Room Treatments

Hawkeye

TOOLFORLIFEFAN wrote: »

Mine are 2" thick and flat to the wall with good results, Should I try and put a 2" space between them and the wall?? Hummm if so I wonder what I could use.. The spacers I did try at one time when I first put them up didn't work very well and I just wanted them up so they went up flat to the wall..

Larry, it depends if you have a solid backing on the trap or not. If you have a solid back, moving it out will not gain you much, if anything. If there is an open back, 2-4 inches will double the trapping surface thereby making the trap twice as big as the dimensions suggest.

Gordon

Hawkeye

bsturgeon89 wrote: »

To go along with Tool's question.....

Any tips on how to hang from a suspended grid ceiling?

I suppose I could take screw eye hooks into the back of the panels and then use some kind of wire to hang them with. Any other ideas?

I've seen folks replace the ceiling tile WITH the trap. You can cover it in the same or contrasting color fabric. This way you don't lose ceiling height.

Gordon

ShinAce

Hawkeye wrote: »

Larry, it depends if you have a solid backing on the trap or not. If you have a solid back, moving it out will not gain you much, if anything. If there is an open back, 2-4 inches will double the trapping surface thereby making the trap twice as big as the dimensions suggest.

Gordon

This is not the reason I pull my panels away from the wall. I do it for wavelength. If the trap has some room behind it, that gives it a chance to absorb even lower frequencies. Think: midbass tightness.

bsturgeon89

Hawkeye wrote: »

Larry, it depends if you have a solid backing on the trap or not. If you have a solid back, moving it out will not gain you much, if anything. If there is an open back, 2-4 inches will double the trapping surface thereby making the trap twice as big as the dimensions suggest.

Gordon

What if the backing was peg board? Would one still benefit from having it off the wall or would it be better to flush mount?

audio_alan

ShinAce wrote: »

This is not the reason I pull my panels away from the wall. I do it for wavelength. If the trap has some room behind it, that gives it a chance to absorb even lower frequencies. Think: midbass tightness.

+1 to ShinAce's comment, but I'll expand upon it a bit...

The main reason to space your trap away from the wall is to lower the frequency range that is trapped. Frequencies are absorbed most when their wavelength is 1/4 the length of the air gap. As we all know, lower frequencies have a longer wavelength. So, the bigger the air gap, the lower the frequency it can trap. Additionally, frequencies that fall fully within a trap are "completely" absorbed.

The reason you should space the trap an equal distance (from the wall as the trap is thick) is to avoid a gap in the frequency range that is being absorbed.

Having said the above, you can already guess that placing 2" thick traps, spaced 2" from the wall, all over the room is going to absorb one frequency range very well, while not doing much for other frequencies. How do you solve that? Two ways:

1) Build traps of varying thickness, spaced at varying depths from the wall.

2) Build corner traps (because by definition, they will have a varying sized air gap behind them).

I think corner traps are the place to start, since just a single one can be considered a "broadband absorber" (compared to building several wall traps to cover as wide of a frequency range). No corner should go untrapped!

Of course, it might be hard to trap a corner that has a door next to it. I suppose you could create a removable trap that you install once you are inside the room. Hey, now that I think of it, that could even be a good excuse to get out of doing things for your significant other... "Sorry honey, I can't help now. I'm in my listening room with my corner trap installed."

Hope that helps,

Alan

P.S. For more in-depth information on this subject, I suggest you go to Ethan Winer's website. He has a wealth of knowledge regarding building and placing traps, including the physics behind it...

Hawkeye

Ok, I guess I didn't get technical enough:D:D:D

I'm able to permanently trap 3 of the 4 corners in my room. The fourth has the door. I move one in and out when listening. I've treated my 11X25 room with four Mondo corner traps, six tri-traps for the floor/wall/ceiling corner intersection, two HF Mini-traps placed directly behind the speakers and two micro traps at the first reflection point. All of them are placed off the wall the same distance as the thickness, so they all vary between 1 and 4 inches. All were purchased from Ethan's company.

