Acoustical Treatments Master Thread [Text View] - Page 22

Jacob B

09-29-09, 05:57 AM

yup.

@Pepar
I am aware that the mat mainly will work for impact noise.
However, I will have butt-kickers installed in the riser as well as the two center seats of the first row (Berkline 090). The riser will have sound insulating rubber feets - but still.

@Dennis E
I still don't understand that the laminar material of the floor won't impact the absorption properties and therefore the in-room acoustics :confused:

I read on a HIFI dedicated forum (danish) that floor construction was very important in regard to avoiding the floor playing along (resonating). The author recommended as many (different) laminar layers as possible to get different structural resonance points, with less amplitude/volume as result:

http://www.hifi4all.dk/content/templates/artikler.asp?articleid=366&zoneid=2
Using translate.google (edited for major misunderstandings, but not grammar etc :) ):
"When the room is playing along
In principle, a floor is not much different from a speaker cabinet acoustic set. The idea is that the floor's contribution must be minimized - ie that ideally you should absolutely not be able to feel vibrations in the floor regardless of the frequencies and sound pressure, there is. As with everything else, the ideal state in practice impossible to achieve.
So what is possible and how?
A little common sense can quickly weed out larger floor plates, since they are very difficult to curb. Just as at the cabinet manufacturing and all other products that should not have natural frequencies, the best results are obtained when laminating materials with individual oscillation patterns - preferably with as little surface as possible, as less resonansamplituder means lower volume .. Just the fact that the amplitude must be minimized means that large floor plates require an extraordinary effort in relation to attenuation.
Completely different is the situation with parquet flooring, which is composed of a multitude of small parquets. The best parquets are actually already laminated to a variety of materials and as such constitutes a sound basis for a well dampened. The problem with parquet flooring is that it must be put together. The assembly of the parquet floor is crucial to the final acoustic result regardless of the insulation to the floor. Parquet exist in principle in two versions: The floors are glued together and they are not glued together. It is the logic of ducks that they glued types are clearly the best, then click floors are naturally plenty of air in between sessions and the edges from rubbing against each other. Do you have a click-floor you can be advantageously either glue it together or put a 1-2 mm silicone-line in the lower half of the session if the floor must be dismantled later. The glue must be made so that all contact surfaces are covered with a thin layer.
The subfloor
The subfloors are very different and depends on the individual building design. The hardest cases are older apartments, where wooden floors are often based on a kind of beams, which lies between the levels. It is a huge task to tackle, and the results are seldom targets of such efforts.
Many houses and newer apartment buildings have a concrete deck as a subfloor.
The most ideal solution to floor problems will be to make the best recording studio - namely to make the entire listening space "float" in an acoustic isolation from the building's permanent structure. However, it is not so easy in an ordinary home, and even these floating listening rooms can be very difficult to construct. The idea of constructing a good listening environment is, of course, to get sound energy is converted into heat at selected locations instead of uncontrolled resonances. Even the best designs can be extremely difficult to channel the energy in the sound on to selected points where it can be converted to energy.
At home with concrete deck the trick, therefore, is to transfer sound energy in floors, insulation and concrete deck in an ideal relationship. With the laminated parquet is much already won because laminate is able to convert large amounts of energy to heat, as each layer restricts another's own structural resonance as opposed to a single layer floor.
Even a perfectly sized, laminated parquet is not without side effects since the total area of the parquet floor in principle represents a giant "membrane" which - ceteris paribus - has its own movement pattern with their own overtones. In practice this means that the entire "cone" has a peculiar resonance, while parts of the floor can have its own resonances of larger or smaller areas, depending on the floor adaptation to space, furnishings, etc. The total floor self resonance is almost never a problem because the resonance often very low, and it can be subdued to inaudible by heavy furniture, etc.. It is the - if I may say so - local resonances, which can cause small problems. Here comes the decoupling or insulation between the floor and into the substrate and the task now is to keep logic in check, since relaying a glued floor will be a headless deed. You therefore need to think of energy transmission when you insulate under your floor. Rule No. 1 is that sound energy must not be translated into movements in the floor. The energy not converted into heat in the lamination in Parkett, must therefore continue down the insulation. The energy not converted in the insulated cavity must ultimately be transferred to the concrete deck. It had been wonderful if concrete deck just grabs the last amount of energy. All know that concrete virtually no potential for oscillation. Unfortunately, concrete largely return energy back where it came from. With a well insulated and laminated parquet floor will again be allocated energy in isolation and parquet albeit in much smaller quantities than the other way.
The [rubber or similar mat] insulation has a major responsibility for the final result. Again, laminating is the answer. An insulation consisting of multiple, suitable materials will translate various energy pathways to heat - just like laminating parquet floor. By choosing a laminated insulation can save several cm insulation, compared with an insulation consisting of only one material. I take one only 8 mm thick lamination of 2 mm rubber while the last 6 mm and consists of 3 different filter types plus the obligatory water-damp sealant layer at the bottom"

Any comments from the experts? :confused: :)

Jacob

pepar

09-29-09, 09:44 AM

Any comments from the experts? :confused: :)
The comment from this non-expert is that you are over-thinking this. ;)

Weasel9992

09-29-09, 09:59 AM

Any comments from the experts? :confused: :)

I know it's hard to believe, but Dennis is right. I'm not aware of any specific testing aside from material absorption properties, and the differences tend to fall within the error range given the sample sizes.

Frank

Jacob B

09-29-09, 10:05 AM

The comment from this non-expert is that you are over-thinking this. ;)
:cool: That's me.:D
However, I think the majority of the population find us (here on avsforum) to fit That description
:)
Jacob

pepar

09-29-09, 10:09 AM

:cool: That's me.:D
However, I think the majority of the population find us (here on avsforum) to fit That description
:)
Jacob
That's true. And humor is the antidote. :)

R Harkness

09-29-09, 12:20 PM

pepar

09-29-09, 12:45 PM

Can anyone reply to this post:

http://www.avsforum.com/avs-vb/showthread.php?p=17257675#post17257675

What kind of acoustic-transfer properties do I need to look for in a roller screen material that will drop down in front of my side FX speaker?

Thanks,
You might be breaking new ground here. I would think that the obvious would be what to look for - something acoustically transparent.

Maybe look at what companies are using for masking systems for AT screens . . .

Dennis Erskine

09-29-09, 01:11 PM

It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material.

R Harkness

09-29-09, 03:18 PM

You might be breaking new ground here. I would think that the obvious would be what to look for - something acoustically transparent.

Maybe look at what companies are using for masking systems for AT screens . . .

Obviously I'm looking for something as acoustically transparent as possible.
The problem is speaker grill cloth doesn't normally come on roller shade mechanisms and you can't just put any material on a roller - typical grill cloth material is too stretchy to roll up and down reliably.

Therefore...since I have to go into non-speaker-cloth territory, most likely what one can find within the offerings from roller shade companies, what types of roller shade materials might I look at that could fit the bill? I know they will come in varying levels of "openness" meant mostly in terms of light transfer, but I wondered if any of the experts could chime in as to whether there are roller shade materials that could work. Perhaps someone - for instance a custom installer here - is familiar with, say a shade with an openness rating of 3 or 5 or 10 and can advise as to whether any of those ought to be suitably acoustically transparent?

Thanks.

(If need be I'll check out what some companies are using for AT masking)

pepar

09-29-09, 04:47 PM

Obviously I'm looking for something as acoustically transparent as possible.
The problem is speaker grill cloth doesn't normally come on roller shade mechanisms and you can't just put any material on a roller - typical grill cloth material is too stretchy to roll up and down reliably.

Therefore...since I have to go into non-speaker-cloth territory, most likely what one can find within the offerings from roller shade companies, what types of roller shade materials might I look at that could fit the bill? I know they will come in varying levels of "openness" meant mostly in terms of light transfer, but I wondered if any of the experts could chime in as to whether there are roller shade materials that could work. Perhaps someone - for instance a custom installer here - is familiar with, say a shade with an openness rating of 3 or 5 or 10 and can advise as to whether any of those ought to be suitably acoustically transparent?

Thanks.

(If need be I'll check out what some companies are using for AT masking)
Hmmm, now I'm thinking the material that is used in woven AT screens might be the ticket. Can't remember the name of the generic stuff off hand, but it is inexpensive. In real life, it is shade cloth.

But they will know about it in the DIY Screen forum (http://www.avsforum.com/avs-vb/forumdisplay.php?f=110). Sheerweave something or other...

Jacob B

09-29-09, 05:11 PM

It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material.

Dennis,
When I read something like the post on the linked Danish HiFi forum, and I don't know the CV of the poster, I look for second opinions. And normally, being a scientist, I look for answers backed by research. Second best is best practice/experience supported by theoretical explanations.
However, I acknowledge this might not be possible in all cases - this included - but I always try, nevertheless.
I think you will find that is the general case in most of the area discussions on the forum.
I don't post a lot, but I have been reading for 8 years know. That solves most of my questions.
When I post, it's because I cannot find the answer in the achives. Or if I think I can contribute. As my post number shows, neither happens very often ;)

I appriciate answers by experienced persons like yourself, and hope you don't take offense when I ask the 'WHY's :)
I also accept that answering the why might not be possible or just not practical time wise - as posting here probably doesn't pay your rent :D

Best regards,
Jacob

pepar

09-29-09, 06:14 PM

I appriciate answers by experienced persons like yourself, and hope you don't take offense when I ask the 'WHY's :)
I also accept that answering the why might not be possible or just not practical time wise - as posting here probably doesn't pay your rent :D
What about his posts lead you to that conclusion?

Jacob B

09-30-09, 02:53 AM

What about his posts lead you to that conclusion?

Well, Dennis' last reply seemed to indicate that he was wondering why I kept asking when he already had answered:
"It appears to me you already have the answer you're looking for. You actually have two; but, it appears you want to get tied up in knots over laminates and adhesives on flooring material."
So I felt the need to explain that I really like to know the "WHYs" :)
I understand that an explanation might not be available and, but that Dennis answers from his vast experience in acoustic designs of rooms
- but I would also accept if he knew the theoretical explanation but felt it would take too long to write it - time he didn't want to spend and his experience told him his answer was correct anyway.

Anywhy, I will use the suggested: acoustic mat - OSB T&G - GG - OSB T&G.

Cheers,
Jacob

Dennis Erskine

09-30-09, 06:44 AM

What field of science, Jacob?

glaufman

09-30-09, 09:52 PM

Hmmm, now I'm thinking the material that is used in woven AT screens might be the ticket. Can't remember the name of the generic stuff off hand, but it is inexpensive. In real life, it is shade cloth.

But they will know about it in the DIY Screen forum (http://www.avsforum.com/avs-vb/forumdisplay.php?f=110). Sheerweave something or other...

Didn't think to test it, but I saw rollup shades in HD today with a perforated fabric that just might work for you.

JapanDave

09-30-09, 10:14 PM

Just a question that maybe Dennis or any other experts could help me with.

I have a room that is 20.1ft long X 16.4ft wide and 7.7ft high, all walls and ceiling are 10" concrete, the floor is 18" thick with one heavily soundproofed door.

I am currently researching on how I should go about treating this room acousticly. I am carpeting the room and using an underlay of some sort, other than that I am not sure how I should approach this room. I understand that the base is what is going to give me problems and of coarse bass traps will be used but this is not going to solve everything.

Any help would be appreciated.

rec head

10-01-09, 12:15 AM

What did that room used to be?

JapanDave

10-01-09, 12:38 AM

What did that room used to be?

Fish room, I had 23 fish tanks including 1 X 18ft (1200g) and 3 X 8ft(400g) tanks, all together over 10,000g of water with tanks from other rooms included. I moved those tank to another room and decided to make a HT. The whole house is solid concrete with the walls ,floors, ceilings all 10" thick. The base of the house has two sections where the floor is 18" and 36" thick. Have to build for earthquakes here.

erkq

10-01-09, 12:45 AM

The whole house is solid concrete with the walls ,floors, ceilings all 10" thick. The base of the house has two sections where the floor is 18" and 36" thick. Have to build for earthquakes here.
Holy crap, we have to build for earthquakes here too. But a wood frame house with engineered shear strength, proper bolted foundation, tie downs, strapping, etc. do the trick. What size earthquake is the house supposed to survive? a 9? a10??

JapanDave

10-01-09, 02:49 AM

Holy crap, we have to build for earthquakes here too. But a wood frame house with engineered shear strength, proper bolted foundation, tie downs, strapping, etc. do the trick. What size earthquake is the house supposed to survive? a 9? a10??

It is designed to handle an earthquake bigger than the one in Kobe in 1995.　I will put it this way, Japan has one of the strickest building codes in regards to earthquakes in the world and in the Kobe earthquake out of 460,000 houses, 104,906 were completely destroyed, 144,274 were partially destroyed and 141,326 houses suffered some kind of substantial damage. Over 90% of the remaining 69,494 houses to be undamaged were solid concrete. No concrete houses were completely or partially destroyed and the ones that did suffer damage was mainly due to fires and other buildings around them causing the damge, 1% suffered structural damge but those houses were over 70 years old. Anyway you look at it, I am not going to risk my families lives by using wood, it is just not strong enough to handle bigger earthquakes.

Sorry for the off-topic remarks, I will get back on topic now.:o

Jacob B

10-01-09, 10:13 AM

What field of science, Jacob?

Political science ;) - albeit I studied mechanical engineering for two years, ages ago.
Cheers,
Jacob

rec head

10-01-09, 05:49 PM

JapanDave

10-01-09, 07:26 PM

WOW. I thought you were going to say a vault or something.
LOL, it could well be made into a bunker!:p

BasementBob

10-02-09, 03:56 PM

It is designed to handle an earthquake bigger than the one in Kobe in 1995.　I will put it this way, Japan has one of the strickest building codes in regards to earthquakes in the world and in the Kobe earthquake out of 460,000 houses, 104,906 were completely destroyed, 144,274 were partially destroyed and 141,326 houses suffered some kind of substantial damage. Over 90% of the remaining 69,494 houses to be undamaged were solid concrete. No concrete houses were completely or partially destroyed and the ones that did suffer damage was mainly due to fires and other buildings around them causing the damge, 1% suffered structural damge but those houses were over 70 years old. Anyway you look at it, I am not going to risk my families lives by using wood, it is just not strong enough to handle bigger earthquakes.

Earthquake proof is lots more complicated than just 'build it out of concrete'.

If you're on sandy soil, like Mexico City, foundations disappear like quicksand, and concrete structures over them break.
If you're on bedrock, then minor earthquakes are often less of a problem for concrete structures, but larger earthquakes seem to magnify the damage. Concrete tends to fail suddenly and catastrophically, whereas wood bends. Coupled with steel to keep the wood together (strapping, 30' bolts, triangular-earthquake-welded-8'-wall-bracings, etc), wood may survive earthquakes that concrete would not. Steel is extremely useful structurally when it is under tension.

I was watching a disaster program the other day in which a fellow had a concrete home and a forest fire went through and it collapsed (obviously a wooden home would have collapsed faster). My friends in Europe can't believe we in North America build homes out of wood.

Japan has one of the strictest building codes in regards to earthquakesUsually nothing wrong with following building codes -- they tend to be extremely practical for each area. They're usually written due to evolution -- when something falls down, they go have a look, and come back and change the building code.

The funniest example of that that I know of is a municipality where it's legal to build a two storey structure out of manure, but not a three story structure out of manure. A three storey one fell down.

Peter M

10-03-09, 10:16 AM

BB,

Good summary.

It's all about ductility. Concrete is fine as long as it's suitably reinforced, particulary at the connections, to ensure appropriate levels of ductility.

Personally I prefer steel ...

citizen arcane

10-03-09, 01:33 PM

I now have bass trapping in the four vertical corners and 2x4 broadband panels on the two side walls of my media room. As this room is a den that gets used for socializing and the occasional movie shown with the pj; I want to add diffusion to the rear wall using a rather large floating shelf and assorted square wall cubbies.

I will add that the chairs used for watching/listening are six feet away from the rear wall so I believe I will benefit from this treatment.The question is: will I realize a markable difference in scatter/reflection adding odd sized books, vases, pictures frames angled differently from one another, etc. Any tips/tricks would be greatly appreciated!

BasementBob

10-03-09, 03:56 PM

I want to add diffusion to the rear wall using a rather large floating shelf and assorted square wall cubbies. Any tips/tricks would be greatly appreciated!

