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post #571 of 682 Old 08-25-2014, 06:19 PM
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Soundproofing emergency!!

My drywall guy put up drywall without insulation!

In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG.

I am concerned about losing this line of defense...AND I already have the insulation!

Should I tear out the drywall? He didn't put in that much of the wall.
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post #572 of 682 Old 08-25-2014, 08:13 PM
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So if one had to choose between only doing sound proofing or only doing acoustic treatments, which would be the most beneficial?
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post #573 of 682 Old 08-25-2014, 09:30 PM - Thread Starter
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Quote:
Originally Posted by thestoneman View Post
My drywall guy put up drywall without insulation!

In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG.

I am concerned about losing this line of defense...AND I already have the insulation!

Should I tear out the drywall? He didn't put in that much of the wall.
Insulation adds a couple more points to the STL rating. Whether or not they are needed depends entirely on what kind of soundproofing you require. If your requirements matched a score that required the insulation then yes, absolutely pull the drywall and install it. If your requirements do not need it... then I'd just let it be.

FWIW, the decoupling, mass, and damping make a much bigger impact than the absorption that drywall supplies (although decoupling does work somewhat better with insulation due to its effect of "widening" the gap, air flow wise).
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post #574 of 682 Old 08-25-2014, 09:37 PM - Thread Starter
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Quote:
Originally Posted by ChldsPlay View Post
So if one had to choose between only doing sound proofing or only doing acoustic treatments, which would be the most beneficial?
In general, acoustic treatments will always win out, since quite a few people do have treated theaters without a lick of soundproofing and are happy with the results.

Your mileage my vary, though! The entire point of soundproofing is to simultaneously lower the noise floor in the theater and to keep the noise from the theater from bothering others. If your normal environment is noisy, then you may find yourself having to raise the volume of your movies to an uncomfortable degree to hear everything. No acoustic treatments will help at that point. Likewise, if you find that you have to keep the volume lower than you'd prefer because of disruptions with neighbors/kids/others than acoustic treatments won't help there, either.

But if you live out in the boonies where there is no real ambient noise and no amount of noise that you make will matter and you don't have kids, then soundproofing would be somewhat pointless.

Personally, I don't see it as an either/or case. The soundproofing gets my theater's sound floor low enough that I can choose what volume I'm comfortable with and still hear even the quietest scenes, while acoustic treatments will ensure that the sound is delivered as it is intended (also helping to keep one volume level for the entire dynamic range of the movie).
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post #575 of 682 Old 08-25-2014, 10:46 PM
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Quick question. Between 2 layers of drywall and roxul sound insulation, which helps block high frequencies and which blocks low ones?
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post #576 of 682 Old 08-25-2014, 11:12 PM
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Quote:
Originally Posted by granroth View Post
Insulation adds a couple more points to the STL rating.

The insulation in the wall acts as damping, increasing the resonance frequency's transmission loss.


It shifts the mass-spring-mass system to a lower resonance frequency
It dampens sound waves transmitted through the wall
It dampens lateral standing sound waves in the cavity of the wall.


Note: overfilling with rockwool (aka stonewool) reduces STC. Overfilled defined as fully filled and then stuffing in 10% more.


Here's an interesting tidbit:


Quote:
In a speaker cabinet adding damping gives a virtual 1.2 (20%) volume increase.
Easy measurable in an impedance graph.

Modes etc are effectively suppressed, especially as you can easily put damping material in the velocity max of the standing wave.

OK,
Best results are when you loosely fill the cavity and when you clad the walls of the box with foam or 703 like stuff.
When you have a standing wave you put a (double) piece of foam (PUR-foam, melamine) in the velocity max.
Stuffing to much to dense absorption in the box will effectively make the box smaller.
You see the resonance shift upwards.
With walls I always learned to use a 60 % filling of loosely stuff, but I don't did research on this myself.
The stuffing will influence air stiffness causing lower fs and suppress modes storing energy.

