Basic design:

Mid\High Frequency Absorption:

Use 1" 3lb (density) rigid fiberglass material (Owens Corning, Johns Mansville, others) on entire front wall (floor to ceiling) and on side walls up to ear height. The ear height number is more a rough AREA and less to do with placement. You can put the panels in the middle of the wall if you desire. You also need to treat several points on the side walls from floor to ceiling. These points are called First Reflection points. It takes two people to find these points. First, place a light at each front speaker location, then have on person move a mirror on the side wall as you sit in the each seat. Watch for the light to appear in the mirror. This is a reflection point and NEEDS to be treated. Repeat for each speaker and each seat. You can also do this for the ceiling if you are feeling adventurous.

So to make this paneling would you use a piece of plywood for the backing and attach the rigid fiberglass to the plywood then cover it with a fabric material? How is it attached to the drywall? With screws or some sort of adhesive?

Can you get the fiberglass from Home Depot or is it more of a specialty item?


Mid\High Frequency Diffusion:

Since you have a very long room, it would be good to put some diffusion on your rear wall. This can be as simple as book shelves, or as exotic as retail foam diffusion panels found online. Smaller rooms don't need this, but at 30', you should consider it.

I am planning on having a bar area on the back wall of the room with cabinets. Would that serve the purpose as far as diffusion goes?

Low Frequency Absorption:

Bass traps are a good thing. Typical placement is in each corner either straddling or filling the corner. Typical material is 4" (3 or 5lb density) rigid fiberglass...again Ownes Corning, Johns Mansville, ect. Typically these run from floor to ceiling and are 24" across. These panels can also be placed across ceiling to wall or floor to wall corners.

The entrance to the theater is in one rear corner of the room so I don't think I could put a bass trap there. Any idea how to work around that?

Thanks for your answers. It helps to have it summarized like that. What would you recommend as a fabric covering for the panels? Also I have pillars that outline my 108 inch screen. It would not be aestetically pleasing to have those covered with the sound panels. Would it hurt to leave the sound treatement off the pillars?

Scott

Ethan,

Thanks for the FAQ page. I'll spend the next couple of nights reading it over.

Scott

Stima,

I forgot another question I had. As far as the side wall full treatments go, how wide should you make the panels for the first reflection points?

Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?

Stima,

I forgot another question I had. As far as the side wall full treatments go, how wide should you make the panels for the first reflection points?
These reflections are relatively localized, so allowing about half a foot around the boundaries of all your reflection points should be sufficient. Just make sure you've got one or more rectangular panels that cover them all, and round up to the nearest foot.

- Terry

So to make this paneling would you use a piece of plywood for the backing and attach the rigid fiberglass to the plywood then cover it with a fabric material? How is it attached to the drywall? With screws or some sort of adhesive?

There are several ways to make these panels. If you are going to make them separate from the wall (which is completely acceptable), you can make them like Christmas wrapped picture. (You know, the way they do it in McDonald's around Christmas) Then, hang the panel on the wall with a hook and wire method. You could also integrate these panels into the wall by using furring strips (thin pieces of 1"x2"). Make "picture frames" on the walls and fill the "picture area" with either fiberglass or polyester batting.



Can you get the fiberglass from Home Depot or is it more of a specialty item?

I have never seen Lowes or HD carry the correct product, so I would say no. It took me calling nearly EVERY insulation dealer in my local area before I found the Knauf brand version.




I am planning on having a bar area on the back wall of the room with cabinets. Would that serve the purpose as far as diffusion goes?

Yeah, that sounds like a good idea. The front of the bar might be a bit reflective, but the back wall (with shelves, etc.) sounds just right.



The entrance to the theater is in one rear corner of the room so I don't think I could put a bass trap there. Any idea how to work around that?

It's rare to find a room that allows you to put traps in every corner. Perhaps you could put a trap that straddles the corner above the door. This corner is called a "tri-corner" and is the MOST important area to treat of any corner. Remember, bass traps are an accumulative thing. In most instances, the more the better. So, if you can't cover an entire corner, but can hit the other three...you are still doing OK. Just consider the fact that ANYTHING you do will be a 1000x better than most home theaters you will ever visit. ;)



Thanks for your answers. It helps to have it summarized like that. What would you recommend as a fabric covering for the panels? Also I have pillars that outline my 108 inch screen. It would not be aesthetically pleasing to have those covered with the sound panels. Would it hurt to leave the sound treatment off the pillars?

Glad to help. I assume I haven't give TO bad of advice as the real experts haven't come screaming as of yet. :p

Fabric to cover the panels can be almost anything breathable. If you can put the material against your mouth and blow through it without much effort...it is going to be a decent material. The status quo here on the forums is a product called Guilford of Maine. (GOM). It resembles burlap, but much much finer. Also, it is fire retardant making it a acceptable wall covering (code wise.)

For your pillars. If they are to the side or slightly behind your speakers I would say let them be. If they are in front, they really need some absorption just as your walls do.

Again, remember your room has to be pleasing to you for years to come. If covering the pillars looks like crap and your going to cringe every time you see them...then by all means leave them be. It is MUCH better to enjoy your theater then to sacrifice the enjoyment just to make it sound just a little better. :)

Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?

Not to bad. I got the Knauf 3lb non-fsk for $0.40 ish and 5lb for $0.60ish. Fsk 5lb was almost double at $0.60ish and $1.10ish.

Ish=I can't quite recal exact price. :p

Hi Stima

Thanks again, maybe this isn't as daunting as I once thought. Do you have any pictures of a tri-corner Bass trap?

Also any pictures of these acoustical panels? I'm a picture guy :)

Is all the GOM fabric basically the same but in different colors and patterns? I went to their website and there are a ton of different choices.

Thanks
Scott

Hi Stima

Thanks again, maybe this isn't as daunting as I once thought. Do you have any pictures of a tri-corner Bass trap?

Also any pictures of these acoustical panels? I'm a picture guy :)

Is all the GOM fabric basically the same but in different colors and patterns? I went to their website and there are a ton of different choices.

Thanks
Scott

I don't have any pics of anything, but here is a better description:

A tri-corner trap looks like a spider web up in a corner. The trap is triangular shaped and extends from the corner an equal distance.

For acoustical panels...just think of a wrapped gift box. Make a frame with wood, put a back on it if you want to have something to hold the fiberglass boards against (NO front as the fiberglass needs to be exposed to the theater to do any good), and wrap the entire thing in GOM.

The standard GOM used is FR 701 - 2100. There are a BUNCH of colors in 701.

Dan

Hi, I can get Knauf rigid plenum board
http://www.knauffiberglass.com/index.cfm?fuseaction=prd.dspProdDetail&ID=16
3.0 PCF acoustic properties
(48 kg/m3) 2"
(51 mm) .33 .67 1.07 1.07 1.03 1.06 .95

(knauf seems to seems to sell the same plenum liner product as Black Acoustical Board
http://www.knauffiberglass.com/index.cfm?fuseaction=prd.dspProdDetail&ID=21 )

or knauf Insulation board (faced or plain - I'd get plain)
http://www.knauffiberglass.com/index.cfm?fuseaction=prd.dspProdDetail&ID=12
3.0 PCF acoustic properties
(48 kg/m3) Plain 2"
(51 mm) .29 .65 1.11 1.13 1.06 1.03 1.00

Both are about $1 per square foot for 2" thick 3lb/ft**3 (the plenum board
is a little more expensive).

It appears to me based on the specs that either would work, but the plenum board has slightly better absorbsion at 125 khz - maybe that is within measurement error.

I'll probably stack these to make 4" think panels.
Will the black polymer overspray cause a problem with this?

I'll be covering with fabric. Do you think the black will show through?

I'd like to use the same fibreglass product for both corner "bass" traps
and first reflection points.

Which one would you recommend using?

I don't have any pics of anything, but here is a better description:

A tri-corner trap looks like a spider web up in a corner. The trap is triangular shaped and extends from the corner an equal distance.

For acoustical panels...just think of a wrapped gift box. Make a frame with wood, put a back on it if you want to have something to hold the fiberglass boards against (NO front as the fiberglass needs to be exposed to the theater to do any good), and wrap the entire thing in GOM.

The standard GOM used is FR 701 - 2100. There are a BUNCH of colors in 701.

Dan

Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.

Glenn

Not to bad. I got the Knauf 3lb non-fsk for $0.40 ish and 5lb for $0.60ish. Fsk 5lb was almost double at $0.60ish and $1.10ish.

Ish=I can't quite recal exact price. :p

What thickness was that for?

Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.

Glenn

What should you use as backing then? Also how do you space it 2" off the wall? with furring maybe?

What should you use as backing then? Also how do you space it 2" off the wall? with furring maybe?

furring strip will work fine, but from a cost and labor standpoint just using more
fibreglass seems to make the most sense to me.

Do not put any kind of solid wood backing on the back of panels.. The air gap between the back of the panel and the corner is very important and the panel will not work if you cover it with plywood.. Even with 2" panels that you put on first reflections should not really have solid wood backings and should be spaced 2" off the wall.

Glenn


YES!! I should have noted about the bass traps and the hard backing not mixing.

For the first reflections, I would be hard pressed to understand why a hard backing flush against the wall would be any different from drywall. Now, if you are spacing your panels off the wall, I could understand that position.

Even for first reflections it is better to space them off the wall. Not only do you get 2" more absorbing (saying that the panel is 2" thick) from sides (this was against the wall and now out in the room) but you get sound coming in from the open area of the back and hitting the wall to the panel.. It will also pick up more of the low end..

Glenn

I understand now about spacing, and would agree you wouldn't want a hard backing in that case. However, flush against the wall...I still don't see any harm in a hard backing. Do you agree???

Sure if your going to put it against the wall, but :)
Hey your in Atlanta also, hello neighbor.

Glenn

Fellow Hotlanta resident? :)

Yes sir!

Is 0.65¢ a sqr. ft. of JM 814 rigid fiberglass board a reasonable price ?


Depending on where you are geographically, the answer would be "yes".


Joel DuBay

A friend's recent visit with an SMS-1 snapped me out of my complacency and lead me back to working on my room's problems. I have a parametric EQ (Rane PE17) on the .1 channel that I had setup when I first built the theater. I used ETF software, but somehow a few bands that I *know* were online bacame bypassed. Re-visiting the EQ and ETF reminded me that I had "cheated" by only looking at the 80Hz and below part of the 20Hz - 250Hz sweep, and that my room is an absolute mess from ~100Hz - 200Hz. Even my 80Hz crossed-over sub (Hsu dual 1220HO's) excites it and excites it to the point where it's 50dB-60dB above the sub's 80Hz & below output. (Very weird.) And I purposely turned off the 7-ch amp so I didn't have to look at their contribution.

Room details: "crooked" walls and ceiling (by 1 degree) nominal 8' H x 13' W x 21' L

False wall in front 24" of room - lined - ceiling and walls - with 2" J-M Linacoustic

2" OC SelectSound - framed, backed and GOM'ed at all first reflection-to-audience points (ceiling, front sides and back)

I have excellent clarity, imaging and front/surround integration. Whispers are crystal clear and sound like whispers. Explosions sound like explosion with no audible distortion.

What and where? I could certainly load up behind the false wall, and I could place "something" in the right rear corner. Head-end and DVDs in the left rear. Soffits are a possibility, too.

Anyway, I think I need bass traps. But what and where? I feel like a noob.

Yes, exactly - you need bass traps. What and where? I though you'd never ask. :D

Look here:
Thanks, I'm on it . . .

I have questions; what's the best way to communicate?

Depending on where you are geographically, the answer would be "yes".


Joel DuBay

Joel...Im in the D/FW area in Texas. I checked for oc 703 of the same density as the JM 814 and prices were a bit higher.

Thanks for your reply. :)

A friend's recent visit with an SMS-1 snapped me out of my complacency and lead me back to working on my room's problems. I have a parametric EQ (Rane PE17) on the .1 channel that I had setup when I first built the theater. I used ETF software, but somehow a few bands that I *know* were online bacame bypassed. Re-visiting the EQ and ETF reminded me that I had "cheated" by only looking at the 80Hz and below part of the 20Hz - 250Hz sweep, and that my room is an absolute mess from ~100Hz - 200Hz. Even my 80Hz crossed-over sub (Hsu dual 1220HO's) excites it and excites it to the point where it's 50dB-60dB above the sub's 80Hz & below output. (Very weird.) And I purposely turned off the 7-ch amp so I didn't have to look at their contribution.

