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Acoustic treatment question/advice


MercedesBerater

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I could do much thicker on the front and rear walls... But would probably keep to 2" on side walls for appearances sake.

What are thoughts on making the rear riser a broadband absorber.. That could be a 10foot x 13foot x 8" absorber! -- if enough pressure can get in through the perimeter vents. In addition to corner bass traps. Which are maybe 8-10" thick??

 

 

I dint bother with Bass traps, but my listening is at moderate levels.   If you do the bass traps, you might want to put the larger ones in the corners near the floor and possibly float two in the center of the rear wall where most bass bloat is heard.

 

You can purchase them with the angles set for corners from Acoustimac...hint hint

 

 

feed-bt4000c-new.jpg

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I was told 2" thick only effects the highs, and to go with 4" thick (which we did).

For anybody who wants to get into it, you can look up the acoustic coefficients for each material. Here is a list of several although they skip from 125 hz to 500.

http://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html

Also keep in mind that on your first reflection points you are hitting it at an angle and not straight on. Not much point in getting real carried away with the thickness on the sides.

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Any pictures of your work?

These are the ones I built.

3" (2.5" actual) poplar frame

12088416_10153352930329401_7105831918041

 

 

Knauf black acoustical board, has an acoustically transparent polymer on the facing.  Slightly thicker than the normal 2", slightly better lower frequency absorption.  The normal 2" is less than half as much though.  

 

12239615_10153405917344401_1490808975464

 

 

 

wrapped it in black crushed panne velvet from rose brand.  These glisten in person, doesn't translate to pictures very well, just looks mottled and dirty.  If you use a thin stretchy material and a wood frame, wrapping is easy if you can figure out how to tuck it at the corners.  Using a thicker material without a wood frame is harder.  

 

12107898_10153350651324401_6870186177471

 

 

 

window plug made out of six normal 2" rigid Knauf panels, backed with blackout material.  You can see the black board on the panel on the left against the trim.  The normal stuff is in the window, just doesn't have that black facing.  I wrapped these in velvet and it insulates, blocks out light, and serves as a first reflection point absorber.  I have velvet drapes that cover it as well, this stuff isn't exposed.  

12357233_10153451569694401_2292412377052

Edited by MetropolisLakeOutfitters
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I would presume you do a 'Marine Corps rack fold' Or 'hospital bed fold'

Those do look nice...

But Max2's company he used is 1/2 the cost of the Acoustical Solutions... They're sending a color swatch for me to compare to the color I really wanted.

At 1/2 the cost... A little color difference I'm sure is juuust fine.

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But Max2's company he used is 1/2 the cost of the Acoustical Solutions... They're sending a color swatch for me to compare to the color I really wanted.

At 1/2 the cost... A little color difference I'm sure is juuust fine.

 

http://www.acoustimac.com/dmd-acoustic-panel-422/

 

Yes those are way more reasonable.  Notice that they're just using Roxul or 703 then adding some hardware and wrapping them.  It's not magic.  At $55 though that's hard to beat if you didn't feel like messing with it.  With a size like that you'd have like $10 in insulation, a yard of material at $12 a yard, a few bucks in wood, few bucks in hanging hardware and staples/glue, basically half of what you're paying for is material and the other half is labor to assemble them.  

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I would presume you do a 'Marine Corps rack fold' Or 'hospital bed fold'

Those do look nice...

But Max2's company he used is 1/2 the cost of the Acoustical Solutions... They're sending a color swatch for me to compare to the color I really wanted.

At 1/2 the cost... A little color difference I'm sure is juuust fine.

 

I went with the Eco cores, just because I'm a little leery of fiberglass anything. I think they are within 2-4% of compressed fiberglass performance cores and are superior than fiber in the lower cycles.  The guy I talked to that recommended my setup was very cool. They also sent me all the colors of the Castille suede that they had which I really liked the look and feel when the samples arrived.  They will also build any custom sized, funky shaped panel you need.  But like you said, their prices are so reasonable its a no brainer for people with limited time. I think they had them to me from Florida in a week, it was fast.

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The fastening brackets aren't extremely accurate and the wood backing panels are so thin its easy to not get things exact, and yes being off even less than 1/4" shows. Multiple panel alignment is a pain or at least is was for me.

If you build a wooden frame like mine, you can hang it like a picture frame with a wire on the back. Very precise alignment. These things don't weigh much, the insulation is only a few pounds.

