Acoustical Treatments Master Thread - Page 75

Depends... both cases are corner mounted panels and will work equally well as bass traps. And either may, or may not, also be useful for controlling SBIR and/or early reflections.


No harm in looking into it I suppose... but you need to find out what the stuff is to make a determination. If its a medium density thermal insulation product, it probably has reasonably good acoustic absorption properties. Find out exactly what it is and look it up. Though I wouldn't settle for anything that didn't have good lab numbers... and good handling properties... as excellent materials in either semi-rigid fiberglass or rockwool are available in mosts markets for modest costs.

Wish I could go, but will be pretty much stepping off a plane back from the UK. Would be way to much "out of town time" for me.
Hope it all works out well for you. BREAK A LEG.

Glenn

I'll try hard not to break a leg.

But I will mention your name when I speak on the panel.

--Ethan

Would it be to much to ask for you to pass out some of our brochures also?

Back in February I posted about building my first prototype panel absorber.

Well, last night I finally finished the last of five planned panels of this design, so I thought I'd share with y'all the fruits of the knowledge in this thread. So far everything is turning out pretty well. Thanks again for everyone who has posted.

The original prototype is in the center of the second shot. Note also that the panels hanging behind the sofa are shorter to leave room for a yet-to-be-built second row riser.

I will be making at least one more of similar design. It will go behind the door seen in the first shot, but it will need to be thinner and mount flush to the wall instead of spaced away like the others.

I'm also planning to do something about the corners, and I have a couple questions about that. (See next post.)

Now that I'm done with my side-wall panel absorbers, I need to turn to my corner bass trapping.

Currently I have eight 2' x 4' x 4" 8lb rockwool batts straddling the room's vertical corners. For aesthetic reasons, I'd like my corner absorbers to extend 14.25" from the corners instead of the 17" you get with a full 24" panel.

(1) Would reducing the width of the panel this much reduce the effectiveness of the absorber more than the simple reduction in the volume of the material?

and on a very related note:

(2) Would building "chunk" style absorbers using all my available material recover the absorption lost due to the width reduction?

Cheers,

Those are great looking absorbers. Are they just a wood frame/cloth over fiberglass? or are they tuned panel absorbers?

Thanks.
They are frames & fabric around 8lb 2" rockwool.
I tried to tune them, but I couldn't figure out where to put the knobs.

Cheers,

I have had that problem, too!

- Terry

Just so I understand correctly. You are going to build the panels that straggle the corners shorter? or are you going to build super chunks that are shorter? Sorry kind of early here.
It is all about coverage, so the shorter you make them the less area it has to pick up sound and it will reduce the air gap in the back. So all and all it will pick up less bass over all. How much, is really hard to tell, but if it was me I would stick with the face to be 24" across the corner. May it be super chunks or panels.

Hope that helps.

Glenn

***
I am finishing a rather narrow home theater (11' by 20') in an unfinished part of the basement by building a 'room within a room' with 2"x4" studs, thermal insulation in the walls, and 1/2 " drywall around the walls. I plan to use two 5/8" drywall layers for the ceiling, using green glue to dampen the sound through the ceiling (plus 8" of thermal insulation above). Got a 12" soffit perpendicular to the main axis of the room about 14 ' back from the front (narrow end) wall. Rug covering concrete floor. 6 reclining seats. Set-up will include a 45" HDTV centered on the front wall. Using Klipsch spkrs for 7.1 sound (Synergy F-3 series). A front projection screen will descend for movies, covering much of the front wall.

First questions concern spkr placement for the mains and the subwoofer:

1) Should mains be placed as close to the screen as possible to minimize corner effects in this set-up (i.e., maybe 6-8 feet apart?). With the screen down, spkrs will be awfully close to the corners ... will this cause a problem?

2) Should the subwoofer be placed in the center to minimize smearing?

3) With respect to acoustic treatments in such a narrow room (and with insulation in the walls), should I use 1" batting or insul-shield around the sidewalls, up to ear height, and no treatment above that? Or something else?
More (or higher) treatment because the room is narrow?

4) Front side of soffet (i.e., side facing the speakers) should be treated, I bet...?

5) Back wall treated same as sides in this case?

-Thanks for sharing your expertise -

jchretien4

Center channel will be below display and screen, mounted forward about 6". Screen will not be perforated. Soffit is drywall enclosing a steel girder.

So, above ear height on the sides, I should leave alone, at least to start?

Thanks for your help -

jchretien4

Anybody know how much of a difference 1/2" vs. 3/4" OSB will make as a second floor layer with Green Glue? I'm looking at sound isolation from the room below in a new home theater (pictures of current status here). I'm trying to get a feel if it is worth the extra weight/expense to go for 3/4" OSB. I don't see much on the Green Glue site other than "3/4 OSB or 11/16 OSB are best, 1/2" is good". I'm trying to see if there is any more data than that. If 3/4" makes a 20%+ difference in perceived noise levels in the room below, I'm all over it. If it's a barely noticable difference, I'll go lighter.

By the way, I know this is very difficult to answer, hard to quantify, and it will vary from room to room and depend on my weakest link. For this discussion, assume the floor is my weakest link and the only path for sound getting to the room below. I'm just looking for informed gut feels.