Room details: "crooked" walls and ceiling (by 1 degree) nominal 8' H x 13' W x 21' L

False wall in front 24" of room - lined - ceiling and walls - with 2" J-M Linacoustic

2" OC SelectSound - framed, backed and GOM'ed at all first reflection-to-audience points (ceiling, front sides and back)

I have excellent clarity, imaging and front/surround integration. Whispers are crystal clear and sound like whispers. Explosions sound like explosion with no audible distortion.

What and where? I could certainly load up behind the false wall, and I could place "something" in the right rear corner. Head-end and DVDs in the left rear. Soffits are a possibility, too.

Anyway, I think I need bass traps. But what and where? I feel like a noob.

sounds like to me your room is in good shape on the high end but a mess at the bottom.. Yep you guessed it bass traps would be in order I would think.. 4" or thicker rigid fiberglass in as many corners as possible would work pretty well for you..

Glenn

sounds like to me your room is in good shape on the high end but a mess at the bottom.. Yep you guessed it bass traps would be in order I would think.. 4" or thicker rigid fiberglass in as many corners as possible would work pretty well for you..

Glenn
Thanks, Glenn. While I haven't built a Rialto, I still need to do something aesthetically pleasing, or at least minimally disturbing. And it looks like that'll be a challenge.

Thanks, Glenn. While I haven't built a Rialto, I still need to do something aesthetically pleasing, or at least minimally disturbing. And it looks like that'll be a challenge.

Take your time, you can do it!

Glenn

Quick question:

Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.

I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.

Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?

Quick question:

Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.

I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.

Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?
AVS member bpape sells this stuff also. You can PM him or check out his WWW site here:
http://www.sensiblesoundsolutions.com/

Quick question:

Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.

I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.

Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?
Go to the "source." Try an HVAC distributor. In construction jargon, that's "HVAC" as in heating, ventilation and air conditioning. That's where I got both my J-M Linacoustic and OC SelectSound Black. The bigger ones usually have some in stock. The Linacoustic comes in roll and I was able to use our SUV, but I had to rent a big van for the more ridgid OC stuff.

Quick question:

Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.

I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.

Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?

Sure you can use the fluffy stuff and compress it.. Only problem is you don't really know what you got after your done.. Bryan is a good source also for oc703..
How many pieces are you looking for? Maybe I could have my supplier drop some off to me and i could send it to you.. I am feeling nice today!! :D

Glenn

You could compress it by 4x and have something equivalent to Owens Corning 703. But the problem is maintaining this fixed amount of compression.

Try:
Homans Associates
4 Armand Lane, Production Park
Williston, VT 05495
802-863-0355

- Terry

You could compress it by 4x and have something equivalent to Owens Corning 703. But the problem is maintaining this fixed amount of compression.

Try:
Homans Associates
4 Armand Lane, Production Park
Williston, VT 05495
802-863-0355

- Terry

I did see one panel one time that someone built. The person used chicken wire on the front and back.. Would not be my first choice, but it could work..

Glenn

You guys rock! (And roll, all night long)

Terry,

Homan's carries rolls of 1" Linacoustic 4'x100' for a very reasonable price. They're delivering it to my door on Monday.

Thank you all very much. I love this forum!

Kip

Quick question:

Can I use fluffy pink insulation on my front wall and let it be or perhaps compress it? It will be concealed behind a false wall that will support the screen.

I can't find any local suppliers of rigid fiberglass here in Vermont. Even the local theater installer doesn't know where to find it. Requests for special orders amount to costs of around $1,000 or more.

Last night, I did find 48 square feet of OC 703 going for $100 with shipping included. Is this a decent price?
Try the source that Terry recommended. They either will have the ridgid stuff or be able to get it in a flash.

You guys rock! (And roll, all night long)

Terry,

Homan's carries rolls of 1" Linacoustic 4'x100' for a very reasonable price. They're delivering it to my door on Monday.

Thank you all very much. I love this forum!

Kip
One inch won't do much . . . and what it will do may not be desireable.

One inch won't do much . . . and what it will do may not be desireable.

He could double it up to 2" or make a bass trap with 4"....

Glenn

"You guys rock! (And roll, all night long)"

and party every day!!!!! Every one sing! To bad there is not a little symbol that could breath fire and spit up blood.. :p

He could double it up to 2" or make a bass trap with 4"....

Glenn
Doh! Of course. But that leads me to wonder if it's more cost effective to buy 4' x 50' of 2" than to buy 4' x 100' of 1"?

Doh! Of course. But that leads me to wonder if it's more cost effective to buy 4' x 50' of 2" than to buy 4' x 100' of 1"?

ha ha ha.. sorry I seee your point now.. :D

I'm going to try the 1" on the front wall behind my speakers. I have room to get as thick as I need in the corners (both front and back walls). I'm also stuffing my columns with it, the first columns are in the first reflection point area. I intend to use it in the ceiling at the first reflection points as well in conjunction with a star ceiling. Away from the first reflection points I am planning on using panels made of 1/4" hardboard, strapped and wrapped in black GOM.

My room is rectangular, 13' x 23.5' x 7.5'. There are three windows on the back wall - each is 22" x 60". The floors are bamboo, but will be covered in front by a large, thick area rug. Behind the 1" material in the ceiling is 6.5" of R19 fiberglass, then 1" rigid foam board, and a 2" air space housing the radiant heating tubes for the floor above it. There will be a row of three and a row of four leather chairs in the room.

I guess I'll play with additional absorbtion on the walls if it's still too bright.

Any recommendations?

By the way, I haven't completed the order with Hamon yet, so I could see if they have the 2" material...

I would stick with the 2" if you can.. Also it is best to space it off the wall 2"...

Glenn

I'm going to try the 1" on the front wall behind my speakers. I have room to get as thick as I need in the corners (both front and back walls). I'm also stuffing my columns with it, the first columns are in the first reflection point area. I intend to use it in the ceiling at the first reflection points as well in conjunction with a star ceiling. Away from the first reflection points I am planning on using panels made of 1/4" hardboard, strapped and wrapped in black GOM.

My room is rectangular, 13' x 23.5' x 7.5'. There are three windows on the back wall - each is 22" x 60". The floors are bamboo, but will be covered in front by a large, thick area rug. Behind the 1" material in the ceiling is 6.5" of R19 fiberglass, then 1" rigid foam board, and a 2" air space housing the radiant heating tubes for the floor above it. There will be a row of three and a row of four leather chairs in the room.

I guess I'll play with additional absorbtion on the walls if it's still too bright.

Any recommendations?

By the way, I haven't completed the order with Hamon yet, so I could see if they have the 2" material...
It's sort of the other way around - 1" will absorb the highs, but the highs only leaving everything else. 2" will absorb lower frequencies, but even it will leave the mid- and upper-bass virtually unaffected. Check my link and scroll through the pages. I've got the false wall thing, too, and have the entire cavity lined with 2" of J-M Linacoustic. And I've got all of the first reflection points (to audience) covered with panels of 2" OC SelectSound Black. I have two problems. First, I have a VERY flabby 100Hz - 300Hz range. It's a real mess in fact. Why? My 2" does diddly at those frequencies. And my second problem is that the room has no "air" - the highs are being absorbed. Oh, I forgot to mention that I've got inexpensive carpet partially up the walls and that contributes to the too dead problem. The fix is to add diffusion.

Really, IMO, you won't be happy using only 1" anywhere. If it's cheaper to do double 1" to get the 2" then go for it. If not, get the 2". As for bass traps, I'm not sure that doubling 2" achieves the same result as real 4" stuff.

>As for bass traps, I'm not sure that doubling 2" achieves the same result as real 4" stuff. <

Yep it will work doubling up 2" to make a 4" panel... If you want to be really cool then make it 6" thick!!

Glenn

Pepar,

> I have questions; what's the best way to communicate? <

Man, I could have sworn I answered this. :eek: Best is to send me email through the Contact page of my company's site.

--Ethan

Glen, I feel cooler already!

For some reason the 2" material was $1.05 per square foot while the 1" was $0.45. I went with the 1". I bought extra so I can experiment with corner traps.

Thanks all!

Kip

Pepar,

> I have questions; what's the best way to communicate? <

Man, I could have sworn I answered this. :eek: Best is to send me email through the Contact page of my company's site.

--Ethan
You did. And I did. We've been corresponding via email. My most recent to you was to ask how to fairly compare your products to the Power Buy offerings from Ready.

> You did. And I did. <

Whew, I thought it my early Alzheimer's kicking in.

> We've been corresponding via email. <

Yep.

Thanks.

--Ethan

>Whew, I thought it my early Alzheimer's kicking in.<
Maybe you have the same thing I have CRS!!!

Glenn

Cold-rolled steel?

CRS = Can't Remember Sh*t


In it's advanced stages it becomes a far more serious condition known as CRAFT.

Can't Remember A Flipping (not allowed to use that "other" word, ya know) Thing

A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.

Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet :)

A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.

Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet :)
Not a pro, but evidently the first to see your question, so I'll take a run at it. I think the answer may rest almost entirely on just what kind of insulation it is. Fiberglass, foam?

Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.

A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.

Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet :)
And perhaps you could post a cross-sectional diagram of your wall construction from the concrete in?

Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.
Without seing a diagram of the entire construction, I'll say that the pink fluffy stuff doesn't have much absorption at low bass frequencies, especially at 2" thick.

A quick question for the pro's on this board. Up here in Canada code requires a builder to insulate 4' of the concrete basement wall from ground level down , which is suppose to be below the winter frost line. The insulation is covered with a vapor barrier. Three of my theatre walls abut the poured concrete walls and I have built standard 2"x4" walls about 2" out from the concrete which will be insulated and covered with a 6 mil vapor barrier. Naturally I have to slit the vapor barrier that is currently in place over the poured concrete walls insulation so I don't create a dead zone between the concrete and stud walls that will be prone to condensation.

Finally to the question! Will the insulation that is now on the current concrete walls act as any type of bass trap or provide any form of acoustical benefit, even when covered up with a stud wall and drywall? Sorry if the question seems a little convoluted but it's still early and my brain hasn't quite kicked into gear yet :)
'Ere ya go - absorption coefficients (http://www.bobgolds.com/AbsorptionCoefficients.htm) of various insulations . .

Sorry, I should have mentioned it's pink fiberglass and if memory serves me correctly, as I'm not at home, it's only R-8.

It is not doing much for you.. You will still need to put bass trapping within the room..

Glenn

Meddy:

If you have an exposed concrete foundation wall, then having insulation go 4' below the outside earth, covered by vapor barior is fine.
If you put a wall in front of the concrete wall, then you should insulate right to the floor, including vapor barier right to the floor.

Walls (drywall) reflect a lot of sound. Think of walls as reflectors, more than as absorbers.

With drywall in front of the fiberglass, the fiberglass stops being an in-the-room absorber. It damps the resonance of the wall, so it's a good thing, but I wouldn't think of the fiberglass in the wall cavity as being an in-the-room-absorber, because the drywall is stopping a significant % of the sound energy from getting to the fiberglass (drywall reflects sound into the room). Nor would I think of the fiberglass in the wall cavity as being a bass trap.

After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...
My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.

Does that sound like a good plan? Or is that a bit of over kill?

The walls I was just going to do R-19 and double dry wall with green glue.

The kitchen is right above where the movie theater will be...

I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.

So any of the guru's out there... could you let me know if this would be a waist?

Thank you in advance..

After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...
My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.

Does that sound like a good plan? Or is that a bit of over kill?

The walls I was just going to do R-19 and double dry wall with green glue.

The kitchen is right above where the movie theater will be...

I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.

So any of the guru's out there... could you let me know if this would be a waist?

Thank you in advance..


As I read it, this does not sound too overkill. Indeed the Green Glue is a good choice if I understand its intended application here. And, as always, you will save money with a DIY approach. From reading this, I assume the duct work is running from your screen wall, to the back of your seating, not acros your seating from left to right, correct?
This is a mite bit better than the other way around I believe, as ceiling acoustic treatments (if you have a hard floor), may be easier to install and may yield a better overall sonic field. I am certain you know this, but you will require bass trapping if you currently do not have any. It is worth repeating this for anyone not familiar with basic acoustic treatment of a critical listening environment.

It sounds like you might be a bit "handy" and I think you'll have an easy go of this.

Good luck as always!

After reading lots and lots about sound isolation.... I think I have an idea of what to do. As with most people I want to keep this as inexpensive as possible. So details...
My room is 14 x 19 with duct work going right down the middle of the room with about a foot in between the duct work. That brings the ceiling height down to around 7 feet in spots. My biggest concern is the duct work since I can't move it I have to deal with it. I was planning on wrapping the duct work with something... not sure yet. After that put R-19 insulation then a layer of MLV then double dry wall with green glue.

