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post #991 of 3269 Old 03-23-2015, 11:56 PM
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Originally Posted by granroth View Post

3/4" MDF? That's give-or-take equivalent -- the double drywall case still has the edge, but I don't imagine it would be noticeable. 1/2" MDF is notably less dense.

MDF is a curious material to use on walls and ceilings. Is this for a soffit or similar?
I will not have soffit or something similar.

this is for my false ceiling actually, "MDF 0.5" + GG + Drywall 5/8"

i was planning to have 3/4" MDF, but it looks pretty hard to deal with in the ceiling. so we went with MDF 0.5" since we have around 25 sheets extra which we could use in my HT.

Do you think i would get similar results compared to DD? or at least closer to DD approach?
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post #992 of 3269 Old 03-24-2015, 01:16 AM
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Smile LF: Staggered Studs

Has anyone here tried installing Staggered Studs? Share link of build please
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post #993 of 3269 Old 03-24-2015, 04:51 AM
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Originally Posted by marlon1925 View Post
Has anyone here tried installing Staggered Studs? Share link of build please
http://www.soundproofingcompany.com/...-construction/

Don't know of any project threads, but there's definitely an effect. Though the effect is lessened by the fact that the studs still transmit vibrations at both ends into the wall, which transmits it to the other wall, even though both sides of the wall have their own studs. If there is a rubber mat between the end of each stud and the bottom and top, then the effect is much greater. Same goes if you add rubber to space the material you lay on the wall from the studs (this can lose some db over simply making a really strong wall, but its much quieter). There's also a greater effect if the space between each stud is halved over the example shown in the link, but this means the wall has to be pretty much twice as thick in order to fit any meaningful amount of rockwool/glasswool.


EDIT: Here's a list of all-wood types and their performances:
http://workshopcompanion.com/KnowHow...d_Strength.htm
It would be wonderful if we could fill in the prices per cubic foot or cubic meter of these things, then we could make a list of price/performance ratio of all the wood types, next to HDP and MDF and drywall etc. performance being how little noise they let through. How much is let through is decided by weight and specific hardness, and a tiny bit because of the bending strength. Specific hardness and weight is good for when db is to be contained (that's why DB drag cars are made from concrete), soft material with high weight is good for when you just care about the db escaping, but don't really care about maintaining high db, since some sound will get absorbed by the soft material.
PS: Don't know how accurate these numbers are, could be taken out of the air.
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post #994 of 3269 Old 03-24-2015, 11:17 PM - Thread Starter
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Originally Posted by hendry98 View Post
I will not have soffit or something similar.

this is for my false ceiling actually, "MDF 0.5" + GG + Drywall 5/8"

i was planning to have 3/4" MDF, but it looks pretty hard to deal with in the ceiling. so we went with MDF 0.5" since we have around 25 sheets extra which we could use in my HT.

Do you think i would get similar results compared to DD? or at least closer to DD approach?
I actually measured some samples of sheet goods in this post: Thoughts on Mass. Extrapolating on those numbers, I'd guess that 1/2" MDF might have a density of about 1.7 lbs/sq ft. MDF is very slightly less dense than drywall, so your ceiling would be the rough equivalent to a 1/2" Drywall + 5/8" Drywall.

No, it won't give you the same performance. Mass does play a big role in soundproofing and having less has a direct impact on the abilities of the partition.

BUT!! Maybe it won't matter to you. Do you have a specific soundproofing goal that you are trying to hit? If you don't, then maybe you would be happy with a lessened solution, if only because you don't know what a more robust solution would sound like. Having a ceiling like yours absolutely will make a meaningful difference compared to not treating the ceiling at all. It may well be enough.

Just don't fall into the trap of thinking "I want to be able to play movies at reference level and not hear one peep out of it if I'm standing just outside the room." That ain't happening with your room. Think "I want to play movies pretty loud in my theater and have it not be quite so loud in the rest of the house" and yeah, you'll absolutely do that!
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post #995 of 3269 Old 03-24-2015, 11:27 PM - Thread Starter
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Originally Posted by marlon1925 View Post
Has anyone here tried installing Staggered Studs? Share link of build please
If anybody does find one, then let me know since I haven't found any. As I mentioned in the "links" section of this thread, it seems that most people that have the space for staggered studs will go with a double wall and those that don't have the space go with clips and channel. Staggered studs is often the odd man out.

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Originally Posted by ronny31 View Post
http://www.soundproofingcompany.com/...-construction/
Don't know of any project threads, but there's definitely an effect. Though the effect is lessened by the fact that the studs still transmit vibrations at both ends into the wall, which transmits it to the other wall, even though both sides of the wall have their own studs. If there is a rubber mat between the end of each stud and the bottom and top, then the effect is much greater. Same goes if you add rubber to space the material you lay on the wall from the studs (this can lose some db over simply making a really strong wall, but its much quieter). There's also a greater effect if the space between each stud is halved over the example shown in the link, but this means the wall has to be pretty much twice as thick in order to fit any meaningful amount of rockwool/glasswool.
Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!

