I think this is no problem. Germany is not known for heavy earthquakes
That doesn't matter. You still cannot leave a wall unattached to the floor. Earthquakes are just an extreme example, but ANY type of vibration can cause the wall to move, even the vibration from opening and closing the doors. Since both leaves are sealed air-tight, opening and closing doors creates large changes in pressure inside the rooms and the walls, and even that could be enough to do damage, if the walls are not anchored into the floor.
Also, the original wall (which stands since 5 years like an oak) is completely non-structural.
That also does not matter. ALL walls need to be attached to the floor, regardless of whether or not they are load-bearing (structural) or not.
However, I already had a friend over who really knows this stuff and he didn't have any complains towards me.
Is he a qualified structural engineer? Is he legally permitted to sign the documents that state that your structure is safe, and meets all legal building code requirements? If not, then his opinion does not count. sorry.
there was no inspector visiting. I just asked the owner, if I may do this and he was fine with it.
Big red flag! You really, really REALLY need to call in a professional, qualified structural engineer, and ask for his signed, written report that says your structure is legal and safe. What ANYBODY else says is simply not valid. The ONLY person who can give you the correct advice, is the person who is technically and professionally trained to do so, and legally qualified to sign the documents you need.
If you do this without making certain that you are doing it legally, then YOU are responsible for what happens, and YOU are liable for all costs, expenses, injuries, damages, fines, and jail time. Not your friend who "said it was OK", and not the owner "who was fine with it". You and you alone are responsible.
My floor consists of heavy Tiles on concrete. While I assume, the tiles will transmit some low end, my situation is probably closer to concrete slab (I am in the basement) than anything else. I will probably not be able to really calculate the needed rubber deflection and area to get it floating. There are simply to many unknowns
Exactly, and since you have a "slab on grade" floor, then it is extremely unlikely that you will need to float the floor.
Regarding the ceiling and the stuffing material: Isolation is not important here. The only isolation I need is between the tracking room and the mixing room.
That also does not matter. Isolation is a "shell" or an "envelope". You cannot only isolate in one direction, because sound travels in ALL directions. sound will not just go the way you want, and the stop when it runs into a strong barrier. It will go in ALL directions at once, and if it finds a way where there is a weak barrier, then it will go through that, and still get around to the other side of the strong barrier, just as though it was not there. So you HAVE to isolate to the same level on all sides, in all directions.
Regarding the ceiling and the stuffing material: Isolation is not important here.
Yes it is. As I said before, "The insulation is there for one purpose only: to damp resonance inside the cavity." If you do not put insulation in there, then those resonance are NOT damped, and that WILL affect not just isolation but also the acoustics of the room.
That is why I was asking, if - in this case - tighter might be even better, because I crave absorption here, not reflection. It might still be better lighter packed.
You cannot "pack" the insulation at all. It can only be placed in the position where it needs to go, and must never be compressed or forced into a space that is too small.
The first thing would be my ceiling, which I earlier described here. It unfortunately is already a hung ceiling with just one layer of gypsum. It resonates as hell with sub woofer frequency
Exactly!
That is EXACTLY what happens when you don't put damping material inside the cavity. It is also what happens when the drywall is too thin, and the air gap is too small. To fix this, that ceiling must be removed and replaced correctly. If not, you will never be able to get your room acoustics under control.
I also couldn't afford to take the hole ceiling off as to do it properly
Then, sorry to say, your room is never going to be usable acoustically. The ceiling as acting as a panel resonator (panel trap, membrane trap), since it is a tuned resonant "skin" over an undamped air space: Basically, it is a drum.
1) Are there any smaller acoustic tiles available,
Those will not be much use. They don't have much mass, and "acoustic" is just a name: they are not meant for acoustic control in studios. The real purpose of those is for offices, schools, shops and places like that, where they need mild acoustic control of speech frequencies. Not major trapping and damping of bass resonance. The damping that you need must go inside the cavity, not on the face. Damping the face will help a little bit, if you do it correctly, but you STILL need damping in the cavity.
2) To insert insulation without having to remove the gypsum there is an approved method of injecting insulation grains (different materials available) into the ceiling from just a few holes.
That probably will not work either. You would have to find out the acoustic properties of those "grains", so call the manufacturer and ask them to send you their technical reports on the acoustic testing of those products. If there is no acoustic testing information, then forget it: you cannot use materials whose acoustic properties are not known.
He gave me green lights. But as he is no acoustic specialist,
The he is probably not the right guy to do the job!
I would think, the additional weight on the gypsum (hence, I would take the heaviest insulation available) must tame that resonance at least a little
You seem to be misunderstanding the acoustic principles here: This is not about mass inside the cavity, it is about DAMPING inside the cavity, and mass on the leaf. Two very different and very necessary things. You need the extra mass, but NOT inside the cavity: the extra mass must be on the "leaf" (in this case, the drywall ceiling). And you need the damping INSIDE the cavity, not on the leaf, to damp the resonances that are going to happen inside there.
It is not about insulation of sound coming in or out. It is just that resonance I want to dampen.
Fine, but the only way to dampen that resonance is by changing the resonant frequency of the tuned system. You do that by increasing the mass of the face, and/or increasing the air gap, and/or increasing the absorption inside the cavity. Doing any of those will bring the resonance down to a lower frequency. You have to calculate what frequency you need to get to, then calculate how much extra mass, extra air gap, and damping you need. This is not about guessing: it is about measuring and calculating.
with adding a lot of treatment to this wall (corner traps and absorbers or more slot resonators), it would be much better than the original wall, that I would otherwise just reinforce with heavier and thicker gypsum. What do you think? Worth it? Better ideas?
That will work, yes. It is not ideal, but if you build that wall correctly, and treat that wall properly, then it should be OK.
- Stuart -
) If the spring is very rigid the full force of the hammer blow will transfer through the spring as if it were a spike, and shatter the glass. If the spring is to soft, the hammer will cause the spring to completely compress and the full force of the blow will shatter the glass. Now if the spring is just right, it will compress enough to be able to absorb the force of the hammer and virtually none of the energy will be imparted to the glass, so it will not shatter. Same effect here with your decoupling. 