Maintain left/right symmetry.

For diffusion, periodicity is your enemy.

The two funniest stories I've heard about using bookcases as diffusers are:
1) the fellow who put down tape under the books to mark where the books should be placed on the shelf. The tape is just hidden if the books are placed correctly. The books were purchased not for content, but such that they could be placed according to a QRD pattern, and the maid kept pushing them back against the back of the bookcase so they'd all look flat rather than the in-out style he kept leaving them in. So he put the tape down so he could fix them after the maid left each week.
2) Another fellow, also got rid of his assorted books, and instead went with stone because the book's spines were too soft to some frequencies. He then painted the stone to look like books, and ...

jvvjvv

10-05-09, 03:00 AM

I have visited a few other HT sites, but this thread has really been helpful.

I am getting ready to finish off my basement HT room, 8' wide x 7'6" high x 19' long. Stairs, ceiling and outside wall have dictated the size, so I am stuck with the poor width and height. I can shorted the room with a partition wall. The 3 existing wall are double 5/8 GG, then covered with 19/32 finished plywood. (3 walls are earthquake shear walls, hence the plywood).

What would be the best length for the room? The wall will be 5/8 2x4 and double 5/8 with GG between on the HT side. This will be the front wall. What is the good acoustical treatment for this wall?

What is the best treatment for the ceiling? Some say from the speakers to the seating and some the whole room.....which and what material? Double 5/8 GG is going to be the base. Would like to put ply paneling on after that.............(need to have several "trap doors" to quickly get at plumbing shut off valves). I can acoustical panel the speakers to seating area........will that work?

The floor is concrete. Carpet is said to work well, but some have said speakers to seating and others the whole room ?

The back wall can be rows of DVD's on shelving........will the be enough diffusion?

The L/R speakers are going to have to be pretty close to the walls to have some 7' between them.......they are 3' tall.........any thing "special" that can be done to make up for the short spread between them?

Thanks, Jack

Noah

10-05-09, 04:37 AM

This isn't strictly home theater related, as you'll see.

I've just moved to a house that's probably 1/4 mile or so from a set of train tracks. You don't so much hear the train (there are no horns/whistles) as you feel a sort of rumble in your ears. Its very low frequency.

So, until Ford stops making the infernal Ranger and shipping them within rumbling distance of my house, is there anything I can do to treat my rooms to reduce that 2 AM train rumble? DD+GG for the whole house is not a viable option.

Right now, I'm thinking the previous owner should have left me a case each of earplugs and Nyquil. The rumble doesn't wake me up, but if I'm up and the train comes by (they're slow and seem to go on for hours) getting to sleep can be difficult. On the positive side, I do catch up on my movie queue and forum browsing. ;)

Ethan Winer

10-05-09, 03:26 PM

What would be the best length for the room?

My Graphical Mode Calculator (http://www.realtraps.com/modecalc.htm) program suggests that making the room shorter will only be worse. Ideally you'd make the width 12 feet instead of only 8.

What is the good acoustical treatment for this wall? What is the best treatment for the ceiling?

That's a big question, and not necessarily the right one. The very short answer is you need as many corner bass traps as posibile, plus absorbers at the side-wall and ceiling reflection points.

The back wall can be rows of DVD's on shelving........will the be enough diffusion?

Bookshelves are not diffusors, no matter how many people might claim that on the Internet. :D This video is aimed at recording studio types, but the principles apply to HT and listening rooms too:

All About Diffusion (http://www.realtraps.com/video_diffusors.htm)

The L/R speakers are going to have to be pretty close to the walls to have some 7' between them.......they are 3' tall.........any thing "special" that can be done to make up for the short spread between them?

You and the speakers should form an equilateral triangle as explained here:

How to set up a room (http://www.realtraps.com/art_room-setup.htm)

--Ethan

JapanDave

10-06-09, 01:43 AM

Earthquake proof is lots more complicated than just 'build it out of concrete'.

If you're on sandy soil, like Mexico City, foundations disappear like quicksand, and concrete structures over them break.
If you're on bedrock, then minor earthquakes are often less of a problem for concrete structures, but larger earthquakes seem to magnify the damage. Concrete tends to fail suddenly and catastrophically, whereas wood bends. Coupled with steel to keep the wood together (strapping, 30' bolts, triangular-earthquake-welded-8'-wall-bracings, etc), wood may survive earthquakes that concrete would not. Steel is extremely useful structurally when it is under tension.

I was watching a disaster program the other day in which a fellow had a concrete home and a forest fire went through and it collapsed (obviously a wooden home would have collapsed faster). My friends in Europe can't believe we in North America build homes out of wood.

Usually nothing wrong with following building codes -- they tend to be extremely practical for each area. They're usually written due to evolution -- when something falls down, they go have a look, and come back and change the building code.

The funniest example of that that I know of is a municipality where it's legal to build a two storey structure out of manure, but not a three story structure out of manure. A three storey one fell down.Understood.
Let me put it this way,from the calculations of the engineer and from past experience with concrete houses in earthquakes, if the foundations were to give out on our house it would simply roll over on itside with out any structral damage. And could be reset after fixing the foundations.

The walls are filled with 13mm re-enforced steel at 4" spacing both vertically and horizontally and due to the thickness of the walls there are two rows built into every wall. And due to the fact that foundations play a big roll our house has 3ft diameter concrete filled bored holes ranging from a depth of 30-50ft, they are strategically placed and reach down to solid rock. There is not much around that is stronger than this house. I put $150K just in the foundations, but like I said before, nothing is better than piece of mind.:)

pyro2003

10-06-09, 04:40 AM

this is suppose to diffuse and absorb, are there any math way to determine the dimensions spacing etc ?

http://www.laudescher.com/images/_PDFCAT_EN_347.pdf

:confused:

Ethan Winer

10-06-09, 02:26 PM

this is suppose to diffuse and absorb

That looks like it's meant for use in a large venue, which has totally different requirements than a domestic listening room or home theater.

--Ethan

velvet396

10-06-09, 04:34 PM

pyro2003

10-06-09, 10:07 PM

That looks like it's meant for use in a large venue, which has totally different requirements than a domestic listening room or home theater.

--Ethan

probably, if nothing else though I'm using the nicer outlook and half openness to hide/expose my absorption panels and let them work, as a compromise in a typical home. From this viewpoint I think you're suggesting to ignore the spacing and thickness of wood to do anything... in fact they should be as small in total area as possible then.

Just found some equations for slat absorbers if they are considered HR

http://accucalhd.com/documents/audio/Acoustics%20Short%20Course.pdf

avare

10-07-09, 01:00 PM

Just found some equations for slat absorbers if they are considered HR

http://accucalhd.com/documents/audio/Acoustics%20Short%20Course.pdf

Nice document. Thanks for the link.

Andre

BasementBob

10-07-09, 05:56 PM

this is suppose to diffuse and absorb, are there any math way to determine the dimensions spacing etc ?

I am not an acoustician, nor do I play on on TV. And I did not even sleep at a holiday inn last night.

This is not a helmholtz absorber. It's more a variation on the 'inside out wall'.

It does have some interesting bits, although I don't think I'd ever do it this way.

1) Structurally, if someone leans against it, they lean against wood, not fabric or compressable insulation. And the wood gives a nice nailing edge to hang a picture.

2) absorptively. It's not a helmholtz absorber. It's a simple foam absorber, spread out between boards. It would be nice to see the absorption coefficients from a lab on this system. But at a guess, I'd say it's just the same as foam, with each absorption coefficient (at each frequency band) halved per surface area due to the wood spacing it out. There might be a bit of a boost due to edge defraction at some frequency band. There might be periodicity issues giving absorptive boosts to some frequencies over others.

3) defusively. The wood will provide spacial and temporal diffusion, relative to the aborptive parts. Not much since it's so long and straight. Also, the absorbers will due to edge effect warp the sound pressure at certain frequency bands and that will give a bit of a diffusive effect too. That said, unless you're very very lucky, this is not likely to be a good thing in your home theatre. Again it would be nice to see diffusive tests from a lab on this system.

4) reflectively. There's wood there. So it will reflect too. If you align the boards so that the speaker, board, ear, are in a line, then high frequency sound going slightly up or slighly down will bounce off the upper and lower parts of the boards back into the absorption. Low and mid frequency sound have wavelengths too big for this to matter. I wonder if this might make the room sound muddy (more highs absorbed than mids), from a home theatre perspective. Or if you'd luck out and get a sence of spaciousness (wouldn't bet a paycheck on that).

-----

I've often thought of putting up what would at first glance look like a slat absorber. Except that I'd have the slats too wide, and the entire cavity filled with insulation, to resonate (i.e. a setup that is so innefficient a resonator, that it wouldn't resonate, and wouldn't behave as a helmoltz slat absorber). Instead of having a peak frequency (helmoltz style), it would combine reflection and low/mid frequency absorption up to the limits of the porous absorption alone. Maybe I'll do that some day. Maybe it will behave the way I expect, and maybe it won't. But it would be a part of a whole room analysis.

LarryChanin

10-07-09, 07:31 PM

probably, if nothing else though I'm using the nicer outlook and half openness to hide/expose my absorption panels and let them work, as a compromise in a typical home.

Hi,

If you are looking for the wood paneling that disguises absorptive material you might want to research RPG's Topakustik perforated wood panels (http://www.rpginc.com/products/topakustik/index.htm). RPG's website provides acoustical data for their various designs. I have no idea of the cost of these panels or whether RPG will even work with anyone other than professionals.

Larry

pepar

10-07-09, 07:34 PM

Hi,

If you are looking for the wood paneling that disguises absorptive material you might want to research RPG's Topakustik perforated wood panels (http://www.rpginc.com/products/topakustik/index.htm). RPG's website provides acoustical data for their various designs. I have no idea of the cost of these panels or whether RPG will even work with anyone other than professionals.

Larry
Congrats, Larry, on hitting 5k!

LarryChanin

10-07-09, 10:34 PM

Congrats, Larry, on hitting 5k!

Hi Jeff,

Thanks.

Now if I could just run 5k without having a coronary. ;)

Larry

pyro2003

10-08-09, 12:26 PM

Thanks Larry and BasemenBob,

actually the picture use acoustic wood panels, which I found some local supply, they're either perforated or made from melamine to have specific absorption properties with only a very thin air gap

thats' a middle of the road cost way - usually it is used for entire wall in public places, schools or conference rooms - so can be too much for an entire wall in a home

citizen arcane

10-08-09, 09:51 PM

I have some leftover OC 705 equivalent and would like to fill the bottom of some plant stands that are in my media room. The 'glass would be semi circular 16" across, 8" deep and 22" tall to fill these spaces. All sides except for the very bottom (which would sit on a shelf) would be exposed and wrapped in GOM 701. This would be very much like GIK's elite table trap.

FWIW these stands are centered on the front wall behind the L/R mains (the placement is symmetrical); that wall is otherwise untreated besides bass traps. The side walls have mid/high absorption panels (2" 705) and the tri corners are treated with traps - floor to ceiling. The rear wall is untreated but have floating book shelves with books and knick knacks.

So I guess my question is: is there benefits in "getting as much acoustic materials you can" in the room?

pepar

10-08-09, 09:58 PM

Jacob B

10-09-09, 06:14 AM

Hi all,
After having solved the floor construction issues (see post 5251 and 5271 this thread), I am now moving on to the ceiling.

Maybe I should lay out the draft acoustic plan first (based on advice from BPape and from reading this thread):
Room dimensions (HxWxL): 5.5'/8.0' x 12.6'/5.0' x 21' (heights are start and end of sloping ceiling, widths are at floor and at ceiling - see attached pictures). Ceiling Joists are currently 5" high, will be 4" after DD with GG between the joists on the current parquet wooden ceiling (which lays on top of the joists and with 8" of fluffy rockwool above, on the loft)
Speaker setup:
- Three floor standing Audiovector M3 Signature speakers behind 110" wide 2.40:1 SMX CineWeave™ HD AT screen mounted on false wall 2½ feet from front wall - underneath joist 2 (top of screen will be 5.5' above floor due to sloping ceiling)
- SVS PB12-plus/2 subwoofer between center speaker and left or right speaker.
- 4 x MK 150 SS Tripole surround speakers

Acoustic treatment plan (all panels will be GOM wrapped):
Front wall: whole wall 2" OC703 (for balanced wall - window will be covered)
All four vertical corners: Bass Traps with stacked OC703 triangles 24"x17"x17" up to the start of sloping ceiling.
Front wall / floor corner: 12" x 12" OC703 Bass trap
Front wall / ceiling corner: OC703 Bass trap panel 6" x 5' x 2' (Whole area between joist 1 and 2).
Sloping ceiling: Panels made of 2" OC703 6"x48" with a wooden frame 3½" deep (thus 1½" of air behind the OC703), wrapped in GOM. These panels will be spaced with 8" along the whole length of the sloping ceiling (Bass absorbtion and crude diffusion)
Side walls: 1" OC703 panels from floor and 4' up

Problems/considerations:
1) I also need bass absorbtion at Rear wall / ceiling corner (between joist 7 and 8 counted from front wall). However, there is only 14" from ceiling down to the top of the door and the MK 150 SS Tripole rear surround speakers are 10.6" high. I think I will have to mount the rear surrounds high enough to clear the door, to get the two rear surrounds spaced far enough from each other, but also to clear the second row on a 20" riser (see rear wall picture).
This means I really can't fit more than a 3.4" thick OC703 panel above them (or 4" with small slots cut out for the two rear speakers), as they need sideroom to fire the dipoles.
Will this be OK?

2) Acoording to Bpape, I also need bass absorption (a 4-6" thick OC703 panel) overhead the seats.
I don't know whether this should be above only the primary row of Berkline 090 (1st row) or above the second row as well? Second row will be on a 20" riser (due to the low screen). Therefore, it would actually be nice to keep the 8' ceiling above second row for "head room" when getting seated :confused:

The 1st row will have their heads beneath 4 and 5, second row beneath joist 6 and 7.

3) What to do with the remaining ceiling (between joist 2-3, 3-4, and 5-6)?
I would like to make a fiber star light ceiling for the whole celing area from joist 2 to joist 8, but can I combine that with the bass absorbtion overhead 1st row (and maybe overhead second row as well) and the rear wall/ceiling panel at joist 7-8? :confused:
I studied SandmanX's star light ceiling, but that will only work for the joist 2-4 area in front of 1st row - masonite star light panels underneath the ceiling OC703 bass absorbtion panels would defeat the purpose of the OC703, wouldn't it? :confused:

And what about 1st reflections from the masonite star light panels, in the joist 2-4 area? I would use fluffy fiberglass to fill the cavity between joist 2-4, above the star light panels, but that doesn't cover 1st reflections, does it? :confused:

This was a lot, I know :eek:, but I hope some of you can give a comprehensive suggestion to my ceiling construction :)

Thanks in advance,
Jacob

Attic Home Theater under construction

giomania

10-09-09, 01:33 PM

I am finally going to start my acoustic treatment installation project this weekend. I am planning to install SSC DIY traps in the front vertical corners of my theater, as well as along the horizontal intersection of the front wall and ceiling. I will then build a screen wall out from the existing front wall. I believe this is similar to Pepar's theater.

Anyway, since the SSC corner traps will be behind the screen wall, I do not see the need for a vertical strip of wood installed at the edges of the corner chunks in the vertical corners. It would seem these vertical strips of wood are typically installed to assist in covering the trap with fabric. I was thinking the wood strips might limit the edge effect?

I was thinking to just install a piece of 2" x 3" wood diagonally along the top and bottom of the vertical corners so that I can string some fishing line or wire from eye bolts to keep the stack from falling over. Here is a crude representation of what I am trying to say: TT

Any input is appreciated.

Thanks.

Mark

ExToker

10-11-09, 09:00 AM

While trying to get a handle on my room acoustics, I felt I should at least get somewhat of a idea of the physics of sound, absorption, reflections etc.

I've had 'The Master Handbook of Acoustics' on my nightstand for a couple months, and to say the least it is daunting to grasp the complexity of sound.