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Originally Posted by ronny31 View Post
EDIT: Here's a list of all-wood types and their performances:
http://workshopcompanion.com/KnowHow...d_Strength.htm
It would be wonderful if we could fill in the prices per cubic foot or cubic meter of these things, then we could make a list of price/performance ratio of all the wood types, next to HDP and MDF and drywall etc. performance being how little noise they let through. How much is let through is decided by weight and specific hardness, and a tiny bit because of the bending strength. Specific hardness and weight is good for when db is to be contained (that's why DB drag cars are made from concrete), soft material with high weight is good for when you just care about the db escaping, but don't really care about maintaining high db, since some sound will get absorbed by the soft material.
PS: Don't know how accurate these numbers are, could be taken out of the air.
Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.
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post #996 of 3269 Old 03-25-2015, 04:03 AM
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Quote:
Originally Posted by granroth View Post
Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!
Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12" Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure.
Precisely how much effect there is, you'd have to dig up, I haven't found much. The effect is higher the more one face of the rubber can move in relation to the other side, so thick stubby bits is better than thin mats, tons of soft stubby bits is better than a few hard rubber bits, and so on. Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between. We can't have vacuums unless at great cost so in our realistic version we'd have air between the layers, and also rubber bricks spaced out so that the weight of the room doesn't just squash the ones under the floor until the inside floor essentially transmits all its vibrations to the outside floor. This is achieved by having the weight of the roof taken by the outside roof through rubber bricks or elastic bands, the wall being held above the floor by the rubber in the wall, the floor being held by the bricks under the floor. Then you'd want to limit weight you put on that floor to maximize effect. The stronger the inside wall in this scenario is, the more db is contained in the desired location, and the more effective the acoustic separation and sound absorbing effect of the inside and outside wall, the more db is lost but not released into the next room.

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Originally Posted by granroth View Post
Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.
"Specific gravity — the weight of a volume of wood divided by the weight of the same volume of water."
Hardness reflects sound, keeping it in the theater, soft stuff absorbs sound, losing db but not adding echo. Basic DB drag 101 in acoustic physics. You want as much hardness as you possibly can, then for sound quality you want to add just enough absorbing surfaces for each of the frequencies. Adding more absorbing surfaces beyond that point essentially makes the theater into an open area with no walls, making it incredibly difficult to fill with sound.

Last edited by ronny31; 03-25-2015 at 04:07 AM.
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post #997 of 3269 Old 03-25-2015, 04:53 AM
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I'm in the process of designing a new home and have yet to start talking to the architect about sound proofing a room for home theatre use. My question is, if starting with a new build, what is the optimal way to sound proof walls and ceiling (will be single story residence)? Is a double stud wall with a floating ceiling what I should be aiming for?
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post #998 of 3269 Old 03-25-2015, 06:51 AM
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need more information like is the theater going to be on first floor 2nd floor or basement. A Room in a room is the best aproach if done properly.
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post #999 of 3269 Old 03-25-2015, 09:12 AM
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Originally Posted by Scott27 View Post
I'm in the process of designing a new home and have yet to start talking to the architect about sound proofing a room for home theatre use. My question is, if starting with a new build, what is the optimal way to sound proof walls and ceiling (will be single story residence)? Is a double stud wall with a floating ceiling what I should be aiming for?
Have a chat with a guy who specifically designs sound-proof rooms. An architect isn't the right man for that bit of the job. I'd wager it involves some concrete walls and perhaps even concrete roof and then an appropriate amount of sound-absorbing material to avoid the sound bouncing around too much. Check with the architect whether what the sound-guy comes up with is up to code.

PS: as with most gardens in suburbia, don't have one if you possibly can. Fill it with house or at least make the house such that you can eventually fill the whole property with one building as much as possible (so you can build more house onto the house without the roof going the wrong way). When have you ever driven through a suburb and seen someone out in the front yard just having a BBQ or something? People have an innate resistance to being out in a front-yard because its so open towards people they don't really know. Better to have inside area, even inside gardens, or at least a backyard of reasonable size. But a backyard is either too cold or too warm, too dry or too wet, since no AC. 900 hours nouveau architecture course completed, congratulations.

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post #1000 of 3269 Old 03-25-2015, 09:33 AM
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Hi All:
I'm planing to add a dedicate home theater room in my basement and want to soundproof the room as much as possible (or in my case as much as the budget could allow!) Anyway, the basement currently has drop ceiling with R19 between joins. My question is should I keep the drop ceiling or install drywall ceiling with soundproofing clips? The reason I thought the drop ceiling would be good is that it is already "decoupling" from the joins and would be as good as soundproofing clips. What do you think?
Thank you,
Bao Tran
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post #1001 of 3269 Old 03-25-2015, 10:05 AM
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Originally Posted by granroth View Post
I actually measured some samples of sheet goods in this post: Thoughts on Mass. Extrapolating on those numbers, I'd guess that 1/2" MDF might have a density of about 1.7 lbs/sq ft. MDF is very slightly less dense than drywall, so your ceiling would be the rough equivalent to a 1/2" Drywall + 5/8" Drywall.

