simple answer. :(

Regards,
Terry

I can say that it sounds alot better than 1/2" DW/insulation inside 2X4 stud wall/concrete and it probobly sounds better than DW/steel ceiling. I'm also glad I didn't keep the concrete & steel room a 20X20 square.

In general, absorption at or near the front is good. In general, bass absorption, as afforded by a thick absorber placed in a corner, is good (though SteveMo's recently posted RT60 times from REW appear to show too much LF absorption).

As to whether it is good for your specific room with a reasonable degree of certainty, I don't know. There is a ton of additional detail required, and even then, it can take me hours to come up with an evaluation/diagnosis/treatment plan. Sorry that there is no simple answer. :(

Regards,
Terry

Thanks Terry. Just so I am clear, you say in general a thick absorber placed in the corner is good for bass absorbtion.

Does the panel location shown in my pictures counts as "being in the corner?" It's a panel that touches the top corner of the screen wall, but I don't know if that counts as being in a corner in terms of the proper place to
get bass absorbtion benefits. (Or whether you need a trap that somehow actually spans the two sides of a corner, like a corner trap, to do the job).

Thanks,

Does the panel location shown in my pictures counts as "being in the corner?"
To be technically correct, I should have said "edges" instead of "corners." A shoe box shaped room has 12 edges. They are all good places to absorb bass. Each edge is a high pressure zone for all the room modes in 2 out of 3 dimensions. Only the "real" (3-way) corners, of which there are 8, cover modes in all three dimensions. But it is hard to place really deep absorbers in those corners without cutting off a lot of space in the room.

Got it, thanks Terry.

My idea is to cover the entire dropped ceiling in a fabric that would be both light absorptive (to cut reflections down for the projected image) and that is also a suitable covering for the portion of the ceiling containing the bass trap. Do I have to limit my choice of fabric somehow? I.e. does the fabric have to have some distinct level of acoustic transparency (like speaker grill) or will most fabrics allow the sound through to let the bass trap material absorb the sound?

Anyone?

Thanks.

Hello, I'm very new to acoustical treatments, I have been reading up on it when I've had the time but I need advice for my small, 10'x12' room. What I need to know is this: on the 12' side walls I have a 5'x6' window on one side and on the other side I have a 7'x6'6" closet with folding doors (made out of the same material that the interior doors are made out of, hollow core). If I use 2" O.C. 703 acoustic panels (4-18"x4') on the folding closet doors and nothing on the other wall with the window will it hurt my SQ, possibly make it uneven? The window is dual paned with miniblinds and lightly insulated curtains. I am also thinking about acoustic panels on the back wall and maybe a couple smaller panels behind my front speakers. Bass traps will probably come a little later. I appreciate any replys at all, I'm planning on starting my DIY panels very soon. Thanks

Hello, I'm very new to acoustical treatments, I have been reading up on it when I've had the time but I need advice for my small, 10'x12' room. What I need to know is this: on the 12' side walls I have a 5'x6' window on one side and on the other side I have a 7'x6'6" closet with folding doors (made out of the same material that the interior doors are made out of, hollow core). If I use 2" O.C. 703 acoustic panels (4-18"x4') on the folding closet doors and nothing on the other wall with the window will it hurt my SQ, possibly make it uneven?

It might not be as noticable if there is lots of absorption inside the closet. Be cautious of things in there that are in contact with the wall that is rigid. If you add panels there will be a damping effect but the stiffness of any shelving in there could add a bump to the absorption based on what frequencies are conducted through the panel. It's like hanging a panel with a larger frame versus hanging one with a smaller frame. Consider the mass of the panel and things nearby because as panels vary in there framing, this alters the absorbtion coefficients of very low frequencies and it can cause decay to last longer or shorter to that direction which can become distracting if there are sounds that are low in frequency panning left to right, or only all left, or only all right. You can experement by listening to the tones of your wall with the closet versus next to the other wall. You may find thicker panels on the door to give it a greater mass works best, but thats only a suggestion and to be taken with a grain of salt. Filling the closet with as much of any kind of damping material will help. Try leaving an air space between the wall in the HT, and the damping material.


The window is dual paned with miniblinds and lightly insulated curtains. I am also thinking about acoustic panels on the back wall and maybe a couple smaller panels behind my front speakers. Bass traps will probably come a little later. I appreciate any replys at all, I'm planning on starting my DIY panels very soon. Thanks

You might place some furniture near the window if there is not already. It may not be a problem. You could try placing a panel on a stand in front of it. Is there room for some panels to straddle the front corners? Might try some thicker panels straddling the corners. Then you can also try them on the back wall and behind the speakers. For smaller rooms it is usually best to avoid thin panels if possible.

It might not be as noticable if there is lots of absorption inside the closet. Be cautious of things in there that are in contact with the wall that is rigid. If you add panels there will be a damping effect but the stiffness of any shelving in there could add a bump to the absorption based on what frequencies are conducted through the panel. It's like hanging a panel with a larger frame versus hanging one with a smaller frame. Consider the mass of the panel and things nearby because as panels vary in there framing, this alters the absorbtion coefficients of very low frequencies and it can cause decay to last longer or shorter to that direction which can become distracting if there are sounds that are low in frequency panning left to right, or only all left, or only all right. You can experement by listening to the tones of your wall with the closet versus next to the other wall. You may find thicker panels on the door to give it a greater mass works best, but thats only a suggestion and to be taken with a grain of salt. Filling the closet with as much of any kind of damping material will help. Try leaving an air space between the wall in the HT, and the damping material.



You might place some furniture near the window if there is not already. It may not be a problem. You could try placing a panel on a stand in front of it. Is there room for some panels to straddle the front corners? Might try some thicker panels straddling the corners. Then you can also try them on the back wall and behind the speakers. For smaller rooms it is usually best to avoid thin panels if possible.
First of all thank you for the quick reply. My closet is filled with lots of clothes hanging on a pole. Also what thickness of CO 703 would you recommend and how much of an air gap should I leave? You are talking about a air gap between the wall and the acoustic panel correct? What treatments in a small room (10'x12') would give me the most improvement? Would it be panels or bass traps? Which area of the room would benefit most from acoustic treatment? I know it's kinda hard to answer these Qs without seeing the room but just general answers would help me. Thanks again. Edit: Is it beneficial to put panels behind speakers that are ported, that includes subs that are rear ported?

First of all thank you for the quick reply. My closet is filled with lots of clothes hanging on a pole. Also what thickness of CO 703 would you recommend and how much of an air gap should I leave? You are talking about a air gap between the wall and the acoustic panel correct? What treatments in a small room (10'x12') would give me the most improvement? Would it be panels or bass traps? Which area of the room would benefit most from acoustic treatment? I know it's kinda hard to answer these Qs without seeing the room but just general answers would help me. Thanks again. Edit: Is it beneficial to put panels behind speakers that are ported, that includes subs that are rear ported?

Clothes, yes those work very well.

A thick panel is considered a bass trap, because it gets down into the low frequencies where bass is a problem. A panel that is 4" - 7" or more is considered a bass trap, and those can be good for straddling the corners. You could also use a pair of panels in the corner to increase the thickness. This is good if you don't want to have to install something permanantly in the corner or build a superchunk to only find it is too small or too large. You can experement with one by placing insulation or other damping materials behind it to see what return benifits you have, and this can give an idea what to plan for should you need to have more effective bass trapping in the corners later on.

