Acoustical Treatments Master Thread - Page 296

I was wondering if you guys could help with possible placement of bass traps. I'm wondering if I need them in corners, where walls meet ceilings etc..

All modes are present in the corners, so that is always a good place.

Jeff

Jeff, I have angled ceiling or walls, should I hit those also?

I have two doors in the back corners also, so that might be a challenge.

With your non-square space I don't know enough to answer confidently one way or another.

Have you done any measuring? That will tell you if you need them at all. Then you can go from there.

Jeff

i dont really have any measuring equipment other than my galaxy spl meter. I have played with sub placement all over the room. It always turns out that the subs end up sounding more prounounced in the ugliest places.

Hello guys!

Hired an architect to do my entertainment room's (not dedicated theater) sound acoustic design.

Room's 3.8m width now and 7m length.

Here's what he came up with:

Metal framing on both sides (and edge of the projector side) with rockwool inside and gypsum board as the final layer.

How effective will rockwool be underneath gypsum boards in terms of helping the room acoustic?

Thank you!

That's just drywall, right? That won't do anything. Perhaps the rockwool will help sound isolation from the rest of the house more than regular insulation, but not much. And regular insulation isn't worth much to start, perhaps an added 3db of attenuation over an open void in the wall. As far as having drywall as the final layer in the media room... that's what it will sound like... drywall.

Sorry for posting this, but I'm kind of in a stump. I'm looking to tame a huge peak followed by a huge dip at my rear seating location without moving subs or seating position. It's been recommended that adding filler subs will bring up the dip but I feel that taming the peak is more important. If I tame the peak via EQ, I will then aquire a huge dip at my front seats. This is why I feel that some sort of treatment will be the recommended solution.

The room is small (18 x 10 x 7) so I don't have mega room for treatment, I already installed 36" faced super chunks in the rear corners but no room in the front corners for the same treatment. I have my whole back wall that I'm willing to work with (roughly 4ft from rear seat back to wall). The superchunks unfortunately didn't help much except with the ringing.

Aagin, I'm sorry for asking, I feel bad that I keep bring up the same issues hoping that someone has a different answer, I almost don't want to hit "submit" even though this forum is here to help me

Please take it easy on me without too much technical wording

Agreed. You won't really see any great benefit at all. Probably not even noticeable without some way to test what it would have sounded without the rockwool. The room inside will still be very "live", and whatever inherent internal acoustical issues you have without the rockwool will still be there when you are done. You might get a touch of sound absorption as it passes through the normally void cavity between the two sides of the same wall, but the fact that the whole wall is connected to itself (drywall inside the room attached to a stud, wood or metal doesn't matter a whole lot, and then connected to the drywall outside the room) means that sound will just transfer right through that wall anyway. Look up "double stud wall" or "staggered stud wall" Those help to "decouple" the inside of the room from the outside. Put your rockwool in the cavities in one of those (just one side of a double stud wall or staggered stud wall so that the rockwool itself doesn't "connect", called couple, the drywall sides again, and you will have a decent core to some sound proofing that you can build off of. Then add more mass (a second layer of drywall inside the room, and the thicker those layers, like 5/8" vs regular 1/2" sheetrock) the better. Put some green glue between the 2 layers, and you will really be doing well. Again, for sound proofing.

None of that helps with in room acoustics. Acoustics as you are saying it (not that you meant it that way) should deal with the sound quality inside the room. Acoustical treatments in that aspect happen AFTER the room is done. Soundproofing is what the designer sounds like he is working towards since it is the room itself that he is working on, and for what he is recommending, you might as well not pay the extra $$ for the rockwool or anything beyond regular construction because, like I said, you won't notice much of a difference at all.

So if you don't care about sound escaping or entering the area, focus on real acoustical treatments INSIDE the room such as bass traps, first point reflection panels, etc. This will clean up the quality of the sound quite a bit, of course in a non-dedicated room, you need to take some care to get things to look good too.

If you want to improve the sound in the room for the least amount of money, have it constructed as the rest of the house is, and spend the money on some decent treatments. This will still be a lot cheaper than the cost of the extra thick walls, rockwool for in the walls, the thicker and double layered drywall, GreenGlue, etc. Plus, those only really help if you have an enclosed space and a nice heavy door to close it all off.

I went for the soundproofing and acoustical treatments for my room that is (almost) finished and absolutely LOVE the results. I can go in the room, shut the door, and if I don't watch a movie, or put on some music, it is just so nice and quiet in there. Great for power naps!