I just found this page this morning. In a nutshell I was able to somewhat grasp what is going on as it is very clear and well written.
I wanted to point it out to those with my minimal level of knowledge, like myself.

http://www.novibes.com/NoiseControl/tech_info/ntech.asp

mike0311

10-12-09, 09:00 PM

I have a couple of quick questions on panels. I read a great deal of this thread so I have a pretty good idea on what I'd like to do. My questions are this, for my side panels I am going to go with 1" oc703. Should the panels I make have a 1" depth or is it better to have another inch of space between the oc703 and the wall and make them 2" deep? I thought someone had said the space was good to have but I didn't find any further discussion on it. My other question is should I wrap a backing on the panels to stop the particles from escaping?

Mike

SierraMikeBravo

10-12-09, 09:24 PM

Should the panels I make have a 1" depth or is it better to have another inch of space between the oc703 and the wall and make them 2" deep?

You might want to just consider this then, instead of buidling 1 inch space covered by 1 inch of material, just go with a two inch panel. Higher density than air, and thus a bit more effective.

I thought someone had said the space was good to have but I didn't find any further discussion on it.

Air is an effective absorber, but not as effective as mass...goes back to the density thing.

My other question is should I wrap a backing on the panels to stop the particles from escaping?

Which particles are you referring to? Air or material? If air is what your referring to, I think you may find it a bit difficult to do that, but you are more than welcome to try.:D

Kal Rubinson

10-12-09, 09:26 PM

You might want to just consider this then, instead of buidling 1 inch space covered by 1 inch of material, just go with a two inch panel. Higher density than air, and thus a bit more effective. And simpler to mount.

SierraMikeBravo

10-12-09, 09:28 PM

I've had 'The Master Handbook of Acoustics' on my nightstand for a couple months, and to say the least it is daunting to grasp the complexity of sound.

You ain't seen nothin' yet! :D Just keep going in the direction you are...you'll find out.

SierraMikeBravo

10-12-09, 09:30 PM

and simpler to mount.

+1

mike0311

10-12-09, 10:15 PM

SMB...Thanks for the info. I don't remember exactly who but I think it was Dennis that said the 2" was too absorbing in most cases? My theater is only about 14' wide so I'd prefer to go the 1" route unless people say it would be totally ineffective or just really a stupid idea. Also I was talking about the fiberglass particles :) Also please don't take this the wrong way because I am actually asking it as a question and not trying to be sarcastic. You say that mass is a better absorber then air. I see what you are saying but wouldn't it depend upon what the mass is? I don't see putting 10" slabs of steel on the wall as being absorbent. I'm just learning this stuff so I am always eager to hear peoples advice. Thanks again.

SierraMikeBravo

10-13-09, 04:04 AM

Far be it from me to argue with Dennis, but IMHO, it all depends on what frequencies you are trying to target. Many have different philosphies, but I prefer to go with 2 inch myself when dealing with the lateral reflections. Not saying Dennis is wrong by any means, but it is just the way I do it, and everyone has "their way" so to speak. Also, not sure where he was referring to inch and what frequencies.

As far as the steel thing, we have to remember that we do want air to penetrate the material fairly easily.

Jacob B

10-13-09, 04:45 AM

giomania

10-13-09, 01:47 PM

giomania

10-13-09, 02:01 PM

I installed my 34" StudioTips Super Chunk (SSC) bass traps this weekend. Since I had plenty of JM 814, I decided to "face" the vertical corner traps with the optional "cover panel". I cut several of the 48" x 24" panels down to 34" wide by 24" high, and stacked them in front of the installed 34" triangles.

This provided a more finished appearance, but I was wondering if the factory surface of panels is more reflective than the cut edges of the triangles. I just thought I would ask.

Thanks for any input.

Mark

Jacob B

10-13-09, 03:11 PM

giomania

10-13-09, 03:21 PM

Depending on how your ceiling, walls and floor is constructed sound wise, you might want to consider the tight fit of the 2" x 3" - you normally avoid having any surface directly touching a neighbour surface for resonance reasons / noise flanking. It might not matter, though. Maybe you could use a little piece of rubber or polyerutane at each end to decouple?

As for the reflecting properties of the cut edges of the fiberglass vs the factory surface, I am pretty sure it doesn't matter for low freq - and probably not for mid and high as well. After all, the front surface is what is used for wall panels to absorb first reflections of mid and high.

Cheers,
Jacob

Thanks for the input. The ceiling of the room is isolated, and the floor is concrete, so I don't think the tight fit of the 2x3 is an issue. However, I had not thought of that before installing it. Regarding the reflectivity, I was thinking along the same lines as you, as the front surface is used on FRP panels.

Mark

ExToker

10-13-09, 06:19 PM

You ain't seen nothin' yet! :D Just keep going in the direction you are...you'll find out.

Thats the intimidating part. I am seeing it. Building my room to preferable ratios was the easy part.

Now I'm hanging around both absorption and equalizing forums. Throw in 1 amazing book by F. Alton Everest and I got a big heaping serving of humble pie:rolleyes:

I do have 3 things going for me though.

1. I love math
2. I crave learning
3. We got a helluva long winter just starting here in Minnesota.

I figure I should make some (a little) headway ( I hope) on this given the above.

Great people here. I'm sure I might have a question, or 2, down the road.:D

giomania

10-14-09, 10:46 PM

Here are pictures of my front wall after working this past weekend.

Mark

Jacob B

10-15-09, 06:35 AM

Giomania:What OC703 thickness do you have on the front wall itself?

Anyone:
Is it is better to make a SSC trap at the horizontal intersection of the front wall and ceiling or at the floor and wall intersection - if you have to choose due to lack of OC703 material....

Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??

No comments on my ceiling thoughts (post 5312)?

Thanks,
Jacob

giomania

10-15-09, 07:52 AM

pepar

10-15-09, 09:16 AM

Here are pictures of my front wall after working this past weekend.
Very nice, Mark!

Next up for me is to install chunk traps in the rear of the room where it will be seen. I have modified my mounting system used behind my false wall to add a GOM-covered . . cover. Over the next few weeks I will execute the plan and post pics here as well as on my site.

have you listened to your system since adding the traps???

Jeff

pepar

10-15-09, 09:22 AM

Is it is better to make a SSC trap at the horizontal intersection of the front wall and ceiling or at the floor and wall intersection - if you have to choose due to lack of OC703 material....

Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??
The more you install, the better. It is difficult if not impossible to have too much/many corner chunk traps. Traps at the different wall-to-wall/ceiling/floor junctures all address different modes, so they are all good to have.

glaufman

10-15-09, 09:45 AM

Would it be better to mount 2" OC703 2' x 4' panels oblique BOTH at the wall/celing and wall floor intersections (like a SSC trap but with air in the triangle cavity behind the panels), RATHER THAN a SSC trap at just ONE of the intersections??
IIRC, chunks perform better in any single given corner, but if material is limited, what you gain from treating more corners can outweigh what you lose by going from chunks to obliques, but YMMV depending on how many more corners you can treat due to both material and WAF concerns...

Jacob B

10-15-09, 09:47 AM

The more you install, the better. It is difficult if not impossible to have too much/many corner chunk traps. Traps at the different wall-to-wall/ceiling/floor junctures all address different modes, so they are all good to have.
Pepar,

Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall and a floor/wall corner basstraps using 2' x 4' panels mounted oblique (with air behind the panels)

OR

I can make either
one "solid" SCC trap at ceiling/wall
or
one "solid" SCC trap at floor/wall

Which would be better? It will be the same amount OC703 material used - just in two different ways..

Cheers,
Jacob

pepar

10-15-09, 10:00 AM

IIRC, chunks perform better in any single given corner, but if material is limited, what you gain from treating more corners can outweigh what you lose by going from chunks to obliques, but YMMV depending on how many more corners you can treat due to both material and WAF concerns...

Pepar,

Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall and a floor/wall corner basstraps using 2' x 4' panels mounted oblique (with air behind the panels)

OR

I can make either
one "solid" SCC trap at ceiling/wall
or
one "solid" SCC trap at floor/wall

Which would be better? It will be the same amount OC703 material used - just in two different ways..

Cheers,
Jacob
I'd go with glaufman's advice, but you should do some acoustical measuring to make the final determination.

dc_pilgrim

10-15-09, 10:15 AM

Just a tip for folks - a lot of the acoustic books on amazon have the "look inside" preview on amazon. If you are looking for info on specific issues, you have an opportunity to sample some of the information. This includes Floyd Toole's latest and Alton Everest's master handbook.

http://www.amazon.com/Sound-Reproduction-Acoustics-Psychoacoustics-Loudspeakers/dp/0240520092/ref=sr_1_1?ie=UTF8&s=books&qid=1255614139&sr=8-1

http://www.amazon.com/Master-Handbook-Acoustics-Alton-Everest/dp/0071603328/ref=pd_bxgy_b_text_b

Obviously, if these books are helping you, you should think about picking up a copy yourself.

glaufman

10-15-09, 10:49 AM

Pepar,

Questions is, with a given number of 2" OC703 sheets, I can make a ceiling/wall and a floor/wall corner basstraps using 2' x 4' panels mounted oblique (with air behind the panels)

OR

I can make either
one "solid" SCC trap at ceiling/wall
or
one "solid" SCC trap at floor/wall

Which would be better? It will be the same amount OC703 material used - just in two different ways..

Cheers,
Jacob

One interesting consideration is if you go with the obliques, how thick will they be? 2" may lose much more vs the chunks than 6"...

giomania

10-15-09, 01:52 PM

Very nice, Mark!

Next up for me is to install chunk traps in the rear of the room where it will be seen. I have modified my mounting system used behind my false wall to add a GOM-covered . . cover. Over the next few weeks I will execute the plan and post pics here as well as on my site.

have you listened to your system since adding the traps???

Jeff

Thanks. What can I say...you inspired me. The only modifications was that I used those metal angle brackets, 1" x 4" wood, and then those wood "straps" to ensure the angle brackets would not bend over time.

I have not listened to it yet. I still have to build the screen wall, re-install the screen, re-position the speakers, re-calibrate with Audyssey, etc.

One thing I was wondering if the (optimal) placement of the subs in the room would change due to the treatments? I found the optimal placement by using the DD-15's built-in SMS-1 software and pushing the subs around on furniture sliders. Will I need to go through this process again?

Logically, I think the optimal placement is based on the room dimensions, and the treatments will only smooth out the room's response. If that is correct, the optimal placement exercise should not need to be re-accomplished?

Thanks for any input.

Mark

pepar

10-15-09, 02:03 PM

Thanks. What can I say...you inspired me. The only modifications was that I used those metal angle brackets, 1" x 4" wood, and then those wood "straps" to ensure the angle brackets would not bend over time.

I have not listened to it yet. I still have to build the screen wall, re-install the screen, re-position the speakers, re-calibrate with Audyssey, etc.

One thing I was wondering if the (optimal) placement of the subs in the room would change due to the treatments? I found the optimal placement by using the DD-15's built-in SMS-1 software and pushing the subs around on furniture sliders. Will I need to go through this process again?

Logically, I think the optimal placement is based on the room dimensions, and the treatments will only smooth out the room's response. If that is correct, the optimal placement exercise should not need to be re-accomplished
I'd be in the "logically" camp if the original locations were optimal based solely on room dimensions, but just for kicks you might want to try the SMS thing again. And report back....

You will be amazed after you've re-done Audyssey!

MikeWojcik

10-16-09, 10:26 AM

Giomania

Nice clean job - what did you use on the vertical wall to hold the panels in place?
I see black circles in the pictures on each panel - what are they?

Thanks
Mike

diesel10pilot

10-16-09, 09:33 PM

Has anyone tried these panels?

http://www.samsclub.com/shopping/navigate.do?dest=5&item=411789&itemid=459945

Thanks,

Mick

giomania

10-16-09, 09:53 PM

Giomania

Nice clean job - what did you use on the vertical wall to hold the panels in place?
I see black circles in the pictures on each panel - what are they?

Thanks
Mike

Thanks Mike. I used 3" drywall screws (#6) that I had, and I went to home depot to get some fender washers. I placed two screw/washer combinations in each panel, screwed into the stud. They are actually silver, since I haven't painted them black yet.

Mark

Jacob B

10-17-09, 08:11 AM

One interesting consideration is if you go with the obliques, how thick will they be? 2" may lose much more vs the chunks than 6"...

I was thinking maybe 4" obliques to make the OC703 last for more corner treatment.
How about filling out the cavity behind the oblique with standard "fluffy" fiberglass?

Jacob

Dennis Erskine

10-17-09, 08:52 AM

Far be it from me to argue with Dennis
SMB ... please feel free to disagree with me at anytime. Please remember the following three points:

1. Your exam hasn't been scored yet;
2. I know where you live; and,
3. I know the HAARP boys.

:D

Kal Rubinson

10-17-09, 11:29 AM

Has anyone tried these panels?

http://www.samsclub.com/shopping/navigate.do?dest=5&item=411789&itemid=459945

Thanks,

MickOnly 1" of polyester fiber will do something but not much.

citizen arcane

10-17-09, 12:44 PM

Has anyone tried these panels?

http://www.samsclub.com/shopping/navigate.do?dest=5&item=411789&itemid=459945

Thanks,

Mick

From Stereophile:

Tom Gorzelski of mytheater acoustic panel showed me his simple and inexpensive kits. Don't expect them to work into the bass, therefore, but Tom acknowledges that they are most effective at 1–2kHz

Kal Rubinson

10-17-09, 01:22 PM

From Stereophile:

Tom Gorzelski of mytheater acoustic panel showed me his simple and inexpensive kits. Don't expect them to work into the bass, therefore, but Tom acknowledges that they are most effective at 1–2kHzSo are my drapes. :rolleyes:

pepar

10-17-09, 04:35 PM

I stopped at "Sam's Club." :)

mike0311

10-17-09, 10:17 PM

SMB ... please feel free to disagree with me at anytime.

So is 1" enough Dennis? If so, should I build a 2" frame so I have 1" of air between the 703 and wall?

johnbomb

10-18-09, 01:25 AM

Measurement/calibration sequence.

1. With all equipment (and the HVAC on) and no sound from the speakers, produce a 1/3rd octave full range RTA. This will give you the background noise floor in the room. This will provide a boundary between what your speakers are doing and what is ambient in the room.

2. Two near field measurements of each speaker. The microphone should be placed approximately 1' meter from the face of the speaker with the microphone aimed directly at the speaker. You may need to increase the distance beween the speaker and microphone slightly if you have multiple, widely spaced drivers. The measurement should be taken using pink noise first with bass management off (no crossovers active) and secondly with bass management and cross overs active. (We like to do a series of off axis measurements as well.) The subwoofer(s) should be measured as well. The purpose of these measurements are to: (1) establish that all drivers in the speaker are working correctly; (2) to give you a baseline measurement of what the speaker is producing so during calibration you can tell room/treatment impacts from the speakers' response; and, (3) determine if bass management is working correctly (correct slopes, 3 dB down at crossover frequency, etc.).

3. With the microphone (or array) set up for the primary listening position, disconnect all but one speaker at a time, and, using full range pink noise, measure the RTA of each individual speaker. You can, at this time level match the speakers as well. Bass management should be on. These plots can be overlaid against the nearfield to provide a rather obvious display of what the room is doing to response at the seating location. Large peaks and dips above 500Hz are most likely as a result of SBIR and point to a need for treatment (diffusion and/or absorption). Typically, you use 1/12 octave, C weighted pink noise. (1/12th isnt how we hear but provides the granularity needed to see problems). At this time, run an ETG (bass management on) for each speaker. This will show you SBIR and early reflections which are problematic. Based upon the later RT60 you plot for the room, you can determine whether absorption, diffusion or a combination thereof is most appropriate (over absorption of early reflection points is a common mistake). The biggest common cause of SBIR is from the front wall (behind the speakers) and the side wall immediately adjacent to the speakers. You can avoid most SBIR problems by keeping your main speakers at least 3.5' away from any surface (assuming a crossover of 80Hz). Subs should be placed closer than 3.5' from a wall (again assuming an 80 Hz crossover).

4. Turn off all speakers but the subs (bass management on) and position the microphone in a right tricorner of the room. The peaks in this plot will show you the actual modes in the room (real, not calculated) and their relative intensity. (Again, pink noise, full range). Run measurements at the primary seating location as well as other seating locations in the room. These latter measurements will provide the modal peaks and nulls which occur at individual seating locations. You might want to look for a null which is NOT a modal frequency.