You want to cover the room in an even amount of absorption spread around the room, and the thicker panels will get into the lower frequencies were most problems will be at. I would try experementing with a pair of thick panels around the room and see where you get the most benifit. The comb filtering can smear the acoustical imaging, and this problem is in the lower fequencies in a small room because the acoustical interferance is greater as speakers are closer to the walls, have more sound reinforcement that is not sound from the speaker, but instead sound reflecting off the wall to the listening area. When you add a bass trap to the wall at your first reflection points the sound is absorbed and what you hear is the off-axis response mixed into the movie that is from the speaker, not effected by the wall. You will probobly want to start with the front of the room, because this is where most sound is being reflected towards what we hear causing the distruction of the soundfield.

I have found that when you put absorption behind a ported speaker there can be a benifit, but this is difficult to predict. It might be treating a problem where in fact the problem is sound of the wall going over into a corner for example. If your not sitting directly in the path of the sounds that are coming off the wall it might not be as noticable a difference with the panel behind the sub. You can easily tune the difference by moving the subwoofer away from the absorption, but it might mean moving it far from the panel. A general rule is to keep the subwoofer X2 the distance from the wall as the diamater of the port on the subwoofer. You can also try experementing as I do by placing you ear right up next to the opposite wall and see if the sound is tight, or muffled with a scene that contains lots of bass bellow the tuning frequency of the subwoofer.

Here is one of my new bass traps in the rear of the room being built. It's a plywood box that has openings and fabric on the front with trim around it. There is R30 and R19 inside.

http://farm4.static.flickr.com/3457/3302500644_c5421c3f9f_o.jpg

In a small room, 10'x12'x8', should I use diffusers or absorbers on the rear wall, behind the listening position? Thanks for any replys.

Nevermind, I found the info, thanks anyway.

Here are some new results. looks like there are now more peaks around the 60Hz - 167Hz area now instead of the ones around 340Hz - 572Hz since moving the speakers some to make them match better.


Took the kraft paper off insulation in the stage & uncompressed it some
Moved more 2" panels over the stage
Covered the front wall with OC 705 2"
Moved the Pillar Traps away from the corners some & removed insulation under them
Removed alot of concrete from the room awaiting to be filled
Filled rear traps with insulation
Removed plywood, blankets clothes, from the rear ceiling & replaced with insulation
Placed insulation in areas to maintain symmetry
Moved speakers away from the listening position inches
Didn't equalize bellow 50Hz


http://farm4.static.flickr.com/3383/3306027418_4a1ec32048_o.jpg

Left speaker + subwoofers

http://farm4.static.flickr.com/3348/3305199139_27cd4f92b8_o.jpg

Right speaker + subwoofers

http://farm4.static.flickr.com/3557/3306029492_6156fffae8_o.jpg

I tried my best to match the speakers but they have been taken apart and repaired, so that may be impossible. I added one layer of the cloth material from extra speakers behind the lower second drivers in each speaker since they did not have any if that makes any difference to these results. The speakers themselves begin to vibrate and resonate some around 250Hz, but they always did. I thought it might help that. One of them may not have the extra material inside of it but I would have to check to be certain. Guessing I would say the right does not. The RS Meter was pointing up for the measurements.

edit: The right speaker had the extra peice of absorption behind the speaker inside I added recently. I don't think that I will need that anymore so I removed it.

Hi Steve,

Trying to read a series of decay curves is almost as hard as reading the tea leaves in a waterfall diagram. Very pretty, but what do they mean? :D

Info that must accompany such diagrams in order to have hope of making any sense at all out of them are the analysis window size in ms, plus the time interval between "slices," or the overall time duration and the number of slices which divide up this time.

Regards,
Terry

Also, better to show RT60 graphs on a vertical scale with at least 0.1 second grid markings, like you did earlier. John Mulcahy's REW calculation for RT60 is one of the few out there that I would trust. :)

Hi Steve,

Trying to read a series of decay curves is almost as hard as reading the tea leaves in a waterfall diagram. Very pretty, but what do they mean? :D

Info that must accompany such diagrams in order to have hope of making any sense at all out of them are the analysis window size in ms, plus the time interval between "slices," or the overall time duration and the number of slices which divide up this time.

Regards,
Terry

To empty my ceiling, rear traps, stage trapping, partition wall, are all very difficult to show as an example, but I can remove all of the others ones more easy. The other ones I measure so they are exact on each side to 1/2". I will remove those later today so we can see the difference I am trying to show. Wouldn't it be easier to simply read the thousands of post about it? ;) The window is the default settings in REW but you can see the vertical and horizontal scale on the graphs.

Here you are. These show some of the changes in a condensed fashion. Sorry if you not are as impressed with this as I am. I choose each treatment the best I could for an even coverage of absorption. I usually listen to music around 92dB and moves from -14dB reference and more commonly -4dB to 0dB reference.

Room treatments where they are.
http://farm4.static.flickr.com/3460/3307198179_6686e4a765_o.jpg

Removed 2" panels from the front of the stage.
http://farm4.static.flickr.com/3436/3308028084_97b100d90c_o.jpg

Removed a pair of 2" ATS panels and 6 GIK 244's from first reflection points.
http://farm4.static.flickr.com/3372/3307195883_d804c94db7_o.jpg

Removed the pair of GIK Pillar Traps. Ouch!
http://farm4.static.flickr.com/3584/3307194327_f5b173b017_o.jpg

Removed the pair of GIK Moster Traps.
http://farm4.static.flickr.com/3621/3307192999_5e2a642e20_o.jpg

Removed the 6 panels of OC 705 from the front wall.
http://farm4.static.flickr.com/3370/3307191783_bdde206571_o.jpg

Left in the room in that graph is the ceiling absorption, rear traps, stage trapping, corner trapping, panels on the door, and the riser if you wanted to count that.

newbie questions to all experts:

with all these graphic testing, data sheets or anything you like it to be called, how and when a hometheater owner can get satisfied, do I need to do these testing too or just listen with my sounds and if I like the way it sounds in my dedicated hometheater do I stop and enjoy movies or should I continue on calibrating my sounds but when should I stop if I go that route. Currently I have sound abpsortion all 12 24x48x2 2 24x24x2 scattered in my hometheater, should I go with more treatment for me right now I am satisfied and very happy with the result, but should I do testing? or stop right here since I am happy already. Very confused with all these graphics :confused:

Thanks

newbie questions to all experts:

with all these graphic testing, data sheets or anything you like it to be called, how and when a hometheater owner can get satisfied, do I need to do these testing too or just listen with my sounds and if I like the way it sounds in my dedicated hometheater do I stop and enjoy movies or should I continue on calibrating my sounds but when should I stop if I go that route. Currently I have sound abpsortion all 12 24x48x2 2 24x24x2 scattered in my hometheater, should I go with more treatment for me right now I am satisfied and very happy with the result, but should I do testing? or stop right here since I am happy already. Very confused with all these graphics :confused:

Thanks

Do you find yourself having to adjust the volume level alot from movie to movie, adjusting the center channel level or perhaps trying to move it to one side? Do sounds from one speaker to the next sound like a smooth transition?

Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.

Previous recording

http://www.4shared.com/file/76595402...tey_dance.html

Recording after new treatments with some other changes in the room.

http://www.4shared.com/file/89479731...dance_new.html

Thanks for the info steve, I will listen to it tonight when I go home, I appreciate it I am sure this will help me understand a lot.

Thanks,

Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.

Previous recording

http://www.4shared.com/file/76595402...tey_dance.html

Recording after new treatments with some other changes in the room.

http://www.4shared.com/file/89479731...dance_new.html

SteveMo-
No dice on those links. Any chance you could re-post? I'd like to try them out.