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post #577 of 682 Old 08-25-2014, 11:21 PM
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Quote:
Originally Posted by plissken99 View Post
Quick question. Between 2 layers of drywall and roxul sound insulation, which helps block high frequencies and which blocks low ones?
Absorbers cause transmission loss on the order of 0.5 of energy
Walls cause transmission loss on the order of 10,000,000 of energy (70 dB).
Thus absorbers make lousy STC devices by themselves, whereas even a single layer of drywall has an easily perceptible sound transmission loss.


Drywall/stone reflect sound, particularly high frequency.
Wool absorbs sound, particularly high frequency.
Thus if you're trying to get rid reflected sound within the room, drywall would be a poor choice, and wool (glasswool/fiberglass, stonewool/rockwool, open cell foam) would be a good choice.




If you mean instead of individual components, the wall system of {drywall, insulation, drywall}, then the drywall stops most of the high frequency transmission of sound energy through the wall, and the three of them {drywall, insulation, drywall} are a system that together reduces low frequency transmission through the wall.

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post #578 of 682 Old 08-26-2014, 12:00 AM
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Right I was speaking in terms of keeping sound from bugging the rest of the house. Sounds indeed like all the above is a good idea.
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post #579 of 682 Old 08-26-2014, 05:25 AM
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Quote:
Originally Posted by thestoneman View Post
My drywall guy put up drywall without insulation!

In his defense, the wall is not a foundation/exterior wall. It is decoupled and will have DD/GG.

I am concerned about losing this line of defense...AND I already have the insulation!

Should I tear out the drywall? He didn't put in that much of the wall.
earlyer in this thread there were some good charts. I know that based on the charts you want to rip it out and put R13 in both of thoes walls. If sound containment is what you want then you need to do it. Even if both walls have DW/GG/DW you are loseing a lot of the dampening

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post #580 of 682 Old 08-26-2014, 06:50 AM
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Quote:
Originally Posted by cw5billwade View Post
earlyer in this thread there were some good charts. I know that based on the charts you want to rip it out and put R13 in both of thoes walls. If sound containment is what you want then you need to do it. Even if both walls have DW/GG/DW you are loseing a lot of the dampening
I want as much sound containment as possible, but it's not critical. Considering I just have to rip out a bit of drywall, I am going to do it right. Otherwise, I will have done all the other sound abatement procedures for naught.

Thanks for the feedback everyone.

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post #581 of 682 Old 08-26-2014, 08:25 AM
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Quote:
Originally Posted by granroth View Post
In general, acoustic treatments will always win out, since quite a few people do have treated theaters without a lick of soundproofing and are happy with the results.

Your mileage my vary, though! The entire point of soundproofing is to simultaneously lower the noise floor in the theater and to keep the noise from the theater from bothering others. If your normal environment is noisy, then you may find yourself having to raise the volume of your movies to an uncomfortable degree to hear everything. No acoustic treatments will help at that point. Likewise, if you find that you have to keep the volume lower than you'd prefer because of disruptions with neighbors/kids/others than acoustic treatments won't help there, either.

But if you live out in the boonies where there is no real ambient noise and no amount of noise that you make will matter and you don't have kids, then soundproofing would be somewhat pointless.

Personally, I don't see it as an either/or case. The soundproofing gets my theater's sound floor low enough that I can choose what volume I'm comfortable with and still hear even the quietest scenes, while acoustic treatments will ensure that the sound is delivered as it is intended (also helping to keep one volume level for the entire dynamic range of the movie).
Well, I'm not really worried about the neighbors, or anyone else in the house. I'm more concerned about the sound coming into the room. The primary concerns would be people running around upstairs and the HVAC system in the next room when it kicks on. How effective can sound isolation be if you just attack the ceiling and the wall leading to that adjoining room (The other walls are along the foundation)?

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post #582 of 682 Old 08-26-2014, 08:46 AM
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sound has a tendency to go around things it is called flanking so if you were not going to do the walls on the concret the sound will just go around all your efferts on the ceiling and the other wall. If your plan is to stud and DW the concret walls then just decouple them with some IB-3 clips add R13 and do the DW/GG/DW. 5/8" fire proof not 1/2" light weight.
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post #583 of 682 Old 08-26-2014, 11:54 AM
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Here's a topic I've seen very little discussion on in this thread. I'll copy granroth's asking format from early in the thread.


