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Soundproofing Gone Wrong

Discussion in 'Home Cinema Building DIY' started by kid of the kop, Sep 1, 2005.

  1. kid of the kop

    kid of the kop
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    hi i recently had a builder to put me up a doublewall for soundproofing .after he was done i recently stumbled across this website http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm. now im getting a bit worried as my contruction worked out like this. sharedwall,airspace,stud,rockwool,double drywall then space,stud,rockwool,double drywall now im getting a bit worried as the picture is totaly different please can someone advise if this is going to do a good job or do i get them back to sort it out
     
  2. mattym

    mattym
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    that link dont work
     
  3. kid of the kop

    kid of the kop
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    sorry try the link again
     
  4. IronGiant

    IronGiant
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    Looks like you've got the double leaf STC 69 but with one set of drywall the other side of the rockwool, don't know if that would actually have any effect (might even be better!), but I doubt it's worth the upheaval of tearing it all down to find out. Who specced the build you or the builder?
     
  5. woody67

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    Exactly what is the percieved problem?

    There are many ways to construct a stud wall, did you give him a specifiaction to build to. If the wall is constructed properly then I can't see what grounds you will be able to call him back for.

    Incidently, that site is american based so the figures may not be relevent in the UK. There are also many other ways to acheive comparable sound insulation without having such a thick wall
     
  6. kid of the kop

    kid of the kop
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    what are the other ways of acheving a soundproofed wall then
     
  7. woody67

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    All walls have some soundproofing, and you have to think of what level of soundproofing is required.

    Single or multiple layers of plasterboard, a layer or two of MDF, 4" instead of 3" timbers, denser quilt insulation, rubber or foam isolation pads, fabric surface finish etc.

    It depends what you are tring to insulate from, the neighbours, the kids in bed, or the next room, or just to enhance the internal room sound. Is it for general sound or the lower frequencies from the sub?

    If its just a typical wall for an HC, the 4" timbers, with 4" rockwool quilt, and one or two layers of 12.5 plasterboars and skim, will be adequate.
     
  8. Gary Lightfoot

    Gary Lightfoot
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    The STC (Sound Transmission Coefficent IIRC) is a universal standard as far as I know, but the figures shown in the link are all relative anyway. The best method is of course STC 69, though it sounds like you have an STC of 40 additional to whatever value the existing shared wall has (Add maybe 4 for that), plus approx an additional 6 for the two extra layers of plasterboard - one on each wall, (so maybe a total STC of 50). It's a common misconception that the construction of the STC 40 diagram should be better, but having a larger gap between the two new walls actually produces better results as the physical walls are further apart and the sound has further to travel from plasterboard to plasterboard so transmission is less (hence no PB on the wall faces facing each other).

    That's not to say that you will not have an improvement in sound travel over the single wall though because you have, and I would think the sound reduction for most frequencies down to 125hz would be noticable.

    Bass frequencies are far more difficult to tame though, and a room within a room is the best method in that respect I believe.

    Gary.
     
  9. baldrick

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    Obviously it's dependent on budget etc... but the optimal configuration for soundproofing is to use isolation so that the walls, ceiling and floor can all move indepently of each other and the superstructure of the room.

    Doing this will absorb huge amounts of sound relative to other methods, especially those pesky bass frequencies.
     
  10. Gary Lightfoot

    Gary Lightfoot
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    A room within a room is the ideal, but you want the room to be isolated from the surroundings and not act as a huge bass trap, otherwise you could lose all of the sub bass from the room as well, and no matter how many subs you had, you'd not have any bass. Resiliant channel can have the same effect.

    EDIT: assumed you meant all of the walls in the new room to be independant of the existing room as well as each other, so I was referring to the issue of floating walls acting as bass traps, but after re-reading, I think you meant the room within a room idea. If that's the case, I'll get me coat... :)

    Gary.
     
  11. baldrick

    baldrick
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    I was referencing to all surfaces 'floating'!
     
  12. Gary Lightfoot

    Gary Lightfoot
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    I wonder if that can be detrimental to in-room bass though - got any links for it Baldrick? What do you mean by 'floating' exactly?

    Gary.
     
  13. baldrick

    baldrick
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  14. Gary Lightfoot

    Gary Lightfoot
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    The first thing I see there is resiliant channel - Aargh, don't use it for a home theater room because although it can do a tremendous job for sound isolation, it can also turn the room into a huge bass trap and you will have no bass at all. It's an unknown quantity so you can be taking a big chance with room response if you use it.

    One example I use is from Dennis Erskine - one such room had used resiliant bar, 5 subwoofers and had no in-room bass. They had to strip down the walls and remove the bar (I assume they rebuilt using traditional methods). Once rebuilt, the room had one sub and plenty of bass.

    I believe that the room should be built so that its audio response will be a known quantity (using RB won't give you that luxury), and then you should use room treatments to address any issues. Once that is done you can use equalisation to fine tune if needed.

    Gary.
     
  15. Gary Lightfoot

    Gary Lightfoot
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  16. baldrick

    baldrick
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    Gary,

    I must confess I hadn't thought about the 'negative' effects of soundproofing!! We are about to embark on a new built and my home cinema kit will be located on the 2nd floor of the house.