SteveMo-
No dice on those links. Any chance you could re-post? I'd like to try them out.

Try using the sites download page.

Previous

http://www.4shared.com/file/76595402/bbeb7456/saftey_dance.html

Recent

http://www.4shared.com/account/file/89479731/1a5b784f/saftey_dance_new.html

You will have to excuse the quality of the RS Meter mic in these. The meter was set to 100 and the playback level was 0dB. Right and left channel levels were the same values which gave results like in the graphs above. The previous one needed some level matching, but I have not checked a calibration disc yet.

Listened to both and definitely could tell the diff from the two, I am glad I put some treatment in my HT. Thanks for sharing steve.


Do you find yourself having to adjust the volume level alot from movie to movie, adjusting the center channel level or perhaps trying to move it to one side? Do sounds from one speaker to the next sound like a smooth transition?

Here is a recording I made awhile back of before making changes to the room and adding treatments and as it is now. It's easy to hear the difference.

Previous recording

http://www.4shared.com/file/76595402...tey_dance.html

Recording after new treatments with some other changes in the room.

http://www.4shared.com/file/89479731...dance_new.html

I am planning to make a false soffit along the lines of this design:

http://i167.photobucket.com/albums/u129/dc_pilgrim/soffit.jpg

I am wondering if it is better to

- fill it to the brim with Acoustic cotton or OC 703, or

- do superchunk wedges of OC 703?

Let me guess, it depends on the room and the problem frequencies?

Here are pics of each basic design, since I like pictures.

Cotton-ie:

Here is the Side Soffit (without Light Tray). Notice the bass absorbtion in there as well.

http://loutrixrecords.com/images/theater-pix/Star-Panels/DSC05992.jpg



Chunky:

http://www.peparsplace.com/assets/images/studiotips_superchunk_18.jpg

Try using the sites download page.

Previous

http://www.4shared.com/file/76595402/bbeb7456/saftey_dance.html

Recent

http://www.4shared.com/account/file/89479731/1a5b784f/saftey_dance_new.html

You will have to excuse the quality of the RS Meter mic in these. The meter was set to 100 and the playback level was 0dB. Right and left channel levels were the same values which gave results like in the graphs above. The previous one needed some level matching, but I have not checked a calibration disc yet.

Thanks for posting that. There's a significant difference in voice intelligibility. Funny, I didn't think the "old" one was too bad until I listened to the new. That's probably what about 95% of home theater owners would say after they've discovered room treatments (if they ever do).

I am planning to make a false soffit along the lines of this design:

http://i167.photobucket.com/albums/u129/dc_pilgrim/soffit.jpg

I am wondering if it is better to

- fill it to the brim with Acoustic cotton or OC 703, or

- do superchunk wedges of OC 703?

Let me guess, it depends on the room and the problem frequencies?

Here are pics of each basic design, since I like pictures.

Cotton-ie:


Chunky:

http://www.peparsplace.com/assets/images/studiotips_superchunk_18.jpg
I think that the SSC profile is triangular because adding the "second" triangle to make it square wouldn't add that much to the performance. And I think the same would apply to the cotton. As for the effectiveness of the two materials, I *think* the 703 is better, but you should consult the absorption chart at http://www.bobgolds.com/AbsorptionCoefficients.htm.

I currently have nearly finished my theater room, now its just a matter of where to place my acoustic panels. I have made six 2ft x 4ft panels and want to know the best placement based on my room design. I have read that you want to absorb any reflective sound between the front of the room and the listener yet leave the back of the room more reflective to liven up the rear channels, is this correct. Any help would be appreciated.

http://i143.photobucket.com/albums/r146/Dizyer/HTDiagram.jpg

Hi guys

silly question but..

If you dont have an acoustically transparent screen (Carada BW 2.35) then is there any benefit in placing acoustic material directly behind the screen?

Will it still absorb some sound reflections?

My speakers will be below the screen.

thanks for any advice
Darren

Triax ...
You're placing a full range speaker next to a wall boundary and effectively in a corner. You'll need very significant treatment in those areas.

I think that the SSC profile is triangular because adding the "second" triangle to make it square wouldn't add that much to the performance. And I think the same would apply to the cotton. As for the effectiveness of the two materials, I *think* the 703 is better, but you should consult the absorption chart at http://www.bobgolds.com/AbsorptionCoefficients.htm.

So that is why they are triangles? Its basically bang for buck? So by doing triangles you can cover double the space for the material provided?

I didn't know that. I'd like to see more on the theory around the how's and why's of the chunks. I picked up some rigid fiberglass second hand, I certainly would prefer to stretch out the stock on hand. . .

I currently have nearly finished my theater room, now its just a matter of where to place my acoustic panels. I have made six 2ft x 4ft panels and want to know the best placement based on my room design. I have read that you want to absorb any reflective sound between the front of the room and the listener yet leave the back of the room more reflective to liven up the rear channels, is this correct. Any help would be appreciated.
If it were my room:

http://www.peparsplace.com/storage/HTDiagram.jpg

4" behind the front speakers, 2" everywhere else. What is the floorcovering?

Also, I would pull the front speakers away from the front wall.

So that is why they are triangles? Its basically bang for buck? So by doing triangles you can cover double the space for the material provided?
Yes.

I didn't know that. I'd like to see more on the theory around the how's and why's of the chunks. I picked up some rigid fiberglass second hand, I certainly would prefer to stretch out the stock on hand. . .
Here is the specific section on the Studiotips forum for the SuperChunk trap (http://forum.studiotips.com/viewtopic.php?f=8&t=535). I suggest you read it and then pull back to and read the other sections in the Acoustics FAQ. If you still have questions, find the appropriate thread and post your question(s).

Pepar, thanks for the advice. It's a crude diagram, I don't know how to use anything other than Microsoft paint but the speakers are about 4-6in's from the wall and the center is elevated on a stand 21in's tall, also 4-6in's from the wall. The floors are all carpeted and on the back wall, behind the couch, is a window which is covered with a thick curtain.

Pepar, thanks for the advice. It's a crude diagram, I don't know how to use anything other than Microsoft paint but the speakers are about 4-6in's from the wall and the center is elevated on a stand 21in's tall, also 4-6in's from the wall. The floors are all carpeted and on the back wall, behind the couch, is a window which is covered with a thick curtain.
If you have the space, I would suggest moving LCR further from the front wall. A thick curtain is not a broadband absorber and that is very important when the listeners are so close to the rear wall. Moving the sectional farther from the rear wall would help if you cannot use an absorber in the window cavity. The ottoman many need to go as it looks like it would block the entryway if the sectional was moved "north."

Just my $.02.

Yes.


Here is the specific section on the Studiotips forum for the SuperChunk trap (http://forum.studiotips.com/viewtopic.php?f=8&t=535). I suggest you read it and then pull back to and read the other sections in the Acoustics FAQ. If you still have questions, find the appropriate thread and post your question(s).I've gone down the SuperChunk path and have a question I haven't seen discussed. Rather then simply putting the wedges into the corner, would there be a negative impact to putting the SuperChunk wedges into an enclosure. Here is an example I built for a small half wall in my theater. Naturally, it's normally pushed into the corner and the front will eventually be covered with cloth.
http://netlowdown.com/blogs/wp-content/uploads/2009/01/small-corner.jpg

4" behind the front speakers, 2" everywhere else.
You're going to need at least 4" (depending upon 4" of what) on those walls to the sides of the speakers to about 6' (if not more) from the corner.

