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235 Build - Page 16

post #451 of 541
You're certainly welcome to come by and check mine out any time. Winnipeg is only about a 50 hour drive from Albany. smile.gif
post #452 of 541
Quote:
Originally Posted by Spaceman View Post

I know the plan was to build your soffits inside the drywalled bunker. Given your decoupling issue, would it be possible to cut out the section of ceiling that is coupled around the perimeter of the room and hide the cutout INSIDE a DD+GG soffit (like the area with the black "X" in the photo below)? Probably not as ideal as your original method, but I'm guessing it would be better than a coupled scenario.



EDIT: Depending on your channel placement in the ceiling, you might not have to cut out as much as I showed with the black "X". Since the coupling is only occuring at the very edge (between the wall and first channel), you would only need to cut back to the first channel. In the pic, that would be much closer to the wall. Is there a chance you don't have that first channel that is shown pretty close to the wall? I could see how the ceiling might get pushed up and come in contact with the joists if the first channel was too far from the wall.
I sent you a Pm I agree you may be able to remove the offending corners than use a OSB/GG/DW soffit and maintain your sound proofing that way. see page four and five
post #453 of 541
Thread Starter 
Quote:
Originally Posted by AirBenji View Post

You're certainly welcome to come by and check mine out any time. Winnipeg is only about a 50 hour drive from Albany. smile.gif
We're practically neighbors, it's only 25 hours one-way wink.gif
post #454 of 541
Thread Starter 
Thanks Bill. Just skipped over to your thread, wish I had time to keep up with all these great builds.
I believe simply removing a few inches off the perimeter of the ceiling could work if my soffit was completely closed all around the room. The problem however is that I have 4 large openings in the soffit for hvac registers (not to mention multiple holes for recessed lighting). This would leave me with many straight-line openings between the inside of the room and the floor joists above. I suspect cutting the wall is still my best option. Any other feedback from anyone on my realistic/unrealistic expectations for sound isolation?
post #455 of 541
Is there space to patch the holes you have to cut? Like this:
post #456 of 541
Quote:
Originally Posted by HopefulFred View Post

Is there space to patch the holes you have to cut? Like this:
maybe a combination of both ideas then.
Quote:
Originally Posted by 235 View Post

Thanks Bill. Just skipped over to your thread, wish I had time to keep up with all these great builds.
I believe simply removing a few inches off the perimeter of the ceiling could work if my soffit was completely closed all around the room. The problem however is that I have 4 large openings in the soffit for hvac registers (not to mention multiple holes for recessed lighting). This would leave me with many straight-line openings between the inside of the room and the floor joists above. I suspect cutting the wall is still my best option. Any other feedback from anyone on my realistic/unrealistic expectations for sound isolation?
I know I actually used one of your soffit register designs for my cold air returns though slightly redesigned. According to Ted and John at sound proofing you want double layer of DW/GG/DW on soffits with ventilation in them anyway so it may be a win win.
post #457 of 541
Thread Starter 
Spaceman's suggestion to cut the ceiling had me change my focus away from the wall again. Given the ceiling is not springing back downward I think a tweak on HopefulFred's suggestion might work out:

Remove strip of ceiling drywall all around room.





Cut a smaller strip of OSB to keep stair-step overlap. No need to worry about cutting into wiring or ceiling not springing back.





Insert new pieces with drywall screwed into OSB on both ends to keep it in place.




I am really hopeful this will work but please burst my bubble now if you see potential problems. biggrin.gif
post #458 of 541
The only part I'm not seeing is how the joint gets secured in the corner. Maybe that won't matter?
post #459 of 541
Thread Starter 
Quote:
Originally Posted by HopefulFred View Post

The only part I'm not seeing is how the joint gets secured in the corner. Maybe that won't matter?

The ceiling OSB is supported in the corner by the existing drywall wall.
The ceiling drywall is fastened in the corner to the new piece of ceiling OSB.
Does that make sense?
post #460 of 541
Quote:
Originally Posted by 235 View Post

The ceiling OSB is supported in the corner by the existing drywall wall.
The ceiling drywall is fastened in the corner to the new piece of ceiling OSB.
Does that make sense?
I think you've forgotten the opposite direction; what keeps it from getting lifted when your subs pressurize the room?