5. You now want to position your various subs to reduce, moderate or eliminate nulls at primary listening positions. This measurement is best done using spatial averaging in each individual seating location....forget about seats within about 3.5' of a wall. Various types of tuned, or broadband absorption can be used to reduce both peaks and nulls.

6. Parametric EQ can be used to terminate peaks (won't help on the nulls).

7. Run another RTA of the subs, together (1/3 octave) and bring the average SPL level of the plot up to, or down to, the same average level of your center channel (L/C/R are already level matched).

It's very difficult to determine a treatment strategy until you actually measure what is happening the room. The various prediction models are not 100% accurate but certainly can provide a heads up with respect to what you might need. During calilbration and set up process, once you change something, do your measurements all over again to see what impact the change had. Also, most important...don't forget to LISTEN to your reference materials between changes.

Mr. Erskine,

First, thank you for such an informative post. I know it's a bit old, but I would very much appreciate your clarifying a few things for me, if you don't mind.

1) Won't room interference contaminate nearfield (1 meter) speaker measurements? I'm guessing you're using at least cardiod, if not super or hypercardiod mics for this test.

2) Regarding the listening position: do you average the graphs you obtain from the various positions, perhaps weighting the most favored listening position? I'm guessing omnidirectional mics are being used at each spot.

3) When "listening" with the mic in a tricorner, I'm guessing that again the mic is omnidirectional.

4) After initial room treatment, lets say I wanted to target a more narrow band of problem frequencies at the listening positions via the use of a resonating (pressure) panel trap. Would I next use a mic to "listen" along the walls/ceiling/floor to find where those frequencies are loudest, and then install the trap at that point?

All this assumes the use of sweeps from Room Eq Wizard.

Thanks very much for your time,
John

Dennis Erskine

10-18-09, 08:21 AM

1) Won't room interference contaminate near field (1 meter) speaker measurements? I'm guessing you're using at least cardiod, if not super or hypercardiod mics for this test.
You don't want to do this with the speakers in a corner...in the middle of the room works. What you want is to have the volume sufficiently higher than the ambient noise in the room. The FR display (short gate time) displays peak and is sufficient (reflected sound will be sufficiently below first arrival as to not skew your results for the purpose of this exercise.. If you want a near anechoic measurement, you can do this outside.

2) Regarding the listening position: do you average the graphs you obtain from the various positions, perhaps weighting the most favored listening position? I'm guessing omnidirectional mics are being used at each spot.
I cheat. I use multiple mics. You can either take multiple measurements and average them in the software or you can take a single mic, use a 6 to 10 second gate average, and keep the mic in motion around the seating location.

3) When "listening" with the mic in a tricorner, I'm guessing that again the mic is omnidirectional.
It is omni directional when oriented obliquely to the source, directional when aimed directly at the source.

4) After initial room treatment, lets say I wanted to target a more narrow band of problem frequencies at the listening positions via the use of a resonating (pressure) panel trap. Would I next use a mic to "listen" along the walls/ceiling/floor to find where those frequencies are loudest, and then install the trap at that point?
If you take a measurement in the tricorner, the peaks will show up. You can do the math to determine if those peaks are L, W, or H modal responses OR you can place the mic at the back wall to read only L modes, etc. For example, placing a diaphragmatic or pressure trap on the back wall will do nothing for a width mode. For this purpose, any particular length mode will be equally apparent anywhere along the front or back wall.

johnbomb

10-18-09, 09:16 AM

It is omni directional when oriented obliquely to the source, directional when aimed directly at the source.

I'm a bit confused here: when I say "omnidirectional", I'm referring to the mic's pick up pattern. If such a mic is used, then I don't see how directionality with respect to the source matters. I have a CAD 179 large diaphragm condenser mic- it's a lower end mic with a continuously variable pickup pattern whose frequency response is (IIRC) flattest in "omni" mode.

Again, thanks very much!

John

Jrek

10-20-09, 12:30 PM

Hello, I was hoping to get a little help,I'll be placing some corner bass traps soon and was looking for placement advise,I will eventually cover floor to ceiling but until I have enough traps for now do I place the panels on the floor stradling the corner or I have seen pictures of panels hung mid way between floor and ceiling which is the correct way to mount?Also should side wall first reflection panels be spaced away from the wall and if yes by how much? Thank you in advance Jim This is all new for me just getting invovled and reading and researching I feel like my head is going to explode. Ha Ha Again Thanks Jim

BasementBob

10-20-09, 10:46 PM

corner bass traps ... I will eventually cover floor to ceiling but until I have enough traps for now do I place the panels on the floor straddling the corner or I have seen pictures of panels hung mid way between floor and ceiling which is the correct way to mount?
All modes are active in tri-corners. Start there.
(wall-wall is a corner. Wall-floor is a corner. Wall-ceiling is a corner.
Wall-wall-ceiling is a tri-corner. Wall-wall-floor is a tri-corner)

If you have measurement software, use that to find your most active/troublesome modes, and that will dictate more efficient placement, and alternative treatments.
i.e. test, hypothesize/diagnose, treat, repeat.

Also should side wall first reflection panels be spaced away from the wall and if yes by how much?That depends on other things (speaker-off-axis-response, speaker-wall-placement, envelopment/spaciousness, imaging at various frequencies, other reflections, other issues, over-absorption of high frequencies, etc etc etc). Nothing, or diffusion, are sometimes appropriate.
A rule of thumb is never more air behind a porous absorber than the thickness of the absorptive material.

In an otherwise empty/reflective room, studiotips superchunks and first reflection point absorbers are a good thing. In other rooms, your mileage will vary.

Weasel9992

10-21-09, 03:40 PM

All modes are active in tri-corners. Start there.

Yep...that'll work just fine. Giving panels a little bit of space will extend their low frequency response a little bit. Every little bit helps.

Frank

giomania

10-21-09, 09:23 PM

Here are pictures of my screen wall with the screen installed. I will cover it with GoM and it will be flanked by curtains on both sides.

I installed an extra 8" deep section of triangles in the upper-right corner of the front wall. The remain un-treated area there in the picture has the electrical panel and the structured wiring (low-voltage) box. I was wondering if I should cut a piece of 2" JM 814 to fit in there. It would have to be moveable for occasional access.

If you recall from my previous pictures, I did not have the lower 16" of the front wall treated. My solution is to lean the 2" panels in the bottom corner like you see in the picture behind the screen wall. That should be OK, right?

Thanks for any input.

Mark

Dennis Erskine

10-21-09, 09:43 PM

Congratulations to SierraMikeBravo ... he is now HAA Level II certified.

pepar

10-21-09, 11:07 PM

Jacob B

10-22-09, 03:59 AM

Jacob B

10-22-09, 04:16 AM

What are the pros and cons for a square vs. a triangle corner bass trap using the same amount of absorbing material?

I am considering doing a 1' x 1' square floor-wall bass trap (to leave room for the three tower speakers and the 19" x 28" SVS PB12-plus/2 sub behind the false wall - I win 5" of floor space this way) and I am wondering whether I should do the same for the ceiling-wall corner or make triangles...?? (planning on triangles in the tricorners)

1' x 1' is exactly the same amount of fiberglass material as a SCC trap measuring 17" x 17" x 24" (see attached drawing) - so what are the pros and cons?

I realize that for visible corners, tiangles are easier to make look nice / blend into the room. However, for treatment behind a false wall, that doesn't really matter. So I guess there is an acoustic reason for choosing triangles as well :D :confused:

Cheers,
Jacob

CCDC

10-22-09, 12:18 PM

I just tore out the old wood panneling in our livingroom and am planning insulation and drywall, but before that goes in I was wondering if there were any recomendations for building in some sort of acoustic room treatment that would have high WAF.

ie flush with the drywall or built into the wall or corners of two walls.

Specific areas of interest include the covering (wood, vinyl, fabric) and how it would be attached and matched to the drywall when it is all in. The angled basstrap across the corner is not gonna fly so looking for other ideas that blend into the room a bit better so that I may avoid hearing the phrase "This is our livingroom, not a theater"

giomania

10-22-09, 01:19 PM

How does it sound? Any difference?

I don't know yet. Final speaker alignment / FRP absorber installation / Audyssey calibration to occur this weekend.

Mark

giomania

10-22-09, 01:24 PM

Why did you prioritize wall-ceiling corner versus wall-floor corner? Just wondering, as I am planning my own treatment now.

Anyway, it looks great :) Can't wait till I get to that point :cool:

Best,
Jacob

Thanks for the compliment, Jacob.

I assume you mean why did I prefer the wall-ceiling corner for the Studiotips Super Chunks?

1) I have a lot of obstructions at the floor-ceiling area (electrical outlets, and wiring conduit / chase openings)

2) I wanted to have the flexibility to move the subs around behind the screen wall.

3) I was copying Pepar's project. :eek:

Mark

rec head

10-22-09, 03:07 PM

pepar

10-22-09, 04:48 PM

I don't know yet. Final speaker alignment / FRP absorber installation / Audyssey calibration to occur this weekend.
A fellow local HT enthusiast installed a fair amount of SSC traps, but it wasn't until we re-did Audyssey that the full improvement in the sound became obvious.

CCDC

10-22-09, 11:02 PM

Are you looking for sound proofing or just in-room acoustics?

in room, acoustics. this is a first for me, but with the walls tore out, i figured now is the time to start.

Room dimensions are 14x21x9h with 'front' on the 14 wall. I had planned to 'treat' the entire front wall with some 703/705 or equivalent but need to find a way to cover that up if possible something seamless. Roof and floor are wood with only an area rug between front speakers and primary listening position.

if this is not the way to go then let me know. I am open to anything that can be concealed on sides and back. got more leeway on the front wall where all the TV & speaker stuff is anyway.

Jacob B

10-23-09, 02:55 AM

Thanks for the compliment, Jacob.

I assume you mean why did I prefer the wall-ceiling corner for the Studiotips Super Chunks?

1) I have a lot of obstructions at the floor-ceiling area (electrical outlets, and wiring conduit / chase openings)

2) I wanted to have the flexibility to move the subs around behind the screen wall.

3) I was copying Pepar's project. :eek:

Mark

Makes sense.

Jacob

citizen arcane

10-23-09, 11:27 AM

Jacob B

10-23-09, 06:06 PM

in room, acoustics. this is a first for me, but with the walls tore out, i figured now is the time to start.

Room dimensions are 14x21x9h with 'front' on the 14 wall. I had planned to 'treat' the entire front wall with some 703/705 or equivalent but need to find a way to cover that up if possible something seamless. Roof and floor are wood with only an area rug between front speakers and primary listening position.

if this is not the way to go then let me know. I am open to anything that can be concealed on sides and back. got more leeway on the front wall where all the TV & speaker stuff is anyway.

If you can't have any visible seems, with cloth covered panels, maybe you can make the walls into Helmholz resonators. Google around (or wait for the xperts to show up :-)), but basicly it is a membrane (plywood, drywall etc) mounted with an air chamber behind with absorbing material like fiberglass. It is not a broadband absorber, but you might be able to construct it to absorb one or two of your room mode peaks (you can use the calculator here: http://www.realtraps.com/modecalc.htm to find frequency candidates). Based on your room dimensions and using modecalc, it looks like frequencies in multiples of 80.71 Hz are potential candidates.
BUT: You will likely need an acoustic expert to help you with the construction design of the Helmholz resonators.

You might be able to get away (WAF) with treating the whole front wall with, say 4-6" of OC703, with vertical wooden strips 1" x 4-6" every two feet and then cover it with some kind of tapestry / paper surface (using the wooden strips to fix the tapestry on). Again, consult with the experts, but this might give you some broadband bass absorption (but reflecting the mids and highs due to use of paper rather than AT cloth). I dont know whether you can make the tapestry look nice and smooth - I am just throwing stuff at ya :eek:

Good luck,
Jacob

CCDC

10-24-09, 04:52 AM

Appreciate it, that was exactly the kind of info i needed Jacob. I do plan to treat the front wall with some OC and covering that with some fabric stretched and tacked or just hang a theater style curtain over it .

A coworker when presented with my situation recommended stuffing the two voids between the studs on either side of a corner with the OC covering with fabric and then using slats of 5/8" wood to create a diffuser panel over the filling and that would bring the design flush with the 5/8" drywall on the studs next to it and could be painted to match the room.

giomania

10-24-09, 07:12 AM

This would not be correct. Nylon, polyester, burlap or otherwise makes no difference. The differences between each fabric is not based upon the material...it is based upon the weave and weight.

Does anyone have a good source for curtains to use on the ends of my screen wall?

Thanks.

Mark

giomania

10-24-09, 07:36 AM

I have installed the FRP Absorption panels (1" JM 817) on the ceiling and the side walls for the front channel speakers. See the first three pictures.

In case you are wondering, the reason why there are two panels each on the side walls is because one controls reflections for the front row seating area, and one controls reflections for the back row seating area. The ceiling-mounted FRP absorbers only controls reflections for the front row seating area.

I have four FRP Absorption panels (1" JM 817) left, but was not planning to install those yet, as I am not certain of the advantages. However, if anyone has any sage advice based on the last picture of the rear part of my room. I also have some 2" JM 814 panels left that I can cut use to treat other areas of the rear of the room.

Today I will run Audyssey and tonight watch a movie.

Thanks for any input.

Mark

cuzed2

10-24-09, 09:34 AM

Does anyone have a good source for curtains to use on the ends of my screen wall?

Thanks.

Mark

We did the same thing:

We flanked the angled (bass-trapped) front corners with curtains. We found ours on sale at that famous French outfitter >> JC Penneee. Takes awhile; but with patience we found a great sale price.

If you dig into my thread you will see an example

giomania

10-24-09, 08:01 PM

We did the same thing:

We flanked the angled (bass-trapped) front corners with curtains. We found ours on sale at that famous French outfitter >> JC Penneee. Takes awhile; but with patience we found a great sale price.

If you dig into my thread you will see an example

Thanks,

Ideas always help; I found lots of pictures of your curtains. Did you have those tassles on the bottom sewn on, or did you find them like that at JC Pene'?

Thanks.

Mark

giomania

10-24-09, 08:14 PM

Well, the results are in:

First, I ran the SMS test tone on one of the Velodyne DD-15's just so I could see the graphed response from the main listening position, and it was pretty flat, within 3 dB, it appeared. I was using a little 7" LCD screen, but I looked really close. I know the response was not that flat before installation of the room treatments.

Next, I performed the Audyssey MULTEQ XT calibration (8 positions), and then watched / listened to the first couple chapters of Master & Commander Blu-ray. It has been awhile since I saw that clip, but I think I heard more subtle details, like more footsteps from above, etc. It definitely sounded more "crisp" and "bright", but not too bright.

I guess as time goes on, I may notice more details. I have two children (2 & 4), so do not have much time for critical listening these days.

Maybe tomorrow we can watch "Monsters vs. Aliens" in the theater.:eek:

Mark

johnbomb

10-24-09, 10:42 PM

Does anyone know at what Hz FRK begins to reflect frequencies?

John

giomania

10-25-09, 09:14 AM

Last night, my wife and I watched "The Soloist", which was the movie we had from Netflix. I had commented earlier in the evening that I was disappointed that was the first movie we had to watch since the installation of the acoustic treatments.

Well, I was pleasantly surprised, to say the least. Even though I have never seen this movie before, I noticed things in my setup that I do not recall experiencing prior to the acoustic treatments. For example: Increased dialogue intelligibility, more low-end subtleties, and better placement of sounds in the front soundstage.

Now, some people may call "BS" because I never saw the movie before, but it was just a sense that I had that everything was better. Even my wife commented that "Everything seemed more contained". Placebo? Perhaps, but ignorance is bliss, my friends. The water is fine...come on in!

Mark

Terry Montlick

10-25-09, 09:22 AM

Does anyone know at what Hz FRK begins to reflect frequencies?

It depends what is in back of it. But generally speaking, between 1 and 2 kHz.

- Terry

cuzed2

10-25-09, 11:05 AM

Mark,

We bought them that way.

BTW - we returned to JCP a few weeks ago looking for some shades for other windows, It appears they still have many choices; however > the curtains we bought for the HT room are no longer carried.

pepar

10-25-09, 01:55 PM

thorr

10-25-09, 02:27 PM

I haven't taken the time to do all of my homework, but I wanted to ask some general questions. I am about to own a new house and I have a room that I will dedicate to my theater. It is rectangular with a closet in the back. The front wall is 95" tall by 145" wide. The side walls are 202" long. It is on the second floor of the house and the ceiling in the room goes up to a peak (because it is under the roof) in the center of the room at 133" high (horizonally when looking at the screen, not front to back). There is a huge window on the left side that I will have to deal with.

