knightfly:
"WHY do you feel you need a floating floor?"
In the beginning the idea for making a floating floor was because i wanted a better sound isolation from the recording room to the control room and from both rooms to the outside.
I'd seen the floating floor idea at the SAE webpages and also in this forum. So i thought... this must be a good idea. So I tried to get any rubber, some rockwool and plywood and tried to start.
But... Last night after reading all the discussion about a floating floor (many thanks for the links!!!) till today at 5 o'clock in the morning (man, this is really interesting) it seems that what iam doing is wrong.
If I understand correctly I have to calculate the resonance frequency, which i can't because i don't know the rubbers values. So in the worst case the floor will not attenuate anything but boost anything in a specific section of the frequency range. (I'd seen the EAR webpage with the diagram) I don't want that
If I understand correctly a proper floating floor will give me a 20% better transmission loss.
Also calculating the MSM isn't easy because the existing floor varied from 15 to 20 cm thickness.
I don't know how much I'd read: "Do it right or don't"
So I think I will... ahem... "don't..."
The only problem then would be to hide the fat metal plate which is now in the control room and corridor. With the floating floor idea from the beginning the metal plate would be "in" the floor. The complete truss and the 1st floor sits on the two iron girder.
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len-morgan:
What kind of music are you recording?
Rock. Which means the tama starclassic drums, mesa boogie 4x12 for guitar, ampeg bass amp (the fridge)... so it will be loud. If it would be possible I'd like to do the band-practice in the recording room as well. And band practice time is mostly from 20 to 23 o'clock.
len-morgan:
Are accoustic drums involved?
Yes. I think the snare will be the problem and the bass amp of course.
len-morgan:
What hours are you going to operate?
Because iam doing this as a hobby I will use these rooms after work and at the weekend. And of course it would be good if I can record anything at the late evening/night.
If I wold know KNOW that I can't record drums at night I can NOW think about making a small booth with better sound insulation in one corner of the recording room. It would be pretty bad to do this when the floor and everything is done.
len-morgan:
How close, and where are your neighbors?
I did a picture
The next neighboring house it 3,20m away. But between the recording room and the neighour there is a garage with lime malm brick and clincer. We build the garage last year.
http://www.nrgrecording.de/tempfolder/house2.jpg <bigger picture
len-morgan:
Is anyone above or below you? Do you share any common walls?
There is no one above me... the recording room is one room from the floor to the roof. The control room has a 1st floor. On top of the control room there is the plant room and a bedroom or rest room or whatever it will be in the future... but thats only for the studio itselfs... no one is living here of course.

The recording room is sharing one wall with the garage behind the recording room, and the garage is sharing one wall with the house. The bedrooms of the 3 tenements are far away from the studio.
len-morgan:
Are you in a similar situation?
30'? The nearest neighbor is 3,2m/126' ?? away from the recording room and thats the distance from the garage to the neigbors wall... the garage is betwenn the neighbor and my recording room.
So i bet IAM in the same situation.
But the inner walls don't rest on neoprene or something like this, the drywalls are fixed directly with a lath construction to the roof but with 16cm fiberglass (6inch) and a layer of plastic as moisture barrier. The drywall at all 3 sides are standing directly on the existing floor only isolated with a kind of foam which is always used here in germany for this purpose. Ok, i bet its made for a building industry standard but not for recording studios.
Some time before I placed a 1.2KW PA system in the middle of the recording room and turned the volume up to 10... that was before I did anything in the studio... and it was loud outside. I could hear/feel the impact sound at the outside and my neighbor was looking out of his window.
When I do this test again next time after installing all the walls, adding additional doors... It could be TOO LATE to do anything. So thats my fear.
Regarding the floating floor i did in one room... Isn't it possible to find out the resonance frequency without calculations? I don't know anything about the rubber material and will never find out anything about it.
So one crazy idea is to put a bass speaker on the floor and use a frequency generator, which i have at home, to sweep all the frequencies to the speaker. With my behringer measurement microphone I could try to find the point with the biggest amplitude. Isn't that my resonance frequency? Ok the resonance frequency of the floor should be 4 octaves lower then the frequency i want to isolate. So if there IS any resonance when turning the potentiometer from 33-250Hz (thats the range of the bass speaker) I should definately throw the floating floor out of my studio.
Crazy Idea... just tell me that iam wrong.
The calculation formulas are any thing else than simple. Iam not a mathematician. Doing the wrong calculations causes a wrong resonance frequency and a useless or even an inferior floor as I understand correctly. I can't ask anyone to do the calculations for me nor do I know a source of an easier spreadsheet do to the calculations myself. And I don't know if it would ever be possible to make a working floating floor with joists, mineral fiber insulation, plywood and MDF. I can't buy heavy iron plates to get a heavier mass. It would be easier to do a conrete floating floor like Paul.

Also when Paul paid over 2000€ just for the sylomer for his studio I have to pay MUCH more. Because this is only a crazy hobby project my budget is limited of course. Removing the existing concrete floor to make a concrete floating floor isn't possible for me i think. The existing concrete floor is 15-20cm thick and it is so damn hard! If it would be screed no problem... but concrete...

I tried to make a hole for the water conduit and the drain with a sledge hammer. It lasts 2 hours for a smaaaaal hole.
What do you think... do I need more noise insulation to the outside. Because thats the most important thing to know.
Kind regards and many thanks for being so patient with such a dum guy
Frank.