Acoustic Panel Issues

[Rich-n-Texas]

I have a couple of problems with the placement and fitment of my 24" x 48" panels from ATS that I need advice about. I've included some pictures to help illustrate my situation. To me, these panels are too large for the area behind my 38" tall mains:

http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/th_LFPanel1.jpg (http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/LFPanel1.jpg)

http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/th_RFPanel1.jpg (http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/RFPanel1.jpg)

As you can see I haven't yet mounted them to the wall so they'll look even more overwhelming for the space when they're 3 - 4 inches off the floor. My plan is to order two custom sized panels that'll look less daunting there. My question is: How small (especially in width) can I go before they start to lose their ability to trap the lower frequencies? I realize there are other room acoustic factors that need to be considered (I have four more 24 x 48 panels still to build and hang), but as I've mentioned I have plenty of furniture in the room now to help with reflections and stuff.

Another advantage of buying some that are already constructed is I can see how ATS does things like fasten the mounting brackets and finish (fold over) the grill material. I have a problem in this area too. On the first panel I put together I used a brand of spray tack that was recommended by a woman at the craft store where I bought the burlap. Problem is, it doesn't hold the burlap to the 703 fiberglass panel on humid days, meaning, bubbles in the burlap form. Unforunately, the panel that I built using 3M Super 77 spray adhesive has the same problem. Maybe I didn't spray enough on the surfaces, maybe I didn't alow enough time for the adhesive to set before pressing the two together... who knows. So the next question is, how much adhesive is too much? At what point will the adhesive become a barrier that actually inhibits the panel's ability to absorb sound?

Any help would be greatly appreciated because I still have four more panels (six after I buy two more) that need to be assembled and placed. I certainly don't want to end up with a room full of oversized panels with drooping grills.

[bfalls]

I'm not a room treatments expet by any means, but I read a lot. It's my understanding for bass frequencies and standing waves tube traps or other mass-loaded tubes are used in corners. Panels are used for live rooms and to absorb reflections (highs/mids).

To install them for the mains usually a mirror is used and run along the side wall. If the speaker is seen in the mirror, it's in this location you need the panel. A carpet or throw rug can be used in the front of the speaker on the floor to absorb floor reflections and some type of panel or pad (room tunes) on the ceiling and corners if needed. Panels on the rear wall I 've read are used for "slap echo" reflections off the back wall.

You're panel may seem large, but I would think it need to be, for releactions around the speaker.

[hmmmm]

Take the advice above. Also, take some of the fabric, get it color matched and paint the wall. They will disappear on the wall and look more custom.
I built a 1 x 3 frame and stretched the fabric around them and stapled. I made the frame tight so the insulation stayed in without any adhesive etc..

[kexodusc]

I did the same as hmm....built frames out of cheap lumper and stapled fabric to the frames, no adhesive.

Those panels will absorb "some" bass frequency if placed across a corner, but flat against a wall behind the speaker they are absorbing reflections more than bass.

[jrhymeammo]

Hey Rich,

That is one GIANT Subwoofer you got there. Are you trying to tame lower frequency from your Matrix or your ASW800? Have you considered getting a Feedback Destroyer?
Placing thick panels behind your speakers is a good idea, especially for rear ported ones, but placing them in your corners diagonally may be more effective.

JRA

[Rich-n-Texas]

Hey Rich,

That is one GIANT Subwoofer you got there. Are you trying to tame lower frequency from your Matrix or your ASW800? Have you considered getting a Feedback Destroyer?
Sometimes more of a burden than I think it's worth.:frown2:

I should've probably included a little background with this subject even though I spoke about it here: http://forums.audioreview.com/showthread.php?t=25045

In brief, I've swapped basically my entire layout to the opposite wall but I still have very little output from my sub when sitting in the room's "sweet spot". I've layed out the mains and surrounds as best I could in an equalateral triangle, and I've also elevated the surrounds so they wouldn't be firing so much into the back of the sofa. I'm going to update the drawing I included previously if there's enough interest with my latest dilemma (this thread).


Placing thick panels behind your speakers is a good idea, especially for rear ported ones, but placing them in your corners diagonally may be more effective.

JRA
I think I mispoke earlier. bfalls, you're correct in that the panels behind the mains are there for mid & upper frequency absorbsion, not lows. My B&W's are all front ported.

I am considering a BFD but I feel that I should get the room as acoustically correct as I can with the materials at hand first. I want to better understand the room's shortcomings before pulling a Microsoft and just start throwing patch on top of patch at it. Right Wooch? :smilewinkgrin:

[Rich-n-Texas]

(I'm in thread ressurection mode today... somebody's gotta do it :rolleyes: )

What you guys have suggested so far, and let me know if I've missed something, hasn't really helped. Building a box frame around the fiberglass would increase the size, but I want a smaller profile for the panels behind the mains. No matter how well you blend them with the wall, they'll still be the center of attention and a distraction, since people's eyes are foucused in that direction when watching TV, if they make too large a statement. I'm going to assume that, if I properly place other panels in the room such that reflections are minimized to a large extent, putting up panels that are smaller and more proportional to the area won't be a big deal.