I've moved the speakers further away from the wall as well as moved the couch further towards the screen about another 1.5ft(not shown in diagram). That's about all I can go without the room looking odd. Here is where I was thinking of placing my panels, I will eventually place some smaller ones behind the front speakers but my panels are just to large for that.
How's this look? (panels are highlighted in red)

http://i143.photobucket.com/albums/r146/Dizyer/HTDiagram2.jpg

I would make those rear corners complete bass traps.

Rather then simply putting the wedges into the corner, would there be a negative impact to putting the SuperChunk wedges into an enclosure. Here is an example I built for a small half wall in my theater. Naturally, it's normally pushed into the corner and the front will eventually be covered with cloth.

Looks good.

I've moved the speakers further away from the wall as well as moved the couch further towards the screen about another 1.5ft(not shown in diagram). That's about all I can go without the room looking odd. Here is where I was thinking of placing my panels, I will eventually place some smaller ones behind the front speakers but my panels are just to large for that.
How's this look? (panels are highlighted in red)

"Small" panels on the front wall won't really do it.

Well I don't have the ability to make a false wall or insulate the hell out of the area. But for what I have will the red area's work?

Hi guys

silly question but..

If you dont have an acoustically transparent screen (Carada BW 2.35) then is there any benefit in placing acoustic material directly behind the screen?

Will it still absorb some sound reflections?

My speakers will be below the screen.

thanks for any advice
Darren

Oh what the heck I will do it anyway. Otherwise it will go to waste.

We are finishing the move in process in our new home, and I have determinede that with the 20 ft catherdaral ceiling, hard wood floors--and of course, monster echo, I will be adding some treatment.

In the time that I've spent reading this thread, I've gathered that independent of the furniture in the room, I need to determine where and whether to use absorbers or diffusers, and that the application of each is subject to much debate!

At this point, It seems that the front wall should be basically panelled with absorbers(I will be ordering some 703 today). My front wall is actually a corner, with the 61" DLP flanked by 2 JBL L880 towers. Should I basically line the corner behind the TV/Stand with the 703, as well as placing one panel immediately to the side of the 2 front speakers?

As far as the remainder of the room--I was thinking that I would simply place a panel of 703 immediately behind the RIGHT rear, and 2 panels in the corner where the LEFT rear is placed. I have also considered placing a panel or two on the wall behind the sofa, at ear level.

This setup seems minimal, and does not include any diffusers. I need to keep this relatively inexpensive, and more importantly adhere to the WAF for aesthetics.

Am I waaay off??

Hi there,

You will probably need far more absorption than planned to control your reverberation time. According to ITU, Rt60 = 0,25 x (V/Vo)^1/3 where Vo = 100 m3. That's between 200 and 400 ms.

Sonart

http://i143.photobucket.com/albums/r146/Dizyer/HTDiagram2.jpg

Where the red is, I'm going 2X4 panels, will this placement work with my room configuration? Keep in mind I have moved the front speakers further from the wall as well as brought the couch closer to the front of the room by nearly 2 feet.

Where the red is, I'm going 2X4 panels, will this placement work with my room configuration? Keep in mind I have moved the front speakers further from the wall as well as brought the couch closer to the front of the room by nearly 2 feet.
It will certainly help. And you will be ahead of most people.

I know a real acoustician recommended at least 4" of absorption, but if you can place even 2" thick panels directly behind each of the front speakers - even if you have moved them away from the wall a foot or two - that would be better than nothing.

Great! Thanks, I will look further into the front panels soon but for now I can enjoy what I have.

Great! Thanks, I will look further into the front panels soon but for now I can enjoy what I have.
:)

Anyone using cork flooring.
How is it compared to carpet?

For cleaning? Wear and tear? Oh, I bet you mean acoustics. For acoustics cork is a non-starter.

Anyone using cork flooring.
How is it compared to carpet?
Cork is - essentially - wood.

Comparing the values for OC 703 and Roxul Safe n' Sound on bobgolds, they appear very similar. Is the main reason for people preferring 703 because it is rigid?

Product thickness 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
703 plain 3" (76mm) 0.53 1.19 1.21 1.08 1.01 1.04 1.10
Safe‘n’ Sound 3" (75mm) 0.52 0.96 1.18 1.07 1.05 1.05 1.05

I also posted another question in here (http://www.avsforum.com/avs-vb/showthread.php?p=15791590#post15791590) that didn't receive any response.

Comparing the values for OC 703 and Roxul Safe n' Sound on bobgolds, they appear very similar. Is the main reason for people preferring 703 because it is rigid?

Product thickness 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
703 plain 3" (76mm) 0.53 1.19 1.21 1.08 1.01 1.04 1.10
Safe‘n’ Sound 3" (75mm) 0.52 0.96 1.18 1.07 1.05 1.05 1.05

I also posted another question in here (http://www.avsforum.com/avs-vb/showthread.php?p=15791590#post15791590) that didn't receive any response.
For those who simply cover it, rigidity is important. For those building a frame, maybe not.

My main question is, the chunk between the insulation and light tray appears to be solid, and I've seen it as solid in nearly every soffit I've seen on here. Does it have to be solid or can that be just fabric too?

So... Is this a completely horrible idea? Keeping in mind I'm going from nothing to some SnS soffits and first reflection/screen-wall treatments.
If the sound can't get to the absorber, no absorption will occur.

If the sound can't get to the absorber, no absorption will occur.
Low frequencies will pass through sealed, solid panels. But then you have a panel absorber, which is a whole 'nother beast. It typically has a narrow absorption band, which may be just the thing for one or two targeted room modes.

For cleaning? Wear and tear? Oh, I bet you mean acoustics. For acoustics cork is a non-starter.

What does that mean? I'm curious because I have cork floors in my basement and I'm trying to decide what sort of treatments to use. Does having cork floors mean I should think about things differently.

Thanks much for your help!

Adam

135614I could use some guidance on treatment locations and speaker placement. I have my screen mounted like you see on the pic. The pic is similar to my space except the I have a wall where the table is and my screen is only 1' to the wall. As you can see, the room is actually open to one side and there is a bulkhead running along the ceiling which acts as the room differentiator. My plan for my speakers is:

Centre - under the screen on my low profile stand
Left and right fronts - mounted on the wall on either side of the screen
Left and right side - mounted on the bulkhead and the opposing wall
Left and right rear - mounted on the back wall

Does anyone see any red flags with this setup?

For treatments, I'm not sure if it's worthwhile having something on the wal on the other side of the bulkhead. I thought I'd put something on the back wall and behind either front speaker.

Thanks in advance for any insight you may be able to provide!

Adam

By the way my speakers are the KEF 3005SE set.

I could use some guidance on treatment locations and speaker placement. I have my screen mounted like you see on the pic. The pic is similar to my space except the I have a wall where the table is and my screen is only 1' to the wall. As you can see, the room is actually open to one side and there is a bulkhead running along the ceiling which acts as the room differentiator. My plan for my speakers is:

Centre - under the screen on my low profile stand
Left and right fronts - mounted on the wall on either side of the screen
Left and right side - mounted on the bulkhead and the opposing wall
Left and right rear - mounted on the back wall

Does anyone see any red flags with this setup?

For treatments, I'm not sure if it's worthwhile having something on the wal on the other side of the bulkhead. I thought I'd put something on the back wall and behind either front speaker.

Thanks in advance for any insight you may be able to provide!

Adam

By the way my speakers are the KEF 3005SE set.
Pic?

Pic?

Sorry. I messed up the attachment. Let me try that again.