No, it won't give you the same performance. Mass does play a big role in soundproofing and having less has a direct impact on the abilities of the partition.

BUT!! Maybe it won't matter to you. Do you have a specific soundproofing goal that you are trying to hit? If you don't, then maybe you would be happy with a lessened solution, if only because you don't know what a more robust solution would sound like. Having a ceiling like yours absolutely will make a meaningful difference compared to not treating the ceiling at all. It may well be enough.

Just don't fall into the trap of thinking "I want to be able to play movies at reference level and not hear one peep out of it if I'm standing just outside the room." That ain't happening with your room. Think "I want to play movies pretty loud in my theater and have it not be quite so loud in the rest of the house" and yeah, you'll absolutely do that!
You are absolutely right, my target is not 100%, if i can reach 85%, then i am happy, and if it can stop the sound from getting in, then i will be more than happy. i am not pretty much concerned about sound going out. This room is in the third floor, surrounded with rooms like stores, my living room. and above me is the roof!

my targets:

1- minimize the sound coming from the roof like foot steps, or from wash machines .etc.
2- rigid ceiling and does not rattle at all!


initially, i had 1 layer of 0.5" drywall + RC & insulation, but it can rattle in certain frequencies which i could not accept.

so i went to re-do my ceiling with the new setup (mdf + drywall + GG), and 2" wooden frames + 3-4" insulation.
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post #1002 of 3269 Old 03-25-2015, 03:13 PM
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Originally Posted by cw5billwade View Post
need more information like is the theater going to be on first floor 2nd floor or basement. A Room in a room is the best aproach if done properly.
Its a single story residence, and we generally don't have basements in Australia, so there will be nothing above or below it.
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post #1003 of 3269 Old 03-25-2015, 11:09 PM
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Staggered Studs Wall

Quote:
Originally Posted by granroth View Post
If anybody does find one, then let me know since I haven't found any. As I mentioned in the "links" section of this thread, it seems that most people that have the space for staggered studs will go with a double wall and those that don't have the space go with clips and channel. Staggered studs is often the odd man out.



Do you have any data or research showing that rubber mats or pads will increase the effect of staggered stud walls? I've seen some suggestions that those do absolutely nothing and I'm wondering if that's just one of those AV myths that tend to stick around with no hard data to back them up, just because they "make sense". I'd love to see some proof that they really do work, though!



Hmm... I don't know how helpful that chart is for determining appropriateness for soundproofing materials. The factor that is most important by a huge margin is density, and density isn't even listed there. I haven't seen any evidence that hardness makes any meaningful difference for soundproofing. For instance, sand isn't hard at all, but it's extreme density (and viscous nature) makes it a wonderful soundproofing component. Various hardwoods have very high Janka ratings but they are typically pointless if you're trying to limit sound from entering or escaping a room.
Finally found a build using staggered studs wall Jijims Take 2! Build
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post #1004 of 3269 Old 03-25-2015, 11:11 PM - Thread Starter
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Originally Posted by ronny31 View Post
Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12" Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure.
Precisely how much effect there is, you'd have to dig up, I haven't found much. The effect is higher the more one face of the rubber can move in relation to the other side, so thick stubby bits is better than thin mats, tons of soft stubby bits is better than a few hard rubber bits, and so on. Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between. We can't have vacuums unless at great cost so in our realistic version we'd have air between the layers, and also rubber bricks spaced out so that the weight of the room doesn't just squash the ones under the floor until the inside floor essentially transmits all its vibrations to the outside floor. This is achieved by having the weight of the roof taken by the outside roof through rubber bricks or elastic bands, the wall being held above the floor by the rubber in the wall, the floor being held by the bricks under the floor. Then you'd want to limit weight you put on that floor to maximize effect. The stronger the inside wall in this scenario is, the more db is contained in the desired location, and the more effective the acoustic separation and sound absorbing effect of the inside and outside wall, the more db is lost but not released into the next room.
The issue I have with the suggestion that rubber will have any notable impact on transmission loss with regards to walls is that I've seen no indication that that is the case, yet have seen multiple references to how it is not the case. Yes, rubber is used very commonly and very effectively in smaller and far lighter entities. It is also often used as a membrane underneath plywood or similar to make a disconnected floating floor. It works in those cases.

But we're talking specifically about walls and while your suggestions sound like they could be true, I have never seen anything that indicates that they are. I would absolutely love if you had any evidence at all that rubber can work in that way effectively.

