Walls in H/T question

Discussion in 'Archived Threads 2001-2004' started by Michael Ipp, Jul 5, 2001.

  1. Michael Ipp

    Michael Ipp Stunt Coordinator

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    What does everyone recommend for the walls?
    I have some thick insulation and also bought some rubber sound proofing material. I planned on using sheetrock. Should I go with 1"? 3/4? or 1/2" + 1/2? MY feeling is the 3/4 would be the cheapest and eaisiest to work with?
    Can you deaden a room too much? Thoughts?
    Thanks
     
  2. BobN

    BobN Auditioning

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    It will not make that much difference whether you use 1" or1/2" sheet rock. Sound is transmitted through the studs. In other words the best way to sound proof a room would be to lay a 2x6 plate and alternate 2x4 studs for the rooms this wall divides. This way sound is not carried from one stud all the way through to the adjoining room. Glue, specific for sheetrock, does help to a small degree because it acts as a dampening agent between the sheetrock and the stud limiting the vibration helping to deaden the sound. Make sure the glue is for sheetrock. The reason is that liquid nails gets hard and will carry the sound waves. The glue for sheetrock stays kind of soft and rubber like when it sets. Insulation does help a little bit. I am not familiar with the rubber sheet you are refering to.
     
  3. Michael Ipp

    Michael Ipp Stunt Coordinator

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    Here is a link to the soundproofing material.
    SilentSource
     
  4. Darren Hunt

    Darren Hunt Agent

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    When I built my room, I had the external walls done with a staggered stud setup like Bob mentioned. I also used a special insulation that is similar to recycled paper. It comes in big 2' by 3' blocks and is feed into a machine that munches it up into a fuzzy mess that is blown into the spaces between the studs. This helps fill any air gaps, and is dense enough to help reduce some of the mid range to lower bass (not that you can stop it completely short of solid concrete walls lined with lead).
    On top of this, I placed acoustic tracking (metal strips about 2" wide in the shape of a flattened 'U') running horizonally across the inner studs for the length of the room (about 5 rows, spaced 1.5' apart). You then attached the drywall to the tracks, making sure to not screw near the studs, but into the tracks. This helps decouple the sound transfer from the drywall to the stud, to the outside stud. Once this is done, your weakest spots in the room will end up being your ceiling and the entrance into the room. One thing to mention as well is that when you do the acoustic tracking, the drywall is essentially floating off the stud, which means you can not attach heavy objects to it, such as speakers. If you do, you run the risk of having the speaker fall off, or the drywall ripping itself off the wall. Also make sure to chalk all the gaps between the walls/ceilings/floors to stop any air gaps. These gaps can cause huge holes in your sound 'proofed' room. Also ensure that you do not place any electrical conducts near each other on opposite sides of the staggered stud wall. I good idea is to keep them at least 1.5 to 2' apart to prevent any gaps for sound to travel through.
    In my room, I had the outer walls sound 'proofed' as best as possible using the above methods, and then had a second wall built within the room that I hung the speakers and such on. Within these walls, I left a 6" gap so that I could install sound diffusors or absorbers where ever I wanted to control any room issues that I find. These holes were then covered with cloth fabric panels (sound transparent cloth) to make the room appealing to the eye. I am still working on it, so I have yet to get to the point of building the diffusors or absorbers to see how it works.
    Good luck with your project!
    Darren
     
  5. Michael Ipp

    Michael Ipp Stunt Coordinator

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    This might sound ignorant, but the reason for "soundproofing" is to keep the sound in right? I am not all that concerned with people in the other room hearing it, I own my own house.
    The room has four walls, three of the are outside walls where one is attached to the house. It is an existing room so staggering the studs does not seem viable.
    If I space the sheetrock off of the studs/sound barrier, don't I create space?? That's ok??
    I guess I really don't understand sound waves as well as I should or what exactly I am trying to accomplish with my soundproofing. Any books I can get and start studying
     
  6. Darren Hunt

    Darren Hunt Agent

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    Yes, the purpose of sound proofing is to keep the sound in. I own my own house as well, but I wanted to make sure that if I was watching a show late at night, I wouldn't disturb my wife and/or future kids because of the noise if they were asleep. Sound proofing has enabled me to reduce all the highs and some mid, leaving just the lows to rumble around the house.
    As for the sound waves....
    Yes, having the drywall on tracks makes a small airgap, which really doesn't hurt. As long as the drywall is completely sealed (i.e. top, bottom, and both sides), the sound will have to pass through it, and not around it. Once it does this, it then has to go either through the small air gap, or through the metal channel, into a 6" wad of insulation, and then through another sheet of drywall to escape. Since none of the studs are connected between the exterior and interior, the sound will have to travel through the insulation. This changing of densities between drywall/metal/wood/insulation attenuates it quite dramatically. Without the staggered studs, the sound will travel through the drywall, through the stud, and finally the last piece of drywall. The big problem here is that sound travels through dense materials very well. The connecting stud will transfer the sound without attenuating it very much. If you make the sound go through more routes to reach its destination, the more it will be attenuated.
    As an example, if you set off an explosion off the coast of Australia underwater, you will be able to hear it off the coast of California (taking in account the time it takes sound to travel). This is just one medium, being water. Water of course carries sound waves better than air does.
    If you only have one wall to worry about, you can take the interior drywall off of it, lay down a 2x2 to create a 2x6 base and header, and then add in a new row of studs between the existing ones. In the big picture you will get the most bang for your buck by doing a staggered stud setup. The other things will improve it as well, but not nearly to the same degree that a staggered stud setup will. Just make sure you seal off the drywall!! Any gaps allows the sound an easy method of travelling through, defeating the purpose of the staggered studs.
    I have a book at home that talks about most of this. It is called something like "The Masters Handbook to Acoustics". I will check when I get to to confirm the title, and respond here. It will be very informative and will fill in most of your questions.
    Darren
     
  7. Darren Hunt

    Darren Hunt Agent

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    The book that I have that I found to be very informative is called:
    The Master Handbook of Acoustics 3rd Edition.
    Author: F. Alton Everest
    ISBN: 0-8306-4437-7
    Tab Books
    It costs about $25 US.
    It could be up to a newer version, as I bought it about 2 years ago.
    Darren
     
  8. Chris Hussak

    Chris Hussak Auditioning

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    Michael,
    I believe the metal product Darren is using to isolate sound is called resilient channel. It works to isolate sound but also can kill your bass response. So it's not really recomended in a home theater. I'm not the expert on it so I would suggest searching for threads on RC and posts by Dennis Erskine before using it.
    Also do the same search atwww.avscience.com , as similar topics have come up numerous times.
    Good Luck with your theater!
    Chris
     
  9. Jeff Loughridge

    Jeff Loughridge Stunt Coordinator

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    I would suggest you also try Acoustical Solutions for ideas. The RPG products are particularly nice. They (RPG) are manufactured nearby, and I have used them for studio treatment. RPG also has a very good section on Home Theaters. I can't over emphasize their knowledge and competence when it comes to acoustics. RPG Diffusors
    ------------------
    Jeff Loughridge
    Director of Engineering
    WPGC/WHFS
    Infinity Broadcsting Corp
    [email protected]
     

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