I've read the previously linked article about using the mirror on the wall method of panel placement, but since I know the dispersion angle of my speakers, I think that's a better way of knowing where the first reflection panels should be.

hmmm, why 1" x 3"? My fiberglass panels are two inches thick.

[kexodusc]

(I'm in thread ressurection mode today... somebody's gotta do it :rolleyes: )

What you guys have suggested so far, and let me know if I've missed something, hasn't really helped. Building a box frame around the fiberglass would increase the size, but I want a smaller profile for the panels behind the mains. No matter how well you blend them with the wall, they'll still be the center of attention and a distraction, since people's eyes are foucused in that direction when watching TV, if they make too large a statement. I'm going to assume that, if I properly place other panels in the room such that reflections are minimized to a large extent, putting up panels that are smaller and more proportional to the area won't be a big deal.

Guess it comes down to style vs substance. Personally I find the panels are unobtrusive but not terribly attractive. That's all you can hope for. People think the room is cool though, but I've been lucky enough to not have to use my main living room for my HT, my wife would kill me!


I've read the previously linked article about using the mirror on the wall method of panel placement, but since I know the dispersion angle of my speakers, I think that's a better way of knowing where the first reflection panels should be.

Dispersion angle? What do you mean? There's sound reflecting off walls, mostly noticeable at the listening position when they bounce at a specific spot on the wall - you cannot get any better than the mirror method without sophisticated equipment. Light waves and sound waves travel in the same path for our purposes here, that's why the mirror method is so good. Compromise for aesthetics and convenience are one thing, but try not to "guess" where the panels should go. Just grab a mirror and know for certain where they should go.

[Rich-n-Texas]

Can some one tell me what this spec from the 804's sheet means? (B&W 804 speaker that is)



Free-Field Response:
Listening axis +/- 2db, 31Hz - 20KHz
+/- 30 degree horizontal +/- 2dB to 10KHz
+/- 5 degree verticle +/- 2dB to 20KHz







If I'm correct that's the optimal listening axis...


I made a little drawing, because I can't explain it that easy (well, I could, but it'd be hard to understand...)

you should aim the speakers so your ears are definately within the 2 outer lines...

you'll get the best frequency response if your ears are on both the middle lines (the optimal listening axis), but this is not always the nicest to listen too, so that's why we play around with placement...
this is why so many people say that the sound is best when your tweeters are at 'ear level', but while this is (theoretically speaking) true, you might more like the sound when you're sitting under the tweeter level, or above...


I hope this was understandable...
(see pic below, note that the drawing is definately not on scale, and the outer and inner line doesn't really form the given angle (30°))

If I'm correct that's the optimal listening axis...


I made a little drawing, because I can't explain it that easy (well, I could, but it'd be hard to understand...)

you should aim the speakers so your ears are definately within the 2 outer lines...

you'll get the best frequency response if your ears are on both the middle lines (the optimal listening axis), but this is not always the nicest to listen too, so that's why we play around with placement...
this is why so many people say that the sound is best when your tweeters are at 'ear level', but while this is (theoretically speaking) true, you might more like the sound when you're sitting under the tweeter level, or above...


I hope this was understandable...
(see pic below, note that the drawing is definately not on scale, and the outer and inner line doesn't really form the given angle (30°))
<LEGEND>Attached Images</LEGEND>
http://forums.audioreview.com/attachment.php?attachmentid=3223&stc=1&d=1199223412

<!-- / message --><!-- attachments -->

Keep them spinning,
Bert.

His drawing shows what I assume to be the dispertion angle of the speaker. If I draw a line 30 degrees from the face of the speaker to the wall, wouldn't that be the first reflection point?

[kexodusc]

His drawing shows what I assume to be the dispertion angle of the speaker. If I draw a line 30 degrees from the face of the speaker to the wall, wouldn't that be the first reflection point?


Hmmm...okay, the angles look fine. That represents the angle in which the signal will be output in accordance with the given response criteria:

listening axis +/- 2db, 31Hz - 20KHz
+/- 30 degree horizontal +/- 2dB to 10KHz
+/- 5 degree verticle +/- 2dB to 20KHz

Rich, all that means is within those angles, the response remains +/- 2 dB.
Once you go outside that angle there's still plenty o' sound. It might be +/- 4 dB or +/- 8 dB. The highs will diminish some. Not as flat, accurate, whatever, but still there. Think about it. If you were to walk in your room outside that angle, you still hear sound, right?