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Originally Posted by ronny31 View Post
"Specific gravity — the weight of a volume of wood divided by the weight of the same volume of water."
Hardness reflects sound, keeping it in the theater, soft stuff absorbs sound, losing db but not adding echo. Basic DB drag 101 in acoustic physics. You want as much hardness as you possibly can, then for sound quality you want to add just enough absorbing surfaces for each of the frequencies. Adding more absorbing surfaces beyond that point essentially makes the theater into an open area with no walls, making it incredibly difficult to fill with sound.
Hard surfaces absolutely bounce back higher frequencies and so mitigating or controlling them is essential to having a great sounding room... but we're not talking about room acoustics so much as sound transmission loss and hardness plays a much smaller role in that case. For instance, say you had a room with walls made of 1/16" thick steel. The walls would be incredibly hard (much harder than any wood or normal sheet goods product) and the room would echo like crazy, but it would also leak noise like a sieve. All but the highest frequencies would just pass through like it wasn't there.

So it's not so much "hard vs soft" surfaces but "dense vs thin/light". The key for all soundproofing techniques is to reduce the energy of the sound waves (by converting them to heat) as much as possible. If the sound wave strikes a less-dense surface, even if it's very hard, then a significant amount of the energy of that wave will be in the surface, making it vibrate and pass along that wave to whatever is on the other side. If the surface is very dense, though, then it requires a LOT of energy to vibrate it and so quite a bit of the wave's energy is lost as heat.
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post #1005 of 3269 Old 03-26-2015, 12:31 AM
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So it's not so much 'hard vs soft' surfaces but 'dense vs thin/light'. The key for all soundproofing techniques is to reduce the energy of the sound waves (by converting them to heat) as much as possible. If the sound wave strikes a less-dense surface, even if it's very hard, then a significant amount of the energy of that wave will be in the surface, making it vibrate and pass along that wave to whatever is on the other side. If the surface is very dense, though, then it requires a LOT of energy to vibrate it and so quite a bit of the wave's energy is lost as heat.
Replace 'dense' with 'massive' everywhere in that paragraph, and it would be correct.
A piece of paper is dense, about the same density of sheet of plywood -- but a piece of paper wouldn't stop much sound, whereas a more massive sheet of plywood would.
The rule is, as you know: doubling the mass of a wall gives an increase of 3-5 dB in STC.
Doubling the density while quartering the mass, would result in a soundproofing loss.
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post #1006 of 3269 Old 03-26-2015, 12:46 AM
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Quote:
Originally Posted by ronny31 View Post
Its used all the time in computers, servers and cars. Also lots of home stereo systems, by having rubber feet between the floor and the speakers, causing less vibration to propagate through the floor into stuff that can make audible vibrations. The engine in your car is kept separate from the chassis with rubber so that the chassis don't act like a tuning fork for the frequencies the engine create. In most buildings it is not used because most buildings don't have a car engine equivalent shaking things up, but with a single 12' Pioneer 1000W rms I managed to shake the walls sufficiently to make glass and dishes in the upstairs floor sound like Ace Ventura delivering a fragile package. Adding rubber between the floor, walls and roof wasn't an option, so I had to just add rubber under the subwoofer enclosure.
Any solution using rubber results in a mass-spring-mass (M-S-M) system, which has a resonance frequency.
Lots of machines vibrate within a higher frequency range, which is so far above M-S-M resonance that using rubber as a sound isolator is relatively easy.
Home theatres, especially those with sub 20hz subwoofers, tend to hit the frequencies which resonance would happen. The good news is that your house probably has a M-S-M of its own, and you might have lucked out with a M-S-M-S-M system that doesn't rattle the dishes.


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Originally Posted by ronny31 View Post
Optimum sound-proof room would give the same effect as having a room inside a room, floating in Zero G with no contact between the inside wall and the outside wall, with a vacuum in-between.

That might be doable. There's a very large all concrete room that they suck all the air out of for experiments -- including the famous feather and canon ball drop which did have both of them hit the floor at the same time. So you could do that as an outer shell. Then get someone from NASA (not the electric boat company because they're overqualified) to build you a metal shell that can handle 10000 foot pressure inside and vacuum outside, and a life support system {NC 5 system for air/O2/CO2, heat/cool for people/equipment, toilet}. Mount the NASA shell on magnetic levitation. Use fail safe vents on the outer structure to return the air pressure to normal in the event of a power failure. Movie goers would enter the NASA shell three hours before the movie to await the vacuum being generated, then the movie would start. I have no idea what that would cost -- but you could lean forward and complain to the front row people that their hearts were beating too loudly for you to enjoy the subtleties of the movie sound track.
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post #1007 of 3269 Old 03-26-2015, 06:43 AM
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Quote:
Originally Posted by granroth View Post
For instance, say you had a room with walls made of 1/16" thick steel. The walls would be incredibly hard (much harder than any wood or normal sheet goods product) and the room would echo like crazy, but it would also leak noise like a sieve. All but the highest frequencies would just pass through like it wasn't there.
This is a fallacy. The weight of the proposed thickness steel is 2.55lbs per square foot and at that thickness have less bending strength than a HDP wall (I eyeball that it would at least). Therefore, it would almost certainly sound like a gong with the proposed steel, but this does not make the argument true.