Question: How efficient is the transfer of sound energy between a slab of concrete and the air? Are there recommended soundproofing treatments for a concrete floor?


Obviously concrete transfers mechanical vibrations very well. So if you have an air compressor running over on one side of the basement, that sound will easily carry through the floor into your theater room. But does that transfer still happen efficiently if the source of the noise is airborne? (I'm assuming that there are no speakers resting on the floor to supply mechanical vibration.) Asked another way, does sound inside your theater flank around your isolated walls through an untreated concrete slab to the rest of the house? If so, what treatments have been evaluated to lessen this effect?

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post #584 of 682 Old 08-26-2014, 12:56 PM
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Quote:
Originally Posted by pitviper33 View Post
Question: How efficient is the transfer of sound energy between a slab of concrete and the air? Are there recommended soundproofing treatments for a concrete floor?
Some people cut the concrete slab to decouple it. (possibly with a Concrete K Saw)
As for if that's Building Code approved in your area (e.g. water table concern), or if you'd caulk the joint with acoustic caulk or silicone, I don't know.


You can cut around the furnace, or you can cut around the theatre. Generally, cutting around the theatre is preferred for both ways (into and from the theatre). And many central air conditioner's have drains that go through the slab somewhere near the furnace.


I don't have any stats on the effectiveness. There is still some flanking transmission through the earth under the slab, but that's less.


Sometimes the transmission through whatever is under the slab is strange. I'm thinking of an example where the theatre sound couldn't be heard in the house next door, but it could be heard the house the other side of it, because the bedrock curved touching the two houses where the noise was generated and heard, but dipped under the house in the middle.




Other possibilities include
a) building a floating floor. Another concrete pad raised on pucks or springs, or (not both),
b) covering the home theatre floor in acoustic-mat (a kind of heavy rubber pad).
c) and of course ignoring it.


In the case of (a) and (b), the stud walls would be built on top of the floating floor or on top of the acoustic mat respectively. In the case of acoustic mat, bolts from the wall base plate through the mat to the concrete slab would also be isolated with rubber and washers.

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post #585 of 682 Old 08-26-2014, 01:58 PM
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The odd sound transmission through the earth is interesting. In the scenario you mention, I wonder how the homeowner receiving the noise ever figured out its source.
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Other possibilities include
a) building a floating floor. Another concrete pad raised on pucks or springs, or (not both),
b) covering the home theatre floor in acoustic-mat (a kind of heavy rubber pad).
c) and of course ignoring it.


In the case of (a) and (b), the stud walls would be built on top of the floating floor or on top of the acoustic mat respectively. In the case of acoustic mat, bolts from the wall base plate through the mat to the concrete slab would also be isolated with rubber and washers.
In my particular case, I intend to build a floating floor within the theater anyway. I plan to do this for the sake of tactile response, which was sorely missing from my last basement theater. For that purpose an OSB subfloor on a 2x4 frame resting on foam isolators should be sufficient. (That's my thought. I'm open to suggestions.) My question was mainly wondering whether I also needed a floating floor in my infinite baffle subwoofer's backspace for the sake of noise isolation. I already intended to have that backspace within my double walled space. I had been thinking that I would have the floating floor within the interior walls. Would it be better to build the floating floor all the way out to the outer walls and rest the interior walls on it?

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post #586 of 682 Old 08-26-2014, 02:49 PM
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Originally Posted by pitviper33 View Post
In my particular case, I intend to build a floating floor within the theater anyway. I plan to do this for the sake of tactile response, which was sorely missing from my last basement theater. For that purpose an OSB subfloor on a 2x4 frame resting on foam isolators should be sufficient. (That's my thought. I'm open to suggestions.) My question was mainly wondering whether I also needed a floating floor in my infinite baffle subwoofer's backspace for the sake of noise isolation. I already intended to have that backspace within my double walled space. I had been thinking that I would have the floating floor within the interior walls. Would it be better to build the floating floor all the way out to the outer walls and rest the interior walls on it?

