John Sayers' Recording Studio Design Forum Archive

If I put a layer of 80 mm of 40 kg/m3 rockwool and 40 mm of 70kg/m3 rockwool over it, does it woks ??

rockwool between joist must be dampen the resonance only? It doesn't matter the place of higher density rockwool??

Yes it does; if you put the lighter material on TOP, it will compress less so you will keep the damping action from the insulation. IF you put the heavy stuff on top, it will crush the lighter stuff more and sooner - NOT good... Steve

ok, thanks. But, its the same using 12 cm of 40kg/m3 rockwool or is better using 8 cm of 40kg/m3 and 4 cm 70kg/m3?? how much diference??

Very little difference either way; the only thing is, the heavier stuff won't compress as much so you have to be careful to get just a SLIGHT overfill of the cavities (like maybe 1/4" with the 70 kG stuff) before putting on the floor material, or you will get less isolation... Steve

http://forum.studiotips.com/viewtopic.p ... 86&start=0


http://www.recording.org/ftopic-28211-0.html

hugo_inside wrote:If I put a layer of 80 mm of 40 kg/m3 rockwool and 40 mm of 70kg/m3 rockwool over it, does it woks ??

Does it work to accomplish what???????????????


You want to build a floating floor because?????????

Rod

"Does it work to accomplish what???????????????"

To absorb the resonance

You want to build a floating floor because?????????

Isolate the recording room of the control room, and both of them of the external sounds. There is something wrong? [/i]

hugo_inside wrote:"Does it work to accomplish what???????????????"

To absorb the resonance

You want to build a floating floor because?????????

Isolate the recording room of the control room, and both of them of the external sounds. There is something wrong? [/i]

My biggest concern with this approach to sound isolation is that you are most probably not going to attain any real additional isolation (compared to a standard concrete deck) and may actually cause problems with the amplification of certain problem frequencies.

It's one thing if you are building an isolated concrete deck - design properly and you'll acheive a 10hz deck assembly - with a weighted attenuation at roughly STC 79.

It's another thing to try to acheive any real sort of isolation thru the use of elevated wood decks. You're building a big drum head there - and not only are they difficult to design to get what you want - but they also have a resonant frequency (just like that drum head) where they actually amplify the signal. Concrete does as well - but if the resonant frequency is 10hz - you aren't going to have a problem.

If you want a raised deck becuase it's great for wiring conduits, etc., then build it and fill it with sand (great mass - great damping effect) but I would never reccomend the approach you're taking.

This is straight from Mason Industries - one of the industry leaders in sound isolation.

It is often necessary to provide a wooden floating floor rather than the heavier concrete construction with wood topping. Cost or weight restrictions may be the factor. In older buildings it is often necessary to improve on existing floors with a lightweight impact noise resistant construction. A resiliently supported wooden floor will reduce the rumbling noise of a bowling ball, the click, click of a woman’s heels and that portion of a typical noise generated by a piano that travels down the piano legs and into the structure. It will offer only minor reduction of airborne sound, as there is insufficient mass in the surface. In some applications on stages or in rehearsal rooms the primary purpose is relief and comfort for the dancers. Landing on concrete or hard mounted wood surfaces is very damaging to a dancer’s feet and legs.

These floors do not have enough mass to acheive what you are looking for.

Hence my original question -

Sincerely,

Rod

Hi Rod,

thanks for answering, but now I'm so confused . I try t explain my problem:

I'm building 10 reherasal rooms and a Recording studio in a 300 sq meters warehouse. All the rehearsal rooms have floating floor, but instead of EPDM, Neophrene, Sylomer, etc... we use very high density pine fiber for floating floors... maybe it's not the best, but we haven't much money for this kind of rubber.

4 of this rehearsal rooms floor are filled with sand,



and the other 3 with rockwool and low density fiberglass. The rockwool and fiberglass floors are very resonant on 440 Hz but people like it. They say: "wow, the drums sounds great!" . Bass and drums makes vibrate the floor and tickle my feet.

But this is very high frecuency for a recording studio...

The studio floor is still not builded but the are some problems:

1.- If I don't float the floor, will rehearsal rooms distort me when I start recording bands? There are 2 walls of 200 mm concrete block filled with sand plastered both sides and floor is made of concrete 150 mm aprox. And then there will be 30 mm of air gap , 40 mm of 70kg/m3 rock wool and 30 mm plasterboard.

2.- what is your advice for the floor? fill it with sand? No floating floor?

this is the studio now:


[/img]

hugo_inside wrote: what is your advice for the floor? fill it with sand? No floating floor?

Hugo,

One nice thing about raised floors is that you can run low voltage wiring in there and then up to your board, gear etc. which is nice for keeping the low voltage away from line voltage.

Personally I would fill it with sand.

Rod

hugo_inside wrote: what is your advice for the floor? fill it with sand? No floating floor?

Hugo,

One nice thing about raised floors is that you can run low voltage wiring in there and then up to your board, gear etc. which is nice for keeping the low voltage away from line voltage.

Personally I would fill it with sand.

Rod

rod gervais wrote:This is straight from Mason Industries - one of the industry leaders in sound isolation. . .

Fantastic quote, Rod! (Here's the source, in case anyone cares...)

Thanks Rod,

The building method if I fill with sand is the same, is not? EPDM rubber pucks under joists, fill the gaps with sand, cover sand with plastic to avoid dampen, drill to joists the particleboard boards (2º layer turned 90º to avoid joints) and then put a floor like this if you want:



Does I need this stud under floor construction?? Is not necessary? is better? this floor will be builded over particleboard.

[/img]

Low voltaje is electric wiring?? or is the electric wiring of the equipment??
And Line voltage??