135618

Sorry. I messed up the attachment. Let me try that again.

135618
Nice. Have a floor plan?

floorplan
135622

Whew, the ground beneath my reno keeps shifting as some possibilities get squashed and new ones arise, for instance for acoustic treatment.

I had a visit from a representative from "Whisper Walls."

http://www.whisperwalls.com/default.asp?P=WhisperCeiling


As I've mentioned earlier in this thread we have dropped a bulkhead ceiling starting over the screen wall and covering the seating area. I want the dropped portion of the ceiling bulkhead to be covered in a fabric for two reasons. One, for light absorption from the screen and a nice aesthetic look and Two, to possibly hide some acoustic absorption material in the ceiling.

The rep gave some interesting suggestions. Their fabric system (like some others such as fabricmate) use a track system. The track is laid in whatever shape, around the perimeter of where you want fabric to to. Then the big sheets of fabric are tucked into the track (using a tucking tool) to be held firm. Once the fabric is tucked into all of the track the fabric is taught and straight, looking like a straight ceiling.

This gives an intriguing possibility. At this stage the dropped bulkhead/ceiling is only framed and not dry-walled. Instead of drywalling any of the ceiling I could simply have the fabric stretched over the existing framing, and so I could put acoustic absorption wherever I want.

Also, at this point the screen wall is actually being re-constructed, so the screen wall drywall is taken down leaving a huge open cavity. The Whisper Wall guy said I don't have to drywall that screen wall and could simply fill it with accoustic material that would make the screen area a big sound absorber. (The main issue being the bass frequencies of my speakers which are near the screen and room corners). Here is an image I made indicating the current opportunity. All the blue areas (including the screen wall) indicate cavities into which I could place acoustic absorption:

http://img116.imageshack.us/img116/4329/avroomframedbulkhead3.jpg

The issue is that, while I want to control the bass frequencies of my speakers, I also I don't want a room that sounds too muffled or too dead.
I will have a fair amount of curtains, a big wall to wall shag rug, a big sectional sofa, and light fabric wall covering.

Also, I generally like the sound of my speakers except for the bass bloat happening now that they are in the room corners. I'm wondering of doing all this acoustic absorption might change their sound substantially...perhaps make them sound anemic or over-emphasize the highs or midrange?

I'm considering putting acoustic material behind the screen, along the bulkhead directly above the screen, and perhaps some in the center ceiling area to cover that "first reflection" point.

If the sound can't get to the absorber, no absorption will occur.

The bottom is open with the exception of the odd brace to hold it all together (covered with fabric, of course). I'm just curious if I'm creating another little bass hide-out in the new little corner where my soffit will meet my ceiling.

It will certainly help. And you will be ahead of most people.

I know a real acoustician recommended at least 4" of absorption, but if you can place even 2" thick panels directly behind each of the front speakers - even if you have moved them away from the wall a foot or two - that would be better than nothing.

Does it make a difference if your LCR speakers are front or rear ported? I have front ports so I'm wondering if I should treat directly behind the speakers?

cheap 18" driver in a sonotube, has an effect on really low specific frequencies.

Is it a good addition to my room? I can get some 18" drivers extremely cheap and I have sonotube so I was wondering if I could try and build something to add control to my ULF (40Hz - 80Hz range).

I already have the wall treatements and big corner tri-traps.

The bottom is open with the exception of the odd brace to hold it all together (covered with fabric, of course). I'm just curious if I'm creating another little bass hide-out in the new little corner where my soffit will meet my ceiling.
If it's that little, the bass won't be able to hide out there.:D

Is anyone familiar with Fab-Trax? I'm looking for something to use on inside edges between the wall panels and columns. The other track systems I've seen are one piece and the plastic edge that hooks to the latch is left exposed. This is a two piece design that's hidden and supposedly easier to install. The down side is that it's quite expensive. It's only available in beige, I wonder if the track will show through GOM fabric.

http://www.cascadeaudio.com/commercial_residential/pdf/Fab-Trax_Data.pdf

http://www.cascadeaudio.com/commercial_residential/pdf/Fab-Trax_Install.pdf

Does it make a difference if your LCR speakers are front or rear ported? I have front ports so I'm wondering if I should treat directly behind the speakers?
We're not talking Bose 901's here are we? ;) Speakers, with or without rear ports, all radiate some sound from the cabinets themselves. When you see cabinets with ""clipped" (45 degree) edges, that is the designer's way of lessening the radiation; the sound likes to jump off of sharp edges. Treatments on the wall behind the speakers absorbs this radiated sound.

Cork is - essentially - wood.

I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.

I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.

Cork flooring is way better than hardwood for impact noise. That is, footfall noise from it is quite low, as from carpet. But that's about it.

This fact is frequently simplified/misunderstood/misstated by sellers of cork floors as "better acoustics."

Regards,
Terry

I heard that it is way better than standard hardwood floor for acoustics. Doesn't really make sense to me.

That is also M&M #5 (not the chocolate candy) in this link.

http://www.cedia.net/homeowners/acoustical2.php

1. I have ordered some 2" Rockwool 80 (8ib density)---is this adequate to use for use for first reflections or should I double them up for 4" thickness?

http://www.acoustimac.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=29&category_id=10&manufacturer_id=0&option=com_virtuemart&Itemid=21

Thanks in advance--I am still on page three of this thread.

Imu

1. I have ordered some 2" Rockwool 80 (8ib density)---is this adequate to use for use for first reflections or should I double them up for 4" thickness?

http://www.acoustimac.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=29&category_id=10&manufacturer_id=0&option=com_virtuemart&Itemid=21

Thanks in advance--I am still on page three of this thread.

Imu
8 pcf density rockwool? Yikes, that stuff has really high flow resistivity! I think its absorption of frequencies in the low couple of kHz to the 90% point will be marginal at best. And that is what you need to achieve reflections which are the recommended 10 dB down. Doubling the thickness to 4" won't help with those frequencies, either. :(

So Terry, what material do you suggest for treating first reflections? I may put something on my ceiling at the first reflection point. Thanks.

So Terry, what material do you suggest for treating first reflections? I may put something on my ceiling at the first reflection point. Thanks.
The same material that has been successfully used for many decades -- fiberglass, with a density in the range of 2.25 to 6 pcf. Or rockwool, but no more than 5 pcf. Its acoustic resistivity shoots up rather drastically above this point. Oh, and acoustic cotton in the same density range as fiberglass will perform as well. That shouldn't limit your choice too much. :D

Regards,
Terry

floorplan
135622

Is it possible to get some guidance on acoustical treatments for my room? My floorplan is pretty elementary so I'm not sure if I've given enough info. My floors are cork. The walls are drywall. And I have a large brick fireplace. I'm using the KEF KHT3005SE system with 2 extra rear speakers.

Any guidance would be appreciated.

All the best,

Adam

Thanks again Terry. That info is very timely for my HT project.

8 pcf density rockwool? Yikes, that stuff has really high flow resistivity! I think its absorption of frequencies in the low couple of kHz to the 90% point will be marginal at best. And that is what you need to achieve reflections which are the recommended 10 dB down. Doubling the thickness to 4" won't help with those frequencies, either. :(

Thanks--not what I wanted to hear. I should have ordered the cheaper stuff (Rockwool 60 or 40). I will try the 80 for first reflections and hope for the best. Their website gave good specifications in terms of absorption saying it was equivalent to OC 705.

Imu

Thanks--not what I wanted to hear. I should have ordered the cheaper stuff (Rockwool 60 or 40). I will try the 80 for first reflections and hope for the best. Their website gave good specifications in terms of absorption saying it was equivalent to OC 705.