Use at least some really good glue!
post #461 of 541
I don't share Nightlord's concern. You make sense, as long as you can cut the wall close enough for that to work.
post #462 of 541
Thread Starter 
I will be buttering up those ends with caulk before installing so that should help. I think this is the way I am going to proceed. I have been really reluctant to start ripping up my brand new 'carefully' constructed ceiling but I don't think I have any other option. The only lingering doubt is whether doing all this work will result in noticeably better isolation performance. I think it will but I wish I had a bit more feedback from those with similar construction on how well they can hear outside noise when standing inside a quiet theater room.
post #463 of 541
I'll throw this out there, not sure it will be of much help, but another point of comparison I suppose. I've been testing as my room progressed, and while I have checked since my soffits have gone up, I can tell you I'm seeing about 30 dB difference between the room above and my theater. I've been using Skrillex - Rock 'N Roll played at 92 dB in my living room as a test. If you're not familiar with Skrillex, think the sound your fax makes combined with bass. I measure around 62 dB at the front of my theater (under my living room) and 58 dB at my door which is further away from the sound source. A couple more points.

  • I have NOT installed my zero seals and I have changed how my door is mounted.
  • I've put a few more holes in my room for wiring and HVAC.
  • I have one layer of DW+GG on the back of the subfloor above, and I can hear people walking (and my dog snoring of all things). However, it's gone from CLACK-CLACK to more of a thump-thump.
  • When my wife is watching Glee upstairs, I can really only hear the bass. I usually don't know it's Glee until I open the door. However, I can clearly hear my 85 lb boxer snoring away (I need to measure it, but it's loud and very bass-y).

On the flip side, I don't remember specific measurements, but I know I've tested my isolation by running my compressor in my room and then gone to my son's room directly above the compressor.
  • In room = greater than 90 dB. Surprising how loud that thing is
  • In my son's room = IIRC it was down around 60 dB which is near the bottom of what my RatShack meter will measure. Again, mostly the bass rumble from the compressor making it through. Certainly not objectionable.

All that said, I was hoping for better performance. I can still hear that there are things going on in my house. Mostly foot fall, but also other noises. if someone yells for me at the top of the stairs I can usually tell someone is calling. Not really make out my name, just make out that someone has yelled something. Audible, but unintelligible. I can hear the baby cry, and people closing doors loudly. I'm not sure how much of that is due to my door not being finalized, but some of these noises seem to originate from the front of my room. I know 30 dB is a heck of a lot of attenuation, but I'm hoping to have reference bass in my room, so suddenly 30 dB is not all that great. Measurement before and after DW+GG+DW+clips+channel only showed 4-6 dB improvement. I was expecting more than that.

Sorry for the novel, but thought I'd add to the confusion smile.gif
post #464 of 541
Quote:
Originally Posted by J_P_A View Post

If you're not familiar with Skrillex, think the sound your fax makes combined with bass.

biggrin.gif Excellent description! biggrin.gif
post #465 of 541
Quote:
Originally Posted by J_P_A View Post

Measurement before and after DW+GG+DW+clips+channel only showed 4-6 dB improvement. I was expecting more than that.

That is certainly a bit surprising and disappointing. Very nice you have been doing measurements along the way but I definitely would have expected more.
post #466 of 541
Keep in mind that sound isolation is going to be frequency dependent. So that 4-6 dB is the worst case range of frequencies (lower frequencies). I'm saving final judgement for when I have the room finished.
post #467 of 541
I think that is a great plan but I would still do DW/GG/DW on the soffits! I agree maybe use some construction adhesive on the OSB to OSB/DW corner than acoustical caulk the room side of the corner for good measure.

Good luck. If you do not do it you will always be thinking in the back of your mind that it could have been better.
post #468 of 541
Thread Starter 
Hey J_P_A, I appreciate a good read so thanks for the novel. I'm familiar with Skrillex, it was one of the first sources I used to 'test' my new subs smile.gif a few months ago. I tried replicating your test with Rock 'N Roll peaking at 92 dB (c-weighted) from within the theater @ 1 meter away. I went above the room upstairs and my readings peaked at 67 dB. That would give me about 25 dB of isolation....not as good as your 30 dB but not that far off either. You're not helping me get off the fence wink.gif
Quote:
Originally Posted by J_P_A View Post

I can still hear that there are things going on in my house. Mostly foot fall, but also other noises. if someone yells for me at the top of the stairs I can usually tell someone is calling. Not really make out my name, just make out that someone has yelled something. Audible, but unintelligible. I can hear the baby cry, and people closing doors loudly.