The goal of a good room for a stereo or surround system is maximum sound levels for maximum headroom in all frequencies. To reach this prerequisite the room pretty much has to be a concrete bunker with no sound being absorbed by the walls, but instead reflected by the walls. No energy given to the speakers should escape the room.
Then the second prerequisite is that the room is acoustically good, so its possible to EQ a stereo to get a flat response with the desired low levels of echo across the spectrum. To do this you add acoustic elements like bass traps, sound absorbing materials and sound diffusers. In the appropriate amount and configuration so as to get an acoustic masterpiece.
If you try to do it differently, and instead incorporate sound-absorbing elements in the wall, ceiling and floor design itself, for example in the form of soft walls with sand. Then you will have parts of your acoustic list of features, which you can't change later. If you happen to have a large dip in db on a particular frequency band because too much db is absorbed by the walls, floor and ceiling, then you can't remove absorbing materials and gain db in that frequency spectrum. You're stuck trying to correct it with having more headroom from the sound system in that exact frequency band.
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post #1008 of 3269 Old 03-26-2015, 09:13 PM - Thread Starter
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This is a fallacy. The weight of the proposed thickness steel is 2.55lbs per square foot and at that thickness have less bending strength than a HDP wall (I eyeball that it would at least). Therefore, it would almost certainly sound like a gong with the proposed steel, but this does not make the argument true.

The goal of a good room for a stereo or surround system is maximum sound levels for maximum headroom in all frequencies. To reach this prerequisite the room pretty much has to be a concrete bunker with no sound being absorbed by the walls, but instead reflected by the walls. No energy given to the speakers should escape the room.
Then the second prerequisite is that the room is acoustically good, so its possible to EQ a stereo to get a flat response with the desired low levels of echo across the spectrum. To do this you add acoustic elements like bass traps, sound absorbing materials and sound diffusers. In the appropriate amount and configuration so as to get an acoustic masterpiece.
If you try to do it differently, and instead incorporate sound-absorbing elements in the wall, ceiling and floor design itself, for example in the form of soft walls with sand. Then you will have parts of your acoustic list of features, which you can't change later. If you happen to have a large dip in db on a particular frequency band because too much db is absorbed by the walls, floor and ceiling, then you can't remove absorbing materials and gain db in that frequency spectrum. You're stuck trying to correct it with having more headroom from the sound system in that exact frequency band.
Well sure, but now we're talking about two completely different things. You are referring to acoustic treatments to make the room sound better; I'm referring to soundproofing components to maximize sound transmission loss between the inside and outside of the theater. Those are two completely different goals with completely different treatments. It's why there are separate Soundproofing Master Threads and Acoustical Treatments Master Threads
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Well sure, but now we're talking about two completely different things. You are referring to acoustic treatments to make the room sound better; I'm referring to soundproofing components to maximize sound transmission loss between the inside and outside of the theater. Those are two completely different goals with completely different treatments. It's why there are separate Soundproofing Master Threads and Acoustical Treatments Master Threads
I do not see how this is two different things. By keeping every single db inside the room you by definition keep it from going to the next room, and vice versa. Only if you obtain this goal by stacking sandbags behind some mdf then you stop the db in the middle of the wall instead of inside the home cinema. Then you need a bigger more expensive home cinema, and more sound deadening to keep the noise in, and so forth. The sound-deadening thread could be a how-to build a 4 inch fiberglass reinforced concrete wall, ceiling and floor. Because absorbing the sound with drywall or even HDP would be considered an acoustic treatment.
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Q - My HT is located in the basement below the dining room of the first floor (which is adjacent to the kitchen and front entrance).
My HT room is fully decoupled + DW+GW+DW. It does a great job of sound containment with all but the "good" LFE scenes played at reference level. Particularly it gives some rumble to the dining room and areas mentioned above. (so my current solution is to lower the sub level during hours people are in these rooms). My wife is looking to redo the dining room floor, so I was thinking about using this as an opportunity to get rid of that rumbling.
i.e. the plan was to buy click together bamboo flooring (like this) directly on top of the existing hardwood floor. However for Sound Containment, I was thinking of the following options, and wondering your thoughts on comparatively, and absolutely how much each would help the LFE containment :
  1. simply putting green glue between the new floor and the existing hardwood floor
  2. putting GG + a 3/8" layer (5/8" if I can fit it) of DW under the existing hardwood floor
  3. cutting some holes (strips) in the existing hardwood + subflooring to get to the ceiling of the HT, and stuffing more pink fluffy insulation in it (as currently the cavity of the ceiling which I'm guessing is 9-12" deep, has about 3" of insulation (maybe 6", I may have stuffed the additional r13 batt in (but in some places I needed to compress it to fit , due to cross supports in the cavity ) - Obviously this would add complexity to the project, so I'd like to avoid, but it the gap at the top of the cavity is creating a big problem, and is necessary to fix, I can do it.
What do you think?