IF I was to start trapping again, I'd start with the corners as mentioned by Alan. It was quite undescribable in the before and after. At first I thought the bass had disappeared but after listening, the presentation was much more refined and accurate. Crisp and solid vs boom and jello. I don't think the SRS2 could survive in my room without them. The "one-note" bass complaint has mostly disappeared and the definition is much more enjoyable now.

Having that many traps in the living room did not make me very popular with the better half but, after she listened for a bit, she was won over, in spite of the frankly ugly appearance of the traps. Ethan is great on room acoustics. I"ve spoken with him on many ocassions, just don't ask him about wires or any other "tweaks" many of us lose sleep over:D

Gordon

Hawkeye

bsturgeon89 wrote: »

What if the backing was peg board? Would one still benefit from having it off the wall or would it be better to flush mount?

From my research, the pegboard does not offer up enough open space for the waves to have much effect. I do understand that if your building a Helmholtz (sic) Resonator to trap a specific frequency, pegboard or several variations of it can affect the response. I can't comment much further than that since it is bumping against my knowledge level.

Gordon

audio_alan

Hawkeye - Glad to see I've joined a forum with people who appreciate and understand acoustics too! Great posts to follow-up my "lecture"... hahaha

But seriously, for those of you that haven't treated your room yet..... JUST DO IT!

(Uh oh, am I going to get sued by that shoe company?)

Polkie2009

Wow, so many options when it comes to all of this. I checked out this thread looking for an inexpensive way to keep from bothering my neighbors if I want to crank the HT. So far, nobody has complained yet and I've been somewhat careful not to be loud after midnight on weekends. On weeknights I shut it down at 10:30pm. I'm mostly concerned with bass since it's the hardest, and most expensive to contain in the house, and I do love my bass,lol. Looking at products like Quietrock, rockwood, GreenGlue, OwensCorning 705 for panels, Realtrap and others. Maybe someone has already tried something like this for their house. Open to all suggestions on this.

Polkie2009

Decided to build a couple of walls and install a couple of doors to downsize my listening area from 11,000 cu.ft to 6000 cu.ft. On the new walls went with a staggered stud frame, R13 batt, 2 layers of 5/8" sheetrock sandwiched with the Greenglue foam on the listening side. On the opposite side just went 5/8" sheetrock. Eventually I'll add another layer of 5/8" sheetrock with the Greenglue foam to the original existing sheetrock walls in the listening room. I"m not sure if the original sheetrock is 5/8" or what, but at least the exterior of the house is all brick. I know there were better ways to quiet the room down,but this was within my budget. True soundproofing is very expensive and better left to those who have a lot of money. Just downsizing the listening area will be a big improvement.

ysss

Hey guys, what's the general treatment for an L-shaped room?
I have an approx 23' x 18' room, but half of the back side of the room opens up to a 10' deep section that leads to the bathroom.

Here's the layout:



I plan to set the screen (100") on the bottom side of the room (of the picture above), due to cabling, window location and shape of wall.

I'm thinking of closing off that L-shaped portion with some drywall\plaster if that may improve things and simplify the acoustic treatment of that room.

I'd appreciate any thoughts and advice on this issue!

Polkie2009

Ysss, you 're right about putting up a drywall and possibly a door to access your bathroom.If anything, it will downsize your listening area and give the room a bit more of a rectangular shape. What is your ceiling height in the room? Like most of us, you have to make due the best you can in the house. Good luck with the project:)

ysss

Polkie2009 wrote: »

Ysss, you 're right about putting up a drywall and possibly a door to access your bathroom.If anything, it will downsize your listening area and give the room a bit more of a rectangular shape. What is your ceiling height in the room? Like most of us, you have to make due the best you can in the house. Good luck with the project:)

Thanks a lot Polkie!

Do you suppose I need to put anything specific behind the (new) drywall? Given the different material density and characteristic to the rest of the walls (concrete)...

The ceiling height is 10'.