Imu
Sorry, Imu.

Can you give me a link to the specific URL where they claim that the two products are acoustically equivalent? It doesn't hurt for me to at least try to set a manufacturer straight.

- Terry

Sorry, Imu.

Can you give me a link to the specific URL where they claim that the two products are acoustically equivalent? It doesn't hurt for me to at least try to set a manufacturer straight.

- Terry


Thanks Terry,
Its acoustimac.com and the link is below---click on the details and they have a table listing the absorption characteristics.

http://www.acoustimac.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=29&category_id=10&manufacturer_id=0&option=com_virtuemart&Itemid=21&vmcchk=1&Itemid=21

"Our Mineral 1280 is sonically comparable to Owens Corning 705. It absorbs as much bass, has similar characteristics but costs a fraction of the price. It is typically used to build bass traps and acoustic panels with a hard frame around it for support, as it is slightly less rigid than Owens Corning 705".

HZ 125 250 500 1000 2000 4000 NRC
MNW-1280 (2")
0.32 0.90 1.11 1.07 1.01 1.05 1.05
4" THICK 1.11 0.91 1.10 1.03 1.06 1.07 1.05

thanks again
Imu

Alright I've made some frames for some acoustic panels now my question is if I should put just fabric on the back or some kind of wood backing? Also how far should the panel be from the wall, I was thinking about 2-4"?

Alright I've made some frames for some acoustic panels now my question is if I should put just fabric on the back or some kind of wood backing? Also how far should the panel be from the wall, I was thinking about 2-4"?
Good luck on deciding on that. :)

I have mine mounted directly on the wall. I think the reason for standing them off is to lower the frequency at which they absorb, but I have bass trap(s?) for the lower frequencies and moving them out from the wall would have encroached more into the space. YMMV.

The front of my dedicated theater is very live, you can hear multiple high pitched echos if you clap you hands in the front of the room. Will putting 2x4 gik panels on the side walls help make my speakers sound better? The room is 25x15, I am thinking of buying 6 panels, 3 on each side, starting at the first reflection point. I think my sound is great right now but I was wondering if it would be better by reducing this echo.

If you're standing at the front of the room clapping, you're hearing flutter echo or slap echo which would require treating the front or back wall (best the front since it will help deal with SBIR). This little test isn't saying much of anything about side wall reflections; but, yes, treatment would help your room sound better (the output of the speakers won't change a twit...what you hear in the room will change a lot).

[Clapping doesn't tell you much ... your speakers are at the front of the room, your ears at the middle to rear of the room; but, when clapping your hands the sound source and sink are in the same place in the room; but, OK, you've got a problem. Enjoy getting acquainted with fiberglass panels.]

Good luck on deciding on that. :)

I have mine mounted directly on the wall. I think the reason for standing them off is to lower the frequency at which they absorb, but I have bass trap(s?) for the lower frequencies and moving them out from the wall would have encroached more into the space. YMMV.

I was hoping I wouldn't get an answer like that. :) Well, at least I now know the reason for spacing them a bit.


As far as building a cloud, I figure it's basically the same principle as the acoustic panels, except bigger and hanging from the ceiling. Would I be close in this assumption?

I figured it was the side walls because they are just drywall with no coverings. As you walk towards the back of the room the sound changes alot, it is basically dead in the back compared to the front. When I am listening, for example to a sacd in my main seating position, and press pause, I can always here the echo of the last note for a split second, very high pitched. The front of the room has two floor to ceiling superchunk bass traps and 2 velvet curtains but no other treatment.

The front of my dedicated theater is very live, you can hear multiple high pitched echos if you clap you hands in the front of the room. Will putting 2x4 gik panels on the side walls help make my speakers sound better? The room is 25x15, I am thinking of buying 6 panels, 3 on each side, starting at the first reflection point. I think my sound is great right now but I was wondering if it would be better by reducing this echo.

Read this great article on acoustic treatment and design (http://www.ethanwiner.com/acoustics.html).

There is a section on optimizing the air gap (http://www.ethanwiner.com/acoustics.html#air%20gap) in particular that says:

"For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed."

To locate the first reflection points on the side walls (and ceiling) treat each wall as a mirror and use geometry (or an actual mirror) to locate each speaker as if you could see it reflecting off the wall from each listening position. It's easier with with someone else to hold a mirror up against the wall while you sit in a chair and have that person move the mirror around until you can see each speaker in the mirror. Put a piece of blue painters tape on the wall at each spot. You'll see a cluster of tape. That's where you'll want to put the panels.

Putting acoustic panels at all of the first reflection points will definitely improve the sound quality in your room. It made a big difference in my theater, and I recommend it to anyone who has a live room.

"For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed."

???

A given thickness of absorber will absorb more at lower frequencies the farther it is spaced away from the wall. It does this at the expense of "ripple" in the absorption frequency response. This ripple is greatest for sound waves at zero angle of incidence, but comparatively much less for diffuse sound -- sound which is averaged over all angles of incidence.

Regards,
Terry

I was hoping I wouldn't get an answer like that. :) Well, at least I now know the reason for spacing them a bit.


As far as building a cloud, I figure it's basically the same principle as the acoustic panels, except bigger and hanging from the ceiling. Would I be close in this assumption?
Sound doesn't know up or down, front or back or left or right. :)

All 8 posts by the previous poster nopq938 are complete nonsense/spam. Can someone delete that account?

I have an odd shaped small room that I need help with. I have 5 pieces of 3" 703 left and would like to know the best places to put them based on the shape and size of my room. I have already added some, but I don't have the tools to do any measurement with, so I am just going by ear. I have my pics in photobucket, but I am unclear as how to add them to my post. If I could get some help with that, I think it would make things alot easier. Thank you, Brian.

Ok, I think I figured it out.
nope, I guess not

Here we go. This should take you to my gallery
http://img99.imageshack.us/gal.php?g=img0123k.jpg
Front wall is 13'
Left wall is 14'
Rear wall is 15.5'
Right wall is 5' to where it opens to the doorway. I hope this is enough info to get some ideas on what would be the best use of the remaining 5 pieces of 703. Any help would be greatly appreciated, Brian

Here we go. This should take you to my gallery
http://img99.imageshack.us/gal.php?g=img0123k.jpg
Front wall is 13'
Left wall is 14'
Rear wall is 15.5'
Right wall is 5' to where it opens to the doorway. I hope this is enough info to get some ideas on what would be the best use of the remaining 5 pieces of 703. Any help would be greatly appreciated, Brian
Floor-to-ceiling with the "across-the-corner" panels would be an improvement over what you have now.

Cool, thanks for the reply. What I have in mind, is to glue 2 pieces side by side and then make 2 3' equilateral triangles to put up in the tri-corners on the front wall. Then possibly one piece at the front wall ceiling junction. That would leave me 2 pieces. Is it possible to over dampen a small room? TIA, Brian

Cool, thanks for the reply. What I have in mind, is to glue 2 pieces side by side and then make 2 3' equilateral triangles to put up in the tri-corners on the front wall. Then possibly one piece at the front wall ceiling junction. That would leave me 2 pieces. Is it possible to over dampen a small room? TIA, Brian
Side by side? You mean end to end, don't you? Anyway, I don't think you can glue 703 pieces together.

Yes, if you can, take advantage of the "corner" formed by the ceiling with a wall. Too many only consider a wall/wall juncture a corner.