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Depends on where the bass is coming through. If its the floor then for bass stopping I'd consider some polished slate stone with electric heating cables (marvelous to walk on). But it can also be that the wall transmits sound from the first floor to the second floor, so a slate floor could not give much of an effect without adding to the walls. But at this point its going to perhaps be easier and cheaper to redo the cinema room walls and ceiling. Please do some checking to figure out the direction the bass is taking. Are the enclosures vibrating, transmitting vibrations to the floor? Then making more solid (massive) enclosures could be warranted. Or is the bass purely vibrating the walls and ceiling in the cinema? If so the walls and ceiling might need more mass and/or less give when you push against it (for stopping bass the wall should ring like a bell if a sound is given at all, if you hit it, not sound like a gong).
To give more accurate help, figure this out: If you put your ear on the bottom of a glass and rest it towards the surfaces in your cinema and upstairs what place has the most sound? Draw the room and mark down perceived sound levels from 1 to 5 in the different locations.
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Q - My HT is located in the basement below the dining room of the first floor (which is adjacent to the kitchen and front entrance).
My HT room is fully decoupled + DW+GW+DW. It does a great job of sound containment with all but the "good" LFE scenes played at reference level. Particularly it gives some rumble to the dining room and areas mentioned above. (so my current solution is to lower the sub level during hours people are in these rooms). My wife is looking to redo the dining room floor, so I was thinking about using this as an opportunity to get rid of that rumbling.
i.e. the plan was to buy click together bamboo flooring (like this) directly on top of the existing hardwood floor. However for Sound Containment, I was thinking of the following options, and wondering your thoughts on comparatively, and absolutely how much each would help the LFE containment :
  1. simply putting green glue between the new floor and the existing hardwood floor
  2. putting GG + a 3/8" layer (5/8" if I can fit it) of DW under the existing hardwood floor
  3. cutting some holes (strips) in the existing hardwood + subflooring to get to the ceiling of the HT, and stuffing more pink fluffy insulation in it (as currently the cavity of the ceiling which I'm guessing is 9-12" deep, has about 3" of insulation (maybe 6", I may have stuffed the additional r13 batt in (but in some places I needed to compress it to fit , due to cross supports in the cavity ) - Obviously this would add complexity to the project, so I'd like to avoid, but it the gap at the top of the cavity is creating a big problem, and is necessary to fix, I can do it.
What do you think?
Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.

In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!

Kidding, of course... If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"

So with that in mind:

1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.

2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.

3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.
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Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.

In general, the more mass, damping, and space you can add, the better it'll be. Can you add a 6ft concrete ceiling? That would work. No? What, are you not committed to this?!

Kidding, of course... If you're not developing a commercial studio or theater, then bass reduction will always be a compromise and trying to get "good enough"

So with that in mind:

1. Putting green glue between the new floor would help (more damping in addition to the new mass); GG tends to amplify the effects of the additional mass. Bamboo flooring doesn't have a significant amount of mass, though, so I'm not sure how much it'd help overall. I love bamboo flooring, btw (installed it in my house) but not necessarily from a soundproofing perspective.

2. Instead of drywall, consider putting cement board, like you might put under tile. A 1/2" sheet of cement board (like DUROCK) has about 3lbs / sq ft, which is quite a bit more than even 5/8" drywall. It is harder to work with, though.

3. Adding more insulation may not help enough to matter. There's a steep cut-off in effectiveness after about 3 or 4 inches. Still, there are some improvements and it does have the effect of "widening" the space, which should help with bass. I just don't know that it would be worth the extra effort.

Thanks, looks like I'll try to add concrete board - and not add the insulation (glad - wasn't looking forward to cutting the subfloor) - note all LFE that comes through - only comes through directly above the HT room, and not that much, so I'm hoping this will take it the extra yard.
2 Q's:
(a) Do I add GG to the Concrete board
(b) with the concrete board it will make the floor level above the bottom of the front door (hallway adjacent to dining room is front entrance). In addition, if I do these areas, it'll be a good 2" above the current hardwood in the rest of the first floor (which doesn't need to be replaced) - any ideas ?
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Thanks, looks like I'll try to add concrete board - and not add the insulation (glad - wasn't looking forward to cutting the subfloor) - note all LFE that comes through - only comes through directly above the HT room, and not that much, so I'm hoping this will take it the extra yard.
2 Q's:
(a) Do I add GG to the Concrete board
(b) with the concrete board it will make the floor level above the bottom of the front door (hallway adjacent to dining room is front entrance). In addition, if I do these areas, it'll be a good 2" above the current hardwood in the rest of the first floor (which doesn't need to be replaced) - any ideas ?
GG works best between two surfaces that are the same, but it still works well with dissimilar surfaces. If you got the GG from Ted, then your best is to call him for his opinion. GG is used frequently between OSB and drywall so it make sense to me that it'd be at least as effective between plywood and concrete board.

In houses that I've been in with offset floor heights, they tended to use a transition strip that eases the edge and then cut the door down so that it clears the higher floor.