Btw, I plan to make some 4" deep panels (approx 10'x 4' size) to line the walls with. Maybe 6 or so panels that I will hang in 'strategic' spots, and a bass trap for each of the corners. With the drywall addition, at least I know where to put the basstrap in that corner. Otherwise there'll be a void right next to the viewer's right ear and I'd reckon that would introduce all kind of audio trouble to the system

Polkie2009

I'm a newbie at room treatments too ysss, just learning from the knowledgeable folks here at CP who have been down this road:) So correct me if I'm wrong, the existing walls are concrete and you're going up with drywall right? There are so many options out there, it just depends on how much you're willing to spend. Right now I'm looking at what would be good as a temporary cover for 2 front windows that are 3'x6' each. I too am looking at the options of basstraps and acoustic panels. The foam stuff is cheaper ,but from what I'm interpreting , it doesn't seem to do as good of job compared to the stuff like GIK and Realtrap etc... have, maybe someone can chime in with some more info.

thejck

I have 5 windows that are 6 foot tall behind me in my living room. I guess I have no choice on acoustic panels behind me. My wife has been working on cloth blinds to add to the windows. They have insulated material called "warm window fabric" in the blinds. I wonder what they will do.

doctorcilantro

thejck wrote: »

I have 5 windows that are 6 foot tall behind me in my living room. I guess I have no choice on acoustic panels behind me. My wife has been working on cloth blinds to add to the windows. They have insulated material called "warm window fabric" in the blinds. I wonder what they will do.

Don't despair, I Acoustimac baffles ($25-35 each) over my windows like pictures, and remove when after 3 days of being up my wife gives me the evil eye.

thejck

can you use canvas picture paintings with the oc 703 stuffed behind the frame as acousitc treatments?

FTGV

thejck wrote: »

can you use canvas picture paintings with the oc 703 stuffed behind the frame as acousitc treatments?

It needs to be acoustically transparent to be effective(ie.absorbative instead of reflective) at high frequencies.A few companies sell panels with prints on them but I'm not certain if it's a special canvas of somthing else.

HTguru1982

I've built four 3ft x 2ft frames for my theater room. I've been trying to locate oc 703 but haven't had any luck so far. Will typical unfaced insulation work if enough layers are packed into the frame?

FTGV

Can you source Roxul mineral wool?

HTguru1982

Okay found a store about 50 miles away that carries it. Looks like I'm set.

thejck

FTGV wrote: »

It needs to be acoustically transparent to be effective(ie.absorbative instead of reflective) at high frequencies.A few companies sell panels with prints on them but I'm not certain if it's a special canvas of somthing else.

So the fabric that is used to cover the OC panels has to be something specific? or can you just use cotton or some form of fabric?

My parents live in India and I am thinking about having my mom send me some decorative wall coverings that have patterns and decorative themes stiched on to the fabric. I was then going to use this cloth to cover the panels I can make with the OC 703.. what do u think?

TECHNOKID

Ricardo wrote: »

The 4" are twice as thick.

FTGV wrote: »

Can you source Roxul mineral wool?

GV, can you explain the benefit of Roxul over Pink to make the panel? I can recall you responding to me to (in your former Polkie life which I believe all threads are lost) use Pink for bass traps.

Cheers!
TK

FTGV

thejck wrote: »

So the fabric that is used to cover the OC panels has to be something specific? or can you just use cotton or some form of fabric?

If the panel is being used for first reflection points the material covering it should be acoustically transparent.The reason for this is so that high frequencies can pass through the cover material unimpeded(ie.speaker grill cloth) so that it can be absorbed in the glass or mineral wool.
If the cover material is not acoustically transparent the high frequencies will be reflected instead of being absorbed,thus reducing the panels effectiness.If you can see light or can blow through it, the material will be acoustically transparent.Most comercial panels use coverings from Guilfords of Maine.
http://gikacoustics.com/gom_fabrics.html

Libertyc

For any Sam's Club members cheap acoustic panels in different colors.

http://www.samsclub.com/sams/shop/product.jsp?productId=193623&navAction=

I might order a set.

FTGV

TECHNOKID wrote: »

GV, can you explain the benefit of Roxul over Pink to make the panel? I can recall you responding to me to (in your former Polkie life which I believe all threads are lost) use Pink for bass traps.