I'm really interested in these points. I realize keeping a cranked up bass from completely escaping the room is next to impossible so I'm not shocked by what I have seen so far. I have been mostly surprised by the lack of keeping everyday noises from entering the room. The foot fall is quite clear and if someone yells down to the basement from the top of the stairs I can not only tell someone is calling but can make out what they said.
I also found some old bpape post that have me hopeful I can get significant improvement if I go ahead and decouple the ceiling. In this same thread someone says foot fall on hardwood above is "completely eliminated". Two of my main hardwood traffic lanes upstairs align almost perfectly with the coupled perimeter of my ceiling giving a very direct flanking path for the impact noise. Given the high amount of traffic and activity above my room I think I need to try this to see how it works out.
post #469 of 541
Thread Starter 
Quote:
Originally Posted by cw5billwade View Post

I think that is a great plan but I would still do DW/GG/DW on the soffits! I agree maybe use some construction adhesive on the OSB to OSB/DW corner than acoustical caulk the room side of the corner for good measure.

Good luck. If you do not do it you will always be thinking in the back of your mind that it could have been better.

Good point, will probably seal it that way. Although cutting this up will be very painful I think you're right.....I can live with less than perfect results as long as I know I did all I could.
post #470 of 541
Apologies if this has been suggested or done ... but before I started cutting I'd want to be very sure of the exact problem ... and I would have thought that more measurements are required. Have you tried holding your SPL meter about 1/2" from the ceiling, both in the center of the roof and near the wall and see how much the readings differ ?

Cheers,
post #471 of 541
You may also wish to consider renting one of these ...

tapping machine

to make sure you can do repeatable tests.

Cheers,
post #472 of 541
Thread Starter 
Thanks Pete, that would be another nice toy to have smile.gif
I can only see 1 major problem from the 4 pillars of sound isolation. I have 2 layers of 5/8" mass, pink insulation filling the cavities, GG between the layers, dual stud walls that I'm certain are not coupled. The only major problem I see is the ceiling hanging from the clips has been short-circuited all along its perimeter. I think it's time to do some major cutting.
post #473 of 541

My apologies for not reading the whole thread (it is voluminous, but some neat graphics along the way) so I apologize for not knowing some important details about your plan and construction techniques.  I do, however, understand your exact concern about the wall impacting the perimeter of the ceiling.  I also apologize if I'm stating what is intuitively obvious to you already.  No disrespect intended.  But I stumbled  upon you and your thread by our mutual observation of a dearth of real feedback about how various design and construction decisions worked out.  That being said, most reports would probably be subjective since most people probably don't have all the right equipment to make consistently comparable tests and measure the results.  (Well, maybe in this particular forum I'm not giving everyone enough credit).

 

By as a summary, I constructed my room with walls attached to the ceiling joists with IB3 clips and then traditional DW/GG/DW attached directly to the studs.  Single wall all around.  The ceiling was constructed with Whisper Clips and drywall furring channel in the typical fashion with some slightly different spacing density based on the the amount of "stuff" I planned to  hang off the finished ceiling.  A layer of 5/8 plywood was attached to the furring channel and then GG and a layer of 5/8" drywall. There is fluffy pink in all the wall stud cavities as well as all the ceiling joist cavities.  But no other preparation to the ceiling cavities was performed.

 

Perhaps of import is to note that the room above my theater is my kitchen.  The kitchen floor construction is plywood subfloor, roofing felt, 1.5" of concrete (in which there are hot water pipes embedded for a radiant floor), a layer of thinset, Schulter Ditra (decoupling membrane), another layer of thinset, and then my tiles.  The net result is a massive solid floor structure that sits right on the joists.

 

Footfall traffic from above is clearly appreciated in the theater.  Talking, music, running water, exhaust fan, blender noise, etc. is not audible to any significant extent.  

 

Based on my research prior to designing the project led me to the understanding that IMPACT noise is a very different animal from SOUNDWAVE (through the air) noise.  It seems to me that the construction techniques that we are using are pretty darn good at reducing SOUNDWAVE based noise but not so good at reducing IMPACT based noise.  From reading various build threads, it appears that the one thing that people do that does have an effect on reducing IMPACT noise may be the double layer of drywall with GG in between placed directly on the subfloor from below.  This was impractical for me because of the amount of stuff that was in my joist spaces already (water, HVAC, electrical, drain, etc.) so I skipped that part.  My bad.  