I'm going to have a higher floor in a future home improvement and my plan is to just chamfer the higher flooring over several inches to ease it down to the same height as the lower one. I haven't done it yet, though, so I can't comment on how effective it'll be
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So I think I got my route planned for my room in the basement (10'x14'x8'), double 5/8"DW with GG on ceiling. Double 2x4 walls on 2 sides with single 5/8" DW on the inside and outside. The other 2 sides are outside walls (concrete) that are already covered with a single layer DW.
But what just dawned on me, once I have the door in, and a heavy curtain in front, I will have likely not much of an air movement. The room had no AC/heat, it was open on 1 side and had a folding door with slots on the other. So far even in the winter time it wasn't to bad there and blankets worked so I wasn't thinking about heating. Though I have a little heater I can plug in. If the projector isn't heating enough already The rack is outside the room. For cooling I would have put in my Dyson fan who would be very quiet on low setting.
But all that would not help with fresh air.
While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ?
Did I just plan to seal my room pretty tight and now I have to punch vents in it ?
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Overall, significantly reducing LFE is the hardest part about soundproofing. Most soundproofing techniques are all about reducing the wall/ceiling resonant frequencies to below the frequency you're trying to stop. But if you're talking about 20Hz or 40Hz, then that requires a lot of mass + damping + space.
Well, yes, and no. Just adding hanging mass with no structural strength would be a very difficult way of keeping low frequency db inside a room. I think the most helpful article I can link to is this:
http://en.wikipedia.org/wiki/Sound_transmission_class
At the bottom there is a list of typical wall options and their STC.
This pdf also has some options and their measured STC: http://www.vibrationdata.com/tutorials/RD066.pdf

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So I think I got my route planned for my room in the basement (10'x14'x8'), double 5/8"DW with GG on ceiling. Double 2x4 walls on 2 sides with single 5/8" DW on the inside and outside. The other 2 sides are outside walls (concrete) that are already covered with a single layer DW.
But what just dawned on me, once I have the door in, and a heavy curtain in front, I will have likely not much of an air movement. The room had no AC/heat, it was open on 1 side and had a folding door with slots on the other. So far even in the winter time it wasn't to bad there and blankets worked so I wasn't thinking about heating. Though I have a little heater I can plug in. If the projector isn't heating enough already The rack is outside the room. For cooling I would have put in my Dyson fan who would be very quiet on low setting.
But all that would not help with fresh air.
While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ?
Did I just plan to seal my room pretty tight and now I have to punch vents in it ?
I have tried (not very hard) to find vents that allow keeping db inside and then being able to provide fresh air occasionally, but I haven't found any. Just the regular plastic stuff that leak db like a hole in the wall. If you try to keep the noise from the rest of the house, more so than the neighbors, then just having vents out of the house would be preferable to having vents into the other rooms. Vents to the outside have to be high up (presumably the air outside is cooler and falls down to the floor then, pushing warm air out, like a room being filled with water).
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post #1017 of 3269 Old 03-28-2015, 05:42 PM - Thread Starter
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Well, yes, and no. Just adding hanging mass with no structural strength would be a very difficult way of keeping low frequency db inside a room. I think the most helpful article I can link to is this:
http://en.wikipedia.org/wiki/Sound_transmission_class
At the bottom there is a list of typical wall options and their STC.
This pdf also has some options and their measured STC: http://www.vibrationdata.com/tutorials/RD066.pdf
No.

STC is a pointless rating when it comes to LFE since it starts at 125Hz and LFE is defined as being from 20Hz to 120Hz. There is no overlap between STC and LFE at all. Therefore, the STC rating of a wall or ceiling tells you nothing of the ability to stop the transmission of bass.

STC can still be a decent measure of the soundproofing capacity of a wall in the sense that there are no other single number standards that are commonly communicated. If you want the canonical list of those values for the biggest arrays of wall construction types, then it's best to go to the source and just download the pdf for IR-761 done by the NRC-CNRC. Link is in the second post in this thread.

Also, no, when soundproofing you are not primarily trying to keep sound "inside" of the room. What you are mostly doing is converting the sound energy into heat inside of the partition. Yes, some of the sound waves will be reflected back and anything reflected back is, by definition, not leaving the room... but that's only a small percentage of the total sound energy. The vast majority is dissipated in the wall/ceiling itself.
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Originally Posted by VolkerH. View Post
But all that would not help with fresh air.
While I likely wouldn't suffocate during a 2 hour movie, I'm wondering how bad the air gets with 4 people watching a 2 hour race ?
Did I just plan to seal my room pretty tight and now I have to punch vents in it ?
If the room is sealed tight, then yeah, it'll start getting "stuffy" feeling in the room during long movies. It won't be anywhere near bad enough to suffocate you or anything even close to that, but it likely will be noticeable, especially since that's a relatively small room.

Definitely don't just punch vents in it, though!! You have a couple of options:

If you don't want to do any kind of construction, then consider the very low-tech option and just have an intermission in any multi-hour movie or show and open the door to air out the room.

If you are willing to do some construction, then the canonical solution for this is a "dead vent". This is pretty commonly done. Details here: http://www.soundproofingcompany.com/...the-dead-vent/

Basically, you are "punching a vent" through the wall, but it's done in such a way that sound cannot bypass your existing soundproofing efforts. You get the fresh air without the reduction in sound transmission loss.
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No.

