Acoustical Treatments Master Thread - Page 142

Thanks for your reply Pepar, I will finish the interior walls per normal standards.. framed, insulated, drywalled. As shown in the pictures, framing is already complete. Are you saying that without a finished ceiling I will need lots of bass traps or were you thinking all the walls were concrete and unfinished? I need to find out what my best ceiling options are.

Also, excuse my ignorance, what does LF mean?

Thanks,
Berk

With a concrete room, I think you will need lots of traps with or without the studded walls. The walls you describe will absorb some, but sound will pass through them to the concrete, reflect and then travel back through the walls. You might want to investigate the special construction materials available to help attenuate this.

LF = low frequency

I am planning to put floor to soffit corner bass traps in. Is it worth considering stuffing the soffit full of insulation (around the HVAC pipes) and then covering the front facing part with fabric?

Is there a spray on insulation that would work on the ceiling? What about egg carton shaped styrofoam?

How is this any different than all the basements here that have concrete block walls? Is poured concrete that much more reflective than block? What special construction materials besides DD ad GG?

Does anyone here know what the acoustically absorption properties are for upholstery foam rubber???

Gentlemen,

I am planning for a new theater and wanted to see if I am missing anything regarding sound absorption. The room is 18'1" long and 16'1" wide. The four walls are 6'6" high and then angle up at 45 degrees towards the ceiling. The ceiling is 11'2" high.

I plan on bass traps in the front corners, 2" OC 705 around the bottom 2 feet of the two side walls and the rear wall, and heavy insulation in the stage and riser to address the low end sound. I plan on 2" OC 703 on the two side walls and the rear wall on top of the OC 705 up to the 6'6" mark.

What else will I need? Do the slanted walls present any kind of unique problem?

It's rubber. Run. Run fast and far. Plastics and rubbers are naturally sound reflectors, even in a foam form. They work well to seal up doors, windows, HVACC and other possible sound leak areas, but they are pretty much useless for acoustical treatments.

That is, unless there are some new rubber-type materials which I am unaware of.

So, my problem is that I have a sound isolated room, which does really well, with the exception of LF. That stuff reverbarates pretty badly.

I have no acoustical treatments in my room yet, and the room's size/ratio is not one of the preferred acoustical dimensions - its 15'x14'x7'.

Now, I'm pretty confident I've addressed all of my possible flanks, so my guess is that it's simply the long wavelengths of the LF making their way through the walls, insulation and just bouncing every where.

So, I suppose my question is this:

When I add my acoustical treatments, including bass traps, will these help circumvent the excessive LF reverb through the rest of the house?

It is not.

And that has got to be the same problem I am having with my basement, but I'm already built with all my walls in, so I'm not left with too many options outside of acoustical treatments.

Guess this is the one thing I miscalculated or flat out missed. And now I have a pretty large LF problem through the house...

Sorry, but the answer is no. This is a sound isolation problem, which cannot be substantially affected by acoustical treatment.

So, what can be done to decrease this? This is interesting because I followed all the guidelines regarding sound isolation and yet I still get this.

So, what did I miss??? What did the guys I spoke to miss?

I used whisper clips and acoustical caulk and green glue and the room-within-a-room technique... Hmph... What did I miss...

Or am I simply pushing more power through the room than the sound isolation can handle?

Low frequencies are always the hardest to isolate. Do you have your own construction pics of the sound isolation methods you used?

Yes I do. I performed all the construction myself as well, so I saw and understood all of the issues revolving around it.

Thank you Will...

Anybody have any thoughts about the room question I presented?

I'm not an expert, nor even all that qualified to try and tackle that one. The ceiling... if it were me, I'd try to put in a flatter ceiling lower down, or talk to an acoustic engineer to see about diffusing up there. I really don't know other than that...

Terry,

Any thoughts?

None whatsoever.
It's the end of the day here, and my brain is fried!
I'll have a look tomorrow, though.

Thank you so much Terry... I find that a little vodka helps with that situation... Enjoy your evening my good man... ;-)

Rats. I was planning on Bourbon.

