Maximum isolation

Greetings everyone on this magnificent forum! I'm in the planing process of setting up a studio that we're going to be building later on next year and trying to get every detail planed out in advance (though i'm sure there will be things that I'll forget, there always is!) and looking for a bit of help! We're planing to build a bit of a complex somewhat with the music side consisting of 4 rehearsal rooms, 4-6 small teaching room 2 control rooms sharing the recording space of a vocal booth, a big live room, a drum booth and 4 amp booths as well. We have thrown the idea of a programming room about but probably be a bit of an after thought if we were to do it. The thought is eventually that in the studio would have either a mixing session in one control room whilst a tracking session is going on in the other or a voice over in one and then a drum tracking in the other or something like that whilst 4 bands are rehearsing all in complete ignorance of one and other! A walk in the park i know. Due to cost restrictions we're doing a phased construction with just the rehearsal rooms and a control room to start with and then build the rest from there. The reason for this is so we don't have to cut corners in the construction of any of the rooms, i think the world is cluttered with far too many places where you can jam with the band next door with far too much ease! I've had quite a few ideas so far but nothing in concrete as yet but i don't think there will be chance to get the studio far enough away from the studio that it wont interfere without serious construction. Just after your thoughts of what would be the most effective way of isolation; I understand that a floating floor is essential for this but was wondering about wall and ceiling construction as well. All help and any ideas are gratefully received; I look forward to reading your replies! Many thanks in advance Jimi

Hi Jimi, and Welcome! :) It sounds like you have an interesting project on your hands, and you have come to the right place to learn how to design and build it correctly. However, we'll need a lot more information than you have given in order to help you. To start with, for example, the total space available for building this complex! The maximum shape and size of the building footprint is pretty important... Also, your total budget! Another very important issue. It sounds like this is a "ground up" project, where there is nothing but bare earth existing right now, and you get to design and build everything from the foundations up to the roof. Is that correct? Your idea of building in sections, a bit at a time, makes sense and is do-able, but you still have to design the entire facility in advance, including the parts that won't be built initially. And you should probably build the entire shell of the building initially, just leaving some areas empty, with no internal walls, until you have the need/budget to do that. There are many reasons for taking this approach. The flexibility that you mention, in being able to use different parts of the facility either jointly or separately is also not a problem. That is more an issue of signal routing than actual acoustic design (although acoustic design and layout of the rooms still comes into it). You might want to think about adding a central machine room to your design where most of the equipment will live, and can be shared as needed among the studios, perhaps with a routing switcher, or at least with a good patch bay. That's the best way to handle signal routing when you have multiple rooms that need to share things.

but i don't think there will be chance to get the studio far enough away from the studio that it wont interfere without serious construction.

Not sure what you meant to say there; "get the studio far enough away from the studio"??? :shock: But in any event, since you plan to have several different things going on in several different rooms at the same time, you will need isolation for all of the rooms. However, placing the rooms a long way apart is not the way to achieve that. To isolate sound you need one thing mainly: Mass. In other words, heavy, dense, thick, weighty materials. The laws of physics are very plain and simple (unlike the laws of myth and legend that you find repeated incessantly on many "studio" web sites). There are only two basic ways to stop sound getting from "A" to "B": you can either remove all possible paths that vibrations could take between A and B, leaving only a total vacuum. Or you can place a barrier between A and B that is too massive and too rigid for the sound waves to be able to move. An infinitely massive barrier will work fine, since the mass will resist all attempts to make it vibrate. If it cannot vibrate, it cannot transmit sound to the other side. An infinitely rigid barrier will also work: if it is perfectly rigid then it cannot move, and therefore cannot transmit vibration. There are no other ways of stopping sound. There are no magical materials (despite what some acoustic snake-oil manufacturers try to convince you to believe). There is vacuum, and there is mass. Period. Nothing else. Yes, distance helps to attenuate sound, but you need a LOT of distance for that to work! In an open field, sound drops off roughly 6 dB each time you double the distance. So if you have a drum kit set up and a drummer playing loudly, measuring 115 dB one meter away, then that will be down to 109 db at 2m, 103db at 4m, 97 db at 8m, 91 dB at 16m, 85 dB at 32m, 79 dB at 64m, 73 dB at 128m, etc.... Simple law of physics. You'd need hundreds of meters to get that down to the point where it is inaudible, so unless you have an entire campus available to you, if you plan to just use distance to isolate your instruments. On the other hand, if you have limited space for your facility, and everything has to go in one building, then you have the issue of building materials that are neither infinitely rigid nor infinitely massive, so they will transmit sound from room to room! What to do then? What is the answer? As it turns out, there is another law of physics that can be used to isolate sound: Resonance. A resonant system loves to vibrate at its own resonant frequency, but resists vibrating at all other frequencies. So if you could build your walls so that they resonate at a frequency that is too low for humans to hear, then the walls will automatically resist all other frequencies. Bingo! It turns out that it is possible to do this, by building something known as "MSM" (Mass-Spring-Mass) or "MAM" (Mass-Air-Mass) walls. Basically, you build a wall with a massive surface on one side, a massive surface on the other side, and only air in between, and you seal it air-tight. The resonant frequency of the wall is determined by the amount of mass on each side and the size of the air gap between. Bingo! Simple, low cost isolation. The best way of doing this is to build ordinary stud frames (wood or metal) separately for each side of the wall, and put ordinary drywall (plasterboard, gypsum board) on only ONE side of each frame. So you have a couple of layers of drywall attached t one set of studs, an air cavity, then a couple of layers of drywall attached to another set of studs. You also have to fill the cavity with damping material, such as ordinary fiberglass or mineral wool insulation. You can achieve very high levels of isolation like this, with walls that are less than a foot thick, in total. A wall with an 8 inch (20cm) air gap and three layers of 5/8" (16mm) drywall on each side will give you close to 70 dB of isolation. So your drummer will be down from 115 dB to practically inaudible in less than a foot, instead of half a mile! That's the way to get high levels of isolation into a small space at low cost. In fact, it is the ONLY way to do so. But it does require careful design, and careful construction. That's what this forum is all about. You can learn how to design your facility, and how to lay out each of the rooms, in order to maximize isolation between them. You can also learn how to treat each of your rooms for the purpose for which it will be used. (Isolation and treatment are two entirely different and diametrically opposed things).