Does that sound like a good plan? Or is that a bit of over kill?

The walls I was just going to do R-19 and double dry wall with green glue.

The kitchen is right above where the movie theater will be...

I know there is so much to sound isolation, and I can't do it all... but this is the way I was planning on going. I found the MLV on a site that will cover the ceiling for around $300.00 this is the cheapest I have found anywhere. It is only the 1lbs per square inch. The green glue will run me around $400 for the entire room. That just leaves the dry wall and R-19 insulation.

So any of the guru's out there... could you let me know if this would be a waist?

Thank you in advance..


Just keep in mind that if you ever get a leak in the kitchen then you are in for a lot of repair.. :eek: Is sounding proofing that important to you? If so then you should be fine..

Glenn

Thank you for your reply's. I do realize I will need bass trappings and have planned it as part of my install along with covering the first reflection points with pannels and adding some more pannels along the wall for looks and more sound dispersion/absorbsion. I know I should probably do the whole Linacoustic just above ear level and GOM and the rest. But for me putting up the pannels will work just fine. I was going to put bass traps in the front two corners and maybe in the back as well. But I was going to wait and see how well everything sounded before I did that, I was planning on putting up some shelving on the back wall. Along with my Equipment rack.

Thanks again.

Just take it slow.. No need to throw 12 bass traps in your room when 8 could have done the trick.. Take a look at Ryan's (member here) case study he did on adding room treatment.. He started with 4 then went to 8..

Glenn

WOW, I can't believe I read through all 36 pages. It took me a few weeks reading a few pages a day, but I did it, and I am GLAD I did, I am definitely much more knowledgeable (at least I hope I am) then when I started.

One thing that I read a few days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?

If I place the 2x4 panels horizontally, is that a 'bad' thing? One advantage is that one panel, 4 feet across, may be able to hit more than one reflection point.

Be warned, I will have a few more questions/clarifications as I get closer to building my panels, but I figured I would start with the easy questions. :)

One thing that I read a fes days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?

Yep...3 points per speaker per wall, ceiling and floor.

As far as using the panels horizontally....no problem there. The sound waves don't care...so you shouldn't either. :p

WOW, I can't believe I read through all 36 pages. It took me a few weeks reading a few pages a day, but I did it, and I am GLAD I did, I am definitely much more knowledgeable (at least I hope I am) then when I started.

One thing that I read a few days ago, that I hadn't realized is that I need to do the 'mirror' method for the center channel as well as the front left and right speakers. Because of this, it is possible to have 3 first reflection panels per seat, is this correct?

If I place the 2x4 panels horizontally, is that a 'bad' thing? One advantage is that one panel, 4 feet across, may be able to hit more than one reflection point.

Be warned, I will have a few more questions/clarifications as I get closer to building my panels, but I figured I would start with the easy questions. :)
Do not overlook the REAR wall. When adding my panels - check my link - I happened to add the rear one first and was blown away by the improvement in clarity and imaging of the FRONT speakers. Much improved main/surround integration as well. Next added were the front sides - I already had a rug in room front with the thickest padding I could find - which further improved clarity, imaging and surround integration. Last added was the front ceiling panel which added even more improvement in the same areas. I now have nearfield listening at my second row.

Unless you have a very small room, 2' x 4' panels may not do it. You really need to visualize incidence/reflection from all front speakers to all seats. My front side panels are 4' x 4', ceiling 4' x 8' and rear is 2' x 8'.

Have fun!

And if you have 2 rows of 4 seats, you'll have 8 points per speaker per wall.

And if you have 2 rows of 4 seats, you'll have 8 points per speaker per wall.
If you do it right, you can "cover" all points from all speakers to all seats with one panel per surface.

I am going to have 5 seats and found that I can use 3 panels for the front speakers reflection points, now I need to figure out the center. Maybe I will get lucky and some of those points will fall on the same panels.

Pepar.

That all depends on how far the speakers are from each other, how far from the walls, how far apart the rows are, etc. I could show you plottings in 18'-20' long rooms with 2 rows and speakers behind a false wall where the distance from the first point to the last point on the wall is almost 10' apart.

Now, if you want 1 big 8-10' long panel in your room on each wall, I'm sure you could cover them in most rooms with 1 panel ;) Personally, if I'm going to see the panels and not have them hidden behind a cloth facade, I try to put up something that is visually interesting instead of just a monolith. Just a matter of personal taste.

That all depends on how far the speakers are from each other, how far from the walls, how far apart the rows are, etc. I could show you plottings in 18'-20' long rooms with 2 rows and speakers behind a false wall where the distance from the first point to the last point on the wall is almost 10' apart.
Yes, of course. My suggestion falls apart in large rooms. :o

Oh, you'll still find 'groupings' of points even in larger rooms. Many times you'll find points for 1 seat in the front row and 1 seat in the back row that have almost identical points. You can still do multiple points with a single panel. Sometimes you get lucky and everything falls right and you can cover all the points with 3 - 2' wide panels - sometimes not.

This is one of the reasons that working behind a cloth covered wall is nice. You can put up panels where they're needed or even do something solid without worrying about what it looks like, is it symmetric between 2 columns, etc.

Oh, you'll still find 'groupings' of points even in larger rooms. Many times you'll find points for 1 seat in the front row and 1 seat in the back row that have almost identical points. You can still do multiple points with a single panel. Sometimes you get lucky and everything falls right and you can cover all the points with 3 - 2' wide panels - sometimes not.

This is one of the reasons that working behind a cloth covered wall is nice. You can put up panels where they're needed or even do something solid without worrying about what it looks like, is it symmetric between 2 columns, etc.
Are you using false walls all around?!

Along my basement walls I have a chair rail, and of course it is located horizontally exactly where the panels need to be mounted. Other than removing the chair rail wherever I place the panels, which would be a last resort, does anyone have any ideas of something I can put behind the panels so that when mounted over the chair rail it can remain level and perform its intended purpose?

Along my basement walls I have a chair rail, and of course it is located horizontally exactly where the panels need to be mounted. Other than removing the chair rail wherever I place the panels, which would be a last resort, does anyone have any ideas of something I can put behind the panels so that when mounted over the chair rail it can remain level and perform its intended purpose?


I wouldn't go through all that trouble. Just make your panesl stop 4" above and below the chair rail. As long as the rail isn't perfectly at ear height, I would say the gap in the panels would cause minimal effect to the absorbtion.

Pepar.

I'm talking about when you use a track system or just firring strips to space the cloth out from the drywall by an inch or 2.

I wouldn't go through all that trouble. Just make your panesl stop 4" above and below the chair rail. As long as the rail isn't perfectly at ear height, I would say the gap in the panels would cause minimal effect to the absorbtion.

That is the problem, the chair rail is at ear height when seated upright and just above when reclined.

Then perhaps you could make the panels appear to "float" off the wall over the chair rail by making your panels stand off a few inches from the wall??

Spacing panels off the wall actually HELPS in absorption so don't be worried about the acoustics if you float the panels.

What could I mount behind the panels to make them float over the chair rail?

You could try using pvc pipe cut to the appropriate length. There is even some that is already grey or black that is used for irragation system risers, it is probably around 1.25" od. Depending on how your panels are made they may just rest in the corners, or drill a hole across the diameter and screw them in, or you could even use hot melt glue to glue them to a wood frame.

Of course, you could also just use some pieces of wood in the same way.

Just a few thougths for some simple solutions, I'm sure there are many other ways also.

Kevin

What could I mount behind the panels to make them float over the chair rail?
You could stand them off - mount them on stand-offs - that clear the rail . . . wood blocks, metal blocks or even genuine stand-offs - metal sleeves that slip over screws. Or, if you are building the panels, scribe and cut the rail profile out of the frame members where they hit the rail. The fiberglass inside would esaily mold itself to the rail. The panel would be flat against the wall and the rail will continue under - through actually - the panel and out the other side. The scribing/cutting would, IMO, produce the most elegant result.

Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.

Any other ideas?

Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.

Any other ideas?
How will you cover the fiberglass bats and then mount them without a frame? They do not have enough rigidity, in my experience, without a frame.

From reading through this thread, and seeing pictures of others that have mounted theirs, I was just planning to wrap them in fabric and use screws with washers and mount them. That is what I have seen and read others have done.

From reading through this thread, and seeing pictures of others that have mounted theirs, I was just planning to wrap them in fabric and use screws with washers and mount them. That is what I have seen and read others have done.
10-4. I've heard of that as well. It seems to yield less of a "finished" look, but that's a matter of preference. Here's some specialized hardware to do just that -

Here (http://adodistribution.com/browseCatalog.cfm?browse=002&catagory=72&dir=Anchors%2C%20Insulation%2FInsulation%20Anchors&CFID=1494691&CFTOKEN=1437632)

and here (http://adodistribution.com/browseCatalog.cfm?browse=002&catagory=75&dir=Anchors%2C%20Insulation%2FSelf%2DLocking%20Washers&CFID=1494691&CFTOKEN=1437632).

Thanks for the suggestions guys. I don't plan to put a frame around my panels, so I will look into either the pvc (in black), stand offs or wood.

Any other ideas?

I'd just put some more rigid fiberglass behind them to fill in the gap above the chair rail.

10-4. I've heard of that as well. It seems to yield less of a "finished" look, but that's a matter of preference. Here's some specialized hardware to do just that -

Or, for compressed panels, here: http://www.rotofast.com/home.htm

Really neat.

Kal

Or, for compressed panels, here: http://www.rotofast.com/home.htm

Really neat.

Kal

Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.

Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.
Used them this weekend for the first time and I am sold. Got them as samples but you should ask at the website.

Kal

Kal, Have you used these? They really look simple and effective. Is there a on-line retail source you used? I was considering a french cleat installation but this looks much better.

I looked at their site and they are .89 each. So at 4/panel cost is $3.50 each panel for hangers. I plan on about 15 panels so that is $52.50 for hangers. Sounds a little pricy, but I have not compared alternatives. I was considering these speaker grill guides (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-367) from Parts Express. They are only 1.45 for a kit of 12 and they would work well if you have any sort of wood frame around your panel like a lot of people do. Just not sure how well they would work with hanging on drywall though...

I looked at their site and they are .89 each. So at 4/panel cost is $3.50 each panel for hangers. I plan on about 15 panels so that is $52.50 for hangers. Sounds a little pricy, but I have not compared alternatives. I was considering these speaker grill guides (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-367) from Parts Express. They are only 1.45 for a kit of 12 and they would work well if you have any sort of wood frame around your panel like a lot of people do. Just not sure how well they would work with hanging on drywall though...
From the looks of those grill guides, they pre-suppose being mounted to a frame. Absent a frame, somehing will need to be driven through an "un-structured" fibelglass panel to have any chance of holding it.

From the looks of those grill guides, they pre-suppose being mounted to a frame. Absent a frame, somehing will need to be driven through an "un-structured" fibelglass panel to have any chance of holding it.
Agreed. Also, I am not sure that you wouldn't need more than four per panel if you wanted to sit beneath them. :D

In addition, the Rotofasts are really easy to set up, align and mount in minutes.

Kal

Used them this weekend for the first time and I am sold. Got them as samples but you should ask at the website.

Kal

I just send a request for information to Rotafast. I like these better than the grill guides since they mount directly to the material versus having to fabricate wood frames.

I'd just put some more rigid fiberglass behind them to fill in the gap above the chair rail.

From everything that I have read, you want to have either 1" or 2" rigid fiberglass, if I used more fiberglass behind them, that would make them too thick for their purpose.

I se all the different suggestions for how to hang the panels above, but is there anything wrong with just using screws and washers or is it more for the appearance?

From everything that I have read, you want to have either 1" or 2" rigid fiberglass, if I used more fiberglass behind them, that would make them too thick for their purpose.

I se all the different suggestions for how to hang the panels above, but is there anything wrong with just using screws and washers or is it more for the appearance?
Oh no, there is no such thing as "too thick" for their purpose, at least not from a purely performance standpoint. (An SO may have other "issues" though.) In fact, if you use 2" like I did you will probably find yourself - like I did - going back and adding bass traps. Two inch of fiberglass - I used OC SelectSound black - will NOT reach effectively to mid- and upper-bass frequencies. And doesn't come close to deep bass. If I had had the room - and the understanding I have now - I would have used four inches of 'glass. I would still need to go back and add some bass traps, but my room wouldn't be such a mess 100Hz - 300Hz.

And 1" is useless for first-reflection-point control.