    My two key aims are to reduce the amount of noise that escapes through the roof for the sake of our neigbours and more importantly all but eliminate the sound transference to the rest of the house...

    I suppose one perk is that the new property is going to be timber framed so the natural 'flexible' attritbutes of should transfer less sound through the struture than rigid blockwork/concrete.

    If you've got any thoughts on the matter then let me know.

    Cheers,

    Ben
     
  17. Gary Lightfoot

    Gary Lightfoot
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    My loft has 'flexible' walls and floor so the bass isn't as good as it is in my lounge with solid walls and suspended wooden floor. The neighbours don't seem to hear much though, and listening in the front and back garden seems to bear that out. I would think any usuall construction methods that don't employ resilliant channel will be fine.

    I find my loft hatch lets through most of the sound, but it's not a big deal in my house so it's not something I really need to address. In your case you may want to use a solid door (I would think a fire door would be essential if it's aloft conversion, and they're better to use for sound proofing), with some form of sealing around it to keep the sounds inside (include sealing the keyhole or not having one).

    If it's a loft conversion then you'll be using a new floor anyway, and that should help towards reducing sound transfer to the house below, but I don't know if there are better ways to mount the new floor supports to reduce bass travel. If your building regulations stipulate a second layer of plasterboard on the ceilings below, then that will also help with reducing sound transfer so try to accomodate that if you can (there are ways around it I believe if you don't want the extra work it entails).

    Make sure all edges in the new room are sealed and that will include the flooring - any air gaps will allow sound to travel so you need to make the room air tight where you don't want sound to leak out.

    I built new walls in front of the party walls of my loft and that seems to have helped with keeping the sound in the room and within my house. Using 4x2 construction with 4" of insulation and 2 layers of plasterboard will go a long way to reducing sound travel into the houses each side, and try to make sure there is something done under the new floor so that sounds doesn't travel down and into next door that way (by-passing the walls).

    I have a single layer of plasterboard on my internal ceiling, with 2" of insulation and a 2" air gap. You may be able to have an external layer on the roof before the tiles are put back, and that will help too.

    If you still end up with less bass in the room than you wanted, then you can fit bass shakers or some other form of tactile transducer into the seating so that you can feel the bass rumble below 80hz (or less 50hz can be better), and give th eimpression of more in-room bass. That's what I dod and I think it adds a lot to the experience so is worth doing anyway - the tactile experience added with the audio and visual adds another dimension IMHO.

    When the room is done, test it with some speakers and see what the sound is like. For multi-channel audio absorptive walls on the screen wall and below ear height are required, and reflective above. You can use Mattym's RPG products and software which will help you to achieve a good balance by identifying reflections etc, so you can look at room treatments after the room is done if slap echo etc is a problem. Floor carpet and furniture/people will make a difference as well so it might be better to try the audio as you get the room furnished.

    Gary.
     
  18. baldrick

    baldrick
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    The company I linked to for the RBs sell an isolating batten to use between the floor deck and the structure of the house, so this could be one option, and stick with 'fixed' walls, just using a double layer of plasterboard throughout.

    This is a new-build detached house, so the noise transference to the outside needs to be enough so as not to over any potential nuisance to neighbours with windows open etc...

    Whilst we've got the option to do whatever we want I would like to do everything I can to ensure that the noise from the HC doens't propogate through the property.

    Again domesticsoundproofing sell a cement impregnated floor board which will probably help...?
     
  19. Gary Lightfoot

    Gary Lightfoot
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    The cement impregnanted floor boards sound like they would work well compared to normal boards. Have you thought about contacting a proffessional person in this field to make sure everything is done as best as possible for this purpose? Dennis Erskine is in the USA but comes from the UK and might be able to point you in the right direction. It would be a shame to spend a lot of money on builders who don't know about soundproofing and you may end up with something that doesn't work as well as you'd like.

    Gary.
     
  20. kidofthekop1972

    kidofthekop1972
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    THE TITLE SAYS IT ALL
    I had a company in to soundproof my living room i asked for a double wall i dont really know much about it but here goes i watched them do all the work this is how they did it they built a stud wall with 2*3 studs a inch away from the wall stuffed it full of rockwool then stuck up 2 layers of plasterboard sealed all round the edges then they built the other wall with 2*3 studs a inch away from the wall stuffed it full of rockwoll then stuck up 2 layers of plasterboard sealed all round the edges then skimmed it with plaster and job done now here is the proplem i found this website http://www.bobgolds.com/WallCharts/QuadTripleDoubleLeafSTC.htm now im a bit worried just had new nieghbours so i dont really want to go round they dont know im into movies so better thatway we live on a noisy main round anyway is their anybody out they who can help me cheers
     
  21. IronGiant

    IronGiant
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  22. mattym

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    lol, 2 whole pages of it too!

    are you having a massive problem then Mr Kop?
     
  23. inzaman

    inzaman
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    yes we did, and now merged with that thread.
     
  24. mattym

    mattym
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    moderator magic dust weaves its intricate spell! :D
     
  25. IronGiant

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    With regards to your problem Kop, you don't have to tell them you're into movies, some music with a good bass track turned up loud would probably do the trick, but I think you have to bite the bullet and go round and see if the sound is coming through.
     

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