 

In the other direction, the construction technique I implemented is quite good at reducing, if not eliminating, most of the higher frequency sound escaping the theater INTO the kitchen.  But when cranked, the LFE still causes stuff to physically shake up in the kitchen.  From what I read, it is next to impossible to really contain this sort of energy transfer with the type of residential construction we are usually starting with.  

 

I'm not sure if this has anything to do with the whole room impedance deal, but I was surprised at how easy it was to tune my subwoofers to a pretty flat response.  It could be due to good design of the subwoofers, the configuration of the walls/ceilings in my room, the construction details of the walls/ceilings (that whole impedance thing), or just dumb luck.  I am left with a null in my crossover region (80-110 Hz) which is very annoying and must be caused by a room mode.  No amount of EQ has been able to touch that so far.  I'm going to have to figure out what variables I can modify in my room to help improve that.  It's unfortunate that my room mode happens to cause a null at the crossover frequency which apparently frequently has decrease output as a baseline!  Changing crossover frequencies didn't seem to help much either.  

 

If I were insistent upon doing SOMETHING, what I would do in your situation is what I think you're preparing to do.  Cut out the outermost few inches of the ceiling and then chisel out the hard connection between the top of the all and the ceiling joist.  If the top of the wall abuts the drywall of the ceiling, then you just need to chisel out the drywall.  Not too hard to do.  Easier than chiseling wood, for sure.  That would re-decouple the wall from the ceiling joist.  Personally, I would just leave the gap open since you are planning on putting a soffit around the perimeter of the room anyways.  The construction of the soffit can be done in such a way as to maintain essentially the same level of soundproofing that your current construction technique affords.  I would however, stuff as much pink fluffy stuff in the soffit as you can.  And then caulk all penetrations as best you can.  I don't believe that this modification would alter the end result very much.  Impact noise coming in is still probably going to be a problem and LFE noise getting out is still going to occur.  These are suppositions on my part.  If one of our professional theater designers/constructors refutes any of my assumptions or conclusions, I'd defer to them.  But I think these are reasonable conclusions based on reconciling what I've read (here and other places) along with my experiences with my own construction.

 

Good luck!

post #474 of 541
Thread Starter 
Thanks Rosso, I had abandoned my thread for a while after hitting this low point. I appreciate your feedback, it has helped set my expectations for this next stage.
post #475 of 541
Thread Starter 
....and now in the interest of not being loganed, here are some updated pics.

Cut away ceiling along perimeter wall. I also cut the drywall further back than shown in this pic to allow for offset seams.

DSCF2535_zpsd0ec7be3.jpg



Cutting through drywall with a circular saw creates a huge cloud of dust (good mask is important here biggrin.gif)

DSCF2538_zpscdbf0b52.jpg



Replace both layers...

DSCF2755_zps82294de2.jpg



Finished product....Now in a position for some forward progress tongue.gif

DSCF2788_zps652297ef.jpg
post #476 of 541
Thread Starter 
I am currently building my soffits and have sent bpape a question about opening up my soffits for some bass trapping. I may have to proceed before I get his response so maybe I could get some feedback here as well. I have 12' sections of my soffits on both sides of the room that will be covered in fabric. The side (ie vertical piece) of these soffits is already installed with 3/4" MDF. I have the choice of covering the bottom of the soffit with 3/4" MDF or simply covering the insulation with fabric for some additional absorption. The insulation (pink or OC703??) would be 7 3/4" high by 12" wide and 12' in length. Any thoughts? Thx.

OpenSoffit_zpsdd8e92bb.jpg
post #477 of 541
Quote:
Originally Posted by 235 View Post

...Now in a position for some forward progress
Sincerely - Congratulations! I know this has been eating at you. I'm glad to see you won't let it beat you. Also - I'm looking forward to seeing how you finish everything here. smile.gif

On the soffits... Have you seen this? http://www.avsforum.com/t/1443066/oc703-on-bottom-of-soffits and the reason that thread got posted: http://www.avsforum.com/t/255432/acoustical-treatments-master-thread#post_2176723
post #478 of 541
Thread Starter 
Thanks Fred, I looked at some of the posts you linked to and my best guess is that some oc703 in the soffits would be beneficial but maybe with some poly facing...
Edited by 235 - 1/22/14 at 7:29am
post #479 of 541
That was my conclusion as well.
post #480 of 541
Glad to see you back in the game here 235. I'm sure that was no fun to deal with, but glad you're past it. Best of luck with the rest of your build!
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