I do like the idea of not building frames. I just want these things done!! Where is everyone getting their rigid fiberglass???

I do like the idea of not building frames. I just want these things done!! Where is everyone getting their rigid fiberglass???
I looked for and fouind a local "insulation distributor" for Owens Corning. I am about to contact them again for 4" 703 for bass traps. There's alot of things I'd rather not do, but no frames was not even considered. I did not build a Rialto, but aesthetics mean something. Frames allowed me to tightly stretch GOM and have a very finished look. Mounting on the wall and CEILING was a breeze with frames.

YMMV.

Check the link in my sig for what I did.

Oh no, there is no such thing as "too thick" for their purpose, at least not from a purely performance standpoint. (An SO may have other "issues" though.) In fact, if you use 2" like I did you will probably find yourself - like I did - going back and adding bass traps. Two inch of fiberglass - I used OC SelectSound black - will NOT reach effectively to mid- and upper-bass frequencies. And doesn't come close to deep bass. If I had had the room - and the understanding I have now - I would have used four inches of 'glass. I would still need to go back and add some bass traps, but my room wouldn't be such a mess 100Hz - 300Hz.

And 1" is useless, even for first-reflection-point control.

I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters. More than this will cause the room to be too dead. From what I understand, you are not trying to trap much base on the walls that is what room boundaries like in the corners are for.

Pepar, sounds like you need one of these acoustic engineers to bring their equipment in, test your room, and make specific recommendations.

I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters. More than this will cause the room to be too dead. From what I understand, you are not trying to trap much base on the walls that is what room boundaries like in the corners are for.

Pepar, sounds like you need one of these acoustic engineers to bring their equipment in, test your room, and make specific recommendations.
I've not seen anything re 1" being sufficient for first reflection points. As for a room being made too dead, that's a function of the percent of room surface area covered with absorptive material. If only the "first reflection" points are being covered, I can't see how that'd be enough to make it too dead - 1", 2" or 4". Why would you cover all of the walls at and below ear level? That most likely would deaden the room too much (even if you only used carpet).

Are you talking about the entire room at and below ear level, or only first reflection points?

I do not understand this at all. I have seen, more than once, the bonafide experts like Dennis Erskine state that 1" on the walls at ear level and below is sufficient for most home theaters.
A 1" thickness of fiberglass is sufficient to control early reflections. These cause imaging problems at medium to high frequencies, and the lower frequency absorption of thicker fiberglass is unnecessary.

- Terry

A 1" thickness of fiberglass is sufficient to control early reflections. These cause imaging problems at medium to high frequencies, and the lower frequency absorption of thicker fiberglass is unnecessary.

- Terry
Bingo! Thanks, I've been enlightened. I thought reaching lower was a benefit with the corollary being 1" was insufficient.

Nope. 1" is plenty - if all you need from those panels is reflection control. If you need additional overall control in lower frequencies, then 2" or more is certainly not going to hurt anything.

Nope. 1" is plenty - if all you need from those panels is reflection control. If you need additional overall control in lower frequencies, then 2" or more is certainly not going to hurt anything.
I guess that was my point/question; if you've got the physical space, why not apply 2" as you will most likely need to control lower frequencies anyway?

I am with you on that pepar... Most rooms need as much low end absorption as it can get.. Not saying bryan or Terry is wrong..
Glenn

I was just agreeing with Terry that 1" is sufficient IF all you need is reflection control. In a small room where you don't have a lot of space, sometimes the reflection panels need to do double duty.

If you're already addressed the bottom end in other ways and don't need it or there are corners free where it's more effective, then 1" would be sufficient.

I was just agreeing with Terry that 1" is sufficient IF all you need is reflection control. In a small room where you don't have a lot of space, sometimes the reflection panels need to do double duty.

If you're already addressed the bottom end in other ways and don't need it or there are corners free where it's more effective, then 1" would be sufficient.
If I've learned anything in building my own home theater, and that's always debatable, it's that a holistic approach must be employed for acoustical treatments. Knowing a little - or even a lot - about one aspect doesn't cut it. Sooo, for every true statement - 1" is sufficient for first reflection control - there are two (or more) "ifs" that may not be obvious unless you have a broad understanding of the whole - a big part of the fact that people make a living at acoustics. :)

Bryan, I think you and I are saying the same thing here.. Most rooms can not fit enough bass trapping in it anyway, so the 2" panels can help with the rest..
Glenn

Now I am unsure again if I am supposed to use 1" or 2" panels for my first reflection points. My basement is over 6000 cubic feet, with about 1/3 of that for the actual theater. The theater itself is open to the entire basement and my plan is to put either 1" or 2" panels at my FRP and 4" thick base trapping at all corners and soffits, a total of 13 corners.

Based on this, should I stick with the 1" or go with 2" for my FRP?

For a room that large, just off the top of my head, I'd probably use 2".

sorry double post

Would that be 13 bass traps or 13 panels all together?

Now I am unsure again if I am supposed to use 1" or 2" panels for my first reflection points. My basement is over 6000 cubic feet, with about 1/3 of that for the actual theater. The theater itself is open to the entire basement and my plan is to put either 1" or 2" panels at my FRP and 4" thick base trapping at all corners and soffits, a total of 13 corners.

Based on this, should I stick with the 1" or go with 2" for my FRP?
Is this not a rectangle? The 13 corners thing makes me ask.

It is 13 bass traps, not including the FRP.

Please see the attachment for a layout of my basement. It isn't a perfect square, far from it, but the reason that I have 13 corners is because I am also including the corner created with the soffits and the ceiling.

It is 13 bass traps, not including the FRP.

Please see the attachment for a layout of my basement. It isn't a perfect square, far from it, but the reason that I have 13 corners is because I am also including the corner created with the soffits and the ceiling.
Just a comment, Kevin12586. The sound coming from the front left speaker will probably sound very different from the right front speaker due to the left's proximity to the wall. Hopefully, someone more knowledgable will chime in, but I don't think any amount of sound treatment will change that. Not able to locate your theater in the "lower left" corner of the diagram facing "west?"

Pepar, I haven't noticed a difference in sound between the 2 fronts (the left is actually about 6-9" off the wall), but I am no expert so maybe that is the case. Because of my screen, I can't move the speaker any further away from the wall but I am happy with the sound I get now. Currently I don't have a center speaker so the 2 fronts are setup as a phantom center and I don't notice a difference when something panes across the front sound stage. Based on what I have read, if I am happy now I will be ecstatic once I get my basement treated.

The basement is a multi function area, the theater is in the top portion of the drawing where you see the screen and speakers, the rest is used for other things. Because everything is open, that is why I am planning on so many base traps.

Pepar, I haven't noticed a difference in sound between the 2 fronts (the left is actually about 6-9" off the wall), but I am no expert so maybe that is the case. Because of my screen, I can't move the speaker any further away from the wall but I am happy with the sound I get now. Currently I don't have a center speaker so the 2 fronts are setup as a phantom center and I don't notice a difference when something panes across the front sound stage. Based on what I have read, if I am happy now I will be ecstatic once I get my basement treated.

The basement is a multi function area, the theater is in the top portion of the drawing where you see the screen and speakers, the rest is used for other things. Because everything is open, that is why I am planning on so many base traps.
Yeah, I tend to be fixated on symetricality, but if you hear no difference, that's the bottom line. And you *will* be a very happy camper with acoustical treatments added. I'd definitely go for 2" on the wall with the close speaker, and elsewhere as well. You will notice a big improvement in imaging, left-to-right, and probably front-to-back (depth) as well. One more thing; the FRONT wall is a FRP. And since it it the closest to the speakers, it produces the closest reflection temporally speaking. The "speaker wall" and the back wall tend to get overlooked.

With the front wall, I plan to put some 2" panels behind my screen and both on top and to the right of it. To the left of it will have a bass trap that will come up right next to the screen.

Since reading this thread I have noticed that I don't 'notice' the pans from left to right or front to back as much as I feel I should. I can't wait to get started to experience more of my system.

Let us know how it comes out.. Glad to hear you are going with the 2" panels.. I think it is better to be safe then sorry!!

Glenn

I understand that sound moves in waves and that virtually all materials, whether sheet rock, rigid fiberglass, mineral wool, plywood, people, etc. absorb some, reflect some and transmit through the material some of those sound waves.

My question is, how do the materials being hit with the sound waves "know" which to reflect and which to absorb? (I know that don't "know" anything, but go with me on this, ok?).

For example, my risers are over a sunken concrete sub floor. The risers are 18" deep and 9" deep. I have blown in cellulose under those risers (about 15" deep and 8" deep, respectively). The risers are topped with 2 layers of 3/4" plywood, separated by roofing felt. The plywood is covered with carpet pad and carpet. The plywood floor should absorb some and transmit some and reflect some of the waves, right? (Maybe to simplify this we should focus on low to medium waves, because I assume that at some mid to high frequency range, the plywood is going to reflect all of the wave).

If the frequency is long enough / low enough to penetrate the carpet / pad / plywood / felt / plywood floor, shouldn't it all be absorbed either going through the cellusose (going down) or if not, then absorbed when it bounces offf the concrete sub floor and travels back through the cellulose going up, or hitting the plywood riser floor, etc.? Seems like I wouldn't need bass trapping in corners, etc.?

Another example: the walls. Higher frequencies are going to be reflected off the sheet rock walls and stay in the room. Lower frequencies will penetrate the walls to the other rooms but some will also be reflected around in the room, right? Why do some penetrate and some stay in the room? If low bass is penetrating the walls, why do we need bass trapping in the room?

Confused in Dallas

Since reading this thread I have noticed that I don't 'notice' the pans from left to right or front to back as much as I feel I should. I can't wait to get started to experience more of my system.
With a completely untreated room, all of the first reflections are at their max. And there is generally nothing to attenuate the reverberance - where all the reflections "merge" to become one big mess. The early reflections (from the FRPs) confuse the brain, robbing the original sound of its clarity and all the subtleties that give us width and depth. In this context, I mean "depth" as part of the FRONT soundstage, not front-to-back pans. Good acoustical treatments will intergrate the surrounds with the front speakers, too, but I mean being able to hear that one person speaking - or singing - is behind a second.

I remember the first time I distinctly heard that. It was the first time I heard a 5.1 DD system and Indiana Jones/lLast Crusade with Harrison Ford and Sean Connery in the front seats of the car and John Rhys-Davies in the back. A sentence or two were exchanged between Ford and Connery and then Rhys-Davies chimed in. Oh - my - god, I thought. And when Rhys-Davies leaned forward and joined the conversation, that was conveyed in the soundtrack as well.

The more you can reduce the early reflections and, to a certain extent, the reverberance, the more the sountrack - or album - will . . take you away. And when it ALL comes together, the A/V gear will disappear and it'll be you and the movie/album. Sorry to sound like an evangelist.

I understand that sound moves in waves and that virtually all materials, whether sheet rock, rigid fiberglass, mineral wool, plywood, people, etc. absorb some, reflect some and transmit through the material some of those sound waves.

My question is, how do the materials being hit with the sound waves "know" which to reflect and which to absorb? (I know that don't "know" anything, but go with me on this, ok?).

For example, my risers are over a sunken concrete sub floor. The risers are 18" deep and 9" deep. I have blown in cellulose under those risers (about 15" deep and 8" deep, respectively). The risers are topped with 2 layers of 3/4" plywood, separated by roofing felt. The plywood is covered with carpet pad and carpet. The plywood floor should absorb some and transmit some and reflect some of the waves, right? (Maybe to simplify this we should focus on low to medium waves, because I assume that at some mid to high frequency range, the plywood is going to reflect all of the wave).

If the frequency is long enough / low enough to penetrate the carpet / pad / plywood / felt / plywood floor, shouldn't it all be absorbed either going through the cellusose (going down) or if not, then absorbed when it bounces offf the concrete sub floor and travels back through the cellulose going up, or hitting the plywood riser floor, etc.? Seems like I wouldn't need bass trapping in corners, etc.?

Another example: the walls. Higher frequencies are going to be reflected off the sheet rock walls and stay in the room. Lower frequencies will penetrate the walls to the other rooms but some will also be reflected around in the room, right? Why do some penetrate and some stay in the room? If low bass is penetrating the walls, why do we need bass trapping in the room?

Confused in Dallas

that is a very big question you asked and to really understand it I would recommend reading the Master handbook of Acoustics.
Just a couple comments,
Yes when you have dry wall SOME of the low end will go through the wall but not all of the sound. So you need bass traps to help with that.. Now if you have concrete walls then most of the LF sound is staying in the room, so you are going to need even more bass traps to help with the sound.. The first question I ask people is dry wall or contrate..
As far as your riser that is only going to absorb HF because it is a thin material.. Sound absorbtion is achieved from Density of material and thickness..

