DYSTONIA wrote:Source of the post Why decoupling the outer wall from the inner frame? They will touch each other at some points (desk, cables etc.).
Actually, they
cannot touch each other! That's the point of an MSM system ("room-in-a-room"). The inner "room" is completely decoupled form the outer "room". Nothing touches. That's what you need in order to get high isolation. All of your furniture is within the inner room, and none of it touches the outer-room. Your desk and chair, equipment, instruments... all sit on the inner-leaf floor (Glenn's riser, in your case), and they don't touch the outer room at any point.
The reason is simple: If they did touch at any point, then you have what is called a "flanking path", which is a path that sound can take directly from one "room" to the other.
Think of it this way: You might have see the "old fashioned" tuning forks that musicians used to use to tune their instruments. They look like this:
- tuning-fork-02--C-note-SML.jpg (41.96 KiB) Viewed 27029 times
- tuning-fork-02--C-note-SML.jpg (41.96 KiB) Viewed 27029 times
To use it, you would tap the "fork" end on something solid, to make it "ring", then hold the "base" end against a surface of some kind, such as a table top, a wall, or your acosutic guitar, and you could then hear the note that the fork is tuned to, and tune your instrument to the same note. Now, if you just tap the fork then hold it out in the air, without it touching anything, you can't hear any noise at all, or maybe just a very faint note. But when you put the base down on the table, then you can hear the note, loud and clear.
The same happens with your studio: the inner leaf wall, floor and ceiling are going to vibrate because of all the sound in the room. The entire inner-leaf-room vibrates. If it is decoupled, not touching anything (like the tuning fork in the air), then no sound transmits across the gap to the outer-leaf room. But if you have a "flanking path" that joins the two rooms, then the vibration also goes across that path to the outer room, and then the sounds can be heard outside of your studio. That's why it is so important to "decouple" the inner room from the original outer room. If there is any connection, even something as small as the shank of a tuning fork (about the size of a nail or screw...), then you don't get isolation. (Cables are OK: they are flexible and there are methods for getting them from one room to another, without "flanking")
For this reason, it is very important to keep the two rooms separate, fully decoupled, as I describe in the article on MSM.
That's why you need to have something under your walls to decouple them from the concrete slab, and it has to be the right product to do the job. Everything in the universe has a natural resonant frequency, including your wall. The material that you use to "decouple" it from the floor must be designed specifically to deal with that frequency, and not allow it to get through. If you use the wrong product, then the resonance will get through, and so will other sounds. the Iso-sill product is designed for that. It has been formulated specifically to isolate studio walls. In fact, it can actually handle a wide range of wall weights, because that's what they designed it to do, and tested it in laboratories to make sure it does that.
I just looked at the "data sheet" from the manufacturer of the product you are using, and there is no useful technical data in there at all! The only actually useful specification there, is the density. At 120kg/m3, it is very heavy, so I doubt it is going to have useful resilience for floating floors or walls. IT seems to be what I first though: a "limp mass" barrier, something like MLV (Mass Loaded Vinyl), so it would be useful if you glued it to a wall, for example. But there's no indication of the resilience, or the spring constant, or the needed compression, or anything else that a manufacturer would publish if the product was meant to be used for acoustic decoupling. They don't even say what it is made of, so it isn't even possible to guess at the characteristics.
The only thing is that I like to make things visual to understand it.
Me too! That's why I put so many visual images and animations in the articles that I linked you to. The images usually make it much easier to understand the concepts. Acoustics is complicated, and I do like to simplify things so people can understand them more easily. That's why I wrote all those articles, and put in all the images. The articles are sometimes very long, but as I said, acoustics is complicated so you need a lot of description to make it easier to understand. IF there is something in one of those articles that you don't get, then please let me know where you are getting stuck, and I'll try to edit the article to explain it better.
But that's the price I need to pay if I'll make a proper sounding room.
Very true! That's one of the reasons why I created this forum in the first place. Home studio builders, like yourself, always want to do the most possible with as little money as possible, and most people cannot afford to hire a studio designer to do the design for them (even though we aren't as expensive as some people think!