I'm thinking if I glue them side by side, that will give me a 4' square and from that I could get my 2 triangles. I was hoping that some 3M spray adhesive would hold good enough for me to get the triangles cut and then once in their frames all would be fine. What do you think? What else could you recommend for the use of the remaining pieces. Would it be best to just focus on the front wall or should I consider the rear wall/rear wall ceiling junction. It will be a while before I am able to afford any more material so I am trying to make the best of what I have. Brian

I'm thinking if I glue them side by side, that will give me a 4' square and from that I could get my 2 triangles. I was hoping that some 3M spray adhesive would hold good enough for me to get the triangles cut and then once in their frames all would be fine. What do you think? What else could you recommend for the use of the remaining pieces. Would it be best to just focus on the front wall or should I consider the rear wall/rear wall ceiling junction. It will be a while before I am able to afford any more material so I am trying to make the best of what I have. Brian
Bass is usually a big problem in home theaters. But dialog intelligibility can suffer from early reflections, i.e. sound reflecting off of the ceiling, walls and floor, and too much reverberance. More bass traps - the corner mounted things - will help with reverberance, so you get two birds with one shot.

You need to listen to your system for the things I mentioned and decide where to use your additional resources.

You can glue two panels edge to edge, but they will break apart exactly at the spot where the adhesive penetrated no further. . . .

Thanks for the help. I think I will try to rig someting up to experiment with the extra pieces in different spots. But I will definitly get someting up in the front tri-corners. I do wish my sound card worked with rew, it would be nice to see what kind of response I have in room and the difference the panels make. Brian

Thanks for the help. I think I will try to rig someting up to experiment with the extra pieces in different spots. But I will definitly get someting up in the front tri-corners. I do wish my sound card worked with rew, it would be nice to see what kind of response I have in room and the difference the panels make. Brian
Sound card not bi-directional?

Unfortunately no. I would invest in a new sound card but since times are tight that is something that will just have to wait.

Not to go off topic of this thread, but I have been thinking about selling some of my vintage speakers and using those funds for my main listening room. What sound card would you recommend, best bang for the buck? Brian

Not to go off topic of this thread, but I have been thinking about selling some of my vintage speakers and using those funds for my main listening room. What sound card would you recommend, best bang for the buck? Brian
The way REW works, it "works around" any non-linearity in the sound card's response, so the lowest priced Creative Labs/Soundblaster with bi-directional operation will work for REW use. Spending more, of course, will get you better sound quality for music, games and those little system event sounds.

Sounds good! I have a ps3 for the games and I stream my music to it anyways so a new card might be possible. Thanks again, Brian

Folks,

Does anyone here know of some acoustically transparent material that does not stretch?

I'm integrating my home theater into an existing living room and have been working at designing in light reflections control in as discrete manner as possible. I'm going dark with the rug, dark with the ceiling, but the walls have to be left fairly light. I have curtains that will be able to be pulled to cover a portion of the light walls for movie watching, but I'm going to other strategies for other portions of the wall.

I'm using an automated roller panel system as part of my light-reflection control. There will be a roller panel over the bright wall of a fireplace near the screen and the panel will roll down (matte black) to cover the wall when watching a movie.

I want to do the same thing on another portion of the wall but the issue is that it will have a side channel speaker on that wall. So the standard materials that come with the roller shades will block the sound. I'd like to replace the standard material with acoustically transparent material. However, my supplier for the roller shades tells me I'd better be able to find a fabric that does not stretch much at all, or after time it's going to run into trouble as it rolls up and down.

Any suggestions for such a material?

Thanks,

Hi can anyone tell me how they attach the OC 703 to their walls.

I have the British equivalent (well 1" 60kg density rockwool) but was wondering what was the best way to fix it. Glue, nails, screws? :)

thanks for any help
Darren

Hi can anyone tell me how they attach the OC 703 to their walls.

I have the British equivalent (well 1" 60kg density rockwool) but was wondering what was the best way to fix it. Glue, nails, screws? :)

thanks for any help
Darren
I made panels with frames and a backer, and then used angle brackets to mount same to the wall (and the ceiling). Check the link in my sig.

Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.

I will be covering it with black speaker cloth though.

Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.

I will be covering it with black speaker cloth though.I use the RotoFast connectors. http://www.rotofast.com/

Hi there thanks for the reply but I want to stick the material direct to the wall rather than build it into frames.

I will be covering it with black speaker cloth though.
It doesn't seem dense enough to hold its own weight.

I have already added some, but I don't have the tools to do any measurement with, so I am just going by ear.

This will give you the tools to measure the room. The best part is it is free.

http://www.hometheatershack.com/roomeq/

Glenn

This will give you the tools to measure the room. The best part is it is free.

http://www.hometheatershack.com/roomeq/

Glenn

You'll have to add a measurement mic like the ECM8000 from Behringer or the RTA-M by DBX (what I use). The first one is maybe $50...the RTA-M is about $85 most places. You'll also need an audio interface or a soundcard that supports it, but most do.

Frank

You'll have to add a measurement mic like the ECM8000 from Behringer or the RTA-M by DBX (what I use). The first one is maybe $50...the RTA-M is about $85 most places. You'll also need an audio interface or a soundcard that supports it, but most do.


Bi-directional operation is the feature to look for . . .

Thanks for those suggestions. I do have a rat shack spl meter but my sound card is not bi-directional. I am in the process of finishing off the last 5 sheets of 3" 703 focusing mainly on the back wall. I do plan on purchasing the outlaw 997 when it comes out which has the trinnov room correction. I believe trinnov will have the ability to show me my in room response when connected to the computer. If this is the case, no need to spend money elsewhere. Brian

I have two floor to ceiling superchunk bass traps in the front corners of my room. There is no way I can put traps in the corners of the rear of my room. I was thinking of adding one of the 6" thick bass traps to the center of my rear wall. Will this help control bass even better since i have no treatments in the rear of the room? Ive read alot of people put diffusion on the back wall so i didnt know if putting a bass trap there was good or not. Thanks.

I have two floor to ceiling superchunk bass traps in the front corners of my room. There is no way I can put traps in the corners of the rear of my room. I was thinking of adding one of the 6" thick bass traps to the center of my rear wall. Will this help control bass even better since i have no treatments in the rear of the room? Ive read alot of people put diffusion on the back wall so i didnt know if putting a bass trap there was good or not. Thanks.
The real bang for buck is in the corners. How about the corner formed by the front wall and the ceiling? That counts, too. :)

The real bang for buck is in the corners. How about the corner formed by the front wall and the ceiling? That counts, too. :)

I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?

I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?
I didn't say it would be a waste. :) How about the corner formed by the rear wall and the ceiling? :D

I am trying to figure out a plan to do that. So do you think placing one on the wall in the back would be a waste?
It helps to know what you are trying to treat. A floor to ceiling absorber in the center of the back wall can be effective on lengthwise room modes, but only on half (the even ones) of the widthwise room modes.

It helps to know what you are trying to treat. A floor to ceiling absorber in the center of the back wall can be effective on lengthwise room modes, but only on half (the even ones) of the widthwise room modes.

I am just trying get an optimal room setup, I did the front corners and read the back corners should be done as well, since i cant do that i am thinking of the trap in the center of the wall.

If you want optimal room treatment placment & the biggest impact on your sound quality, As pepar stated you must treat all 4 corners floor to ceiling with broadband bass traps 4"-6" thick any thing else is just A compromise untill this is accomplished ...

Cheers....