My theater is 16' wide and 19' long. We have one sofa about 12' back and behind that is a 37" high wall which goes about 10' across (see way cool drawing).
Behind the theater is the rest of my finished basement which extends another 30' or so.

Speakers won't move, sub may.

I will treat the front corners (floor to ceiling) and lower right corner (37") with bass traps. Should I be concerned about the wall behind the sofa?

Bonus question. The SPeakers are AV123 X-Statik open baffle speakers (tweeter and mids). I haven't read much about treating rooms with these types of speakers.

Thoughts?

Front
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|...-Sofa--....|
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......._______| <-1/2 wall
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Any update on this project? Pics?

I need something to copy.

This is a follow up and more info about the room I mentioned earlier.

In the planning stages for a new theater in a new house. Need some help and input for sound...

The new theater is already "built". The room is on the 2nd floor over a 3 car garage. Please see the pics, which includes a diagram of the rough space.

The floor space of the room is currently 19'4" wide (from the entry to the left wall)) and 20'6" long (from screen wall to rear). Because the current wall heights of the room are too low for what I want to do, I will be creating a "room within a room" effect, that will create some "unused" space that might be able to be used for sound absorption, but it will not be symmetrical.

All four walls will be 6'6" high and then begin angling at 45 degrees to a ceiling height of 11'2". By setting the wall height at 6'6" around the entire room, the room dimensions become 18'1" long and 16'1" wide. I'm including some pics. In the pics, where you see the boards taped to the wall, that is where the "false" wall height will be. The space behind those false walls is the unused space. On the screen and rear wall, I lose about 14" of floor space. On the left wall, I lose 3'3" of floor space. I plan on a 120" diagonal, non-acoustically transparent screen. I'll be running a 7.1 system. Infinite Baffle subwoofer that will have a large manifold opening the floor of my front stage and the manifold will actually be in my garage below the room. The manifold opening in the floor will span about 8' wide and will be centered in the front stage. Stand up floor speakers for L/R and each approximately 3' from the front wall and side walls. The center channel will rest on the stage floor and be aimed upwards.

I plan on using bass traps in all four corners, and either 2" acoustic foam or OC 703 at ear level and below. Perhaps do the bottom 2 feet of the 3 non-screen walls in 2 or more inches of OC 705 for even more evenly-distributed bass absorption. The room is carpeted. Will I need to put some sound absorption (either batting or 703 or 705) in the ceiling or on the slope walls going up to the ceiling? I can make the "inner" walls acoustically transparent and use the space behind the "inner" walls for sound absorption, but it won't be symmetrical. What are my other acoustic concerns for this room? I know angled walls are difficult to model...

Thanks in advance for the help guys... Todd

More pics...

I'm just getting the trim painted for the adjacent room and the door way sealed up. So, I have not yet started this phase of the project.

Due to a recent addition to the family, it is probably about a month away from being implemented.

Once I get a chance to get my theater build updated, I'll definitely post what I'm doing in there.

Sorry it's going to be so long, but having a new born in the house keeps you preoccupied.



I still need to figure out if there's anything I can do regarding my LF sound isolation problem. ALL other frequencies - you can't hear a thing... But I might have an idea of where my flank is that's allowing the sound to permeate through the house. I just need to do a few more tests and then come up with a solution - which might actually mean taking up the carpet and floor from the room above the ceiling.

Todd, if you haven't done so already, I suggest you start your own theater build thread to help isolate your specific issues, and then direct a bunch of us over there. We're all here to help as we can.

Ah. Now I see what you mean. I would definitely look into using an AT screen and placing the speakers behind the screen and use that space to help with acoustics and asthetics.

Well, I thought I'd just bring up the acoustics part here in this thread since angled walls aren't really covered much... There will be a separate build thread.

OH, I'm not saying you shouldn't have done that. I'm simply stating there sounds like there's more to this build than just the angled ceiling, that's all.

Anyone know where to buy corning 703 in the san francisco bay area?

I'd like to get 12 sheets or less of the 1". I saw one place in oakland that sold it, but it was still cheaper on ebay even with shipping....