soundproofing my home theater

Discussion in 'Home Theater Projects' started by marc-s, Sep 22, 2007.

  1. marc-s

    marc-s Auditioning

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    what do u recommend for the best soundproofing at the most affordable rate?

    i have been told of a drywall material which is as effective as 5 regular pieces of drywall.

    of course i have been recommended a cork material as well

    what material do u guys recommend whether it be the above or other material?

    thanks

    marc
     
  2. Gerry S

    Gerry S Stunt Coordinator

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    I guess you are referring to quietrock. The cork sounds useless.

    When it comes to containing sound, mass and isolation are what you need to consider.

    There are also building techniques you can consider, if the walls have not been built yet. For example, a staggered stud wall can help minimize sound transmission to other rooms. Some even build a room within a room, to completely isolate the walls and ceilings, and thus prevent the transmission of sound.

    There is much to learn about this topic. My plan is to use two layers of 5/8" drywall with a layer of green glue between. The product comes highly recommended by some respected theater builders. There website has a ton of information that you should read to learn about sound isolation, including independent lab tests comparing solutions:

    http://www.greengluecompany.com/

    good luck.
    -Gerry
     
  3. BruceSpielbauer

    BruceSpielbauer Second Unit

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    The above response is excellent. I will add to it, and mention this:

    1- There is no such thing as soundproofing. You can reduce the amount of audio which enters or leaves a room. That is all.
    2- The best "bang for the buck" seems to be what you are asking about. Sadly, most of the techniques for reducing sound travel also tend to cost quite a bit of money. There are a few exceptions. IF you are still in the early construction phase, then you can incorporate some of the ones which do not set you back a ton of bucks. For example, staggered stud walls do not cost all that much more than a regular stud wall, if you can give up a bit of space. And, a true double wall can also be done for not that much more, since you are mostly doubling up on construction-grade lumber. The results of these approaches have been scientifically measured, and the results are always effective, compared to other techniques.
    Or, consider double drywall. Obviously, more money, But, compared with many of the products available, this can often be much, much les expensive than throwing your money at some product. And, it is a definite sound reducer.
    3- The subwoofer... when you you do your research, you need to realize that almost all of it uses a scale which ignores the subwoofer noise. You will see lots of results which talk about reduced STC levels. This is valuable, as long as you remember that it ignores all low frequency stuff -- your subwoofer. And, unfortunately, the subwoofer noise seems to eb the toughest type of sound to try to kill.
    4-The reply above mentions Green Glue -- great product. Uses scientific test to validate their claims. As mentioned, cork will be next to useless, or more likely useless. I am going to suggest you read a report from their web site carefully, in fact you should read all of the reports. NOT because you should spend the money on their product. But, because they deal in the truth, and if you notice their emphasis on mass, and decoupling, and resonance, and damping, you will be able to quickly answer your questions above.

    Later, you can decide if their product is worth it, as an ADDED feature.

    Here is the article:

    http://www.greengluecompany.com/five...ndproofing.php

    -Bruce
    -A customized intro for your home theater: http://www.S2Digital.com
     
  4. Jeff Kelley

    Jeff Kelley Extra

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    What about roxul safe n sound insulation? Does it work?

    Jeff
     
  5. AquaSerge

    AquaSerge Extra

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    I plan on creating commercial business with HT setups in each room (pretty much a HT theatre if you can call it that) and my idea for sound dampening in each room is using the THX qualified quietrock, with some insallation (after I take a look at it it might even be safe n sound insallation) inbetween each wall. Because I will actuall have 2 layers of this material (one layer on each side of the wall) it should nullify pretty much all noticable sound leaking from either side. This may be overkill, however keeping sound from leaking from one room to another is extremely crucial in my case, and replacing drywall in a commercial area is alot cheaper than replacing damaged or destroyed sound panels. I have yet to test this theory but from those I have talked to it doesnt sound like a bad idea. Even if this is overkill, customizing a little of what I have suggested could be exactally what you are looking for.

    If you could apply that to your senario i think it would help alot. any suggestions on my idea would also be appreciated.
     
  6. Robert_J

    Robert_J Lead Actor

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    Double drywall and QuietRock will stop the majority of the sound from leaking. But you have to go to the next level if you want to contain reference level bass. Room within a room. I went with staggered studs and that stops the highs pretty well. But my subs will vibrate the entire concrete foundation of my house at reference levels.

    -Robert
     
  7. AquaSerge

    AquaSerge Extra

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    I think i get the idea of a room in a room, but im not so sure on staggard studs. Could anyone enlighten us newbs to these methods?
     
  8. Robert_J

    Robert_J Lead Actor

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  9. BruceSpielbauer

    BruceSpielbauer Second Unit

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    Robert's chart above is an excellent one. Study it, carefully. I found a very similar one, and because the results are based on scientific testing, you should pay careful attention.