) . Some people can afford it and do want a professional design, and I'm very happy to have those customers who put bread and butter on my table! But most home studio builders can't afford to use up some of their precious budget to pay a consultant, so I made this place where people can get the information they need for free, and if they still have trouble, then they can ask! And folks like Glenn, Andre, myself, and others, will try to answer the questions, also for free. Because we get it: building a studio is expensive, and it would be terrible to spend all that money in your budget, but then get a studio that sounds horrible! So we try to help out people who are on a very tight budget, with as much free advice as we can.
As you already found out, sometimes the advice you get from people who might have good intentions but don't actually know what they are doing, can be very bad and can waste your money. Which is what happened with your resonating floor. You found that information on the internet, you bought the materials they told you to, and you built it the way they said... then it didn't work. That's NOT your fault! I say it again: It is NOT YOUR FAULT! Don't blame yourself for that. You are not an acoustic expert, so you don't have to know that stuff. But the people who gave you the info are also not acoustic experts (obviously! Because they gave you bad advice that didn't work!). The problem is
their fault, for giving you wrong advice because they don't actually understand the science of acoustics, and just wanted to sell you their products. On the other hand, Glenn and I are not selling you anything! We both make our living by designing successful studios for our clients, and we do know what we are talking about (as you can see, from the hundreds of threads here on my website, and the same on Glenn's website [please do visit his website too!]), along with the testimonies of people who have taken our advice, and are very happy with their studios. We are just here to help folks who need help, and we do it for free. Why do we do it for free? Because some people who have big budgets find our websites, and hire us to design their studios. God is good, and we make enough from that to live on, so we can be a bit generous with our knowledge and our spare time, for other people, who don't have big budgets.
So that's what's happening here: Glenn and I and Andre and Jennifer and Starlight and many others here, understand the physics and science of acoustics, and we want to help others who don't have the time or inclination to learn it, but still want to build their studios. And very often people like you come to the forum, because they found out that their studio is not working, and they get very frustrated about that, just like you are right now. Which is very understandable! If I spent a lot of money building something, then it didn't work, I would be upset and frustrated too!
We can't fix your budget issue, but we
can tell you what needs to be done to re-make your studio the way you want it to be. We can help you re-use some of the materials you already bought, as much as possible, but if you want it done right, then you are probably going to need to buy other materials too. We can recommend the least expensive materials and methods, because once again, we've been doing this for years, and we know what works... and what doesn't work(!).
So, what I'd suggest is that we should "rewind" a bit, and start over with the basic concepts for your studio. What I always do with a new paying customer, is try to understand what the problems are with his place, and what he wants it to be like when it is done. I want to understand the type of music he makes, how he makes it, how loud he is, where his studio is located, what his neighbor hood is like, even what the climate is like where he lives, because all of that matters when designing a studio. I want to understand the person, so I can understand the studio, then I can design it better. That's what I'd like to do with you too, even though you aren't a paying customer.
So, first: Where is your studio located? From what you have said so far, I'm assuming that this is located in your apartment, which is some type of multi-story apartment building. So I'm assuming that you have neighbors above and below, and on each side. It would be good if you can confirm that, and maybe add some more details about that. Are your neighbors noisy? Do they slam doors, dance with clogs on upstairs, sing loudly? Or is it quite in your building? Do they get upset with the noise YOU make in your studio? Have you ever had someone complain, or come knocking on your door, telling you to turn it down?
Then: What do you use the studio for? Do you record live instruments in there, such as acosutic guitars, drums, bass, keyboards, etc? OR do you just mix in there? Or do you make electronic music yourself but without any acosutic instruments? Those are all very different scenarios, regarding isolation: It would be great if you could download a good "Sound Level Meter" app to your cell phone, and measure how loud you are inside your studio when you are doing whatever it is that you normally do, at he loudest levels that you normally do it. And also measure the ambient noise level inside your studio, when you are NOT doing anything in there: just sitting quietly. Those two numbers are very important for helping you decide how to isolate your room... or even if it needs isolation at all!
Finally: What type of music do you make in there? Heavy metal is one thing, rock is another, reggae something else, classic different again, jazz also different...
So, if you can give us that information, we can pretend that you didn't actually build anything yet, and imagine that your room is still empty, then tell you what you should do to it to firstly isolate it to the level you need, and secondly to treat it so it sounds neutral and you can mix properly in there.
- Stuart -
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