Time for a diagram, or three. Ball's in your court.


Short answer to your last question -- probably. My first concern is: Depends on how thick sound path through the floated floor to the furnace room is. If the 'thickness' consists of a single layer of OSB that can be seen from the furnace if you put a mirror on the concrete slab beside a 'foam isolator', whereas your walls were going to be double stud walls with double layer's of 5/8" drywall with green glue, then nope.


BTW, pucks and springs are engineered (I think there's an exception that comes in sheets with the pucks amongst fiberglass, but usually they're engineered). The companies that manufacture them will ask you all the right questions, hand it off to their engineer to do the math, who will tell you how many and what type to buy and give instructions on how to install them.
This differs from e.g. floating the floor on rigid rockwool or acoustic-mat.

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post #587 of 682 Old 08-26-2014, 03:08 PM
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The numbers below are not representative of any particular room in existence -- so don't go thinking ALL slabs are 30dB, when few of them would be.
The diagram is presented only as an example of dB addition (adding several dB values), and the idea of flanking -- at least how I think of both concepts.
(The gif was first created back around 2004 I think. Old stuff.)
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post #588 of 682 Old 08-26-2014, 07:14 PM
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Rereading my last post... it didn't make much sense. I did a poor job of describing my space.


I will have a medium sized theater space (about 17'x30'x9.5') on a concrete floor. That entire space will be soundproofed. The ceiling with clips and channels, some of the walls double stud and some of the walls single stud spaced from concrete block foundation walls. All of it with double drywall and green glue. Within that soundproofed space, the room is divided into three sections. Those are an equipment/projection room at the back, the main theater space, and space behind the baffle wall at the front. The dividing walls between the three sections are single stud, single layer of drywall. The main theater space will have some kind of floating floor. The question is whether the space in front of the baffle wall and the equipment room also need some treatment on the floor. They are still on the "noisy side" of the soundproofed walls, though the high frequency content will be somewhat attenuated by the dividing walls within the space. The low frequency content will be at full intensity in these areas.


The image you posted is helpful. Though the numbers aren't real, it at least suggests that once soundproofing techniques are applied to the walls and ceiling, a concrete floor might have the potential to become the weakest link for noise getting in or out.


As for how exactly I'll float the floor, I've been struggling to find much information on how that should be done for even tactile response. Maybe it's just a matter of using the wrong search terms. If you could point me in the direction of some information on the subject, or even just name one of these puck and spring companies, it would be much appreciated.

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post #589 of 682 Old 08-26-2014, 08:26 PM
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Quote:
Originally Posted by pitviper33 View Post
I will have a medium sized theater space (about 17'x30'x9.5') on a concrete floor. That entire space will be soundproofed. The ceiling with clips and channels, some of the walls double stud and some of the walls single stud spaced from concrete block foundation walls. All of it with double drywall and green glue. Within that soundproofed space, the room is divided into three sections. Those are an equipment/projection room at the back, the main theater space, and space behind the baffle wall at the front. The dividing walls between the three sections are single stud, single layer of drywall. The main theater space will have some kind of floating floor. The question is whether the space in front of the baffle wall and the equipment room also need some treatment on the floor. They are still on the "noisy side" of the soundproofed walls, though the high frequency content will be somewhat attenuated by the dividing walls within the space. The low frequency content will be at full intensity in these areas.

I take that to mean something like this



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post #590 of 682 Old 08-26-2014, 09:00 PM
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Originally Posted by pitviper33 View Post
As for how exactly I'll float the floor, I've been struggling to find much information on how that should be done for even tactile response. Maybe it's just a matter of using the wrong search terms. If you could point me in the direction of some information on the subject, or even just name one of these puck and spring companies, it would be much appreciated.