If you want optimal room treatment placment & the biggest impact on your sound quality, As pepar stated you must treat all 4 corners floor to ceiling with broadband bass traps 4"-6" thick any thing else is just A compromise untill this is accomplished ...

Cheers....

I am trying to state that there are no corners to treat. The door is on the one corner and the equipment cabinet is on the other. The rear of the room is not square the walls come together at 45degree angles. Thats why I am asking whether or not it would be worth it to put the trap in the middle of the rear wall. This is the only place it can go in the rear of the room.

I am trying to state that there are no corners to treat. The door is on the one corner and the equipment cabinet is on the other. The rear of the room is not square the walls come together at 45degree angles. Thats why I am asking whether or not it would be worth it to put the trap in the middle of the rear wall. This is the only place it can go in the rear of the room.
Then put one there. :)

Is GIK the only company that makes a Tri-Trap Bass Trap?

Is GIK the only company that makes a Tri-Trap Bass Trap?
I believe that is one of their product names.

Real Traps makes something called a "Tri-Corners" trap.

The designs are far from proprietary, but everyone has their own names.

Then put one there. :)
I agree. As I pointed out, it helps a lot if you have some measurements to know if this will have any positive effect on treating your room's modes. But if you want one there, by all means, add it! If is a full-range porous absorber (no covering layer) and not just limited to bass, it will likely have other beneficial acoustical effects.

- Terry

Here is another place thast sells bags for corner traps if you want to make some on your own and save a few bucks:

http://www.readyacoustics.com/index.php?go=products.proddetails&prod=RT426B

Sorry to interrupt, but I just finished researching the various materials used for acoustic treatments including bass traps, etc... I decided on OC 703 and just bought some and I figured I'd post where I got it from and what I paid to help out any fellow North Texas people (Dallas / Fort Worth) that also choose to go this route. Sorry if I posted it in the wrong place, it's the best place I could find. I just want to give back a little bit of helpful info to this community.

Their website is easy to google but the forum won't let me post it since I'm newly registered (this is my first post actually).

Specialty Products & Insulation Co (SPI-CO)
11232 Leo Lane
Dallas, TX 75229
(800) 927-7742

I bought:

480sf of OC703 2" thick (unfaced) 2x24x48 at $0.84 per square foot
this comes 12 panels to the bundle so I bought 5 bundles

192sf of OC703 1" thick (unfaced) 1x24x48 at $0.42 per square foot
this comes 24 panels to the bundle so I bought 1 bundle

My subtotal was $483.84 plus $39.91 sales tax so grand total $523.75. I know there have been plenty of posts that discuss places to purchase this material but I figured it always helps to have some recent information. Plus, I had never seen anyone mention such a cheap price for the 1" thickness. It's half the thickness and therefore half the price. Most (if not all) other places charge substantially more than this for the 1" stuff. They have other locations in the metrolplex (and nationwide for that matter). This location usually has lots in stock. The Fort Worth location would have transferred some over free of charge but it's Friday and I want to get some work accomplished this weekend so I drove over to Dallas to pick it up. By the way, if you're buying as much as I did, drive your truck (obviously) and don't forget to bring straps, rope, etc... (don't ask me how I know):eek:

I have no affiliation with them whatsoever, but finally decided to post some helpful information since I have spent MONTHS of my time on here reading thousands of posts from other helpful people.

I now return you to your normal broadcasting.:)

Derek

SPI is part of the thread's collective wisdom and the pricing in line with what I paid a few years ago. They actually have locations all over the country.

For those of you who have used 3m or other spray adhesive to attach your treatments (OC703) how much was enough?

I'm looking at attaching almost 600sqft and looking at $25/can. Wondering how far a can will go. Wondering if rotofast might be cheaper?

Thanks

For those of you who have used 3m or other spray adhesive to attach your treatments (OC703) how much was enough?

I'm looking at attaching almost 600sqft and looking at $25/can. Wondering how far a can will go. Wondering if rotofast might be cheaper?

Thanks

I use rotofast for my wall and ceiling panels. They work great and only require a few small screw holes. I can't even imagine gluing panels to any permanent surface.

And I don't think 703 is dense enough to hold its own weight with applying adhesive directly to it.

hello, gents. just found this thread.

my questions ?

when using MCACC. looking at the adjustments it makes, is that a way to get an idea of what area/s need treatments ?

i am sure there is a "good" & "waist of effort" material list in here somewhere.
can someone point me to its direction ? thanx a ton.

And I don't think 703 is dense enough to hold its own weight with applying adhesive directly to it.

ya, I'm going to build a small frame around all of mine so the material is actually attached to the frame and the 703 just kinda floats behind it within the frame.

ya, I'm going to build a small frame around all of mine so the material is actually attached to the frame and the 703 just kinda floats behind it within the frame.
You can adhere the 703 to the inside of the frame, or to the backer if you have one, and then use fasteners from the frame to the wall. I did mine that way after covering with GOM.

Hi all, Thanks to all the great advice I got here my HT has come along nicely in the last couple weeks. I was trying to start a build thread but I am having problems posting pictures. I'll try to work on it again soon, but my 'puter with all the pics on it is having some other issues now tool. Once I get it fixed I'll give it another try. In the meantime, does anyone have any suggestions on how to stop sound from going through the HVAC ducts? My room is almost completely sound proof but I can hear sound coming into the room through the ducts. I'd hate to have spent all this time, effort and money and not be able to fix this problem. Is there something that you can do to the ducts that restricts sound without killing the airflow?

Thanks,
Berk

Hi all, Thanks to all the great advice I got here my HT has come along nicely in the last couple weeks. I was trying to start a build thread but I am having problems posting pictures. I'll try to work on it again soon, but my 'puter with all the pics on it is having some other issues now tool. Once I get it fixed I'll give it another try. In the meantime, does anyone have any suggestions on how to stop sound from going through the HVAC ducts? My room is almost completely sound proof but I can hear sound coming into the room through the ducts. I'd hate to have spent all this time, effort and money and not be able to fix this problem. Is there something that you can do to the ducts that restricts sound without killing the airflow?
Duct liner. Not real practical to retrofit though.

Hi all

my new room will be 20' x 12' I plan to cover the screen wall in 4" auralex wedges and Lenrds corner base traps. The side wall will have 1" rockwool from about 1' up to 4' up covered with acoustically transparent cloth.

What should I do with the back wall. I have a 7.1 system with 2 speakers alongside the seats and 2 at the rear around 7' apart. The side speakers are tripoles (M&K SS-150)and the rear speakers are direct front firing (M&K S-85).

The rear settee will be on a 11" riser and there is a heat radiator in the lower centre of the rear wall. I was going to leave the wall untreated (as most of the area will be blocked by the settee and riser) but now reading various reports to others I am confused.

I can have anything on that wall to a 1" depth so should I go for more rockwool or should I go for diffusion tiles to diffuse the rear sound stage.

thanks very much for any help
Darren

You can adhere the 703 to the inside of the frame, or to the backer if you have one, and then use fasteners from the frame to the wall. I did mine that way after covering with GOM.


Right. the only thing is that with my wall being floating (I used RISC clips and/ green glue) I want to minimize the number of fastener holes I have to use to attach stuff to the walls, so I'm going to basically attach some "posts" at the proper weight bearing areas, and then build the frame and attach it to that. Then I think I'm going to attach the gom to that frame, and loosely attach the 703 behind it.

The 703 I'm putting up is 4'x8', 2" thick sheets, and I'm going to double layer them for a total of 4" of 703 material. That should be enough to kill the front wall reflections.

This is just for my front wall, which is going to have an AT screen hung in front of the material.