Has anyone had great isolation on a floating concrete slab??

> since low frequency is the hardest to stop and arguably the most obnoxious to others You want to know what's obnoxious? An STC of 100!! Now THAT's obNOXious! Are you serious?!! Holy moly. Okay, sir, patience. Please humor me a little more. By nature, I tend to be a skeptic until I see the point driven into obliteration.... I see your point about the floor being the same as a wall. It's just a boundary, an ideally massive one, at that. If this boundary is truly suspended above the outer floor boundary, it still must be held up by some 'thing', as we all know. This thing, being added, is a non-rigid material, often in the form of rubber. The argument seems to be that if the vibrating object (drum) is placed directly on this floor, it should be decoupled from the outer boundary by the amount of 'cushion' provided by this pliant material, the vibration being only a product of the vibrational values of ths rubber when it has X amount of weight compressing it. Correct me if I misrepresent you: You said that placing another boundary on more pliant material over the first floor will merely add to the compression of the original pliant material (yes, I buy this), and therefore, whatever is 'soaked up' by the upper platform, is now lost in the lower platform. In other words, the extra weight of the upper layer compresses more onto the layer below. I'm struggling with this reasoning because: 1) It seems to assume that the upper platform cannot be made light enough so as to not add to the compression between floors. What if, in a sense, the drums were (let's make this proposterous) floating on balloons? Assuming the drums were very light compared to the floor, how much compression would balloons add to the floor? Pretty much nothing. So in comparison to a 2.5" slab of concrete, how much compression is added by a lightweight platform? 2) It seems to assume that the upper platform cannot be made resilient enough so as to not add to the compression wave. If the platform were raised above ground and (let me renig on making it stiff) were resilient enough that low wavelengths merely bent the platform like a panel resonator. I can see that the amount of compression wave striking the outer floor may remain relatively unchanged merely because the upper platform may support the wave if it were stiff, actually adding to the noise below. But what if it gives as though it weren't there? It all comes back to the "What if we can just float the drums?" theory. I apologize to the originator of this thread :wink: . Forgive me for using this as a point of self education (and much interesting argument), especially if you are bored to tears! I'm not challenging you, Steve, nor Mr. Desart's mathematics. I'm genuinely trying to understand the physics. I just can't quite buy it yet.

OK, part of the problem seems to be that I didn't make clear my reasons for a third leaf NOT working - it has nothing (or very little) to do with more sprung weight, (since that can be compensated by different spring rates) and (nearly) everything to do with the extra air space and mass negatively affecting mass-air-mass resonance - this part would be true whether the different leaves were separated by anti-gravity generators, springs, rubber, dried cow patties, or rocks. The spring material, obviously, will make a difference in decoupling between leaves; I'm not saying it won't make a difference. Only that one would get better isolation by combining the masses of the second and third leaf, with corresponding increase in spring rate (or decrease in spacing) to compensate for the extra weight. The rest of the problem is that I barely understand what I'm trying to explain, and have (in this particular case and time) essentially decided to take Eric's statements at face value, considering that only ONE of us has the distinction of being responsible for the worlds' quietest recording studio - Since Eric drops in here from time to time, maybe the most practical way of increasing BOTH our understandings of the reasons why a third leaf isn't a good idea, would be for you to start a separate thread using Eric's name and specifically linking to this one - that way, the discussion can get as far afield as we all can stand, and not impact Govinda's thread for readability... Steve

An stc of 100 is not obnoxious its AMAZING! ej bragg thanks for the drum riser thing...The whole reason im going to the drama of pouring a floating concrete slab is "one reason" to stop sound getting to my neigbours! I personally have allways liked the sound of drums directly on a wooden floor anyways! Apologies accepted ej bragg! :lol: Steve i'm not trying to boast but I have known for at least 10 years that tripple leaf walls are not very good for stopping extreme noise and music, I dont need to know the complete science of why!!..read alot of data, quite straight forward when looking at the results! :roll: I'm a musician not a studio building technician and all I know is the Guys with credit know and understand and teach! I have been very fortunate to come into contact with 2 great studio builders gunter wagner and john sayers! I never knew that eric had built the worlds quietest studio! Eric that is a really amazing achievement!! What I learnt from this topic and found very interesting was that a hollow core building block if not filled caused the tripple leaf effect, when building a room within those walls! Thanks for all your help steve, right now my house plans are at the engineers I will keep you posted of the outcome! BTW steve if I want a studio wall height of 3 metres (internal) am I looking at the outside shell walls being at say 3.6 meters? Thanks again, Govinda

That would be minimum -more if you intend to do deep ceiling trapping with hangers, etc... Steve