Prior post I mentioned Acoustik-mat as an isolator.
People used to put rigid rockwool under floating floors. It lasts quite a while.

http://www.auralex.com/sound_isolati...tion_uboat.asp
http://audioundone.com/studio-floors


Kinetics RIM pucks and springs
http://www.kineticsnoise.com/arch/pdf/rim.pdf
http://www.kineticsnoise.com/hvac/fds.html
http://www.kineticsnoise.com/arch/lsm.html
http://www.bobgolds.com/HomeTheatreD...b03Room2bb.JPG
http://www.kineticsnoise.com/products.html
http://www.gearslutz.com/board/attac...floors-rim.jpg


"Neoprene" and ethylene propylene diene monomer (EPDM) pucks.
from http://www.earsc.com/HOME/engineerin...dex.asp?SID=61


And possibly the most important
http://www.johnlsayers.com/phpBB2/vi...t=8173&start=0


There might be something here at AVS about floating floors too. Certainly more relevant to our darn subwoofers.

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post #591 of 682 Old 08-27-2014, 03:45 AM
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I take that to mean something like this
Yeah, exactly. Nice job on the diagram! The only difference between what you drew and what I had in mind is the connection you questioned, between the baffle walls and the ceiling. My thought was for those walls to not penetrate the soundproofed space by going through the drywall. They would be free standing walls, tied into studs on the sides and resting on the concrete floor, stopping at the ceiling drywall. I thought I'd replace the top layer of drywall with OSB in the ceiling in that area, and I'd screw them in. But those connections wouldn't take any vertical load. They'd just add some stiffness to the wall if somebody decided to lean on it or something. If I instead move the base of those walls up to on top of the floor treatment as you've suggested, I'll have to think about how that affects their stiffness compared to being on the concrete as I'd expected.


I'll review the links in your second post. Thanks a lot!

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post #592 of 682 Old 08-27-2014, 05:40 AM
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I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.
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post #593 of 682 Old 08-27-2014, 07:30 AM
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Quote:
Originally Posted by pitviper33 View Post
I'll review the links in your second post. Thanks a lot!

re Floating Floors:
a) Beware resonance, where sound actually gets louder through the floor. If you're using pucks or springs, then you need a floating concrete slab above them because you need a resonance under 10 hz or so, and a wood deck just isn't going to get you there.
b) by the time you decide to float a floor, it's time to stop asking questions on an internet forum and hire an expert to design the space for you. Otherwise, odds are good you'll design something else that will negate the benefit of a floating floor.


Personally I might google through AVS for Dennis Erskine talking about Acoustik-mat and I might try that the way I drew it, but I'd up the weight by using 2 layers of MDF sandwiching a layer of drywall on the floor instead of 2 layers of OSB, with green glue once. Dennis, alone, seems really fond of Acoustik-mat for certain applications like isolating subwoofer stages filled with sand. I'd want to do the math, and maybe an accelerometer experiment, to figure out what the resonance would be -- neither of which I know how to do right this moment. But by the time you're up to springs and pads, it's time to wander over to real pro's (not your local contractor, and not me) to design the entire shell for you.


If you haven't already, consider picking up a copy of "Home Recording Studio, Build it like the Pros" by Rod Gervais. Pg 44 through 46 in the first edition talk a bit about floating floors, including the 'probably not' suggestion, and there's lots more useful information in that book too.

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Last edited by BasementBob; 08-27-2014 at 08:01 AM.
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post #594 of 682 Old 08-27-2014, 07:43 AM
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Originally Posted by pitviper33 View Post
Yeah, exactly. Nice job on the diagram! The only difference between what you drew and what I had in mind is the connection you questioned, between the baffle walls and the ceiling. My thought was for those walls to not penetrate the soundproofed space by going through the drywall. They would be free standing walls, tied into studs on the sides and resting on the concrete floor, stopping at the ceiling drywall. I thought I'd replace the top layer of drywall with OSB in the ceiling in that area, and I'd screw them in. But those connections wouldn't take any vertical load. They'd just add some stiffness to the wall if somebody decided to lean on it or something. If I instead move the base of those walls up to on top of the floor treatment as you've suggested, I'll have to think about how that affects their stiffness compared to being on the concrete as I'd expected.