Hope that helps answer some of what you are wondering..

Glenn

I've been lurking this thread for a few weeks and want to thank all of you for your insight. BTW, great job on your panels, Pepar. I made mine in almost the same way using the same materials. HUGE improvement in the sound quality of my room.

I had a question about Kevin's last quote:

With the front wall, I plan to put some 2" panels behind my screen and both on top and to the right of it.

Does it make a big difference to put treatments behind the screen if the screen is not accoustically transparent? I thought that the screen itself reflects the sound. again, many thanks,

scott

Does it make a big difference to put treatments behind the screen if the screen is not accoustically transparent? I thought that the screen itself reflects the sound.
The screen is more "acoustically transparent" than you think. For the purposes of placing a center speaker behind, it is not, but still a lot of sound goes through it. And lower frequencies go around it like a wave going around a small rock.

I've been lurking this thread for a few weeks and want to thank all of you for your insight. BTW, great job on your panels, Pepar. I made mine in almost the same way using the same materials. HUGE improvement in the sound quality of my room.
Thanks, and 10-4 on the HUGE improvement. I am now working on designing, building and installing bass traps. Pictures of the whole process to follow.

thanks, I did not realize that. makes sense on the lower end, though. If the lower frequencies are penetrating my drywall, the screen shouldn't offer much resistance.

Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?

Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?
Ideally, the corner formed by two walls and the ceiling (or floor, if possible). Ceiling/wall (one of them) corners come next.

Im also in the process of building a dedicated home theater room. The room is 14'x21' with an 8 foot ceiling. I know about placing absorber panels to treat the 1st reflection points but what else do I do with the remaining side walls? Leave them reflective? I keep reading about bass traps placed in corners. You mean the corners on the side and front walls? Or just the side wall thats nearest to the corners?

You want to hit as many corners as possible in your room.. Starting with the front two corners and working from there.. take a a look at a case study a member did on AVS..
http://www.sbrjournal.net/currentissue/articles/acoustics/Acoustics.htm
It really shows how bass traps work and the benefit you will get..

Glenn

So what do I do with the rest of the side walls? Other than the absorbers do I just leave the other walls reflective or do I put panel traps?

I'm building some room treatments, and can't remember the name of that cloth that is popular to cover them in. Starts with an A? I remember seeing an inexpensive place to buy it on the web.

Also I have heard any cloth will do, so long as you can "blow through it" - right?

You want to hit as many corners as possible in your room.. Starting with the front two corners and working from there.. take a a look at a case study a member did on AVS..
http://www.sbrjournal.net/currentissue/articles/acoustics/Acoustics.htm
It really shows how bass traps work and the benefit you will get..

Glenn
Ah, 45's and reel-to-reel . . .

I'm building some room treatments, and can't remember the name of that cloth that is popular to cover them in. Starts with an A? I remember seeing an inexpensive place to buy it on the web.

Also I have heard any cloth will do, so long as you can "blow through it" - right?
Blow through it equally at all audible frequencies.

Blow through it equally at all audible frequencies.

What do you reccomend?

What do you reccomend?
I used/use Guilford of Maine, referred to as "GOM". It is not cheap, and perhaps something of equal performance could be found, but it has been tested and they have a nice assortment of colors and textures. My thinking is that for the amount I need to use, it wasn't going to break the bank. I suggest you google "grille cloth" and do a LOT of reading.

Just my $.02.

Blow through it equally at all audible frequencies.
LOL :D

Fortunately, the DC blow-through test generally extends to high frequencies! :)

Regards,
Terry

I'd like some advice on how to treat my HT room. The room is 14x21 with 8 foot celings. Right now its still bare cement walls. Im gonna be doing 2x4 studs with soft insulation in between then cover with drywall to add to isolation.Ive listed below different options for treatments so please advice me on which one should I use.

1) 2 4x8 mid/hi absorbers for the 1st reflection points on the side walls ( 1 panel on each side ) all remaining walls will be deep bass traps.

2) 2x2 deep bass panels for the upper and bottom part of the side walls from front to back. 2x4 mid/hi absorbers for the middle part of the wall also from front to back.

3) back wall is all mid/hi absorbers

4) BACK WALL in between the 2 rear surround speakers are mid/hi absorbers while the left and right side of the rear wall s
urround speakers are diffusers.

That should really go in your own thread.

This is going to sound crazy but I saw in a friends house a ceiling covered in peg board. ( tHIS was done for some other reason than accoustics) and then covered in textured wall paper.It looked dam good considering. If it was painted flat black it may look great, and it was cheap. I was wondering how well this would work in my theater in place of drywall if the joist cavities where filled with insulation. and the holes in the peg board where for 1/4 in. hooks. I am clueless as to whether this would work or not. But I am temped to try it because like I said, It was very cheap. Maybe $100.00 for my room --- 12 x 20 x 7 (Dam low ceilings)

Bighoot,

It would work better then drywall, but it is not going to let the HF absorb enough... I would not do it.. You are much better off putting a drop ceiling in..

Glenn

A Problem of Too Much Absorption


I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?

I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.

Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.

I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.

Tumara Baap

A Problem of Too Much Absorption


I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?

I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.

Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.

I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.

Tumara Baap
Well, there's probably something more tuned to the room's problem bass area that wouldn't absorb too much high frequencies, but it may not be a DIY item and therefore much more expensive that the 'glass you mention. Based on what I've done so far, I'd do the first reflection points and then take some measurements before and after adding the bass traps, including RT60. (I'm sure the traps are needed.) If it's too dead, research diffusors.

Just my novice $.02.

First, the Setup:

My theater is in a basement alcove. LCR speakers hang from chains about 1 foot out from an untreated masonry wall. Surrounds are along the sidewalls, also untreated masonry. There is no back wall, it opens to the rest of the basement and is visually separated from the rest of the basement by a painting tarp, floor to ceiling. Room is roughly 15x15 or so. Floor is carpeted and there's a big couch that spans the width of the room. Ceiling is unfinished. I've heard this type of setup called "Live in front, dead in back."

The Sound:

Bass is good and deep, not too boomy, with the SVS subwoofer at the back of the room behind where the side walls end. My only complaint is that the sound gets rather harsh at loud volumes. I think this comes from reflections between the side walls, as the harshness does not depend on where you are in the room (first reflection issues would be location-specific, right?). I hear multiple echos when I clap my hands.

The Question:

I am planning wall treatments for the side walls. Given there are no reflections from the back of the room, do I need treatments on the front wall too? Also, would diffusors on the side walls do any good in my case? I could always do a layer of 703 as an absorber and put pyramid or egg-crate diffusors on top. Give it that post-modern recording studio look. :rolleyes:

Thanks for any and all advice!

HDD

A Problem of Too Much Absorption


I'm planning on using 2" rigid fiberglass for 1st reflection points & flutter echo on the side, front, rear walls and ceiling. In addition I plan on 4" to 6" panels of the same in the corners for bass absorption. Room is 16 X 13 X 9. Too much fibergass for a fairly small room! My concern is making the room too dead. I looked at ASC tube traps, Studiopanel bazorbers & springtraps, mondo traps etc for bass absorption but prices are sobering to say the least. Any tricks to keep the room somewhat "alive"?

I'm thinking of having open back bookcase towers (interspersed with books) in front of corner fibergass panels to add to HF dispersion without too adversely affecting bass absorber performance. Will this work? In fact I understand this would actually assist mid-bass absorption.

Also, will it help going with a wood floor instead of wall to wall carpet? Of course with a wood floor I would have carpet pad plus area rug midway between listening seats and front loudspeakers.

I've ruled out using thinner fibergass panels... my understanding is thinner panels greatly reduce broadband range without affecting amount of absorption at most (mid to high) frequencies.

Tumara Baap

Don't know if you know about some of the newer sound absorbing materials being used in the world of faux finishes.There's an all-natural material that I install that you can custom color and design, trowel on, and get a 20% sound absorption. What is nice is that you can put it on any surface (ceilings, doors, etc.), repair it if needed, and even strip it. The thickness is only about 1/8" too. So if you are worried about thickness I thought I'd mention this other alternative.

>I am planning wall treatments for the side walls. Given there are no reflections from the back of the room, do I need treatments on the front wall too? Also, would diffusors on the side walls do any good in my case? I could always do a layer of 703 as an absorber and put pyramid or egg-crate diffusors on top. Give it that post-modern recording studio look. <

I would treat the front and side walls with the 703.. You said you are not having bass problems, but are you sure of this? Did you test the room? I talk to a lot of people that say the bass is fine but it is the high end that is the problem.. You may be right, but a lot of times the problem is more on the low end then the high..

Glenn

Thanks for the treatment advice. As for the bass, I have done a very simple set of tests. I burned a bunch of test tones onto a CD and measured each with my Radioshack meter. No glaring peaks or valleys, and the transition at 80HZ crossover between mains and sub was smooth. I also verified this with my ears when listening to frequency sweep tones on DVE.

Regards,

HDD

Dangeresque -
Treatments like that are upper mid/high frequency only - at best. They're also inherently something that's done to the whole wall surface - which may or may not be acoustically correct for a given room. While I'm sure it would work wonderfully for board rooms and other places where the vocal range is paramount, in a broadband room I'd avoid them.

HardDrive,

When you take your measurements, you need to do them at 1 -2Hz intervals. Anything coarser will hide problems that can be pretty steep. I'll guarantee you that you're having bass issues. While it may not be frequency response related, it's absolutely decay time related.

In that room, you're going to need some control spread throughout the room. For starters, as Glenn said, kill the front wal and make sure you have ALL of the early reflection points covered on the side walls. From there, you can do an analysis and determine where you stand in terms of a target for your room and usage.

I'd just plan on some soft broadband bass absorbtion in at least 2 of the corners. This will not only help with the bottom end control but will also, if constructed correctly, provide some of the overall decay time absorbtion you need.

Bryan

When you take your measurements, you need to do them at 1 -2Hz intervals. Anything coarser will hide problems that can be pretty steep.
HardDrive might be referring to burning Ethan's test tones to CD and those are, I believe, at 1 Hz intervals. It's certainly not the easiest way to check system/room response, but he's ahead of a lot of people who do nothing. This method can also serve as a "gateway" that whets one's appetite and leads to acoustical testing software and a better microphone. It has for me.

Agreed. Absolutely better than not doing anything. Just trying to make him aware that issues may be 'hiding' in the details that can easily be missed with 1/6 or even 1/12th octave tones. I don't know what he is using specifically.

Agreed. Absolutely better than not doing anything. Just trying to make him aware that issues may be 'hiding' in the details that can easily be missed with 1/6 or even 1/12th octave tones.
Very good point, and he's now aware of it, which hopefully will cause him to dig deeper into the subject of his test tones.

HardDrive might be referring to burning Ethan's test tones to CD and those are, I believe, at 1 Hz intervals. It's certainly not the easiest way to check system/room response, but he's ahead of a lot of people who do nothing. This method can also serve as a "gateway" that whets one's appetite and leads to acoustical testing software and a better microphone. It has for me.

Actually doing the test that way SUCKS!!! Trust me you will want to go kill someone after spending 1 hour listening to test tones.. :D
If you are going to test it is best to download ETF software.. Doing the test takes about 5 seconds and as I have learned you really should do 10 tests to to get things right.. so if you use the test tones give yourself 10 hours!! ha ha ha

BTW, this is in no way taking away from the fact that Ethan Winner took the time to put this on his website, which you can download for FREE!!!!

Glenn

Actually doing the test that way SUCKS!!! Trust me you will want to go kill someone after spending 1 hour listening to test tones.. :D
True, but I was practicing tact. ;)

If we shouldn't use 1Hz increments, what would be better, 5Hz, 10Hz?

If we shouldn't use 1Hz increments, what would be better, 5Hz, 10Hz?
Oooh, 1 Hz is the right increment. Respectfully to Ethan, it's the test CD generated from his website that's, um . . . unwieldy.

True, but I was practicing tact. ;)

sorry if I came off untactful, I just remember doing the test that way myself.. It cost me a lot of years of therapy.. :D

Glenn

Thanks for all of the advice. I'm sure the tones I used were more like 5-10HZ steps. So I'm missing alot, woundn't be the first time. My plan is now to treat front and side walls with DIY absorbers, then build a bass trap for each front-side corner. Unfortunately, there are many projects on my honey-do list, so it could be several months before I get to making the treatments and traps.