I want the room as dark as possible. I am planning on either covering all the walls and ceiling with black felt using push pins or possibly covering the walls and ceiling with something like this: http://www.foamexpress1.com/Acoustic_Sound.php For the window, I will probably get some heavy curtains and fasten the sides down so there is no light leakage.

My questions are, if I were to cover the room in acoustic foam, would it sound better or worse? Is it better to have a higher NRC, or would it make the sound too dead? In the future I could add base traps or whatever else, but I am mostly concerned about making the room dark and making the sound better while making it quieter for my neighbors. If I am better off with black felt for better overall sound quality at the expense of noise for the neighbors, I will go this way.

Thanks!
Mike

pepar

10-25-09, 02:58 PM

Just one alert: It is VERY easy to over-dampen the typical room in a residence.

thorr

10-25-09, 05:38 PM

So I am better off with just the felt then? Or perhaps just put the foam on the screen wall which is next to the neighbors?

Thanks,
Mike

kiwishred

10-25-09, 06:37 PM

Just one alert: It is VERY easy to over-dampen the typical room in a residence.But, is overdampening actually a bad thing for sound clarity ? What are the effects of over-dampening on sound ?

The reason I ask is that song vocals and such always sound clearest to me listening through headphones. Presumably headphones = zero reverberation. Also, presumably any desired room reverberation effects are already recorded into the sound track. Is it a good thing to allow the theatre room add additional, largely uncontrolled, reverberation ?

This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.

Brent

pepar

10-25-09, 06:53 PM

So I am better off with just the felt then? Or perhaps just put the foam on the screen wall which is next to the neighbors?

Thanks,
Mike
I am not an acoustician, but I will say that I regret applying carpet up to (seated) ear level all around my room and am looking at installing diffusors.

pepar

10-25-09, 06:56 PM

pepar

10-25-09, 07:00 PM

This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.
1) Right-sized absorbers at the first reflection points. Look around; there are more than most people think. (The one on my rear wall made the MOST difference in my room.)

2) SSC-style (http://forum.studiotips.com/viewtopic.php?f=8&t=535) bass traps.

3) Measure. Listen. And go from there.

johnbomb

10-25-09, 10:06 PM

It depends what is in back of it. But generally speaking, between 1 and 2 kHz.

- Terry

Thanks, Terry.

John

bpape

10-28-09, 10:03 AM

Overdoing coverage, especially in something thin that only impacts high frequencies is not a good idea. The idea is to have a balanced scheme of absorption in the room.

As for target decay times, it depends purely on the usage of the room and the size of the room. A single number isn't adequate nor accurate for every room.

Bryan

giomania

10-28-09, 01:57 PM

I was wondering if there is any advice for FRP Absorber installation for surround and surround back speakers in a 7.1 setup? Ethan's article only covers a 5.1 setup with surrounds at 110-120 degrees. I have surround speakers located at 90 degrees and surround back speakers located at ~150 degrees.

For the surround speakers at 90 degrees, I would think there is no FRP absorber required, as they are pointed right at the listener?

For the surround back speakers, Ethan's formula can be used to calculate the placement of FRP absorbers on the side walls, correct?

Last, what is the recommendation for FRP absorbers on the rear wall? If I remember correctly, Toole's new book was discussing diffusion? I suspect this depends on a number of factors. My main lisenting position is about 15 feet from the rear wall.

Thanks for any input.

Mark

Ethan Winer

10-28-09, 03:24 PM

For the surround speakers at 90 degrees, I would think there is no FRP absorber required, as they are pointed right at the listener?

It depends on the width of the room. Better safe than sorry, especially if the room is less than 15 or 20 feet wide.

what is the recommendation for FRP absorbers on the rear wall?

At 15 feet away you could add absorption or diffusion or neither. The "crossover" point is around ten feet away, where the reflections arrive sooner than about 20 milliseconds.

--Ethan

pepar

10-28-09, 03:42 PM

LarryChanin

10-28-09, 03:50 PM

But, is overdampening actually a bad thing for sound clarity ? What are the effects of over-dampening on sound ?

The reason I ask is that song vocals and such always sound clearest to me listening through headphones. Presumably headphones = zero reverberation. Also, presumably any desired room reverberation effects are already recorded into the sound track. Is it a good thing to allow the theatre room add additional, largely uncontrolled, reverberation ?

This is a very topical question for me as I begin planning how best to distribute a pile of 30 sheets of 2' * 4' rigid fiberglass throughtout my new home theatre build.

Brent

Overdoing coverage, especially in something thin that only impacts high frequencies is not a good idea. The idea is to have a balanced scheme of absorption in the room.

As for target decay times, it depends purely on the usage of the room and the size of the room. A single number isn't adequate nor accurate for every room.

Bryan

Hi,

Here's a couple of oldies but goodies on the subject of "ideal" reverberation time.

RT60 what is a good value! (http://archive.avsforum.com/avs-vb/showthread.php?threadid=332289&highlight=rt60)

what's the holy grail for rt60? (http://archive.avsforum.com/avs-vb/showthread.php?threadid=418231&perpage=20&highlight=rt60&pagenumber=1)

Larry

SierraMikeBravo

10-28-09, 04:24 PM

Congratulations to SierraMikeBravo ... he is now HAA Level II certified.

Thanks Dennis! Could not have done it without your help and guidance!:D

LarryChanin

10-28-09, 06:42 PM

Congratulations to SierraMikeBravo ... he is now HAA Level II certified.

Thanks Dennis! Could not have done it without your help and guidance!:D

Hi Shawn,

Congratulations!!

Larry

giomania

10-28-09, 09:30 PM

It depends on the width of the room. Better safe than sorry, especially if the room is less than 15 or 20 feet wide.

At 15 feet away you could add absorption or diffusion or neither. The "crossover" point is around ten feet away, where the reflections arrive sooner than about 20 milliseconds.

--Ethan

Thanks for the responses, guys.

The room is 20 feet wide, so I am at the border. However, they are Mirage Omnipolar's, so I think the wall should be bare behind them. The one thing I am concerned about are the parallel surfaces. If you clap in the rear part of the room, it reverberates.

Any guidance on parallel surfaces?

Thanks.

Mark

SierraMikeBravo

10-28-09, 09:33 PM

Hi Shawn,

Congratulations!!

Larry

Thanks Larry! :D

lucifers_ghost

10-28-09, 09:39 PM

Terry Montlick

10-29-09, 09:25 AM

What if one was to take a standard movie poster and have it laminated. Then what if one took that laminated picture and installed it over an acoustic panel (say a GIK 242 panel).

Would that effect the functionality of the acoustic panel? Or would it not make a difference?

Just curious.
It would make it reflect high frequencies, and potentially enhance the absorption of lows. Not good for early reflection treatment!

- Terry

lucifers_ghost

10-29-09, 09:54 AM

It would make it reflect high frequencies, and potentially enhance the absorption of lows. Not good for early reflection treatment!

- Terry

Boooo! Thats what I was afraid of.

Just trying to think of some inventive ways to "dress up" the acoustic panels. While they are certainly not unsightly, they are rather .. meh .. bland I guess.

Terry Montlick

10-29-09, 10:24 AM

Boooo! Thats what I was afraid of.

Just trying to think of some inventive ways to "dress up" the acoustic panels. While they are certainly not unsightly, they are rather .. meh .. bland I guess.
Digital images can be custom printed on some acoustically transparent fabrics. If it is a dye process and the printing doesn't screw up the acoustical transparency, this is an excellent solution.

But beware of manufacturers claims, and ask for acoustical transparency test results. I came across one fabric printer/manufacturer advertising acoustically transparent fabric images. I asked for a sample, and tested it. The fabric was terrible, even before it was printed on! In this case, the manufacturer simply didn't know enough about acoustical testing. They used the NRC (Noise Reduction Coefficient) of acoustic panels made using the fabric, and this was indeed pretty good. But the NRC is the sound absorption average for major speech frequencies only. There is no testing for frequencies above the 2 kHz band.

When I brought this fact to the manufacturer's attention, they very responsibly withdrew the acoustical transparency claim.

- Terry

Ethan Winer

10-29-09, 04:16 PM

they are Mirage Omnipolar's, so I think the wall should be bare behind them.

I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a byproduct of the design, not a design goal. Untamed reflections give bass peaks and nulls, and also "smear" (though I hate that word) mids and highs.

Any guidance on parallel surfaces?

Yes, you need either diffusion or absorption. :D

--Ethan

giomania

10-29-09, 08:44 PM

I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a byproduct of the design, not a design goal. Untamed reflections give bass peaks and nulls, and also "smear" (though I hate that word) mids and highs.

Yes, you need either diffusion or absorption. :D

--Ethan

Thanks Ethan. I did cover my front wall, so am "covered" there. Regarding the placement of the diffusion or absorption on the parallel surfaces, is there any guidance on placement?

Mark

pepar

10-29-09, 11:31 PM

I'm not familiar with that specific model, but generally, dipole speakers benefit from absorption on the front wall behind them. As I see it, when speakers radiate equally front and rear that's a byproduct of the design, not a design goal.
Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?

Dennis Erskine

10-30-09, 05:39 AM

Omni polar designs came from a necessity to use the room as a surround processor for two-channel applications. They are not well suited for multi-channel applications in small rooms.

Weasel9992

10-30-09, 10:47 AM

Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?

There are different ways to do things of course. I know that we've specified diffusion behind a pair of dipoles with absorption between them (if space and set up permits).

Frank

pepar

10-30-09, 11:53 AM

There are different ways to do things of course. I know that we've specified diffusion behind a pair of dipoles with absorption between them (if space and set up permits).

Frank
The diffusors behind the dipoles would serve to reflect more sound out into the room, right? The absorption in between is for what - general room treatment?

Ethan Winer

10-30-09, 01:53 PM

Regarding the placement of the diffusion or absorption on the parallel surfaces, is there any guidance on placement?

This depends on so many things I'd be writing for half a day to explain it all. It also depends on the size of the room and where the listener sits. Here are the high points:

* Diffusion is very common on the rear wall behind the listener.

* Diffusion can be used on the front wall behind dipole speakers if the listener prefers more ambience, but wants to avoid the small-room boxy sound often caused by leaving those early reflections untreated.

* IMO, diffusion is not useful at reflection points, but I've tried that only in my 16 foot wide living room. In much larger rooms diffusion there might be okay.

* Diffusion can be useful elsewhere on the side walls, especially if the room is small and you want to make it sound larger.

These two videos have further information and also let you hear what diffusors sound like:

All About Diffusion (http://www.realtraps.com/video_diffusors.htm)
Hearing is Believing (http://www.realtraps.com/video_hearing.htm)

--Ethan

Ethan Winer

10-30-09, 01:55 PM

Really? Then how do the front and rear lobes create the diffuse soundfield and a sense of envelopment if they are absorbed?

My personal preference is for whatever "envelopment" that's embedded in the recording to come through unchanged. I don't want early reflections to cause comb filtering, which to my ears makes a room sound smaller, not larger. But that's me. :D

--Ethan

pepar

10-30-09, 02:46 PM

My personal preference is for whatever "envelopment" that's embedded in the recording to come through unchanged. I don't want early reflections to cause comb filtering, which to my ears makes a room sound smaller, not larger. But that's me. :D

--Ethan
I thought the context here was surround speakers and, IIRC, dipoles are used for surrounds because that's what Tom Holman determined was needed to recreate the sound of surround arrays in commercial cinemas. So, the goal as I understand it is not to recreate what is in the soundtrack, but to recreate how the soundtrack sounds in a commercial cinema.

If the context was dipole or omnipolar main speakers, then...nevermind. :)

johnbomb

10-30-09, 04:16 PM

Anyone ever heard of hemispherical diffusion? A (bad) example: mount a big wooden salad bowl on your wall. I wonder if a properly executed solution would be analagous to primitive root (skyline) diffusers, in that 2 dimensional diffusion is provided.

John

MikeWojcik

10-31-09, 09:56 PM

Was planning on using some rigid styrofoam behind my fabric walls where i do NOT want any absorption - just to keep the same 2" thickness.
Am using 2" OC703 at first relfection points and a few other reflection points.

Will the styrofoam be relatively equivalent to nothing there?

Thanks!

SoundProgression

11-01-09, 10:57 PM

If I have an area behind cloth that doesn't need treatment I leave it bare if the area is not subject to abuse. This is especially true if the cloth is very shear (acoustically transparent). If it's a heavy absortive cloth I'd either bring cheap sheetrock or MDF forward (light fiberglass between the sheetrock and exisiting wall) and keep the fabric very close to the sheetrock.

If you decide to use Styrofoam make sure you paint it because it's light color will telegraph through cloth.

SoundProgression

11-01-09, 11:06 PM

There are many companies that make spherical/hemispherical diffusers. The main problem compared to a Skyline is their efficiency and uniformity. Skylines scatter very well and that can be very important if the source or the receiver are close to the diffuser.

So, use a hemispherical diffuser but make sure they you give them a little extra distance to spread the sound, alter their size and you'll probably need to use a few more than you would skylines. You may want to use 2d diffusion and make the sound fan out more effectively in the direction needed than a poor 3d diffuser.

Ethan Winer

11-02-09, 12:29 PM

dipoles are used for surrounds because that's what Tom Holman determined was needed to recreate the sound of surround arrays in commercial cinemas.

I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.

--Ethan

pepar

11-02-09, 12:43 PM

I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.

--Ethan
Perhaps they were the best simple way or they were better than monopoles as used in commercial cinemas, but I'll dig up the info.

rhcorolla

11-02-09, 02:46 PM

Follow-up to my post #5108: Utilizing 2” thk. OC703 w/ FRK foil face from a local insulation contractor, I treated my problematic/ severely compromised live/ hot room layout (wood floors w/ area rugs, painted wood panel walls, brick front wall, many openings) w/ (5) 2” thk. early reflection panels (FRK face @ back) & (2) 4” thk. 2’ x 4’ bass traps (FRK face @ front: both panels). I saw greatly improved results: tighter bass, more detail, far less echo.

After reading about the Studiotips Super Chunks (SSC) corner adsorbers, I decided to modify my (2) flat panel bass traps accordingly. My 17.5’ w x 11’ d x 8’ h den only has 1 true corner (back left behind recliners) where I located 24” w x 64” h solid diagonal super chunk to replace diagonal 4” panel & wall 4” panel directly opposite sub.

6.1 System: av123 ELT525 towers & center, Paradigm Cinema diopole surrounds & single surround back, Rythmik F12G subwoofer (sits on DIY subbdude located behind recliners in corner near diagonal trap); Denon avr-1909 w/ Audyssey speaker auto calibration but w/ Multi EQ set to OFF, Front/ sub xover: 80 Hz, Center 90 Hz, Surrounds 150 Hz, Surround back 110 Hz, Oppo BDP-83 Blu-ray player.

Utilizing RealTraps 10 Hz- 300 Hz test tones w/ Rat Shack SPL meter before/ after results are as follows (avr volume set @ 70 dB per track 30 pink noise) Seating/ mic position 3’ from back wall of 11’ room depth

10 Hz: corner super chunk: 64 dB, flat panels: 82 dB
20 Hz: corner super chunk: 76 dB, flat panels: 86 dB
30 Hz: corner super chunk: 81 dB, flat panels: 88 dB
40 Hz: corner super chunk: 81 dB, flat panels: 84 dB
50 Hz: corner super chunk: 82 dB, flat panels: 85 dB
60 Hz: corner super chunk: 84 dB, flat panels: 85 dB
70 Hz: corner super chunk: 78 dB, flat panels: 80 dB
80 Hz: corner super chunk: 84 dB, flat panels: 86 dB
90 Hz: corner super chunk: 83 dB, flat panels: 88 dB
100 Hz: corner super chunk: 90 dB, flat panels: 92 dB
110 Hz: corner super chunk: 89 dB, flat panels: 89 dB
120 Hz: corner super chunk: 83 dB, flat panels: 83 dB
130 Hz: corner super chunk: 86 dB, flat panels: 82 dB
140 Hz: corner super chunk: 78 dB, flat panels: 77 dB
150 Hz: corner super chunk: 74 dB, flat panel: 71 dB
160 Hz- 300 Hz: pretty much the same results for before/ after

While I haven’t tweaked sub location, etc.; I am encouraged w/ initial readings utilizing SSC corner trap. I did try dialing back sub volume an additional 4-5 dB, but overall sound was greatly diminished to my ears. I also prefer Audyssey MultiEQ On vs. Off audio-wise (boosts 10- 80 Hz sub readings on avg. by 5 dB).