For your middle walls, since what you're trying to do basically is building an I-beam, just an idea, perhaps skip the OSB up there and instead replace the top plate with a horizontally mounted 2x12 LVL. Set the height so that the first layer of drywall butts against the low side of the LVL, and the 2nd layer of ceiling drywall goes under it and screws into it.. Another alternative is to use a 2x4 top plate, with a steel I-beam bolted to the top of it, and a 2x4 bolted to the top of that, which would be plenty stiff.

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Last edited by BasementBob; 08-27-2014 at 07:49 AM.
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post #595 of 682 Old 08-27-2014, 08:01 AM
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I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.

Yes, definitely ask people who've done it before.
I see at Stockmonkey's thread, page 9, that he used Delta-FL and Subfloor, between walls mounted on the slab. That's probably great for a basement (moisture, warmth, usual basement issues), which might be the primary and dominant consideration. But from a resonance point of view, I don't know.

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post #596 of 682 Old 08-27-2014, 08:10 AM
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I think Mario and Stockmonkey did what you are asking in their builds. Stockmonkey also had a frount IB chamber like you want check out his build and ask questions there.
On your suggestion, I just found both of their builds. Thanks for pointing me to them.
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re Floating Floors:
a) Beware resonance, where sound actually gets louder through the floor. If you're using pucks or springs, then you need a floating concrete slab above them because you need a resonance under 10 hz or so, and a wood deck just isn't going to get you there.
b) by the time you decide to float a floor, it's time to stop asking questions on an internet forum and hire an expert to design the space for you. Otherwise, odds are good you'll design something else that will negate the benefit of a floating floor.
Actually, after reading through the johnsayers thread you pointed me to before, I'm a little more comfortable with the idea that flanking through the concrete floor isn't a big deal. The book you recommend is quoted in the first post saying as much. That pretty much answers the question that I came here to ask.


This is good news for me, in that my floating floor design can focus entirely on what was its primary purpose all along: tactile response. It can be built completely within the soundproofed space and only where seating is located, so it doesn't need to affect my soundproofing plan at all. The bad news for me is that there's even less information out there about this goal than there is about soundproofing (or not) a concrete slab. This thread isn't the place for that topic, so I can take that discussion elsewhere.

I'm not into "thumbs upping" or "liking". Don't take it personally. Just assume that I found your post helpful. Unless it wasn't.
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post #597 of 682 Old 08-27-2014, 10:00 AM
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Actually, after reading through the johnsayers thread you pointed me to before, I'm a little more comfortable with the idea that flanking through the concrete floor isn't a big deal. The book you recommend is quoted in the first post saying as much.
Sounds good to me. (i.e. I'm comfy you've made a good decision)

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post #598 of 682 Old 08-28-2014, 07:11 AM
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So what is my best bet for mitigating sound from the adjacent utility room and sounds from upstairs without doing full isolation? What "little" can I do to get the most results?
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post #599 of 682 Old 09-01-2014, 11:04 AM
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I've already posted this in my theater thread, but decided to repost the question here so I can get a broader expert opinion on this soundproofing issue.

I'm about to build my screenwall. Since the stage is essentially sitting free from the walls to isolate any sound transmission, should I also decouple it from the ceiling when I build the screen wall? I would think the answer is yes, but I don't think I've seen any build on here that has done that. Everyone seems to just run posts from the stage floor straight up to the ceiling with no decoupling brackets. I would imagine there would be some transmittal of sound, especially low frequencies, into the ceiling this way, but maybe it is negligible?
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post #600 of 682 Old 09-01-2014, 11:29 PM
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I've already posted this in my theater thread, but decided to repost the question here so I can get a broader expert opinion on this soundproofing issue.

I'm about to build my screenwall. Since the stage is essentially sitting free from the walls to isolate any sound transmission, should I also decouple it from the ceiling when I build the screen wall? I would think the answer is yes, but I don't think I've seen any build on here that has done that. Everyone seems to just run posts from the stage floor straight up to the ceiling with no decoupling brackets. I would imagine there would be some transmittal of sound, especially low frequencies, into the ceiling this way, but maybe it is negligible?
If the stage is decoupled, I'd prefer to run the posts clear in front of it if possible. If not possible I'd try to decouple at the top.

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