In the meantime, can anyone point me to some ETF software and the required equipment? In the past this seemed pretty expensive, so I went the burn your own test tones and use an SPL meter route. That was over a year ago, so maybe things have gotten more affordable since then.

Thanks for the help and advice!

HDD

In the meantime, can anyone point me to some ETF software and the required equipment? In the past this seemed pretty expensive, so I went the burn your own test tones and use an SPL meter route. That was over a year ago, so maybe things have gotten more affordable since then.
ETF and its successor, RPlusD can be found here (http://www.etfacoustic.com/index.html). The software is $150 and the calibrated mic and preamp are another $325. On the brighter side :) , Room EQ Wizard is free and can be found here (http://homepage.ntlworld.com/john.mulcahy/roomeq/). The ETF package is still relatively inexpensive, but free is obviously better. I've got them both, but have not yet used REQ, nor am I qualified to compare the two tit-for-tat. Regardless, I recommend a better mic than the Rat Shack unit.

The software is $150 and the calibrated mic and preamp are another $325. Room EQ Wizard is free ... I recommend a better mic than the Rat Shack unit.

The mic and preamp are going to cost far more than the room treatments themselves, though it does seem that the RS meter can work as a mic. Still need a soundcard with line-level ins and outs. I'll take the advice of many and treat first, EQ second.

Thanks for the info.

HDD

Just FYI - a Behringer mic and pre-amp can be had for around $100 for the pair if you look around...

I've been wondering if the Nady CM-100 might be an even more economical solution. Plus, you could sleep easier knowing that you haven't supported Behringer! :)

The mic and preamp are going to cost far more than the room treatments themselves, though it does seem that the RS meter can work as a mic. Still need a soundcard with line-level ins and outs. I'll take the advice of many and treat first, EQ second.
I'm not so sure about the first part. I did mine DIY and have "somewhat" more than $325 in them so far and am about to add a bit more for bass traps. The RS meter can work as a mic, but not a particular accurate one. There are chartsx floating around - "inaccuracy charts" in my jargon - but that assumes a level of QC (unit-to-unit) that I just don't think is there.

I've been wondering if the Nady CM-100 might be an even more economical solution. Plus, you could sleep easier knowing that you haven't supported Behringer! :)
Inside joke? :confused:

Does anyone have any experience, good or bad, with the NCH Tone Generator (http://www.world-voices.com/software/nchtone.html) ?

Inside joke? :confused:

I think he is referring to Behringer not being the most up to par stuff on the market.. They have always been know for have the bottom line quality when it comes to studio equipment..


Glenn

I think he is referring to Behringer not being the most up to par stuff on the market.. They have always been know for have the bottom line quality when it comes to studio equipment..
Gotcha! But how is the BFD for notching out a few nodes in a home theater? It's my understanding that ADC/DAC conversions and signal degradation is not an issue at subwoofer frequencies. Bottom line: How does it SOUND compared to an SMS-1?

Yes, Glenn nailed it. I sometimes forget that not everyone is coming from a recording engineering background like I am. :o

Gotcha! But how is the BFD for notching out a few nodes in a home theater? It's my understanding that ADC/DAC conversions and signal degradation is not an issue at subwoofer frequencies. Bottom line: How does it SOUND compared to an SMS-1?

I have no idea on that maybe Terry could chime in.. I would tend to think that the SMS-1 (which I have not used) is better quality.. Also I am not a big fan of EQ anyway.. :)
Behringer's stuff works, but if you work in music day in and day out you will find it breaks down a lot and the sound quality is not as good as other products.. I am talking more the studio side of things so this may not apply to the listening rooms/HT market..

Glenn

For a sub only, it would be fine IMO. I'd never put it on my mains though.

If you don't want to spend the $$$ on ETF, you can check out JohnPM's freebie Java based tool. There's a thread for it in this forum titled Room EQ Wizard.

For a sub only, it would be fine IMO. I'd never put it on my mains though.

If you don't want to spend the $$$ on ETF, you can check out JohnPM's freebie Java based tool. There's a thread for it in this forum titled Room EQ Wizard.
Thanks. Actually, I purchased ETF a year or so ago and have d/l'd the free upgrade to RPlusD. Got John's app as well. Haven't looked at either yet, but will soon. Until I can build bass traps, I just need to generate a sweep up to 100Hz or so and set my PEQ to enjoy the system with some friends next month.

Can anyone tell me if this is a good price for some rigid fiberglass.

The manufacture is Knauf and the panels are the equivalent of OC 703, 2" thick and 2x4 panels. For this I am being charged $55 for a bundle of 10-2x4 panels.

What do you think?

I think I am embarrassed by what I paid for OC 703!! That sounds pretty good to me.

Can anyone tell me if this is a good price for some rigid fiberglass.

The manufacture is Knauf and the panels are the equivalent of OC 703, 2" thick and 2x4 panels. For this I am being charged $55 for a bundle of 10-2x4 panels.

What do you think?
I just ordered 2" Owens Corning 703 plain (unfaced) 24" x 48" for $.65/SF. That's $5.20 per panel with 12 per pack being $62.40. If all things are equal, the price you paid seems pretty good.

Agreed. Knauff makes several 2" products - just verify what you're getting. If it is the equivalent product, it's a very good price.

I paid $.91 \sq ft. 1 1/2 years ago. I'd say it was a very good price.

Thank you everyone, I just wanted to make sure that it is a good price before I purchase :)

Really guys if you plan to build them then I would go with Sensible Sound Solutions.. Yes you may pay a little more but you can rob Bryan of free advise.. :)

Glenn

I recently purchased DIY material from Bryan, so I hope I have a few credits for a bit of free advice that might help some others at the same time.

My room is about 16.25 x 22.75 and has a ceiling that starts at 8' along the long walls rising to 10' in the center of the room. Facing material came this week and we are ready to make the frames for the 703 material and acoustical cotton corner traps, but I'd like to take into consideration anything that you smart guys deem important due to the ceiling. We are going to do some corner traps for the bass and some panels to tame slap echo on the walls and ceiling.

I'm curious if there are any "general rules" that apply to non parallel ceilings when it comes to additional treatments, especially as it pertains to the lower registers. I have some problems with a couple of nulls in the bottom end (mid-30's and early 60's) and and mid-bass (don't recall the frequencies offhand). Any general hints that apply when we are dealing with something other than a traditional 6 surface cubical room (ceiling soffit at the peak, higher likelihood of needing soffit treatments at the wall/ceiling vertex).

Thanks guys.

Hey John.

There are a couple of things with a ceiling like that.

- There is no real corner so you can't run bass absorbtion there (unless you want to square it off and make it look like a rectangular soffit - done that before - works well)

- Angles surfaces like that can reflect things back at the seating position at odd angles. Just like the others though, you can plot the points with a buddy and a mirror and address them. Also potentially right beside each row of seating on the angle.

If you did the fake soffit thing, it will deal with both issues if you fill it with absorbtion - you get some bass control, good speading of absorbtion throughout the space, and killing any direct reflections off that angle.

Bryan

What's the best way to cut a rigid fiberglass panel if you need to contour it?

What kind of contour? If you're just wanting to cut a bevel, you can use a table saw with a very fine blade. If you want a radius, you'll almost have to resin harden the edges and use a router on it though that's pretty tough.

What's the best way to cut a rigid fiberglass panel if you need to contour it?
I've done contouring with a cheap electric razor. I emphasize "cheap" because you will not want to shave with it after cutting 'glass. Cutting it in a straight line, as Brian said, can be done with a fine blade on a table saw. If precisenss is not an issue, a very sharp - razor-sharp six-inch knife works.

The method I used was a cheap electric knife I bought
at the grocery store (Procter Silex Easy Slice 9.99.) It will cut any contour you
throw at it. Best 10 bucks I ever spent. No mess to boot.
Matt

The method I used was a cheap electric knife I bought
at the grocery store (Procter Silex Easy Slice 9.99.) It will cut any contour you
throw at it. Best 10 bucks I ever spent. No mess to boot.
Matt
Cool, that sounds even better. I've got a bass trap project coming up soon and will give it a shot. Thanks!

I want to make absorbtion panels to tone down the mid to low high (basically foot traffic and speech and radio) frequencys in a bonus room which is being turned into an art studio for teaching. I'm not concerned about low / subwoofer type frequencies.

The room is about 900 feet, with wood (laminate) floors, windows, and sheet rock walls. There will not be carpets, rugs, etc. The room is very, very, very live. I have a few questions:

1. Is there a formula / rule of thumb for determining how many square feet of absorbtion panels I need to tame this room?

2. I plan to buy OC 703 (3 pound density rigid fiberglass) and wrap those panels in fabric (adhere fabric to fiberglass with spray adhesive), then velcro the panels to the walls and/or ceiling. For simplicity, I don't really want to build frames around the fiberglass.

Is this a recommended way to do this? Or do I need the frames for structural integrity? If the frames are needed, I can do that, but from a time and money standpoint, if they aren't necessary, I'd rather not.

(The panels need to look good, but not as good as GPowers theater! )

Thanks for you help.

I finally found a good search that answered some of my questions. I still need help with:

1. Is there a formula / rule of thumb for determining how many square feet of absorbtion panels I need to tame this room?


Thanks

Hi-

I found a great deal on Speaker Cloth to use for acoustic panels that you might like. I posted it here. (http://www.avsforum.com/avs-vb/showthread.php?p=7567497#post7567497)

Hope this helps,

I've been auditioning speakers ($2,000 to $2,500 for full 7.1) and thought I had made up my mind using Def Tech BP7006 Fronts. However, these are Bipolar speakers and I have read some earlier comments in this thread that even with Bipolar speakers the screen wall should still be treated with 1" of acoustic material.

This obviously is going to wipe out majority of that rear propagated sound.

I just can't get my head around why a reputable company like Def Tech (and others) design Bipolar front speakers if these rear reflections are so bad.

I'm no audiophile and room will be 99% movies.

I'm really not sure what to do. :(

My options seem to be:
1) Stick with the Bipolars and not treat screen wall (just 1st reflections that impact listening position and bass traps) and hope I still like the sound (and make sure good return policy).
2) Keep looking for Mono pole speakers (going to try to adition 3x CLR2003 to see if they sound similar)

Are there are others out there that have used Bipolar speakers in a HT proscenium build? (especially if your in the NoVA area).

I did ask some Q's in Speaker Forum (http://www.avsforum.com/avs-vb/showthread.php?t=671780) but thought some advice from the acoustic folks would be useful

I've been auditioning speakers ($2,000 to $2,500 for full 7.1) and thought I had made up my mind using Def Tech BP7006 Fronts. However, these are Bipolar speakers and I have read some earlier comments in this thread that even with Bipolar speakers the screen wall should still be treated with 1" of acoustic material.

This obviously is going to wipe out majority of that rear propagated sound.

I just can't get my head around why a reputable company like Def Tech (and others) design Bipolar front speakers if these rear reflections are so bad.

I'm no audiophile and room will be 99% movies.

I'm really not sure what to do. :(

My options seem to be:
1) Stick with the Bipolars and not treat screen wall (just 1st reflections that impact listening position and bass traps) and hope I still like the sound (and make sure good return policy).
2) Keep looking for Mono pole speakers (going to try to adition 3x CLR2003 to see if they sound similar)

Are there are others out there that have used Bipolar speakers in a HT proscenium build? (especially if your in the NoVA area).

I'm not the expert here, nor did I stay at a Holiday Inn Express last night :) , but I *think* the front wall should be covered regardless of the speakers used. I happen to have a false wall to hide such things, but my front is completely lined with 2" J-M Linacoustic.

The issue with a bipole in a multi-channel environment is that you're between a rock and a hard place. The speaker is voiced and balanced to have that back information as part of the balance. But if you leave the wall live, then you're messing up your front soundstage with information from the surrounds coming back at you. In a 2 channel environment, this is not as much of an issue as the front wall can be left a bit less dead.

I think you have 3 options.

1. Use diffusion behind the speaker. This will at least still scatter the sound from the rear wave and from any reflections to minimize the effects. Downside is that effective diffusion is relatively 'thick' for front wall usage unless you have a false wall.

2. Do nothing behind the speaker. ONLY do this behind the rear driver(s) over maybe a 30 degree cone. This will still keep most of the wall relatively dead but allow the speaker to retain it's voicing and balance with a minimal compromise to reflection control.