I understand that a floating floor is essential for this

Actually, it isn't essential. That's another myth, commonly perpetuated around the internet. Floating floors are only needed in a very, very few cases, and probably not yours, assuming that you will be building the facility on a concrete slab. Floating floors are hard to do right, and very expensive. The calculations are complex, the construction isn't easy, and most likely do not need them. I wouldn't bother even thinking about floating your floors at all, until you have the basic numbers in place. You won't know if you need them until you have your basic specs and goals defined, in real-world acoustic terms (not guesses), and your basic layout in place. So leave that decision until the time comes.

but was wondering about wall and ceiling construction as well.

Walls and ceilings all need to be done to the same level of isolation, as proper fully-decoupled MSM systems, tuned low enough. The weak points will be doors, windows, the HVAC system, and the electrical system. All of those imply perforations in the MSM system, and need to be done with great care in order to not damage the isolation attained with the MSM system. So those will be the key areas for your attention: sealing doors and windows, and designing the HVAC and electrical system to retain the same level of isolation as the walls and ceiling. Anyway, if you provide some more details on the available space and budget, and do a rough layout your self of how you think the rooms will be arranged, then we can help you optimize that. It's a big project, and a rather large challenge! But there are people here who can help you along the way, to ensure that it turns out right. - Stuart -

Hey Stuart, thank you for your speedy reply. We're currently looking for premises to build in but with rent so cheap (600 sqm for £14,000 pa) space will not be an issue. We want to have a design idea and room construction sorted before we find one so then we can shift things about and see if we can make it fit. I don't want to compromise the quality of build in any way so hence why we're we here so early on in the development. From the buildings that we've seen so far its almost certainly going to be a solid concrete floor. I've included a ruff plan i put together at the when we first started talking about putting a studio together and after many hours of reading threads stuff is changing somewhat! also i didn't find the tape measure till after i did this in sketch up so not all to scale! Ive seen the MSM talked about but now it makes perfect sense! Correct me if i'm wrong, if you had 2 msm rooms next to one another and a drummer was in one playing at 115dB then you shouldn't be able to hear him in the other one because between them both you have 140dB of isolation right? Would it be best to fill the whole space with rockwool or just part? if you filled it all wouldn't that mean that the walls were coupled or is that me getting a little muddled? Also how would one tuned the walls? is there an optimum frequency to tuned to? would you tuned the walls the same or at different frequencies? Also would sheetblock be any good in-between the drywall at all? i've seen it about and it does look quite good and high mass. would you suggest just using the concrete floor already there then? We don't really have a set budget in mind, from a guesstimate i'm hoping sub £20,000 to get started for the 5 rooms and build it up from from there for the rest! Though we have friends that are in the trades and in the builders merchant industries so hoping to get things a little cheaper. I just finished working at a studio and it had so many imperfections and bugbears with the building and construction that i don't want any of that to come into play here. Stuart, thank you again for your help, I'm sure you'll prove to be worth your weight in gold! Many thanks Jimi

Do you think the "inside out" design would be better for the teaching and rehearsal rooms? I've seen it mentioned quite a bit and thought it looked interesting!

We want to have a design idea and room construction sorted before we find one so then we can shift things about and see if we can make it fit.

That makes some sense, but I wouldn't go too far with the design (just basic layout), since it could all change drastically once you find your actual space. The locations of any existing doors, bathrooms, windows, power feeds and HVAC systems (not to mention shape and dimensions) could mean a drastic re-think! For example, it might not be possible to change the main entry door, which might turn out to be in the back corner of one of the rehearsal rooms! So you'd need to re-arrange everything, to accommodate that. Etc.