Cheers!
TK

TK, it's because of it's increased material density.If you are making 2"-4" panels then the greater density of the Roxul will give it improved absorbtion at lower frequencies vs the run of the mill pink glass.The pink stuff can work fine for corner bass traps given enough depth of material .

Though not exactly high on the WAF quotent I have heard that just placing unopen bags of standard insulation in the corners works wonders.Since in the corners your only dealing with low frequencies so the plastic covering though reflective will actually improve it's effectivness in the bass range by work as a diaphramic absorber.

btw.AFAIK all the old thread are still there.:frown:

TECHNOKID

btw.AFAIK all the old thread are still there.

OK, I tought they were all deleted (misunderstanding) when you tought someone had taken your web ID. I guess one would be lucky to potentially find them in the history threads? I would hope so, as IMO there was a wealth of knowledge sharing. Yet, the only posts I've ever encountered under GV were other peoples threads you participated and GV is under "guess".

Now, I tought like everything sound panels shouldn't be overdone but according to this thread, it seems the more the merrier??? I f so, I was thinking of giving the walls irregularity (which is also suppose to improve by minimising wall reflections) by means of having different thickness panels. Also, it seems to be the consensus that using the backing peg board is not ideal since one wants to keep the panel away from the wall for more sond absortion effectiveness. However, which one would be best: 4" panel on wall or 2" panel with 2" airgap for example???

Cheers!
TK

FTGV

TECHNOKID wrote: »

OK, I tought they were all deleted (misunderstanding) when you tought someone had taken your web ID.

Someone did and they only made a few smart **** posts. I believe the ID still appears in the members list and the account still active.

GV were other peoples threads you participated and GV is under "guess".

Some are still around,I was able to find an old mod thread,. http://www.polkaudio.com/forums/showthread.php?t=55733&highlight=pioneer+dv563

. However, which one would be best: 4" panel on wall or 2" panel with 2" airgap for example???

Cheers!
TK

IMO the results would be equivilent.

aboroth00

I'm using a pair of Kappa 9's with dipole midranges (midrange back shooting backward) and a bipolar tweeter shooting backward toward the wall. The room is about 14x18 with the speakers on the 14' wall about 9 feet apart and each speaker about 2-3 feet from either wall.

Formerly, I had been using monopolar speakers and per the advice of many experts here, I treated the entire front wall or the majority of it with 4 2'x4' OC703 1" panels. However after upgrading my speakers to bipole/dipole speakers, the ambience of the speaker and the room seem rather dead. I suspected as such I was absorbing too much of the backwave from the speaker (I know is desired in HT). So I took down the 2 panels directly behind the speakers (they are the two panels closest to either side wall), but I had left the panels on either side of the TV (the panels closest to the center). After listening to music and judging with my own ears, there was clearly more richness and ambience to music and while the center image seemed only a tad less focus, the soundstage grew by a bit, which I preferred for music (unpreferred for HT).

So down to my question, should I play with diffusion directly behind the speaker rather than absorption. Seeing that my room is relatively small, I'm not sure leaving it bare is really an option acoustically. Unfortunately I don't have any ficus plants to play around with to position behind my speaker. Or should I just use diffusion on the entire wall for music? The occasional movie will be played but it is not of primary concern. I also have 2x4 oc703 panels at the first reflection point and will definitely use diffusion behind the main LP when I get the chance.

After doing some more research on the matter, perusing 1D QRDs and 2D diffusors, I've stumbled upon a most novel solution a polycylindrical diffusor. From my understanding you of all people would probably recommend a 1D QRD to diffuse horizontally rather than dissipate energy into the ceiling or the floor. So ideally a 1D QRD is ideal, but I have read that a polycylindrical diffusor would be ideal in the sense that it can diffuse just as well horizontally if there was enough distance from the listener to the diffusor which is not a problem if the diffusor were to be placed on the front wall.

However, behind the LP, I will use a traditional 1D or 2D diffusor. Has anyone accomplished a polycylindrical diffusor? I'm reading on the subject and it's rather confusing to extrapolate measurements for one to DIY. I'm getting things such as a "half sine wave," angle of incidence of 30 degrees. If anyone can clarify that'd be great.