3. Don't use a speaker with this type of design so it's a non-issue.

To me, in your situation where you don't yet have speakers and HT is 99% of the usage, #3 seems like a no-brainer. If not, then #2.

bpape - for now I'm going with #3 and will revert to #2 should I not find anything else to my liking (and in my budget).

Thanks,
Mark

Don't get me wrong - #2 will work if you have the room and money for the diffusion.

By diffusion you mean using Linacoustic or similar accross screen wall and 2ft up side? If yes this is my plan.

I'm going to continue to demo speakers ----- got at least a month before I need to start making final decision ---- so plenty of time.

I was really trying to home in on speaker choice so I can build for my in-ceiling rear surrounds. From those I've looked into so far (DefT, Polk, Sonance) providing I box and leave 0.75 to 1 cu ft of volume I should be OK.

By diffusion you mean using Linacoustic or similar accross screen wall and 2ft up side? If yes this is my plan.
Linacoustic, as far as I know, is only a fiberglass product. I've never heard of it as being anything else.

Linacoustic, as far as I know, is only a fiberglass product. I've never heard of it as being anything else.

But this is what many have been using on their screen walls and along side walls up to 44" (or so).......are you saying this is wrong?

But this is what many have been using on their screen walls and along side walls up to 44" (or so).......are you saying this is wrong?
No, I have it there too, but it's fiberglass for absorption. Diffusion is always hard - reflective. Go here (http://www.silentsource.com/diffusors.html) and click on the two styles of diffusion they sell.

OK - Thanks - Think I get it now :)

Diffusion is not in my current plan - just absorption on Screen wall and on panels along the side walls. Not decided yet about bass traps (still need to do some research)

Not decided yet about bass traps (still need to do some research)
Skip the research, unless you have a HUGE room, you will benefit from bass traps. Notice I did not say you NEED them, only that you'll benefit. Of course, once you have them, you will NOT want to be wthout them. And then you'll think that you needed them. :)

Gentlemen,

I don't understand which type of acoustical backing I should use on my back and side walls. What is the rule of thumb? Over 40 pages of posts, and I still don't understand what you all are talking about.

http://www.mavromatic.com/images/grouse_theater_wall.jpg

I was thinking of using homosote? Would that do the trick?

Danny

Panels can be done several ways. Some people use Linacoustic up to ear level then batting above. Others use hard or empty panels in some places and 703/cotton panels in others depending on reflections and general distribution of absorbtion througout the room.

Whether or not you want diffusion or absorption in the areas indicated will depend on several factors:
1. Are these panels in mirror points for the seating positions? If so, if your speakers have excellent off axis response, you want diffusion. With poor off axis response you'll want absorption.
2. Based upon the total of all materials in the room, what is the predicted decay time and, based on that, is more, or less, absorption needed (at what frequency ranges)
3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.

3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.

If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?

If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?

In the context of what he is talking about the answer is no. What Dennis is speaking about is using bass traps that are more broad band. Meaning the traps are actually picking up more high end then low end. This is sometimes good, but we have found that a bass trap that has a limp membrane system in it has the proper balance. More low end then high end. Leaving the room with tight bass but keeping life (high end) within the room. Dennis is right about most bass traps don't perform as well below (ok I am going to change that :D ) 50 to 60 hz.

Glenn

If I read this correct, it is possible to have too many bass traps in a room? I was always under the impression from reading this thread that as long as you have a bass trap in each corner, you won't do any 'damage' to the sound, only improve it. Am I mistaken?
Yes, you can have too many bass traps, though it would take quite a few. With too much low frequency absorption compared to high, the room will sound too bright. There are optimal levels of reverberation for different room sizes and room purposes (2 channel, movie surround, etc.), and the ideal thing is to make these reverberation times close to the same over all frequencies.

Regards,
Terry

Edit: Glenn, we seem to disagree. :)

So as long as I place my bass traps in each corner (about 14) and treat the first reflection points from each seat and speaker, as well as the front wall, then my room shouldn't be too dead or live? Is this 'fairly' accurate?

So as long as I place my bass traps in each corner (about 14) and treat the first reflection points from each seat and speaker, as well as the front wall, then my room shouldn't be too dead or live? Is this 'fairly' accurate?

I believe you would be fine. Not sure if you really need 14 bass traps though.

Glenn

Yes, you can have too many bass traps, though it would take quite a few. With too much low frequency absorption compared to high, the room will sound too bright. There are optimal levels of reverberation for different room sizes and room purposes (2 channel, movie surround, etc.), and the ideal thing is to make these reverberation times close to the same over all frequencies.

Regards,
Terry

Edit: Glenn, we seem to disagree. :)

No I think we agree. :) It is all about balance. But it takes a lot more bass traps then HF treatment and that is the reason why I like the membrane system in bass traps. It seems to give the right balance. :D Now not every room is the same so this is a general statement and for small rooms.

Glenn

Thanks Dennis & bpape for the response.

Dennis, I do have a couple questions...

1) you state that if the panels are in mirror points (first order reflection point), I'll want diffusion. What material is recommended for diffusion? Then for the reset of the panels, what is recommended? Plywood? Homosote? Fiberglass?

2) How do I figure out the predicted decay time? The room is 20x15 but the actual area (non-stage) is about 16x15. The stage and room is carpeted, I do have wood panels on the angled part of the stage left and right (see rendering above).

3) Bass traps... I'm clueless... wasn't even considering them.

Thanks for the help... I'm doing fabric stretch walls, so if I don't get it all right the first time... the idea is, I can tweak them later...

Danny

I believe you would be fine. Not sure if you really need 14 bass traps though.

Glenn

Here (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=55445) is the layout of my basement, my theater is in the top portion, from left to right, but it is also open to the rest of the basement. Because of this, and the soffits that run across the basement, if you count all corners and soffit corners, it comes to 14 bass traps. Because it is open, I figured it would be best to treat all corners, not just the ones in the theater.

Here (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=55445) is the layout of my basement, my theater is in the top portion, from left to right, but it is also open to the rest of the basement. Because of this, and the soffits that run across the basement, if you count all corners and soffit corners, it comes to 14 bass traps. Because it is open, I figured it would be best to treat all corners, not just the ones in the theater.

Well 14 traps will work pretty well, but I would start with 8 traps and see how it sounds. Focus on the front corners and corners close to sitting. I can see why you want to do what you are saying though. I would start with 14 panels myself (maybe more) but I get them for FREE. ;)

Glenn

Where I am buying my panels from, they come in bundles of 10 and I will be buying 2 bundles. I might as well do the 14 at once since I will have so much left over if I only did 8 panels. Thanks for the advice though.

What do bass trap panels look like?

Where I am buying my panels from, they come in bundles of 10 and I will be buying 2 bundles. I might as well do the 14 at once since I will have so much left over if I only did 8 panels. Thanks for the advice though.

Confused - couldn't you just buy 1 bundle if you were to try 8?

3. And, be real careful about bass traps. Most of them do nothing in the 80Hz and below range ... the first three or four (and most audible) axial modes in the typical room are below 80Hz. Most bass traps are also serious absorbers at all frequencies above 120Hz and can result in over absorption, reduction of room reverberation way below what you'd want, and you can find yourself needing to get more powerful amps and then speakers that can handle the addition power.
Any suggestions on how to deal with problems at 80Hz and below? TIA!

Edit: OK, after reading subsequent posts, I'm thinking the answer to my question is "membrane" trap? Whazzat and where do I find one (or plans to build one) for my problem frequency?

Further, I just bought 2" unfaced 703 to make "SuperChunks" for three of the four corners in my room and three areas where the wall meets the ceiling, two 48" sections above my front L&R FRP absorbers and one 96" section above my rear FRP absorber. Does this seem, on the face of it, way too much or way too little? TIA, again!

Any suggestions on how to deal with problems at 80Hz and below? TIA!

Edit: OK, after reading subsequent posts, I'm thinking the answer to my question is "membrane" trap? Whazzat and where do I find one (or plans to build one) for my problem frequency?

Further, I just bought 2" unfaced 703 to make "SuperChunks" for three of the four corners in my room and three areas where the wall meets the ceiling, two 48" sections above my front L&R FRP absorbers and one 96" section above my rear FRP absorber. Does this seem, on the face of it, way too much or way too little? TIA, again!

For DYI stuff you would want to use FRK on the fronts to have a membrane.

Glenn

What do bass trap panels look like?

go to our website, you can see pictures of them or go to www.realtraps.com.

Glenn

For DYI stuff you would want to use FRK on the fronts to have a membrane.

Glenn
Thanks, I'm doing the SuperChunk trap with triangles of 703 stacked as opposed to a single 2x4 panel forming a hypotenuse across a corner. I guess I could make my own "membrane" and place it under the GOM covering the stack. I *think* I saw data that showed a solid stack of 703 as having better absorption at lower frequencies than a single panel - with or w/o a face - across a corner.

Should I "make" a membrane for the face of the SuperChunks? Can you point me to data that shows this would improve the performance at lower frequencies?

Confused - couldn't you just buy 1 bundle if you were to try 8?

8 corners needs more than one bundle of 10-2x4 panels

I have another question, for my first reflection points from my front speakers, the panels will be mounted about 4' from the ground. I will be mounting my center channel speaker above my screen, 7' up in the air pointed down towards the sweet spot. Since it is pointed towards the sweet spot, do I still place a panel about 4' off the ground to treat the reflection from this speaker or should it be mounted higher?

8 corners needs more than one bundle of 10-2x4 panels

I have another question, for my first reflection points from my front speakers, the panels will be mounted about 4' from the ground. I will be mounting my center channel speaker above my screen, 7' up in the air pointed down towards the sweet spot. Since it is pointed towards the sweet spot, do I still place a panel about 4' off the ground to treat the reflection from this speaker or should it be mounted higher?
Use a mirror or visualize your "bank shots" from the center speaker to the ears of the audience . . .

Don't forget to look at your ceiling.

Thanks, I'm doing the SuperChunk trap with triangles of 703 stacked as opposed to a single 2x4 panel forming a hypotenuse across a corner. I guess I could make my own "membrane" and place it under the GOM covering the stack. I *think* I saw data that showed a solid stack of 703 as having better absorption at lower frequencies than a single panel - with or w/o a face - across a corner.

Should I "make" a membrane for the face of the SuperChunks? Can you point me to data that shows this would improve the performance at lower frequencies?


A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)

Use a mirror or visualize your "bank shots" from the center speaker to the ears of the audience . . .

Don't forget to look at your ceiling.

Thinking of it as a bank shot makes 'perfect' sense and easier to figure out.

Thanks

A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)
I'm now contemplating running some tests with and w/o a DIY "membrane" applied to the edges of the 703 pieces that make up the SuperChunk. As it is DIY, I get to select the material; can anybody give me some guidance on what weight paper to use? Or, should I use someting else entirely?

Is there something I can use to extend lower the effectiveness without losing the absorption up to ~300Hz?

A HUGE TIA on this one!!

A solid stack does SLIGHTLY better than a thick layer. Also, I plan to do the same "chunk" style as you, however I plan to put one FSK piece on the "front" of the stack to A) give it a smooth appearance, and B) provide a membrane for mid-hi freq. reflection. (As some have pointed out...bass traps made of 703 are essentially broad band absorbers. I already have enough absorption...thus the membrane for the "front".)
Two of the corners in my theater and one wall/ceiling juncture that are getting superchunks are behind my false wall, an area that is already lined with 2" J-M Linacoustic, so I don't believe they will be contributing any "additional" mid-/hi-frequency absorption to my room. And the remaining superchunks have such a small surface area compared to the rest of the untreated room I'm hoping they won't complicate things for me at the non-bass frequencies.

How wide our the fronts of the super chunks?

Glenn

How wide our the fronts of the super chunks?

Glenn
I'm doing the 24" version.

What is FRK...and where do you get it?

Would it be used where my front corners are bridged with 24" wide 4" thick BAC floor to ceiling (9') ?

What is FRK...and where do you get it?

Would it be used where my front corners are bridged with 24" wide 4" thick BAC floor to ceiling (9') ?
FRK is a Kraft paper facing that comes on fiberglass panels. I don't think it can be added later; the panels must be ordered that way.

Seen this (http://forum.studiotips.com/viewtopic.php?t=534)? The linked site has a wealth of information on all acoustical treatments.

Actually, FSK scrim is available separately. It can be attached using Scotch 77 spray adhesive very easily. This is generally a more cost effective solution than buying it already faced. While it won't act exactly the same as the factory bonded material, in practice, it's very, very close - probably closer than the variances in coefficients.