    Now, for the only caveat... The chart that Robert provided (and also the one that I consulted) both display the STC reduction you can expect. While this is a very valuable measurement, we should also keep in mind that the STC measurement completely ignores one area of sound: the low bass.

    Read what follows, carefully:

    "The STC number is derived from sound attenuation values tested at sixteen standard frequencies from 125 Hz to 4000 Hz. These transmission-loss values are then plotted on a sound pressure level graph and the resulting curve is compared to a standard reference contour. Acoustical engineers fit these values to the appropriate TL Curve (or Transmission Loss) to determine an STC rating. The measurement is accurate for speech sounds but less so for amplified music, mechanical equipment noise, transportation noise or any sound with substantial low-frequency energy below 125 Hz. "

    What this means is that STC completely ignores any frequencies below 125 Hz. And, anyone who has set up a subwoofer knows that the most common cut-offs for sound that is sent to a subwoofer is usually a ways below that. (note that 80 Hz is often the reference level starting point). This means that ALL of the sound from your subwoofer is not even measured in those tests that were performed to make up the charts you will see. Sadly, there is no universally-accepted measure for your subwoofer "thump," so you will probably not find any scientific data on reducing the subwoofer noise.

    Worse, those who have tried to reduce sound transference in a home theater will attest that the subwoofer noise tends to be the TOUGHEST type of noise to try to reduce. Think of the last time you were stuck at an intersection and noticed the "thumpph! thumpph! thumpph! " coming from that car which was four cars behind you, waiting on the same traffic light. Note that you did not hear the rest of the music that the offender was listening to. You did not hear the guitar, or the pianos, or the vocals, or the high-pitched whine of the lead guitarist. For some reason, you only heard the "thumpph! thumpph! thumpph!" coming from the subwoofer. The subwoofer noise (the LFE or low frequency noise) tends to be the most difficult to reduce. The car's chassis and the car's doors, and the air gap between his car and your car managed to greatly reduce the vocal track, and the rhythm guitar, and the horns, and the keyboard, and the lead guitarist. Yet, none of those things seemed to have much impact on the subwoofer "thuumph!" And, the chart referred to above does not even measure that same subwoofer "thuumph!" at all.

    My own thoughts... The same sorts of construction which reduce STC also does reduce the LFE or subwoofer noise. Somewhat. However, I have noticed that a lot of the subwoofer noise will typically still get through. From my own experience, if you hope to greatly reduce the subwoofer noise, one may have to examine the true room-within-a-room approach, complete with air-tight sealed up seams, and add decoupling, as well. And, this also means you carefully examine what the weakest link might be -- for example, replacing regular doors with a heavy solid core exterior door, complete with threshold, perhaps even using two doors separated by an air gap.

    I am not trying to "dis" the chart in any way. Rather, I would hate for anyone to follow it and expect nirvana-like results, only to discover they still have complaints of a "thuumph! thuumph! thuumph!" throughout the rest of the house, after putting in a great deal of effort.

    Take care,

    -Bruce
    -The ultimate Home Theater Add-On: http://www.S2Digital.com
     
  10. AquaSerge

    AquaSerge Extra

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    So basically about the best thing to do (besides using dampers on the walls) is to do a room in room layout using the staggard stud method WITH the QuietRock and Safe and Sound isulation. I wonder just how expensive doing all of that would be.
     
  11. Gerry S

    Gerry S Stunt Coordinator

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    If you are using the room within a room construction technique, you won't need the staggered stud wall. Staggered studs are used when when two adjacent rooms share the same wall. That does not occur in a room within a room construction.

    If this is a commercial venture for you, consider hiring an acoustic consultant to advise you how to get it right the first time. Again, you can learn a great deal yourself about sound isolation construction and products at http://www.greengluecompany.com/ .

    Good luck,
    Gerry
     
  12. BruceSpielbauer

    BruceSpielbauer Second Unit

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    GerryS is quite right -- you would be well-served to read all of the various documents at the Green Glue website, EVEN if you end up not purchasing their product. I have yet to find any information within those documents that has any innaccuracies, nor has anyone else, apparently. This includes the very best in the industry, who have studied and scrutinized those documents at length. The articles there will teach you more about sound isolation and how to maximize your dollar if you wish to minimze the sound traveling into your room or out of your room.

    As GerryS points out, the staggered stud approach is not at all beneficial if you are going to do a room-with-a-room. They are two separate approaches, and not intended to be used together. Think of them as separate items, and one will simply achieve even "better" results. The staggered stud approach reduces total room size a bit, and does not in and of itself cost all that much more than a standard stud wall. It definitely can show results, and does not cost a lot more at all. In general, you are only paying a bit more for using 2 X 6s at the tops and bottoms of the walls (the top plate and the bottom plate) instead of the normal 2 X 4s.

