R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: small floating room, with a light weight concrete floor  (Read 9123 times)

Thomas Jouanjean

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 342
Re: small floating room, with a light weight concrete floor
« Reply #15 on: November 24, 2010, 06:08:08 am »

PeterDraaisma wrote on Tue, 23 November 2010 15:57


But is this the reason why you didn't recommend the use of a layer of glaswool/rock wool under the floor?



Yes indeed Smile
Logged
Thomas Jouanjean
Northward Acoustics - Engineering and Designs
http://www.northwardacoustics.com
http://www.facebook.com/pages/Northward-Acoustics/1062876633 71

Pro Audio Partners:
ATC Loudspeakers
FOCAL Professional Speakers

PeterDraaisma

  • Newbie
  • *
  • Offline Offline
  • Posts: 30
Re: small floating room, with a light weight concrete floor
« Reply #16 on: December 01, 2010, 05:44:53 pm »

And that is the reason why the floor's self resonant frequency is so important?

Would it be a good idea to put a thin layer of Akotherm 1.5 cm between the benches so there is room for the airflow and there is damping for the resonance.

Do you have some info for me to calculate the floor's self resonant frequency. I only found a post by you on gearslutz.com regarding the floor's self resonant frequency.

http://www.gearslutz.com/board/studio-building-acoustics/529 223-sylomer-floating-floor-load-calculation.html

Best regards,

Peter

Logged

Thomas Jouanjean

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 342
Re: small floating room, with a light weight concrete floor
« Reply #17 on: December 02, 2010, 06:30:19 am »

If you want to reduce the floor's resonance you can always put additives to dampen the concrete itself. The brand MAPEI in Europe has a few good options. Usually sand/cement chape additives that make the floor more resistant to torsion will have a good damping effect on it too. Careful on the % you add to the mix. Don't put too much or at one point it will actually lower your floor's strength... And you need it strong.

Don't put that 15mm layer.

Re: the resonance calculation. It's too complex and time consuming to be explained on a forum, it would take me hours to write about that. There are loads of variable that vary with each particular situation too. There is not a "one-fit-all" calculation.

The one on GS is a very fast and easy situation because a steel deck with well known properties is used. So it can be modeled quickly and simplified enough to make a quick and dirty 'forum' rough estimate.

The floor provider in your case may have some data though. Depends if they have an engineer that does that in the company or not. Ask them Smile



Logged
Thomas Jouanjean
Northward Acoustics - Engineering and Designs
http://www.northwardacoustics.com
http://www.facebook.com/pages/Northward-Acoustics/1062876633 71

Pro Audio Partners:
ATC Loudspeakers
FOCAL Professional Speakers

PeterDraaisma

  • Newbie
  • *
  • Offline Offline
  • Posts: 30
Re: small floating room, with a light weight concrete floor
« Reply #18 on: December 02, 2010, 04:38:49 pm »

Why does a company like kinetics use glaswooll around their pucks? Does the air don't need to vent by their product? Just curious:-)

http://www.kineticsnoise.com/arch/rim/concrete.aspx

and according to their test the stc is higher:

http://www.kineticsnoise.com/arch/tests/rim.aspx

best regards,

Peter
Logged

Thomas Jouanjean

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 342
Re: small floating room, with a light weight concrete floor
« Reply #19 on: December 03, 2010, 07:43:20 am »

They do what they want to do. It's all a question of how low the frequency has to be, deflection of the floor, etc. It also depends on how they measure the IIC, so how low you get in the data you look at. For info, to put some perspective on numbers:



"Impact Insulation Class (or IIC) (or IIC Rating) is an integer-number rating of how well a building floor attenuates impact sounds, such as footsteps. A larger number means more attenuation. The scale, like the decibel scale for sound, is logarithmic. The IIC is derived from ASTM method E989, which in turn uses a tapping machine specified in ASTM method E492."

The IIC number is derived from sound attenuation values tested at sixteen standard frequencies from 100 to 3150 Hz. Unfortunately, "real world" footstep noise is also generated at frequencies below 100 Hz, so the IIC value may not accurately describe the complete noise attenuation profile of a floor."




Natural frequency of a studio floated floor is usually close to 6Hz. If you don't manage the air gap you'll get in trouble but under 100Hz. With a natural frequency at 20Hz instead of 6Hz, you won't see a difference at 100Hz. You will at 60Hz. See my point?

I do remember they recommend even sealing the floor with caulk or something like that.

I disagree with that, for the reasons mentioned earlier, especially for lighter floors with small air spaces between the 2 floors. It WILL make your natural frequency go over 20Hz to maybe even 30Hz, just from air stiffness.

So, I stand my ground...

You'd have 120mm of air space to play with we'd be discussing some 60mm Rockwool in there.

BTW I don't see where they mention the natural frequency of their floor. I don't think I've ever seen that number either. It's likely written somewhere though.

I have given you advice about how to manage your problem, but you don't have to follow that advice... Do what you want.

Logged
Thomas Jouanjean
Northward Acoustics - Engineering and Designs
http://www.northwardacoustics.com
http://www.facebook.com/pages/Northward-Acoustics/1062876633 71

Pro Audio Partners:
ATC Loudspeakers
FOCAL Professional Speakers

PeterDraaisma

  • Newbie
  • *
  • Offline Offline
  • Posts: 30
Re: small floating room, with a light weight concrete floor
« Reply #20 on: December 04, 2010, 05:25:19 pm »

Thomas,

Thanks again for the info, I really appreciate you input Smile . It is almost my private forum here. I don't question your expertise  Very Happy

I just wondered why there a difference approaches for floors. You told me that studio building design isn't voodoo,but a lot of calculations, but I do understand your point. I will contact the floor metal company to ask them about the self-resonant frequency of the floor.

But the floor design venting started me to think over the m-a-m wall designs, do the walls need to vent to? Can you vent the floor in to the walls etc.

Best regards,

Peter
Logged

PeterDraaisma

  • Newbie
  • *
  • Offline Offline
  • Posts: 30
Re: small floating room, with a light weight concrete floor
« Reply #21 on: December 06, 2010, 03:52:01 pm »

Hi Thomas,

I found this: http://www.hifiladen.de/tools/index.htm?/tools/t_helmholtz.h tm

It is a room resonance frequency calculator, when i put in the dimensions of the space under the floor, does this say something about the floor resonance?

Best regards,

Peter
Logged

PeterDraaisma

  • Newbie
  • *
  • Offline Offline
  • Posts: 30
Re: small floating room, with a light weight concrete floor
« Reply #22 on: December 17, 2010, 09:50:42 am »

I have got the floor's resonance frequency according to the papers I got from Reppel bv is with a width of the benches,( hart to hart)60cm, 11.5 hz. So is this low enough?

Best regards,

Peter

Logged
Pages: 1 [2]  All   Go Up