Let us know what your goal is, and people will chime in. Some of the above is just my opinion and others will say that you need to do soundproofing to improve the sound in the room (which IS true), but if you have open paths for sound to escape, then it, in my opinion, isn't worth the cost/effort to end up with a flawed design. Sort of like buying a beat up but expensive sports car and only driving it a couple of blocks at 20 MPH to and from work. You don't get to utilize the performance under the hood, and since it is beat up, it isn't pretty to look at either (like the soundproofing - you can't see it, so people don't even appreciate the effort/cost of it)...

You might benefit from some kind of tuned absorbers -- like membrane/panel absorbers or helmholtz based absorbers. They are more effective for narrower frequency bands for a given size than insulation. Lots of tips and plans here and online for how to design and construct them.

Thanks for the info guys! Really informative!

Well... That's a bummer if it won't help. I trusted his design since I thought that gypsum board as the final layer will help in room acoustics. What it'll do it seems is just sound proofing the room?

My ultimate goal is to have better room acoustics... as in better sound quality inside the room. Sound passing out of it is not an issue.

If you guys have time... Can you kindly check on my attachments? I would greatly appreciate it.

Ouch, that is a LOT of reflective surface, between the drywall, cement, plywood, glass, and hardwood floor.

I'll put heavy drapes on all glasses.
Area rug on the floor.

Guys. Sad thing is I already bought the Rockwool. :-( How can I put it to good use?

And that may help with clarity issues in the highest frequency ranges (depending on location and types). That will leave most of the most important frequency ranges (speech, most music) untreated aside from the two or four "acoustic panels" indicated in the drawings. It's tough to suggest what specifically would be a better plan (I am not a professional - not even an experienced hobbyist), but that looks to me like a recipe for problems... not to mention bass...

I'm also a little dubious about the speaker locations. The front speaker locations aren't specified, but I'll assume they will go on shelves below the screen. Especially in that context, I am confused by the placement of the surrounds - I want them out of the corners and down from the ceiling.

As long as you're amenable to adding more "acoustic panels" (whatever that is, specifically) at a later time - hopefully after determining what acoustic problems there are in the room - then the speaker positions are my only objection to those plans.

The rockwool can be used to build "acoustic panels" that can absorb the sound the would otherwise reflect off the walls and interfere with your ability to hear the speakers clearly.

That looks like a cool room, but there is essentially no acoustic design in those plans.

Thank you nathan for the compliment. I helped with the room design.

I'm just a hobbyist but I'm entirely new to the room acoustic scene (which now seems bigger than video!) Thankfully, there's AVSFORUM to help me.

I talked to him and raised my concerns. He insisted that since the room will essentially be double-walled, there will be an effect in room acoustic. He even stated that Rockwool (ROXUL) serves double purpose in the form of soundproofing and room acoustics.

Don't worry guys though. I know that the plan has many reflections, but I won't leave it that way. I may add more Acoustic Panels if you guys advice it so. Also, an area rug will definitely be there in the absence of a carpet. All windows and sliding doors will also have draperies.

He told me that since we downgraded the budget... we went from

1) Rockwool + Padded Fabric
2) Echo Stop on the Ceiling
3) Carpets on the floor

To...

1) Rockwool + Gypsum Board
2) Acoustic Panel
3) Drapes and Area Rug

Question... Will it have a great effect on Acoustics? The way he designed the room?

As I've said, already bought Rockwool but I haven't given the metal framing a go yet... plus the gypsum boards.

And here I thought that gypsum board is better for sound acoustics.

EDIT: Forgot to note that the positions of the speakers are my responsibility. So its not by any means final. I've decided to put it high because my surrounds are going to be satellites only. Plus I've followed the THX lay out. The fronts are going to be floorstanding speakers, 90 degrees angled to the main listening position.

I will be blunt... That guy doesn't seem to know what the heck he is talking about. It doesn't surprise me and is more common than you would think. Don't get into an argument with the guy since he is working on your house and you don't want to tick him off. The drywallers here told me that GreenGlue wouldn't work, and that I should fill the wall cavities with insulation (instead of one side of the staggered wall and leaving the other side for an air gap), or that thin curtains would help against a window reflection, etc. The guy thought that he knew a lot and wanted to debate it, but my room results prove that he was wrong.

Drywall is very reflective and doesn't do anything in a single layer form to help really anything. Adding more or building a room inside a room is sound proofing (a small piece of it), but NOT helping with the sound inside the room.

As for the other pieces, sure they will help. Just do NOT put the Rockwool inside the walls. If the guy demands to put something in there, have him put something cheaper in there. It will absorb some frequencies, but not much. Save the Rockwool for corner bass traps or something. You will want to cover as much of the surface area that you can and still be aesthetically pleasing. If using drapes, you will need some good fabric there that will cost more. An area rug is really only treating a small amount of one of the major surface areas in the room. It is also thinner than a carpet and pad. Acoustical panels for first reflection points will be more and more important as there really isn't a lot of treatments in the plan for acoustics. These will help to reduce some of the echo/muddiness from your speakers.