I realize any given room can vary & YMMV, but thought a comparison of the 2 bass treatments would be interesting for those considering SSC or 4" bass traps.

Any thoughts/ comments on these results are most welcome.

pepar

11-02-09, 02:52 PM

Any thoughts/ comments on these results are most welcome.
Not that you can - or would want to - but your room has corners where the walls meet the ceiling and the floor. The former might be a location to consider if you want to add more traps.

Just throwing that out there . . .

Jeff

pepar

11-02-09, 02:57 PM

I'd have to see the context of that quote, but on the surface this seems very wrong. You can't "recreate the sound of surround arrays in commercial cinemas" in a small room unless you add artificial delays and reverb. A living room is just too small. And that shouldn't be needed anyway because many DVDs and Blu-rays claim to be re-mixed for home theaters.

--Ethan
'Ere ya go (http://www.paradigm.com/en/pdf/dipolar_confusion.pdf)!

Ethan Winer

11-03-09, 12:00 PM

MikeWojcik

11-03-09, 12:20 PM

Have read in numerous places that it is better to locate the subwoofer as close to the floor as possible. I will be installing the subwoofer inwall at the bottom of the screen wall. Recently decided to add a small stage about 6-8" high.
Will fill it with sand per many plans / recommendations I've read. Will this reduce the performance of my sub?

Thanks
Mike

pepar

11-03-09, 12:53 PM

That's an interesting article, but I'm not sure how relevant it is today where DVD mixes are done specifically for HT. His tests sound interesting, but I didn't see a room size for either test described. This makes all the difference in the world. Regardless, I'm not a fan of dipole speakers generally, so maybe I'm biased.

--Ethan
I know that some movies are remixed for the home market, but not all are. (Maybe even not that many?) But even with a home mix, do you think that they are doing any more than readjusting levels which still does nothing to create the diffuse field of a surround array in a commercial cinema?

Do you mainly listen to music?

Jeff

Roger Dressler

11-03-09, 01:26 PM

I know that some movies are remixed for the home market, but not all are. (Maybe even not that many?) But even with a home mix, do you think that they are doing any more than readjusting levels which still does nothing to create the diffuse field of a surround array in a commercial cinema? Very few are remixed. Noteably those from Disney and New Line (RIP). The vast majority are not remixed, but are cleaned up wrt edit gaps, clicks, or other such flaws that were not noticed on the dubbing stage, and the EQ is tweaked if needed.

pepar

11-03-09, 01:39 PM

Very few are remixed. Noteably those from Disney and New Line (RIP). The vast majority are not remixed, but are cleaned up wrt edit gaps, clicks, or other such flaws that were not noticed on the dubbing stage, and the EQ is tweaked if needed.
Roger, what is your thinking on dipole vs monopole surrounds for movies wrt Tom Holman's earlier research?

Kal Rubinson

11-03-09, 02:12 PM

Have read in numerous places that it is better to locate the subwoofer as close to the floor as possible.Where? It is usually on the floor because it is small and heavy and people do not want to see it, if possible. That, unfortunately, assures that it will maximally excite at least one room mode and, if close to other boundaries, possible more. This give maximal output but the most nonlinear output.

ASC makes a trap (http://www.acousticsciences.com/subtrap.pdf) which raises the sub off the floor to prevent this.

Roger Dressler

11-03-09, 03:09 PM

Roger, what is your thinking on dipole vs monopole surrounds for movies wrt Tom Holman's earlier research?Tom's stated goal was to try to replicate the theatrical experience, circa 1989, when that was dominated by Dolby Stereo, a.k.a Pro Logic, a single U-shaped mono array spanning the side and back walls of the theater. Diffuse rears was the order of the day. THX's dipoles attempted to recreate that same feeling, and it does work reasonably well.

Yamaha had their own approach with Theater DSP. They came to Dolby around that same time and, since they had been developing their DSP concert hall processing for several years prior, were not keen to toss it out and adopt THX as were their various competitors. Rather, they made new DSP modes to mimick theater acoustics. They brought an early unit to Dolby and set it up in our theater to show us how well they succeeded. Our theater experts acknowledged they succeeded, only too well, and reproduced some of the things that happen in theaters with undesirable acoustics--too much reverb mainly. Of course that is an adjustable parameter on the Yamaha products, but too much of a "good thing" turned out not to be on that day.

Getting reverb down in a huge space is no easy task, nor is it inexpensive, but it is desirable in order to improve clarity and detail. If the mixers want to create the sensation of hiding in a clothes closet--it's not easy when the room overlays a long reverb tail. If they want to create a pinpoint sound to the left of the audience, it's not easy when it comes out 6 speakers spanning 50 feet.

While of course there were some 70mm movies with split surrounds long before digital audio arrived on film, it wasn't until the overall theater industry moved to 5.1 discrete that more attention was drawn to the ability to create spot effects in theaters--taking full advantage of the technology. Then EX added one more degree of freedom to directional control. If you look at the SMPTE Digital Cinema specs, there are some 20+ channels identified in an attempt to future proof the path forward, and it includes not only the current Ls/Rs,Cs surround arrays, but discrete speakers in the rear corners for even more precisely focused spot effects.

In other words, one could say that the trend is toward better directional control, and in that sense, theaters are trying to catch up with the capabilities of smaller rooms (home theaters).

My thinking is that theaters suffer certain compromises in order to uniformly cover 200-300 wall-to-wall seats with sound, and we need not faithfully mimic those, nor the sticky floors, when we design home theaters. Let home theaters do what they do best. Clean sound, low reverb, presentation of pinpoint directionality and immersive spatial diffusion (as dictated by the mix, not the acoustics), for movies and music. Vive la différence.

pepar

11-03-09, 03:29 PM

In other words, one could say that the trend is toward better directional control, and in that sense, theaters are trying to catch up with the capabilities of smaller rooms (home theaters).

I thought that we had gone beyond the commercial cinema experience, and it make sense that they would try to outdo the home theater experience like they did with early television and 'Scoped movies.

So bipoles for home theater surrounds? :)

Roger Dressler

11-03-09, 04:05 PM

I thought that we had gone beyond the commercial cinema experience, and it make sense that they would try to outdo the home theater experience like they did with early television and 'Scoped movies.Yes, I'm saying that commercial theaters are the ones trying to catch up.

I think in certain respects Commercial theaters have always exceeded the capabilities of home theatres, and always will--the sense of an event shared by a hundreds of people. If they'd only stop texting...

So bipoles for home theater surrounds? :) Absolutely. They are a good tool. Wide, smooth dispersion. One of Floyd's faves, too. Can't argue with that.

giomania

11-03-09, 07:51 PM

So bipoles for home theater surrounds? :)

Absolutely. They are a good tool. Wide, smooth dispersion. One of Floyd's faves, too. Can't argue with that.

Whoo-Hoo! Finally, I have the right type of speaker in the right place: Mirage Omnipolar (OM-5, OM-7) in the surround and surround back positions.

Mark

pepar

11-03-09, 07:56 PM

Whoo-Hoo! Finally, I have the right type of speaker in the right place: Mirage Omnipolar (OM-5, OM-7) in the surround and surround back positions.

Mark
Adjustable radiation pattern? Omnipolar is not the same as bipolar. :)

giomania

11-03-09, 07:58 PM

Adjustable radiation pattern? Omnipolar is not the same as bipolar. :)

They radiate front and back, in phase, at the same time.

Mark

pepar

11-03-09, 08:10 PM

They radiate front and back, in phase, at the same time.

Mark
Yep, that's bipole. "Omnipolar" must be part of the product name.

Ethan Winer

11-04-09, 11:08 AM

I know that some movies are remixed for the home market, but not all are.

I have a bunch that claim to be special HT mixes, but I have no idea how many DVDs do that. If others here say it's rare, I have no reason to doubt that.

Do you mainly listen to music?

In my living room HT my wife and I watch regular and HD Television, DVD and Blu-ray movies, and we listen to music. Of course, a lot of movies have music! :D

--Ethan

Ethan Winer

11-04-09, 11:10 AM

Was planning on using some rigid styrofoam behind my fabric walls where i do NOT want any absorption - just to keep the same 2" thickness.

That should be fine. Styrofoam is mostly "inert" for acoustics.

--Ethan

Ethan Winer

11-04-09, 11:13 AM

'Ere ya go (http://www.paradigm.com/en/pdf/dipolar_confusion.pdf)!

I'll look later and comment when I can. I admit I don't have a lot of experience with dipoles, mostly because the few times I heard them I wasn't impressed. But that doesn't mean they're never useful.

--Ethan

maxfli

11-04-09, 07:22 PM

Hi all,

I have been reading this forum for some time and have now decided to begin treating my room. My room is a converted 2-car garage designed more for visual appeal than acoustics. As you'll see it has several design features that may or may not help with acoustics, so I'm not certain as to what and how many treatment panels the room will need.

This is my first attempt at posting images, so I hope this goes as planned.

157209

The projector screen sets on a false wall which is 10" from the back wall. The plasmas on the left and right are on levers that allow them to be moved behind the false wall when just watching the projector screen. This results in a pocket between the back wall and the false wall per the next image.

157210

In the next attachment, you can see the tray ceiling and pillars on the side wall that were added for visual appeal.

157211

The left side wall has arched pillars around the wet bar and door to a storage closet. The room entry is on the far left side of the above image.

157222

The right wall has similar arched pillars with a bay window of sorts.

157227

maxfli

11-04-09, 07:30 PM

Continued - the back wall has no pillars or shapes like the side and front walls, just 2 rear channel speakers.

157239

So, the room has several arches, a tray ceiling, coveys for wetbar and bay window plus curtains on the walls and carpet that influence the sound in the room, which right now is pretty good.

I am expecting to add some 2' x 4' bass traps on the back wall under the plasma screens, a bass trap on the rear wall between the rear surround speakers, and maybe some traps in the tray ceiling. I also may add a trap or two inside the arched areas as it makes sense.

But I'm trying to maintain the design of the room without adding any eye sores for treatments. Any thoughts or ideas would be appreciated.

thanks,
Max

Weasel9992

11-05-09, 02:08 PM

I am expecting to add some 2' x 4' bass traps on the back wall under the plasma screens, a bass trap on the rear wall between the rear surround speakers, and maybe some traps in the tray ceiling. I also may add a trap or two inside the arched areas as it makes sense.

That sounds like a good plan. You can just see where you are after that and add more if you need to.

Frank

johnbomb

11-10-09, 12:06 PM

I've read that FRK is flammable. Does anyone know of a non flammable FRK alternative- one with similar acousitcal properties? Preferably something that reflects frequencies above 1k hz. This may sound silly, but how would tinfoil or thin plastic do (don't worry, I'd cover it w/ fabric :D)

Thanks,
John

pepar

11-10-09, 02:07 PM

johnbomb

11-10-09, 09:00 PM

Non-flammable? :)

Woops! Plastic, not so much (that was an afterthought). I had GOM in mind for fabric- supposed to be non flammable.

bmwnbnw

11-11-09, 01:51 AM

hello guys, im new here but can someone provide some insight on treatment for my humble stereo room?

avsforum.com/avs-vb/showthread.php?t=1195503

thank you

stgdz

11-13-09, 01:23 PM

Doing a search for green glue I came upon this thread
http://www.gearslutz.com/board/1480199-post21.html

So has anyone attempted this blocking technique?

KERMIE

11-13-09, 02:18 PM

I don't know what I am talking about but I always understood things need to be able to flex a little- that blocking looks like it won't allow that.

Bill Mac

11-13-09, 06:55 PM

I just started looking at room treatments for my HT/Audio/Livingroom. The GIK 242 panels and the Tri-traps look like they will blend in my room if that is possible:). My room is 13' deep by 17' wide which is open on one side to a woodstove hearth/staircase with 8' ceilings. Basically a acoustical nightmare but it is what it is;). I am able to place my LCR (Ascend Sierra-1s) fairly well about 6' apart and my seat is dead center about 8' away. I feel I have a decent system but from what I have read treating my room might improve overall SQ quite a bit.

I am curious at the quality of GIK panels or is the DIY alternative a good choice to save on the cost for an entire room? I saw a post with a link to a company that sold various foam panels as well as cloth but can not recall the name of the company. Are there many companies out there that cater to DIYs for room treatment products? Any advice or thoughts would be appreciated:).

Bill

yacht422

11-14-09, 08:40 AM

Where? It is usually on the floor because it is small and heavy and people do not want to see it, if possible. That, unfortunately, assures that it will maximally excite at least one room mode and, if close to other boundaries, possible more. This give maximal output but the most nonlinear output.

ASC makes a trap (http://www.acousticsciences.com/subtrap.pdf) which raises the sub off the floor to prevent this.
walt here:
this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?
thx
walt

yacht422

11-14-09, 09:00 AM

walt again, new question(s).
same 16x22x10 room, concrete floor, carpeted.(man cave!)
1) ihave o/c 703 at 1st and second reflection points, all facings removed, prox 4' X 6'. covered in guliford with wood frames(all diy) the ? is, are these the correct size???
2) said panels rest against the walls. I am considering "framing" the rear of the panels with additional 703 which allows an additional 1.75" behind the panels, but, with open space inside of the "framing". is there any advantage to doing so?
3) i built corner traps (ala super chunk concept i think it is called) - - - floor to ceiling - - - the ?? is, what should they be faced with? since this is a bass control concept, do i face with guilford, or 1/4" plywood, or or pegboard, or diffusion?(additional info - - we have 8 leather recliners, the outermost seats are located 6" from the rear wall, and prox 2.5' from the corners traps)
4) putting a sub on a stand. there are commercial units out there, but, is seems to border on smoke and more smoke to me. so - do they really offer sonic benefits?
finally, the room has a trey ceiling. the plate height is 9' with the trey gaining an additional 12" for a total of 10'. any recommendations as to the need to treat, and if so, how.
many, many thanks for insights about to be gained!!
walt

Kal Rubinson

11-14-09, 11:57 AM

walt here:
this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?
thx
waltI was not really suggesting that you buy it, only that you read what they have to say for ideas. My experience with it is here: http://www.stereophile.com/musicintheround/904music/index1.html

yacht422

11-14-09, 02:04 PM

I was not really suggesting that you buy it, only that you read what they have to say for ideas. My experience with it is here: http://www.stereophile.com/musicintheround/904music/index1.html
thx for the insights. i'll look into "the box" on monday.
Taming the mighty bass beast is a task :eek:- especially in a multi-chair movies dedicated room. [i have read books on how to tune a room (jim smith comes to mind -there are others) and they devote 90% of their teachings to a single chair in a small room - the writings did me next to no good at all in room dedicated to movies (and dvd classical music).]
the quest continues:)
again, my thanks
walt

SoundProgression

11-15-09, 03:05 PM

Doing a search for green glue I came upon this thread
http://www.gearslutz.com/board/1480199-post21.html

So has anyone attempted this blocking technique?

I haven't used this technique exactly. I do use blocking very near the ceiling lid to help with flanking noise that may make it into the wall cavity not going vertically into the joist or floor above.

I'd never use the one shown for noise isolation when there are others about as simple but much more effective. Adding extra blocking (looks like fire-blocking) makes the wall more stiff and adds coupling points for the two sides of the wall and should make it sound transmission worse.

Leaving the cavities alone and adding unfaced fiberglass and carefully sealing the perimeter framing, the GWB and other openings with acoustical caulking would be better.

There are several better ways to improve a simple wall. One way is making the studs staggered (not as simple)(1" offset is fine) and make the studs 16"-24" O.C. Use fiberglass or similar in the cavities. Then you'd have a decoupled wall, it's cavity depth is greater (thicker is better).

SoundProgression

11-15-09, 03:20 PM

walt here:
this is an expensive unit. how great an effect will it have on the sound? i have a 16' x22' x10' room, two subs on a concrete floor. anyone have real life experience with the concept?
thx
walt

I put multiple subs in most room designs. Concrete floors are usually not the issue. The construction of the rest of the room is.