    A room within a room is quite different. It is usually thought of as two separate stud walls. (The ceiling and floors also usually require separate study.) Two walls are built, separate from one another. One is located next to the other, and runs parallel along it. There is usually an air gap between the two. There is no real hard connection between the two walls -- they remain completely "de-cooupled" from each other. The inner wall should not be able to transmit the sound vibrations very well to the second outer wall. That can have terrific results (assuming you also address the ceilings, floor, and any openings such as doors). This approach requires more cost, of course. Twice the lumber, to start. It also results in a smaller room, since one must figure the width of a 2 X 4 stud, plus that air gap (often an inch), plus a second 2 X 4 stud wall. And, of course, none of this is even taking into account the drywall thickness. I built this type of structure, and it takes up a lot more space, which generally means a lot oless space for the room inside of the walls.

    You should also arefully look at the effects of doubling up on the drywall. Yes, this means more money, of course. But, it adds a lot of real mass, and it will always yield results in reducing sound transference. This can be done in conjunction with either method above. But, it can also be done without the methods above. It achieves measurable results, due to the increase in mass. It will also reduce the size of any room, but perhaps not by all that much. THIS technique can be combined with either of the approaches above, to yield great returns on sound reduction.

    Similar -- 5/8" drywall is better than 1/2 " drywall. More mass. So, one layer of 5/8" is better than one layer of 1/2". And, two layers of 5/8" is better than two layers of 1/2". This can be a mainor increase in dollars (if doing single layer, and you upgrade to 5/8") It can also be a lot more money. --I did the room within a room, and I used two layers of 5/8" inside the inner wall, and I also did two layers of 5/8" outside the outer separate wall. This means more than twice as much drywall as a regular room, and it was alo 5/8" which is a bit more expensive, and the 5/8" stuff is also tougher to work with, as it is heavy.

    Look at the chart on this page, regarding doubling up on drywall and types of walls:

    Sound Transmission Class Examples
    STC - What can be heard

    25 Normal speech can be understood quite easily and distinctly through wall
    30 Loud speech can be understood fairly well, normal speech heard but not understood
    35 Loud speech audible but not intelligible
    40 Onset of "privacy"
    42 Loud speech audible as a murmur
    45 Loud speech not audible; 90% of statistical population not annoyed
    50 Very loud sounds such as musical instruments or a stereo can be faintly heard; 99% of population not annoyed.
    60+ Superior soundproofing; most sounds inaudible


    STC Partition type
    33 Single layer of 1/2" drywall on each side, wood studs, no insulation (typical interior wall)
    45 Double layer of 1/2" drywall on each side, wood studs, batt insulation in wall
    46 Single layer of 1/2" drywall, glued to 6" lightweight concrete block wall, painted both sides
    54 Single layer of 1/2" drywall, glued to 8" dense concrete block wall, painted both sides
    55 Double layer of 1/2" drywall on each side, on staggered wood stud wall, batt insulation in wall
    59 Double layer of 1/2" drywall on each side, on wood stud wall, resilient channels on one side, batt insulation
    63 Double layer of 1/2" drywall on each side, on double wood/metal stud walls (spaced 1" apart), double batt insulation
    72 8" concrete block wall, painted, with 1/2" drywall on independent steel stud walls, each side, insulation in cavities

    STC partition ratings taken from: "Noise Control in Buildings: A Practical Guide for Architects and Engineers"; Cyril M. Harris, 1994

    *Remember, though, that none of the STC ratings above include that low, deep LFE noise from your subwoofer.

    So, for example, if you just doubled up on the drywall, and added regular fiberglass insulation, you could go froman STC of 33 to an STC of 45.

    If you also used staggered studs, you then could improve things from the STC of 45 to an STC of 55.

    Note -- you ALSO must think about everything else -- the ceiling; any openings at all; the doors; you must realize that you can build great walls, but if you use a regular interior door with a large air gap at the bottom, it will be like leaving a hole in an aquarium. The sound will just pour out (like the water would pour out of a hole in an aquarium.)




    And, you should also consider the effects of partial decoupling. Finding a way to get the drywall so it does not "directly" transfer vibration to the studs is one approach. A second approach is find a way to get a stud wall so it does not directly transfer sound vibrations to the rest of the structural house.

    The partial decoupling usually requires some specialized hardware. One example is the use of RSIC clips. Yes, they cost money.

    You should also consider the benefits of Quiet Rock and Safe and Sound insulation, and similar products. But, these do cost more money.

    Yes, you should also consider the use of Green Glue, since it is one of the very few products that does seem to work on that LFE bass (the subwoofer noise) I discussed above. Yes, it is also very expensive.