I know it sounds like I am being a big downer, but I just want to help you be realistic. You CAN do a lot without spending a fortune, but the tricks are 1) glass is one of your enemies. Glass doors and windows have been known to be immune to some basic acoustical treatments. 2) reflections are your enemy too, obviously. My latest build gave me a room with so much echo that if you tried to talk to someone in there, it was next to impossible due to SO much echo. This was resolved by a good carpet with a thick pad, furniture, and covering the front wall with what comes to be sort of like a giant acoustical panel. 3) Bass likes to boom in the corners. A fun thing I did was I would talk to someone in the room, and then start walking towards one of the corners. Without me doing anything different, my voice would sound deeper and deeper the closer I got to the corner. People thought that I was faking it, but I wasn't. I put bass traps in the front 2 corners, and it resolved the boomy voice (and bass) in the front, and in the back 2 corners, my voice doesn't start sounding deeper until I get within maybe 6-8 inches of the corner. A LOT better than 4-5 feet from the corner.

Remember acoustical treatments INSIDE the room make the sound better. Once you hit the room itself (hard surface), doing anything there or "outward" deals with soundproofing. They are NOT the same thing. (I think that YOU get this now, but your designer/builder person doesn't)...


Stick around and keep firing off your questions. I learned SO much from this thread, but there is SO much contained in the 296 pages that it can be hard to find exactly what you want or need. So just ask away.

Thank you nick for a solid, solid post. I'm with you on this one. I'm not closed-minded anyway... and I don't mind if people are blunt in pointing out where we have gone wrong.

I don't own the house. My father does. And he has given me the whole second floor to play with but ultimately that room (Entertainment Room) will house my video and audio equipment. One thing that I didn't touch is the windows, because from the outside the Entertainment Room is visible across the street and our architect created a good exterior enough for me to rule removing the windows out.

What additional treatments do I need to do? My ceiling is bare... As in NADA. Do I need diffusers? Will it greatly help?

Talked to him again. Told me to canvass acoustic panels... Something like .6mx.6m so we can add a lot.

EDIT: Can I do it like this?

Continue the rockwool inside (since I bought truck load of it already) and then put holes on the Gypsum boards? That way the sound will be absorbed by the rockwool? In our office, our ceiling has gypsum board with lots of holes for room acoustics.

If you don't treat the inside of the room, you will have reflections from the drywall. Putting insulation inside the wall IS NOT doing anything.

Acoustic panels and bass traps is the only way.

+100

Plus, drilling holes in drywall:
1) makes a huge mess
2) takes a long time
3) greatly reduces the structural ability of the drywall
4) would need to be covered by something as it would look just silly

For the ceiling, you might see a diffuser in an audio only room, but rarely will see something in home theaters. Not saying that they don't exist, but usually you want to absorb the reflecting sound and not scatter it all around.

I would look at creating some corner bass traps and acoustical panels using some of the rockwool. It isn't super rigid, but people have done it. That will yield the best results in my opinion vs. diffusers or a bazillion drilled holes into drywall (yuck. I can taste the dust now.)

If you bought a truckload of the rockwool, then I would check on the return-ability of it. I mean, if it really isn't going to help you in the walls, then why use it. Even if there is a trucking and return fee, at least you would have some money back.

Just a thought that is worth checking in to.

Keep the questions and ideas coming. We won't shoot them *all* down.

Plus one.. 90 degree corners are generally best so I would start with those. Don't forget that even floor to wall corners around the room is a great place also. In fact if you are in a basement with a concrete floor it could be the best place to start.

CaliCool, you seem like perhaps the ideal candidate for the Pro Theater design service offered here - I suggest you contact them and discuss your situation. Make sure to be up front with your budget for treatments etc.

The target frequencies for an office ceiling are a whole lot different than a theater room. You can't compare the two.

I would love to avail the Pro Theater Design, but I live in the Philippines. So that seems like a no-no as of now.

Truth be told, the audio video services offered by "professionals" here are lacking, and we are often left with over-priced services or just DIY methods.

I'll shop for Acoustical Panels. Can you guys suggest ideal positioning? How much do I need? I'll also look for bass traps today.

Don't rule out using a US based designer. Many of us have rooms which were designed from afar ... AVS and email are wonderful things !

Why would living in the Phillipines preclude you from taking advantage of the layout service? As far as I know, they have serviced clients all over the world. Why would you say the services are lacking? Also, placing panels is precisely what the layout provides.

Shawn,

I think he meant pro services in the Philippines are lacking !