Multiple subs can improve low frequency performance significantly. However, you need to put them in the right places. And, you need to be sitting on the right place.

ASC Sub-Traps work great and I recommend them if: you need to decouple a vibrating sub from an upstairs room so it doesn't vibrate the floor below and annoy people below or the sub (subs) can't be located where they should be and you need to "soften" the subs output (meaning remove from a boundary) a little to help improve (flatten) low frequency response (seems to help above the first order modes).

If possible put the subs where they can be and try the ASC Sub-trap to see if it works in your case.

yacht422

11-15-09, 04:11 PM

I put multiple subs in most room designs. Concrete floors are usually not the issue. The construction of the rest of the room is.

Multiple subs can improve low frequency performance significantly. However, you need to put them in the right places. And, you need to be sitting on the right place.

ASC Sub-Traps work great and I recommend them if: you need to decouple a vibrating sub from an upstairs room so it doesn't vibrate the floor below and annoy people below or the sub (subs) can't be located where they should be and you need to "soften" the subs output (meaning remove from a boundary) a little to help improve (flatten) low frequency response (seems to help above the first order modes).

If possible put the subs where they can be and try the ASC Sub-trap to see if it works in your case.
thank you for your response - my h/t is a self contained man cave. totally isolated from everyone/everywhere. that said, i have total location options as the room is dedicated to movies / classical music and there are no wife factors to deal with.
kal seems to like the units, and you are offering conditions where they would be of most assistance: none of those conditions exist for me.
so - - - is the elevation of the sub the trick:confused:, or is it the construction of the box itself that does the trick? this may be unanswerable except by mr noxon himself, and he has a product to sell.
gents: any additional insight you can offer me? i can build a box with a ported tube inside of it (with insulation) which seems to be the heart of the asc unit - - -or, as usual, am i missing something?
thanks
walt

SoundProgression

11-15-09, 06:06 PM

thank you for your response - my h/t is a self contained man cave. totally isolated from everyone/everywhere. that said, i have total location options as the room is dedicated to movies / classical music and there are no wife factors to deal with.
kal seems to like the units, and you are offering conditions where they would be of most assistance: none of those conditions exist for me.
so - - - is the elevation of the sub the trick:confused:, or is it the construction of the box itself that does the trick? this may be unanswerable except by mr noxon himself, and he has a product to sell.
gents: any additional insight you can offer me? i can build a box with a ported tube inside of it (with insulation) which seems to be the heart of the asc unit - - -or, as usual, am i missing something?
thanks
walt

Most guys would envy your situation. Yes, there are lots of ways to make something similar. Art's box is very similar to a short fat Super Tubetrap. But is this the solution you need?

Your right. Getting the sub off the floor is part of it then absorbing some bass is another.

Multiple sub-woofer position, setup, and acoustical and electronic correction is a great subject. I hope others join in. Maybe I should I start another thread?

I'd like to make sure the product you're looking at is actually the solution to the problem. May I ask a few questions so I know where you're at. Let me know if I'm going in the wrong direction.

1) Are you having problems with your subs now and if so can you describe what you hear?
2) Have you experimented with different positions for your seating and sub positions?
3) Have you tried using an SPL meter and graphed the frequency response where you currently sit and with the speakers are? Often we guess at the problem and sometimes there may be two or more convoluted issues that confuses our ears that only looking at a measurement can sort out.
4) How is the rest of the room constructed: sheetrock, wood paneling, lots of doors, windows, symmetrical seating (a sketch usually works, send me one)?
5) How do you set up your processor for your front speakers and subs.

Let me know if can help.

jvvjvv

11-16-09, 05:04 AM

pepar

11-16-09, 09:07 AM

SoundProgression

11-16-09, 11:19 AM

Want to thank those you helped me get this far. I have decoupled the ceiling and double SR/GG the room and a few other things I would not have done, save this forum.

The room is 8'W x 17'L x 7'H.......(no choice in the dimensions as to basement lay out).

I have a 60 in monitor on the way with floor speakers about 38" tall and the center speaker will be 38" off the floor. This will pretty much match ear height in the listening area.

If I build DVD storage shelves on both side walls, how will this impact reflection? Or, if I place the shelves above the 4' area and add absorbers from the shelf bottom to the floor. Also does this create another "corner" under the shelf, that has to be treated with a base trap?

Thanks, Jack

I'd break the problem into two parts, those above about 100Hz and those below 100Hz. Modes don't start getting smoothed out until about 150Hz (more evenly spaced and dense).

The good news is small rooms generally have shorter decay times than large rooms (less need for general absorption) and the bad news is room modes (hard to treat) and first reflections (need effective spot absorptive treatment) can be severe.

Below 100Hz

Your modes are very widely spaced below 150Hz. They're hard to treat acoustically. The problem is usually not just the peaks but the extreme difference in the amplitude of the peaks that are right next to a null. Basstraps might help a some. You'd need to target your strong length modes first. Upper frequency basstraps (100Hz to maybe 250Hz) would be more useful. Corners are the usually the best choice as another person already mentioned.

You have modes at 33Hz (1st order length), 66Hz (second order length) and 70-80Hz (1st order width and height).

I've put a downloadable chart here, www.soundprogression.com/Download/SPCalc.pdf , showing peaks and nulls for your room (doesn't show expected levels of the peaks and nulls) to help you choose where to sit (where modes cross or meet). At least you'll get an idea of the issues.

You're an ideal candidate for two subs, one in the back center and the other in the front center (see page 75-76 of www.harman.com/EN-US/OurCompany/Technologyleadership/Documents/White%20Papers/multsubs.pdf ). It's works very well eliminating or at least reducing peaks and nulls.

Equalization would be a big help too.

Above 100Hz

I'd spot treat the first reflection points with a minimum of 2" fiberglass. I usually increase that area by 18" or more so often the treament spot is 3-4' x 3'x4'. I also like to use small ASC TubeTraps that can be moved along the reflection path and are free standing. Include the rear wall, sidewall and the ceiling (if possible). Your DVD storage might work but you'd need to purposefully avoid making the DVD's evenly spaced and stack right next to each other(leave holes in rows). Basically, you need to provide spacing so sound will go into an opening but not come out or be "broken up" or diffused so you don't get a strong reflection.

highcap

11-16-09, 11:32 AM

pepar

11-16-09, 11:51 AM

Hope this is the correct thread for this question. Does anyone know of a wholesale/retail location in or near St. Louis, MO that sells OC703 or Roxul/Lineacoustic equivalents? ATS has great pricing, but the shipping costs would kill me.

I'll need about 90 2x4 sheets of OC703 to do all my walls.
Look in the yellow pages for an HVAC insulation distributor. SPI (http://www.spi-co.com/directory.html), the company I always link people to, doesn't seem to have a branch close to you.

Jeff

audhunt

11-16-09, 01:00 PM

Does anybody here know anythig about ownes corning SOFTR® All Service Fiber Glass Duct Wrap? It is the only duct wrap i can find in houston Texas. It has a backing on it and its 1 1/2 inches thick. Can this be used on the walls and screen wall?

audhunt

11-16-09, 01:47 PM

ok...just came across another type, Knauf Friendly Feel Duct Wrap. Again this is 1 1/2 inches thick and is faced. What to do? I would love some advice on the two options.

Thanks

pepar

11-16-09, 01:54 PM

Bob Gold's Absorption Coefficient List (http://www.bobgolds.com/AbsorptionCoefficients.htm) is your friend. :)

yacht422

11-16-09, 01:56 PM

Most guys would envy your situation. Yes, there are lots of ways to make something similar. Art's box is very similar to a short fat Super Tubetrap. But is this the solution you need?

Your right. Getting the sub off the floor is part of it then absorbing some bass is another.

Multiple sub-woofer position, setup, and acoustical and electronic correction is a great subject. I hope others join in. Maybe I should I start another thread?

I'd like to make sure the product you're looking at is actually the solution to the problem. May I ask a few questions so I know where you're at. Let me know if I'm going in the wrong direction.

1) Are you having problems with your subs now and if so can you describe what you hear?
2) Have you experimented with different positions for your seating and sub positions?
3) Have you tried using an SPL meter and graphed the frequency response where you currently sit and with the speakers are? Often we guess at the problem and sometimes there may be two or more convoluted issues that confuses our ears that only looking at a measurement can sort out.
4) How is the rest of the room constructed: sheetrock, wood paneling, lots of doors, windows, symmetrical seating (a sketch usually works, send me one)?
5) How do you set up your processor for your front speakers and subs.

Let me know if can help.
1) bass was somewhat loose, but, with the addition of the corner traps, (newly installed) things have improved. do not know how much better it really can be - not certain how to determine such a thing!
2) seating (8 leather recliners) are fixed in place. subs can( and have been) moved about.
3) the short answer is no. the longer answer is i use the anthem room correction (ARC) software, which is similar to the audussey (sp) system, but i am told, better. my processor is the anthem D-2 unit, with the anthem P5 amp. all feeding revel ultima II l/c/r and surround spkrs. ACR smoothes things out, provided the basic room issues are not past +/- 6DB from a 75 DB baseline. using the above i am provided a chart(post measurements) graphing what ARC found and corrected. My issue to date is a -7DB drop in the surrounds in the 1000 to 2000 range, and a room hump at the 20hz to 70 hz range in the mains(which included the subs) which exceeds +7DB. also, the sub profile is not smooth, but, rather, is bimodal.
none of this is extremely troublesome, but i am looking to improve. (are not we all?):)
4) the room is concrete block on concrete floor with rigid f/g glued to the block, then wood 2X4 with pink insulation, then 1/2" drywall. there is one door, and one double wide window, located in the rear of the room, covered with velvet drapes. there are other sound containment things that i did to ensure that the neighbors would not be offended by Mahlers' 2nd at 2am!;)
5) answered above. Anthem D-2 processor + ARC.
the sub box is really an afterthought to my primary concern, which is what to do about the existing reflection point(s) wall units. [posted just prior to the sub post.
walt

Dennis Erskine

11-16-09, 03:59 PM

SoundProgression

11-16-09, 04:05 PM

Fire Man

11-16-09, 04:29 PM

Looking for feedback on panel placements. This is my set up...

http://www.gliffy.com/pubdoc/1895194/M.jpg

Panels are in red.

The entry and the window on the sides will have curtains, hoping those double as panels. My biggest question is to the right of the front left speaker. I'd prefer to put a flat panel on the wall starting at the corner. In the diagram I have a triangle panel simply to match the other corner.

If anyone could offer an insight on what might work for me I'd appreciate it.

audhunt

11-16-09, 04:43 PM

Bob Gold's Absorption Coefficient List (http://www.bobgolds.com/AbsorptionCoefficients.htm) is your friend. :)

That's all greek to me. Anyone else have some input on the two types?

pepar

11-16-09, 04:48 PM

If anyone could offer an insight on what might work for me I'd appreciate it.
What software did you use to generate the room graphic?

Fire Man

11-16-09, 04:52 PM

What software did you use to generate the room graphic?

Gliffy (http://www.gliffy.com/)

Just found it on a simple search. It's free and easy to use. Pretty sweet.

yacht422

11-16-09, 05:23 PM

Actually, you'll find the transition to phase based (modal) problems will occur between 500 and 300 Hz depending upon the room. Generally (not always) it is the first three axial modes that will cause the most audible problems. That is not to say other modes will not be problematic. If you have an RTA, the first thing to do is measure response in a right tri-corner of the room to determine exactly what your modal frequencies are. The second is to do a near field measurement of your speakers (you don't want to be fixing speaker problems with acoustical treatments).
walt here. i assume this message related to my recent post.
i lack the RTA ability - part of the problem is i am a MAC person, and the software is PC based.
measuring in a tri corner now is more difficult as i have floor to ceiling corner traps installed(rear only - the front to side wall is angled so there are a pair of 45 deg angles per "corner", in the front.)
and - dumb me, but help with axial, please.
thx
walt

pepar

11-16-09, 07:22 PM

walt here. i assume this message related to my recent post.
i lack the RTA ability - part of the problem is i am a MAC person, and the software is PC based.
measuring in a tri corner now is more difficult as i have floor to ceiling corner traps installed(rear only - the front to side wall is angled so there are a pair of 45 deg angles per "corner", in the front.)
and - dumb me, but help with axial, please.
thx
walt
Axial is along the three axes of a rectangular room. Tangential and oblique are the others. Google work on Mac? :p

VideoDrone

11-17-09, 08:36 AM

I have at least 40' left of a 100' x 48" roll of 1" linacoustics left, $40 plus shipping if outside my area, dayton ohio.

Ethan Winer

11-17-09, 09:35 AM

Looking for feedback on panel placements.

This isn't what you're asking, but it's important:

If at all possible, you should rotate your setup 90 degrees counterclockwise so the TV is in front of the window on the left side of the drawing. Put the TV on a stand if that's what it takes. The acoustic advantages are overwhelming:

* You won't have a reflecting wall right behind the seating, which will make a huge improvement in the bass response.

* You'll be able to place your surround speakers correctly, rather than directly to the sides as they are now.

* You'll have better choices for sub placement.

Then put bass traps in the corners, and absorbers at the side-wall and ceiling reflection points.

-Ethan

audhunt

11-17-09, 04:59 PM

Clearly there are many people here who understand the fine details of frequencies and sound coefficients on this forum. Could you please help out someone who knows absolutley nothing. I have been searching all over my region for the standard insulation everyone mentions here. However I have only been able to come up with some linacoustic in 1 1/2 inch and knauf freindly that also comes in 1 1/2 inch. Will either of these work on my side walls and screen wall?

1 1/2 in linacoustic
Sound Absorption Coefficient at Frequency
Thickness (Cycles per Second) of
in mm 125 250 500 1000 2000 4000 NRC
1/2 13 0.07 0.20 0.44 0.66 0.84 0.93 0.55
1 25 0.08 0.31 0.64 0.84 0.97 1.03 0.70
11/2 38 0.10 0.47 0.85 1.01 1.02 0.99 0.85
2 51 0.25 0.66 1.00 1.05 1.02 1.01 0.95

1 1/2 in knauf
INSERTION LOSS (DB/LF), 1/3 OCTAVE BANDS
(SOUND AND VIBRATION DESIGN AND ANALYSIS, NEBB '94)
Duct
Dimensions Sheet
Metal Nominal Wrap
Thickness Nominal Wrap
Density 63
Hz 125
Hz 250
Hz 500
Hz 1000
Hz 2000
Hz 4000
Hz
12" x 12"
(305 mm x 305 mm) 24 GA 1.5"
(38 mm) .75 PCF
(12 kg/m3) .6 .6 .6 .7 7.4 14.2 20.9
24" x 12"
(610 mm x 305 mm) 24 GA 1.5"
(38 mm) .75 PCF
(12 kg/m3) .6 .6 .6 .7 7.4 14.2 20.9
48" x 12"
(1219 mm x 305 mm) 22 GA 1.5"
(38 mm) .75 PCF
(12 kg/m3) .5 .5 .5 .6 7.4 14.1 20.9
24" x 24"
(610 mm x 610 mm) 22 GA 1.5"
(38 mm) .75 PCF
(12 kg/m3) .5 .5 .5 .6 7.4 14.1 20.9
24" x 12"
(610 mm x 305 mm) 26 GA 1.5"
(38 mm) .75 PCF
(12 kg/m3) .8 .8 .8 .8 7.5 14.2 21.0
24" x 8"
(610 mm x 203 mm) 26 GA 2"
(51 mm) .75 PCF
(12 kg/m3) 1.0 1.0 1.0 3.6 10.4 17.1 23.9

Fire Man

11-17-09, 05:24 PM

This isn't what you're asking, but it's important:

If at all possible, you should rotate your setup 90 degrees counterclockwise so the TV is in front of the window on the left side of the drawing. Put the TV on a stand if that's what it takes. The acoustic advantages are overwhelming:

* You won't have a reflecting wall right behind the seating, which will make a huge improvement in the bass response.

* You'll be able to place your surround speakers correctly, rather than directly to the sides as they are now.

* You'll have better choices for sub placement.

Then put bass traps in the corners, and absorbers at the side-wall and ceiling reflection points.

-Ethan

I have no doubt your suggestions would be more ideal, but I don't think I can shift the set up. I appreciate your input but I'll have to work with what I have. I'm not looking for perfection but to better my set up with what I have to work with. When I finally buy my own house I will do things the right way.

jvvjvv

11-17-09, 10:05 PM

soundprogression, pepar.....

