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PostPosted: Sat Nov 16, 2013 11:26 pm 
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Location: Queensland, Australia
We are trying to work out which treatment we are using on top of our existing plywood floor to reduce sound from coming into the studio.
The pic below shows a rubber composite product called Acoustamat.

Attachment:
Acoustamat.jpg


The other way was recommended by others here at the forum. This was using 50mm thick rigid fibreglass under the new plywood studio floor.

Attachment:
Screencapture_118.jpg


Any thoughts appreciated.


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PostPosted: Thu Dec 05, 2013 12:55 pm 
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Location: Santiago, Chile
What type of sound is coming up from below? (frequency). And how loud is it?

It would probably be much easier to isolate that from down below, rather than trying to do it from above. If you have access to the room below, installing an isolation ceiling would be a relatively simple and relatively low cost solution, compared to trying to do it from above.

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PostPosted: Thu Dec 12, 2013 8:46 pm 
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Location: Queensland, Australia
We moved the studio build to the other side of the building so there is only metal posts and dirt underneath. The sound from a refrigerator compressor that is about 20 meters away underneath is probably the only concern at the moment. It just seems easier to do the work from above. There is only about a 1 meter space between the earth and the bottom of the original timber floor.


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Under studio 1.JPG


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PostPosted: Thu Jan 02, 2014 10:27 am 
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Either of those should work, but they are both meant mainly for isolating impact noise from above: ie, to stop the sound of footsteps, drum kits, or bass guitars from getting into the floor structure. I recently did something similar for the stage of a new church here in Santiago, where their original plan was very much inadequate. We built a steel frame (instead of the wood they had planned), and used a sandwich of two layers of 21 mm plywood with the local equivalent of Acoustimat between, and EPDM between the steel and the lower layer, mostly to damp the steel. It worked out great, but the purpose was NOT to create an acoustically isolated space below: it was only meant to create a stage that does not resonate and reverberate when walked on or jumped on, and does not vibrate with the bass amp and the drums. Right now, it sounds very solid and quiet as you walk over it, not the typical "boomy" sound of light weight stages.

So if that is what you are after, then either of the methods you prose would work.

However, I'm curious about two comments on the wall part of the second image: One is a label pointing at the drywall that says "Do not glue to timber here". Umm.... do not glue ANY part of your drywall to ANY timber!!!! The drywall should be ONLY nailed or screwed to the framing, following the normal nailing schedule, never glued. Gluing it creates line contacts instead of joist point contacts, which changes the behavior. Take a look at the Wyle report, to see the difference.

The other is a label pointing at a white thing between the two bottom plates of the wall (why 2?), that says "rubber puck". That implies that you are attempting to float your wall. Floating a wall is just as hard as floating a floor, and requires the same amount of careful calculation and attention to detail. Are you aware of what you will need to calculate? Do you have all of the relevant characteristics of the rubber that you plan to use there? To be honest, with the type of construction you are planning, I would not go to all that trouble to try to float a wall. That's a huge amount of effort (mental mostly) and expense for very little added benefit.

The final thing I would do is to still put some type of insulation in that cavity under the floor, to damp any resonance that does make it through. I would install that right under the floor itself, between the joists, to keep it off the dirt (which seems to be damp in some places?).


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PostPosted: Thu May 14, 2015 8:41 am 
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What is the "Wyle report"? Can you give me a link to this?


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PostPosted: Thu May 14, 2015 12:43 pm 
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Quote:
What is the "Wyle report"? Can you give me a link to this?


Sure!

https://app.box.com/shared/jcaoavdc8g

It's a research paper about increasing the isolation of typical house walls, from way back in 1973. They went through a lot of empirical tests, came up with some equations, and reported on all of it.

It's pretty old, but still very, very valid. And easy to understand, as well. It's a great work. Very comprehensive.

- Stuart -

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