I am about to figure out where to place my mineral wool sheets (24"X48"X4"). I was originally going to make corner traps with triangles in the back corners, but I think it will be difficult to make them look good. I have room behind my screen wall and than I don't need to worry about a finished look. Is there any benefit to putting them on the back wall corners as opposed to front?? Also any advantage over corners vs. where ceiling meats walls. Thanks everyone.

From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.

Given that understanding...I would say go ahead with bass traps behind your screen. I will be putting traps behind my screen and have said so here on a couple occasions. I haven't heard any warnings or cautions yet. :cool:

Actually, FSK scrim is available separately. It can be attached using Scotch 77 spray adhesive very easily. This is generally a more cost effective solution than buying it already faced. While it won't act exactly the same as the factory bonded material, in practice, it's very, very close - probably closer than the variances in coefficients.
OK, I really need to stop answering questions that I specifically do not know the answer to. :o

If one is attaching something after the fact (of buying them plain), is there something BETTER to use than FSK?

I am about to figure out where to place my mineral wool sheets (24"X48"X4"). I was originally going to make corner traps with triangles in the back corners, but I think it will be difficult to make them look good. I have room behind my screen wall and than I don't need to worry about a finished look. Is there any benefit to putting them on the back wall corners as opposed to front?? Also any advantage over corners vs. where ceiling meats walls. Thanks everyone.
I'd start there - I will be as I have the same situation - and maybe that'll do it. If not, additional traps may be needed. I will also be "chunking" the ceiling/wall intersection behind my false wall as well.

From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.

Given that understanding...I would say go ahead with bass traps behind your screen. I will be putting traps behind my screen and have said so here on a couple occasions. I haven't heard any warnings or cautions yet. :cool:

Nice thanks guys for the info. It will make my job MUCH easier and actually allow me some wider traps.

From what I understand...a corner is a corner, regardless of location. Every corner will produce some kind of "hump" in the bass frequency response.

Corners produce tangent or oblique room mode "humps," which are generally lower in size than axial room modes. Axial room modes are produced by opposing wall surfaces only. To the degree that a corner trap will cover a wall, it may reduce an axial room mode. However, the relationship between how much you have to span a wall or corner and how much the room modes are reduced is neither simple nor well understood.

Keep those traps a-trappin'!

Regards,
Terry

After watching the videos over on Realtrap...I got to thinking the amount of bass traps I am planning on will not be enough.

I roughly have a 18'x11'x8' room (not counting the area behind my AT screen). The Q will be pretty low as I only used a single layer of drywall. I had planned on 6, 24"x48"x4" 703 FSK panels (1"x4 sheets).

I had planned on the following layout: one each across the rear\side wall corners, one behind the rear seats (floor to rear wall corner), and three behind my AT screen. Since the wall behind my screen is actually the area under a bay window, the wall is made of three 50" sections. I plan to put one trap across the floor to center portion corner, and one each across the two 145 degree angles.

On to my questions: in the video, they state 8 traps is generally the right amount to use in a typical home theater room. So, A) is my room typical, B) should I sacrifice aesthetics to put traps along the left and right sides of the theater in order to get 8 traps instead of 6, C) can I make my 6 traps 2" thicker to achieve the same bass control, and D) finally, EVERY sheet of 703 I have is FSK...I can't remember if I am supposed to tear off all the FSK except one, or leave it on every sheet.

THANKS IN ADVANCE for any help!!

Stima,

making 6 traps thicker will help a little but probably won't make up for the surface area of 8 traps. Bass absoption is challenging, and short changing the number of traps won't help.

703 is an adequate material for 1st reflaction points, but denser stuff is preferred for bass traps. 705 FSK perhaps. FSK should only be on one side of the trap; the side facing into the room.

Ethan goes over all of this at http://www.ethanwiner.com/acoustics.html

Oops, I meant 705!! I have been putting up 703 all day and had that on the mind! :o

SURFACE AREA!! Yeah...that would be more important than thickness. I will re-read Ethan's write up. I will also look into it about FSK. I don't remember him stating anything about removing ALL the layers or just leaving them be with the last layer facing the room.


***EDIT***

After re-reading...I confirmed your advice to remove all but one layer. :p

Surface area was also discussed, but I didn't quite understand how to correctly compute absorption coefficients since the manufacture doesn't take into consideration all surfaces.

After watching the videos over on Realtrap...I got to thinking the amount of bass traps I am planning on will not be enough.

I roughly have a 18'x11'x8' room (not counting the area behind my AT screen). The Q will be pretty low as I only used a single layer of drywall. I had planned on 6, 24"x48"x4" 703 FSK panels (1"x4 sheets).

I had planned on the following layout: one each across the rear\side wall corners, one behind the rear seats (floor to rear wall corner), and three behind my AT screen. Since the wall behind my screen is actually the area under a bay window, the wall is made of three 50" sections. I plan to put one trap across the floor to center portion corner, and one each across the two 145 degree angles.

On to my questions: in the video, they state 8 traps is generally the right amount to use in a typical home theater room. So, A) is my room typical, B) should I sacrifice aesthetics to put traps along the left and right sides of the theater in order to get 8 traps instead of 6, C) can I make my 6 traps 2" thicker to achieve the same bass control, and D) finally, EVERY sheet of 703 I have is FSK...I can't remember if I am supposed to tear off all the FSK except one, or leave it on every sheet.

THANKS IN ADVANCE for any help!!

A) No room is typical, but I have found that 8 traps do work pretty well.. See case study at http://www.sbrjournal.net/currentissue/articles/acoustics/Acoustics.htm
I would focus on the front 2 corners of your room and put the panels floor to ceiling if you can
B) You can put panels on side walls but straddle floor to wall or ceiling to wall, if you are going for bass trapping
C) We have a 6" trap that does VERY well but it does not replace the amount of traps. For the most part.
DA) I would leave the FSK on the panels that are straddling walls. For first reflections you want to remove it.

Glenn

Remember that there are more corners in a room than the vertical corners. Where the wall joins the ceiling is also a corner - one that I rarely see used for bass traps.

A) No room is typical, but I have found that 8 traps do work pretty well.. See case study at http://www.sbrjournal.net/currentissue/articles/acoustics/Acoustics.htm
I would focus on the front 2 corners of your room and put the panels floor to ceiling if you can
B) You can put panels on side walls but straddle floor to wall or ceiling to wall, if you are going for bass trapping
C) We have a 6" trap that does VERY well but it does not replace the amount of traps. For the most part.
DA) I would leave the FSK on the panels that are straddling walls. For first reflections you want to remove it.

Glenn

Thanks for the link; I read through it and came away with the feeling I really need to get my hands on equipment similar to yours. The improvement in your bass response is quite dramatic!!

Concerning your advice to focus on the front corners; Since those corners are 145degree instead of a typical 90 degree....will straddling them still work as a bass trap? It will be very easy to straddle them from floor to ceiling, so if the angle doesn't screw up the functionality, I will be golden.

As far as the FSK, I plan to leave it on the three panels located in the rear of the room. Those were across the wall corners and floor to wall corner. What I had question on was whether to leave the FSK on all 4 sheets or just the sheet facing the room. According to Ethans write up, I would actually HURT the bass absorption if I were to leave it on EVERY sheet.

So, my new plan given straddling a 145 degree corner is viable:

Front wall behind screen: Two, 4 in. thick, floor to ceiling (@7.5 ft.) panels one each across the 145 degree corners. One, 4 in. thick, 4 ft. long panel across the floor to front wall corner. One layer of FSK left on, but facing wall rather open theater.

Rear wall behind seats: Two 4 in. thick, 4 ft. tall panels one each across the rear 90 degree corners. One 4 in. thick, 5 ft. long panel across the floor to rear-wall corner. One layer of FSK left on, however FACING theater.

This gives me essentially 8 panels worth of surface area coverage. This layout puts essentially 5 panels in front and 3 in the rear. I am hoping that is OK.

AGAIN everyone thanks for the thoughts and helping me talk through my ideas. If this forum wasn't here I don't know WHAT I would do for help! (Well besides pay big bucks for a pro to do it all. :eek: )

>As far as the FSK, I plan to leave it on the three panels located in the rear of the room. Those were across the wall corners and floor to wall corner. What I had question on was whether to leave the FSK on all 4 sheets or just the sheet facing the room. According to Ethans write up, I would actually HURT the bass absorption if I were to leave it on EVERY sheet.<

Oh yes Ethan is right you only want the FSK on the front.

Sounds like to me you are off and running. Keep us posted on how things work out for you!

Glenn

I just ordered 2" Owens Corning 703 plain (unfaced) 24" x 48" for $.65/SF. That's $5.20 per panel with 12 per pack being $62.40. If all things are equal, the price you paid seems pretty good.


Where did you find it for this Price?

Where did you find it for this Price?
Here (http://www.spi-co.com/), but fuggedibout getting it there unless you're local and can pick it up. It is not practical to ship it UPS, Fed Ex or USPS. You need to find a large insulation contractor or an insulation distributor that is local to you. You now know what's possible pricewise; use that information to get the best deal you can.

Here's another one that I never see mentioned:

LW Supply (http://www.lwsupply.com/default.asphttp://www.lwsupply.com/default.asp)

Here's another one that I never see mentioned:

LW Supply


I went to the LW website and found that the have a location here in miami, but when I called they said they don't carry it. I have called a few other places and have had no luck yet.

I went to the LW website and found that the have a location here in miami, but when I called they said they don't carry it. I have called a few other places and have had no luck yet.
You should be able to go to your yellow pages or even YellowPages.com (http://www.yellowpages.com) and search for "insulation." Or to to the manufacturer's website and look for distribution information. I located a Johns-Manville distributor in Philly and an Owens Corning one in Balto. that way with YellowPages.com or SuperPages.com. Recently, AVS'er craig john turned me on to a more local OC source - with even better pricing. This stuff is used by the TRUCKLOAD in the HVAC industry everywhere commercial construction is occurring.

Here's a raw list (http://yellowpages.superpages.com/listings.jsp?C=insulation&R=N&STYPE=S&L=Miami+FL&MC=1&OO=1&F=1&CP=Construction+%26+Contractors%5EBuilding+Materials+%26+Sup plies%5EDealers%5EInsulation+Materials%5E) of twenty-five greater-Miami companies listed under "Insulation Materials Dealers." Call some more. :)

I've just finished treating the first reflections in my HT with acoustic panels, and it's now time to address the bass frequencies.

Here's my plan:
I'm going to make bass traps out of 6" (2 x 3") thick rockwool acoustic panels. They are 2 feet wide and 4 feet long. I'm going to make frames and feet so I can move them around, not unlike the Mondotraps from Realtraps.com They're going to be placed in the five corners of the room, floor to ceiling.

My questions are:
1. How effective will these traps be, down to 80hz or is that too ambitious?

2. Should I make them even thicker, or is 6" enough?

I've gotten a lot of good tips from this thread, and Ethan Winers articles were really informative, but it's better to be a 100% sure what to do before I start. I hope you understand that.

I've just finished treating the first reflections in my HT with acoustic panels, and it's now time to address the bass frequencies.

Here's my plan:
I'm going to make bass traps out of 6" (2 x 3") thick rockwool acoustic panels. They are 2 feet wide and 4 feet long. I'm going to make frames and feet so I can move them around, not unlike the Mondotraps from Realtraps.com They're going to be placed in the five corners of the room, floor to ceiling.

My questions are:
1. How effective will these traps be, down to 80hz or is that too ambitious?

2. Should I make them even thicker, or is 6" enough?

I've gotten a lot of good tips from this thread, and Ethan Winers articles were really informative, but it's better to be a 100% sure what to do before I start. I hope you understand that.
At this point I think you should "discover" StudioTips (http://forum.studiotips.com). This is a site devoted entirely to acoustics and acoustical treatments and is chock full of helpful information, including graphs comparing absorption of various traps. You might even get some trap design ideas. I'm doing SuperChunks myself.

Thanks for the link, pepar.

The SuperChunk traps seem great, but it will take a lot of work to fill five corners, and it will also cost more because I would need more panels, if I were to use acoustic panels. I also like the idea of having mobile traps that I can move around or remove easily if I want to.

Is the SuperChunk more effective than the type of trap that I'm planning on using?

As one of the resident StudioTippers here at AVS, with great pleasure, I give you this:

http://forum.studiotips.com/viewtopic.php?t=536

:)

Thanks, David, that's good information.

English is not my first language, and I don't understand what "sabins" mean, but is the conclusion that all three do a good job absorbing LF and that the Lenrd's has a bit of an advantage on the other two constructions? I could be very wrong. :)