Thanks for the input, it helps. Sp.......great charts, still trying to "totally" understand all this stuff.

Still wondering if having shelves on both side walls above ear height will hurt.

Jack

jvvjvv

11-18-09, 12:48 AM

pepar

11-18-09, 10:15 AM

One last question.......(I think)......I have to raise my center speaker 6 1/2 inches.......(on the stand)...... to get the tweeter the same height as the tweeter in the towers. How important is this?

Jack
It is optimal that all three front speakers be on the same level. That said, there is more "tolerance" in human perception wrt elevation than there is with left-to-right variations.

I think you're good to go. :)

Jeff

Ted White

11-18-09, 05:16 PM

Doing a search for green glue I came upon this thread
http://www.gearslutz.com/board/1480199-post21.html

So has anyone attempted this blocking technique?

An infinitely stiff wall would theoretically not be able to create a sound wave, so many look to build such a stiff wall. Sort of like building a perpetual motion machine...

Any partition will resonate. Stiffening could only serve to raise the resonance, however that reduces the systems ability to isolate low frequencies. Generally we are looking to add mass and flex, not stiffen.

KERMIE

11-19-09, 04:48 PM

Terry Montlick

11-20-09, 05:10 PM

If one is unable to do triangle corner traps in the back of the room can you make 2 end table-like traps on each side of a couch (rear seating)

I am thinking a cube shaped:

36"H x 20"W x 30"D with a hard table top/bottom, 4 legs, filled with rigid FG and covered with GOM placed in the corner?

would that do any trapping?
It won't work like a corner bass absorber. But you could always mock it up with a plain stack of rigid fiberglass, to see if it did anything at all beneficial.

- Terry

highcap

11-21-09, 09:44 AM

I plan on using the DW laminate for my screen. At almost 12 feet wide, it will take up most of my front wall. I plan on putting 2" OC around the edges and 1" along the walls, but should I try to put something behind the screen? Or would it not make a difference since the highs will bounce off the screen anyway?

Dathon

11-21-09, 10:43 PM

How safe are acoustic panels that use fiberglass? Is the fiberglass wrapped in a protective bag and then the acoustic cloth put over it? What is the chance of fiberglass shedding or poking through the cloth? I see several companies now offering panels made with recycled paper and polyester fibers. I think I would rather have this or foam panels, than fiberglass hanging on my walls.

Terry Montlick

11-22-09, 08:14 AM

If you are concerned about fiberglass, use Bonded Acoustical Cotton. Just Google it. For the same densities and thicknesses, it has equivalent performance.

- Terry

Electric_Haggis

11-22-09, 09:03 AM

G'day again.
I've recently put in two small but significant additions.

* A pair of 600 x 600mm acoustic tiles.

Although the rear reflections weren't nearly as audible as they had a right to be, these tiles have helped clean things up a little... and look quite decent too!

http://farm3.static.flickr.com/2642/4123935487_391726ca80.jpg

* An 850mm-wide x 1000mm-high bass trap that doubles as a corner-stand.
This is filled with triangles of 48 kg/m³ polyester bats (http://acoustica.com.au/hdbatts.html).

Does a very nice job of knocking back the room's bass boom problem, which was its biggest failing.

http://farm3.static.flickr.com/2699/4124814796_64689c72b8.jpg

http://farm3.static.flickr.com/2678/4124043941_3e713c1169.jpg

http://farm3.static.flickr.com/2680/4124043269_3ec7e8d8a5.jpg

http://farm3.static.flickr.com/2693/4124820434_38157feac7.jpg

You can see the room by clicking on my signature.

Combined with the speaker placement, carpet, curtains, etc, it's now an exceptional sounding room.

Thanks to everyone here who threw in advice and suggestions!
:D

KERMIE

11-23-09, 02:49 AM

http://farm3.static.flickr.com/2680/4124043269_3ec7e8d8a5.jpg

To the experts, is this something that generally works. I like this idea as well since I cannot go from floor to ceiling in my corners.

Nice work EH

Terry Montlick

11-23-09, 01:17 PM

To the experts, is this something that generally works. I like this idea as well since I cannot go from floor to ceiling in my corners.

Nice work EH
Yes. Half a loaf is better than none! BTW, Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.

- Terry

A9X-308

11-23-09, 02:06 PM

Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.

- TerryWould you have a link or brand/model please Terry?

Elill

11-23-09, 04:26 PM

G'day again.
* An 850mm-wide x 1000mm-high bass trap that doubles as a corner-stand.
This is filled with triangles of 48 kg/m³ polyester bats (http://acoustica.com.au/hdbatts.html).

Does a very nice job of knocking back the room's bass boom problem, which was its biggest failing.

G'day mate,

Is that the Acoustica White HD Batts (http://www.acoustica.com.au/hdbatts.html)?

I get to start our room in January from the look of it - cant wait! I'll have the same traps floor to ceiling and across the bottom of the screen in our room. Probably stuff the soffits with it as well.

Elill

11-23-09, 04:51 PM

Actually, while we're talking about these batts. My plan for reflection absorbers was to have:

wall - 50mm of 48kgm, 25mm of 32 kg, and 25mm of ~20kg - room

I had read somewhere that having increasing density was more effective then just 100mm of 48kg. Is this correct? I cant find the reference anywhere, been driving me nuts.

johnbomb

11-23-09, 05:37 PM

I have two questions regarding primitive root (skyline) diffusers:

1) How would substituting round wooden dowels for square rods affect performance?

2) How would mounting these dowels (or rods) on a curved surface, such as a large polycylindrical diffuser, affect performance?

Thanks,
John

Weasel9992

11-24-09, 10:10 AM

G'day again.
I've recently put in two small but significant additions.

* A pair of 600 x 600mm acoustic tiles.

Hmmm...I'd usually want to see some thicker bass trapping back there. Are you finding that you have an exaggerated low end response with your head that close to the back wall?

Frank

Gelinas

11-24-09, 05:05 PM

Hi All,

I am considering adding acoustic panels to my theatre. Below are a few pics.
Any advice on location? I'm thinking 2 ATS 24/48/2 Chocolate Microsuede panels could look good behind my mains. I'd probally take down the small square pictures. May even do 3 across if they fit.
Or I could do the 24/24 in place of the square pictures and one 24/28 where the long pic is.

The chocolate microsuede would be a nice match for the sofa.
Currently all that is on the one side wall is that mirror and its unlikely I could talk my wife into letting it go.
Unless I come up with a cool design to go on 3 GIK ArtPanels.
As you can see there is a big bay window to factor in as well.

I'm open to ideas with what to do in the back of the room.

The wall not pictured has a closet door, bathroom door, aquarium, open stairwell to upstairs, and big opening to kitchen.
We have a long picture over the aquarium like the one above the TV so maybe I could put another ATS 24/48/2 Chocolate Microsuede panels in this location.

Finally not sure where I could put bass traps. Only place I can thing of is the back corner behind the sofa, but isn't the sofa like a big bass trap? In addition to the fact that we have to have a table there to hold that lamp up.

thanks in advance for the assistance.

http://i41.photobucket.com/albums/e251/mg14136/Copyofht007.jpg

http://i41.photobucket.com/albums/e251/mg14136/ht009.jpg

Weasel9992

11-25-09, 12:33 PM

...Unless I come up with a cool design to go on 3 GIK ArtPanels.

That would be good right where that mirror is. The bay window is probably helping you in terms of low end response. Hmmm...I'm not sure what else you could do. You've got one of your surrounds too close to the rear corner to treat it, and I'm wary of treating the front corner with nothing on the other side.

Frank

Gelinas

11-25-09, 01:29 PM

Thanks for the input, Frank.
Your artpanels are indeed very cool. But also very expensive (for me).
I'll cross my fingers and hope that I am the contest winner over at your Home Theatre Shack contest. Those panels are goergous with the wood frame.

It's funny that you mention the bay window and bass...anything remotely deep makes the windows rattle.

dweltman

11-26-09, 08:57 AM

I have 2 questions:

1) The GIK elite bass pillar trap seems like it would more much more acceptable cosmetically (and much less expensive) than ASC Tube Traps or other large bass traps. How effective is it? My middle channel speaker is up about 10dB at 50Hz and down 6dB at 100Hz. My right and left speakers are up 6dB at 40 and 70Hz and down 4-5dB at 200Hz. This is based on my Anthem ARC measurements.

The swing is so big my Anthem ARC is not fully able to compensate for the center channel. So I clearly need room treatment. Would 2 GIK pillars be somewhat effective in the front corners? Or do I need to go with ASC or Real Traps? It is going to be difficult to convince the wife to allow me to put any traps in the room, so I need to make choices that will give me a biggest bang for each trap I convince her to put in the room. (I do understand that most of you will recommend 4 or more bass traps, but it is going to be a work in progress with the WAF. So if the GIK pillars are more acceptable cosmetically, it is a big advantage).

2) As you can guess by these numbers, my home theater is in my living room and not a dedicated space. The hardwood flooring in the master bedroom above the living room is original with the house and sqeaks terribly. So we are going to pull it up and put down new flooring next month. The contracter in question has indicated that he wants to pull up the subfloor and put in a new one to make sure that it stays quiet. So this will be the only time I will ever get access to the living room's framing, albeit the ceiling joists. Should I take the opportunity to put something in the ceiling? My room, aside from the bass issue also has an RT60 which is too high, according to a recent calibrator (umg). What should I put in, and what would be the benefit?

dweltman

11-26-09, 10:00 AM

My room is 13'6" x 21'3" x 8'. The listening position is 2'6" from the rear wall. I have attached a quick and dirty Giffy layout of the room, unfortunately I have to put everthing oriented along the long wall because of the windows. The doors in the schematic are actually open archways, and cannot be closed off:o

It's a tough space to work with:(

And happy Thanksgiving folks!

Weasel9992

11-27-09, 01:09 PM

IThe GIF elite bass pillar trap seems like it would more much more acceptable cosmetically (and much less expensive) than ASC Tube Traps or other large bass traps. How effective is it?

Would 2 GIF pillars be somewhat effective in the front corners?

I assume that you mean GIK, so I'll answer. The Pillar Bass Trap falls right in between the Monster Bass Trap and the Tri Trap in terms of effectiveness. Two in the front corners would function somewhere better than two Tri Traps in the same places. The absorption range is the same, but the PBT's absorb a little bit more than the Tri Traps given a corner placement.

Frank

dweltman

11-27-09, 02:18 PM

I assume that you mean GIK, so I'll answer. The Pillar Bass Trap falls right in between the Monster Bass Trap and the Tri Trap in terms of effectiveness. Two in the front corners would function somewhere better than two Tri Traps in the same places. The absorption range is the same, but the PBT's absorb a little bit more than the Tri Traps given a corner placement.

Frank

Sorry about the typo:o

dweltman

11-28-09, 10:05 AM

Anyone have any suggestions about my ceiling?

KERMIE

11-28-09, 11:57 PM

Yes. Half a loaf is better than none! BTW, Haggis is lucky to be in Australia, where they have easy access to high density (48 kg/m^3 = 3 pcf) polyester. It is tough to find in the US.

- Terry

Thanks Terry,

Does it have to be tight into the corner or can it be a inch or so off? I have trim and chair rail up currently>

Dadshouse

11-29-09, 06:07 PM

I have at least 40' left of a 100' x 48" roll of 1" linacoustics left, $40 plus shipping if outside my area, dayton ohio.

was curious if you still have this? I sent a PM.

sebberry

11-30-09, 11:41 PM

Jacob B

12-01-09, 01:01 AM

Sounds like you have done your home work. :)
My knowledge comes from reading up on this myself, I am not a pro. But my two cents:
As for insulation in the cavity between the beams, standard r13 should be ok, as I understand. No need for special sound proof fiberglass.
You could add two layers of drywall with GG on the underside of the upstairs floor, between the beams. That extra mass will help, especially when combined with your current plan.
Remember use acoustic seal to make it air proof.

Good luck,

Cheers
Jacob

yacht422

12-01-09, 04:50 PM

I need some advice please with respect to noise control.

I live in a wood framed condo. Now before you say "end of thread, move out now".. can't.

Upstairs noises include:
-Heavy heel walking on both wood and carpet floors
-Constant assorted floor impact noises (perhaps from playing the Wii or something?)
-The "beep beep beep" from the microwave
-Toilet being used (not just flushed, but being peed into)

Needless to say if I can hear that you can imagine what else I can hear.

Anyway, I approached the owner upstairs to mention the noise and he had said that he could hear my movies downstairs. Now I don't usually play my stuff loud. I have all of an 8" sub and a couple of 4.5" booskshelf speakers.

I was considering the following and am looking for some input:

-Rip down sheetrock ceiling
-Install sound proofing insulation between ceiling joists
-Suspend new sheetrock from Green Glue clips (http://www.greengluecompany.com/noiseproofing_clips.php)
-Use green glue and a second sheet of sheetrock

What are everyone's thoughts on this? Despite the conversation with the neighbor, the heavy walking can still be heard loud and clear and any time he has guests over noise is really noticable.

Thanks! :)
1) insulate between joists - thicker absorbs more sound.
2) hang the drywall, as per your note above - but - first nail a layer of accoustiblok across the joists - then, the Drywall from clips.
N.B, : acoustiblok (www.acoustiblok.com) is both expensive and very heavy - you will NEED help to install. it is a thick rubber based product, difficult to manage, but very effective.
I used it on selective walls of my man cave to minimize leaking sounds to the neighbors. you also want to pay attention to any shared HVAC ducts. They readily convey sound!
GOOD LUCK
walt

yacht422

12-01-09, 04:54 PM

the least expensive way out of what is going to be an expensive retrofit is to buy earphones - good ones - - - and you will be very happy with the surround sound, without the noise of a strong stream streaming from upstairs.
just a thought
walt

velvet396

12-02-09, 11:38 AM

I was watching the HGTV show Holmes on Homes (cool show) and they were fixing a townhouse with neighbor-sound issues. They used a soundproofing drywall that had the sound-deadening properties of 8 sheets of normal drywall. Check into that stuff as well. Think it might be called ToughRock or Quiet Rock... whatever it was it was drywall with a thin layer of absorbing material in the middle of it.

Ted White

12-02-09, 12:01 PM

The assertion that 1 sheet = 8 is a marketing tact. Not ever validated or documented. That product is excellent, but 1=8 is hype, I'm afaid.

Ted White

12-02-09, 12:05 PM

1) insulate between joists - thicker absorbs more sound.

Not necessarily so. Tests show that in a joist cavity, a 50% filled cavity is about the same as a 100% filled cavity.

2) hang the drywall, as per your note above - but - first nail a layer of accoustiblok across the joists - then, the Drywall from clips.

Disaster. You've created a triple leaf. Absolutely this method is to be avoided at all costs.

N.B, : acoustiblok (www.acoustiblok.com) is both expensive and very heavy - you will NEED help to install. it is a thick rubber based product, difficult to manage, but very effective.

Works about as well as anything else that heavy... like drywall.

The overall solution doesn't have to be so complicated.

Ted White

12-02-09, 12:06 PM

I need some advice please with respect to noise control.

I live in a wood framed condo. Now before you say "end of thread, move out now".. can't.

Upstairs noises include:
-Heavy heel walking on both wood and carpet floors
-Constant assorted floor impact noises (perhaps from playing the Wii or something?)
-The "beep beep beep" from the microwave
-Toilet being used (not just flushed, but being peed into)

Needless to say if I can hear that you can imagine what else I can hear.

Anyway, I approached the owner upstairs to mention the noise and he had said that he could hear my movies downstairs. Now I don't usually play my stuff loud. I have all of an 8" sub and a couple of 4.5" booskshelf speakers.

I was considering the following and am looking for some input:

-Rip down sheetrock ceiling
-Install sound proofing insulation between ceiling joists
-Suspend new sheetrock from Green Glue clips (http://www.greengluecompany.com/noiseproofing_clips.php)
-Use green glue and a second sheet of sheetrock

What are everyone's thoughts on this? Despite the conversation with the neighbor, the heavy walking can still be heard loud and clear and any time he has guests over noise is really noticable.

Thanks! :)

http://www.soundproofingcompany.com/solutions/soundproofing_ceilings/

This article describes various ceiling solutions. Pros and cons.