The 30 degree dispersion has nothing to do with it. The 1st reflection point represents the mirror point for light and sound waves between you, the wall, and the speaker. It's the first thing you'll hear after the initial sound reaches you directly from the speaker . That's the unreflected sound. The reflected sound travels outside that 30 degree angle in all likelyhood, unless your room is very skinny.

Use mirror, dude, please!

[GMichael]

Hmmm...okay, the angles look fine.

Use mirror, dude, please!

Maybe he thinks that he's such a good pool player that he can pick out the reflection points like a shark picking bank points.

Rich,
How many diamonds between you and your speakers?

[Rich-n-Texas]

Thanks Kex. That makes things much clearer now. I know you guys know me well enough now to know I like to over complicate things, but PLEASE, if I start to sound too much like SVI, send me a PM or even better, a red chicklet okay? I'll put my niece to work with her vanity mirror next time she's over. :thumbsup:

Umm, GM. I can still see the footprints of my pool table legs on the carpet, so theoretically... :biggrin5:

[L.J.]

I've added alot of panels to my room and I don't think they look bad. My wife likes them and most people think it's decoration. You should see the look on their faces when we explain what they're for though.

I added alot of plants and other things throughout the room so it looks pretty nice. I'll post some pics when I get a chance.

[Rich-n-Texas]

300 posts later L.J. finally chimes in. :rolleyes:

[kexodusc]

I've added alot of panels to my room and I don't think they look bad. My wife likes them and most people think it's decoration. You should see the look on their faces when we explain what they're for though.

I added alot of plants and other things throughout the room so it looks pretty nice. I'll post some pics when I get a chance.

Yeah, the natural burlap rectangle look is back in style I hear. :p

I've had a few women ask if I got them in town at some artsy import place. A few people think they're "different" but not unattractive. My wife was thrilled that I took the burgundy coloured Auralex/Sonotec foam wedges down. In hindsight, I think I agree with her.

I've got 13 panels up in the room right now. In my room they're not ovewhelming. I helped a friend make 8 in his room which was maybe 18' x 11' and it might have been a bit too much. But boy did they ever help expand the front and side soundstages in that narrow room.

[hmmmm]

hmmm, why 1" x 3"? My fiberglass panels are two inches thick.[/QUOTE]

Well, a 1 x 3 really isn't 3 inches deep...it's closer to 2 3/4". But having said that I actually made more of a column wrapped in fabric that is almost 8 feet tall, to become a design element in the room.
With a good fabric wrap, you will not have to worry about the fabric bubbling with bad adhesion. You can still spray the wood with 3m 77 spray and then staple in back if you want.

If you choose the right paint, trust me, they will become less of a focal point. They will "visually shrink." I work with interior designers on a daily basis and this is a trick that is frequently used. I'll post a pic of one of my acoustic panels later.

[hmmmm]

Here's a pic of my recently covered Owens Corning 703 2". I covered it in Acoustic Seude.

[kexodusc]

Here's a pic of my recently covered Owens Corning 703 2". I covered it in Acoustic Seude.
Hey hmmmm, how ya been...
Nice room...should get ya to design the HT in the house I'm building...

Nice speakers :)

[hmmmm]

Hey hmmmm, how ya been...
Nice room...should get ya to design the HT in the house I'm building...

Nice speakers :)

Doing much better thanks! (still hate typing though:)
Everytime I listen to the Roman 2.5s I'm amazed. He designed a great project.
Hey, why don't you fly me up there, I'll help with that theater for a few Canadian Beers!

[Rich-n-Texas]

Hey, why don't you fly me up there, I'll help with that theater for a few Canadian Beers!
Whoa up there pardner! Get in line Kex!

As far as the wall color, I just painted the entire room in "Parchment", a nice neutral color, and one that closely matches the "natural" burlap color. I purposely used the darker color burlap that is shown in the pictures to match other elements in the room (furniture, picture frames, shelving...etc), but I will use the natural colored burlap in areas where they will have more visibility. Obviously home decorating isn't my strong suit, and having a female's perspective would go a long way (hope that doesn't sound sexist... whatever), but I have no intention of painting again anytime soon.

hmmmm, I looked at your pictures in the thread you started before before realizing that column in your room was for acoustics. That's amazing and all those pictures give me some great ideas. I've got miles to go with my room and the more pictures I see (L.J.) the better off I am with my project. :thumbsup:

[Rich-n-Texas]

...as I'm going.

Just a couple of pics to prove that I really am working on my room's acoustics. :yesnod:

They ain't nothing special, but it's a monkey off my back and I felt like sharing.

Problems, questions comments are welcomed...

http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/100_0676.jpg

http://i115.photobucket.com/albums/n286/rich3fan/Home%20Theater%20photos/100_0677.jpg

[johnny p]

I'm planning on doing some "First point of reflection" panels, and bass traps.... I heard many people use rock-woal???????? anyone know about that? either way, it's looking good!