STC is a pointless rating when it comes to LFE since it starts at 125Hz and LFE is defined as being from 20Hz to 120Hz. There is no overlap between STC and LFE at all. Therefore, the STC rating of a wall or ceiling tells you nothing of the ability to stop the transmission of bass.
http://www.acoustiblok.com/PDF/Acous...Assemblies.pdf
Page 15, 8 inch concrete block with standard wall on both sides. About twice as good at stopping bass than all the non-concrete stuff in IR-761 (the best bass transmission design in IR-761 is 25db I think, spent 20 minutes scrolling through to see if I found out what was best in that regard but got bored).
When DB drag car builders make panels to stop bass transmission they hammer on it with something, then if they hear something they reinforce it. Then they repeat until they no longer manage to transmit any bass through it. And what they always end up with is a concrete panel. You need concrete to stop bass. To stop bass without concrete you'll need half spacing studs and double 22mm high density variable particle size particle board akin to the stuff Scandinavians use for floors. And even then concrete is much better. Even just thin fiber reinforced poured concrete and then a normal wall at both sides (with some rockwool or something to stop high frequencies). Am I the first on this forum to advocate the use of concrete to stop bass transmission or something? With the amount of resistance and general lack of response to my points in favor to responding to the next guy who mentions drywall, I'd certainly think so.

EDIT: Come to think of it, why should I argue otherwise? Maybe I'll just let you be happy with drywall combos in respect to bass transmission. Then I won't come across as an a-hole in my effort to argue otherwise.

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http://www.acoustiblok.com/PDF/Acous...Assemblies.pdf
Page 15, 8 inch concrete block with standard wall on both sides. About twice as good at stopping bass than all the non-concrete stuff in IR-761 (the best bass transmission design in IR-761 is 25db I think, spent 20 minutes scrolling through to see if I found out what was best in that regard but got bored).
When DB drag car builders make panels to stop bass transmission they hammer on it with something, then if they hear something they reinforce it. Then they repeat until they no longer manage to transmit any bass through it. And what they always end up with is a concrete panel. You need concrete to stop bass. To stop bass without concrete you'll need half spacing studs and double 22mm high density variable particle size particle board akin to the stuff Scandinavians use for floors. And even then concrete is much better. Even just thin fiber reinforced poured concrete and then a normal wall at both sides (with some rockwool or something to stop high frequencies). Am I the first on this forum to advocate the use of concrete to stop bass transmission or something? With the amount of resistance and general lack of response to my points in favor to responding to the next guy who mentions drywall, I'd certainly think so.

EDIT: Come to think of it, why should I argue otherwise? Maybe I'll just let you be happy with drywall combos in respect to bass transmission. Then I won't come across as an a-hole in my effort to argue otherwise.
Any resistance you are getting is mostly because your responses are a curious mix of being very helpful; somewhat misleading; or outright wrong. You clearly think you know a lot about soundproofing, but it seems like a lot of your background info is either wrong or is right but in ways that you don't understand.

This response is an example of where you start off 100% right and but then start subtly veering off.

First, you are 100% correct that concrete is a fantastic way to stop bass! I've never heard anybody say otherwise. As I mentioned earlier, stopping bass means tons of mass, plus ideally damping and space. Concrete works so well with bass because it is very dense and so has a ton of mass for the amount of space it occupies. There are elements that are even better (lead and sand, for two quick examples) but all other alternatives are either prohibitively expensive or are difficult to work with in a construction capacity. So concrete is king when it comes to bass.

So why isn't it concrete block recommended more often around here? Because this is a primarily US-central forum and concrete block is relatively uncommon in homes here. Most homes in the US are "stick" homes, made with 2x construction. Drywall is recommended so pervasively because it gives a reasonable amount of mass for relatively low cost.

Yes, it certainly sounds like the sponplat (high density panels) would be even better. I'd love to try the stuff myself. As far as I know, it doesn't exist in the US. Until it does, drywall is the best compromise (performance for price + availability + workability).

Now, there is arguably an even better solution than drywall for bass that is still doable and that's concrete backer board. I suggested that in a previous post. The problem with concrete backer board is that it's notably harder to work with than drywall and is about double the cost.

But I want to quibble with your response, nonetheless, because you are pointing to a bunch of wall assemblies that do work well with bass and are implying that their STC rating has something to do with that. It doesn't. Even with those examples (several of which are IR-761 assemblies, btw), you can clearly see that the STC value has little to no relation to the wall's performance under 125Hz. Also, you mention "half spacing studs"... I'm not 100% certain what you mean by that. If you mean just spacing them closer together (8" spacing, perhaps) then no, that won't help from a soundproofing perspective. If anything, that would make things worse, since you are now doubling the amount of transmission paths for the sound waves to travel on. Halving the number of studs (going to 24" O.C., if code allows) does work, since it reduces the number of pathways.
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