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Erskine group knows what they are doing. However they don't just hang panels all over. When you pay them 15k for their cheap help they fly a guy out and do measurements of your room and go from there. I have been in an erskine designed room. His room was Insanely nice. He actually had Klipsch when I first went. He had something like 70 grand in the room alone. Doctor of some sort I believe. I'm a mechanic. Lol first reflection point was plenty for my first theater. That and carpet. Next theater i may read more into it. And also I went with acoustimac. When I lpriced stuff out to build or buy it was like 10$ more a panel to just buy. I was only getting a couple so no brainer. I bought pre made ones.

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The fastening brackets aren't extremely accurate and the wood backing panels are so thin its easy to not get things exact, and yes being off even less than 1/4" shows. Multiple panel alignment is a pain or at least is was for me.

If you build a wooden frame like mine, you can hang it like a picture frame with a wire on the back. Very precise alignment. These things don't weigh much, the insulation is only a few pounds.

 

 

 

Yes, my front wall and my rear wall, which you cant see in the photo was pretty easy since I didn't do any stacking and what not, they just hang normal.  My side walls though have a lot of angle where I had to attach the bottom as well and the same thing for the ceiling.  Attaching the sliders on the panels is easy and they work great as they are the full width of the panel and very secure, but pulling on them or tweaking them causes the small screws used to mount them get a little wallowed if you tweak them too much.  Mounting the additional top and bottom sliders on the ceiling or wall and aligning them up when you have 3 or more took some finesse getting everything aligned well enough to keep the eye twitch at bay. The guy told me I need to use the heavy slider brackets even if just hanging them normally. He said you will lose performance just hanging from a screw and they needed to be snug and not free to vibrate or move at all...for what that is worth. I used the screw cam sheet rock fasteners and you cant really pull them out short of 50lbs or so.

Edited by Max2
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Silly question... Because I don't think I have the power required to do such a thing.. But maybe as I haven't moved speakers into their final home yet.

If these panels aren't secured to the wall... Let's say using a wire hanger style like MetroLake suggested-- is it possible that the panels will vibrate or bounce a little off the wall and cause noise? Should they be glued & impaled in a perfect world?

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Silly question... Because I don't think I have the power required to do such a thing.. But maybe as I haven't moved speakers into their final home yet.

If these panels aren't secured to the wall... Let's say using a wire hanger style like MetroLake suggested-- is it possible that the panels will vibrate or bounce a little off the wall and cause noise? Should they be glued & impaled in a perfect world?

 

 

The tracks they come with wont allow it. They cant tip or sway. On a vertical wall you're good to go with just one slider

 

 

 

Wait, wait.  They call them Z bars.   This is what you want to use.  I wouldnt use impalers unless you wanted them offset

 

Z Bar

 

zbarx4.jpg

 

 

 

Impaler

 

standoff_2.jpg

Edited by Max2
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is it possible that the panels will vibrate or bounce a little off the wall and cause noise? Should they be glued & impaled in a perfect world?

There should be fabric on the back side. You'd have to have pretty crazy pressurization from the subs for them to slap the wall hard enough for you to hear it. Of course I've seen videos of scrappy's room slamming an 8' ladder up against a wall. I've seen people nail/tack felt pads on the back side though.

As for it absorbing stuff better, the real issues are for 400-500 hz and on up. I can't imagine that those frequencies are going to vibrate it in such a way that it won't work as well.

Generally the speaking the impalers seem to be used for when you don't feel like making a frame. Seems like everything I've read acts like a frame is better if possible. I've got a box of them at home, not sure if I'll use them or not.

Edited by MetropolisLakeOutfitters
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For those who haven't messed with them, the neatest effect of these is the clap test. Just clap real hard in various parts of the room. If you pay attention you can hear the decay time in some spots, it's this weird feedback like the ripple effect. Put up the acoustic panels and its just dead. Once mine were up I felt like dialogue was more intelligible at lower volumes.

Edited by MetropolisLakeOutfitters
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I doubt I have the power required to build that kind of pressure to move the frames from the walls... Just paranoid since the guys that CAN move stuff made me wonder.

It's usually the real lightweight stuff that rattles. Sheet metal on lighting fixtures and rack panels, and hollow core doors. Adding weight fixes it. At least with mine you'd have to try pretty danged hard to slam them up against a wall hard enough to notice. If you got to that point you'd have ten other things rattling harder.

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