    There are excellent charts which will show you the added benefits of many different approaches.
    Visit their site. Read.

    -Bruce
     
  13. marc-s

    marc-s Auditioning

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    thanks for all your information.

    have any of u guys heard of
    Supress Products' Sound-Engineered Drywall

    they claim to offer a STC 50-78+ with their product

    thanks

    marc
     
  14. BruceSpielbauer

    BruceSpielbauer Second Unit

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    Those are generally referred to as "Factory damped panels." They can be very good, especially at reducing the normal range of audio (the range covered by the STC ratings, above 125 Hz).

    As a rule, though, they are not the best for reducing the LFE noise (the stuff below 125 Hz).

    And, they tend to be expensive. I suggest you get some actual price quotes, and then do the math to see how much more one layer of this would run versus two layers of regular drywall.

    Here is an interesting test. It compares two layers of 5/8" drywall with Green Glue sandwiched between them to one layer of "Factory damped panels" alone.
    Note that the Green Glue company claims that the cost of two layers of regular drywall and Green Glue will still cost less than a single layer of factory damped panels. I cannot vouch for the accuracy of that statement, as I have never priced the factory damped panels that you referred to above.

    Here is a paper which describes the test results:

    http://www.greengluecompany.com/gree...mpedPanels.php

    Note that the results are VERY CLOSE if one is looking only at the STC results. But, look at the differences inside the red circle on that one chart.

    I am NOT suggesting you go with Green Glue. I am not suggesting that you avoid Green Glue. Instead, I am reminding you that you should factor in the actual costs of any assembly versus the actual reduction which was verified by test results in a third-party lab. And, of couse, you should also always take any STC results with a grain of salt, if you hope to also combat the low frequency LFE bass from a powered subwoofer.

    Actual costs -- if you are paying for labor, would the additional labor to install two layers of 5/8" drywall be lot more as opposed to installing only one layer of factory damped drywall, such as you suggested? It would most certainly be more. If you are seriously narrowing to those choices, find out how much more you will pay someone to hang two layers, and factor that in. This might cause the factory panels to end up being the better bargain. I do not know.

    Just my take... and, no, I have no stake in the product known as Green Glue. I am also a huge fan of complete decoupling (a room within a room, which requires no special add-on products to accomplish) or partial decoupling (usually requires some added specialized hardware, such as RSIC clips or resilient channel or hat channel). And, I am also a huge fan of simply doubling up on drywall, and using two layers of 5/*" instead of the 1/2" stuff, as it increases mass a lot without increasing your costs so much.

    I am not an expert. I did read a lot about this prior to building my own basement home theater, though, and I did my own cost projections using a lot of different systems. Time-consuming, but easy to actually do.

    Take care,

    -Bruce
     
  15. AquaSerge

    AquaSerge Extra

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    I have been reading quite a bit on green glue and other various methods to isolate sound lately. I really like the room - in - room idea, with some variation as to how i would assemble it. However, in my case I have to remember that more lost = higher overall sq footage of a building and a higher overall cost of rent, with no way to justify balancing that out.

    I do have one question though. In the room in room method, how would you fill in the small gap around the two doors to prevent trash, children, people, equipment, all that sort of stuff from having any access into it?
     
  16. BruceSpielbauer

    BruceSpielbauer Second Unit

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    I was told by some of the best to leave that 1 inch air gap alone, and to merely "dress it" for cosmetic purposes. I was told to be careful not to try to connect the two doors in any way. Any hard, real structural connection would defeat all of the work done to decouple things. The suggestions I read of all discussed using soft materials, such as rubber flashing, or viny flashing, etc. I went to my hardware store and bought some rubber material which normally is used at the bottoms of garage doors. I bought very wide stuff (1 3/4 thick). I installed it along the edge of one of the doors, using simple screws with a washer. It overlaps the air gap, covering it from view. It is not even actually attached to door number two. I ran this up both sides of the door, and also above. It looks fine (in fact, it actually looks kind of cool, in a heavy duty industrial way). I can peel back the one edge to who curious visitors how the room was built, as I explain.

    Hope this helps,

    -Bruce
    -The ultimate add on for any Home Theater: http://www.S2Digital.com
     
  17. AquaSerge

    AquaSerge Extra

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    For my buisiness, I really kinda like the room in room idea. However I'm having a trouble with the layout. Considering it will actually be set up much like a mini cinema theater, my wall concept is this, however I'm not sure if it is over kill.

    Interrior wall------Room------Interrior wall |||||||Middle wall|||||||| Interrior wall------Room------Interrior wall |||||||Middle wall

    Now I'm not building a room in a room persay, it is actually each room is built on its own, with no connection to any other room. So even if I didnt have that middle wall there, each room would never touch another to begin with. Im just not sure of the middle is overkill or not.
     

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