My theater is going in an existing room in a room. The current floor is 3/4" OSB on 2x8 floor joists 16" OC with a 3" gap over the 2x6 ceiling joists in the room below. Blown in insulation on the ceiling below, R-30 pink between the floor joists.

The walls are 1/2" drywall on 2x4 studs with minimum 3" spacing to another 2x4 wall. Most of the walls and the ceiling actually face attic or roof. I'm already planning on GG/double drywall (another layer of 1/2") on the walls (5 cases of green glue up there right now).

I've just thrown GG/OSB for the floor into the plan (my wife's idea, I've been trying to avoid overdoing it). It'll cost me 12 sheets of OSB and another two cases of GG, but it'll be easy to do now that the floor is torn up.

However, I have to decided between 3/4", 11/16", or 1/2" OSB (or something else, if there are better/cheaper/lighter options) I haven't explored price yet, but the lighter the better as my wife and I have to lug it upstairs. Also, the hallway outside the room has 3/4" wood floors on top of the same subfloor. If I put 3/4" OSB, my pad/carpet will start flush with the outside floor. I'm worried about dealing with the step up on entering the room. I don't want people tripping.

Any thoughts?

Has anyone tried this product?

http://www.fibratec.com/

The blanket sounds like it could work, just waiting to see what the sound attributes are for it before I order any.

.

Currently I have my 4" batts straddling the corners. The room sounds OK. I could use some more absorption from 30hz to about 80hz...but then who couldn't? (See the waterfall charts in my gallery)

What I want to do is make them shorter - from the 17" of wall space they currently occupy, down to 14.25". This will reduce the front-side length from 24" down to just over 20". I know that this will reduce the effectiveness of the panel...So, I'm wondering if switching to a "super chunk" design will adequately compensate.

Therefore, what I'd like to know is how the performance of a 20" wide "super chunk" compares to that of a 24" wide panel?

Look into a roomeqwizard/BFD combo. Google "Room EQ Wizard". If you pull down those two huge peaks, you'll notice a world of difference, and it'll only cost you about $150, which is much less than most eq solutions.

If you like it, throw the guy a couple bucks so he'll keep developing the program.

The more I read, the more confused I become.
Can I use 2" rockwool to deaden the entire front wall?
I am going to use 4" rockwool for bass traps in all four corners.
Can I treat the lower half of the side walls with 2" rock wool like the frontwall?
Does the rear wall get treated like the front wall or just some panels placed to help absorb and diffuse?
I will be placing quilt stuff on the outside of the rockwool before covering with GOM.
The floor will have pad and carpet over cement. The cieling will be treated with a few panels if I have the materials left over,
My room is 17X12.5X8.3,
I have a Sony 60XBR2, Rocket 760(l&r), Bigfoot, 300's (ss) and MFW-15 sub.
My seating will be about 7'&11" from front of TV(3"from wall).
Any comments or suggestions on my plans and questions are greatly appreciated.
Humbly.

The 2" on the front wall, and 4" bass traps should be a safe bet (are you going wih superchunk or panel style?). So would treating the first reflection points from the floor to a foot or two above ear level. Beyond that, you'll want to put you system in and give it a listen. I'd say a panel on the ceiling is a safe bet also.

Beyond that, you're going to have to see how the room sounds. If it's starting to feel dead, stop. If it sounds small, try some diffusion in the back. If it's still really live, go with absorption.

eugovector;

I was going to cut the 4" into 2' triangles and stack in the corners.
So do you think treating the entire length of the side walls up to 4' would be too much?
This all completely new to me, but I have a clean slate with my garage conversion and I want to do it the best that I can.
Thanks again.

Without hearing it it's hard to say. There are no hard and fast rules. Put in a sytem, fire it up, and then add or remove absorption, and listen some more. This isn't baking, it's a fine saute.

Dennis or whomever,
Hey guys I usually build home theaters and am currently doing a commercial acoustic job. I have mostly done fabric over 1x lumber and have started using fabric mate recently. Usually I do the lighting and audio also and am dealing with any cutting that is done myself. A large local company is doing the audio and a large electical outfit is installing about 150' of track light over my fabric. Any ideas besides glueing the fabric to lumber blocking so they don't destroy my fabric when they install the track? Thanks

eugovector,

Thanks again for your response. If you are in the neighborhood in the next few weeks, stop buy and you could help me place my treatments. This invitation is open to everyone here at AVS, I could really use the guidance and support.
But, irregardless(really a word?), I will continue on and hope for the best. I know it has got to turn out better than my chainsaw modification to the spare bedroom. That is where everything is right now.

I think starting out I would go with the bass traps in the corners, 4" panels on the back wall with 2" panels in the first reflections on the side walls. Putting panels on the front wall will help but I would not deaden it right away.
Hey I would come over but you are WAY FAR!!!!!!!!!!!!

Glenn

Thanks to all for your suggestions. I will be incorporating much of them in the comming days. I will let you all know how it turns out.
Thanks again.

I just got quoted a price for 1.5" insul-shield of $31.25 for 144 sqft. It comes in 2'x4' panels in a bag of 18 pieces for that price.

Now the question is just how much can I fit in my car.

Any good Pinots nearby?

That's a great price. What company did you get this from?

You're welcome. I'll be in Portland in late June, don't wait for me though.