From the buildings that we've seen so far its almost certainly going to be a solid concrete floor

Great! That's an excellent start, for both isolation and for acoustics. Concrete makes an excellent floor for a studio, and if it is in good shape, it needs nothing more. Maybe just stain it artistically. Or if you don't like the look of concrete, then just lay laminate flooring on top.

I've included a ruff plan i put together at the when we first started talking about putting a studio together

There's several ways that can be improved. For instance, the shapes of the two control rooms is not good. They should never get narrower at the back. Start narrow at the front, and widen out all the way back, walls splayed (angled) at least 6° on each side (12° total) (or maybe more, if you want an RFZ design). Or if you can't splay them all the way back, at least splay the front half, and keep them parallel from there back. I also wound not have an angled machine room! I've designed enough machine rooms in my time to recognize that angles and machine rooms do not live well together. Make it a simple rectangle. Other things can be improved there, too.

Correct me if i'm wrong, if you had 2 msm rooms next to one another and a drummer was in one playing at 115dB then you shouldn't be able to hear him in the other one because between them both you have 140dB of isolation right?

Well I doubt you'd ever get 140 dB of isolation, anywhere! There's a thing called "flanking limit", set by the building structure itself (slab, outer walls, roof, air, etc.), so no matter how good your isolation is on each room, there's an overall maximum that you can obtain in any building. The best studio I ever heard of had 100 dB isolation. That's about as good as it gets. If you can get 80 dB TL, you are doing extremely well, and even 70 is damn good. You most likely don't need more than that anyway. To put the numbers in perspective, 100 dB of isolation is enough to make the engine of a 747, at full take off thrust, totally inaudible in the room next door... That's pretty major accomplishment. Most folks here are happy to get 50-something, really happy to get 60-something, and ecstatically jumping-up-and-down happy if they hit 70-something in their builds. To put it even more in perspective: dB is a logarithmic scale. Each time you go up ten points, that represents ten time the energy. So going from 40 dB of isolation to 50 dB means you have absorb ten times the amount of energy. Going from 40 to 60 means 100 times the amount of energy. 40 to 70 is one thousand time the energy. 40 to 80 is ten thousand times the energy. Etc. Getting to 140 dB implies absorbing about 1,000,000,000 times more energy... :shock:

Would it be best to fill the whole space with rockwool or just part?

Theoretically, filling the entire cavity gains you up to 16 db of isolation over no fill at all. Partial fill gains you between 1 and 16 dB, depending on how much. So you need to cover at least the entire surface area of the mass on each side at least 2 inches deep, or 4" even better. Filling the entire cavity gains you more isolation, and lowers the MSM resonance frequency.

if you filled it all wouldn't that mean that the walls were coupled

As long as you don't force it in, and don't use the wrong density, it wont couple. Fiberglass and mineral wall or fluffy and springy, so they don't couple the two sides ("leaves") of the wall unless you start compressing it, forcing it into the space. If you just lay it in gently, then that's fine.

Also how would one tuned the walls?

The equation is simple, and depends almost entirely on the surface density (mass) of each wall, and the depth of the air cavity. Increase the mass and you reduce the frequency. Increase the air gap and you reduce the frequency.

is there an optimum frequency to tuned to?

For full range isolation of the entire audio spectrum, you need to tune the wall below 10 Hz. The audio spectrum covers 20 Hz to 20 kHz. High frequencies are not a problem: it's the lows that matter. They are the hardest to isolate. The math is also simple: the wall does not isolate at all for sounds at its own resonant frequency (F0), and in fact can amplify the sound in that range. It starts isolating at 1.4 times F0, and isolates reasonably at 2 x F0, and well from 3 x F0 upwards. So basically the rule of thumb is to tune your wall to half of the lowest frequency that you need to isolate. If you only record vocals, then you could happily tune it to 50 Hz., but if you need to record bass drums and bass guitar then you'll have to go much lower than that.

would you tuned the walls the same or at different frequencies?

All the same, generally.

Also would sheetblock be any good in-between the drywall at all? i've seen it about and it does look quite good and high mass.

You can use whatever materials you want, but consider this: sound waves don't care how much you paid for each kilogram of mass! They only react to the mass itself, not the price tag. So go with the cheapest mass you can find, which is generally plain old drywall in most places on the planet. You don't need more expensive materials where cheaper ones will do the same job. You only need more expensive materials in places where the cheap ones cannot be used for whatever reason. For example, there might be a limit to how thick you can make a wall in a certain place, so you can use more dense materials there to keep the total wall thinner. Plywood, MDF, OSB, HDF, fiber cement, aluminium, steel.... all are good alternatives to drywall, and the last few are far more dense. You could even go with something like sheet lead, which is about seven times the density of drywall Building a wall with a 2mm of sheet lead on each side of a 2 inch gap is about the same as building it with a couple of layers of drywall on each side of a 4" gap. But vastly more expensive.

would you suggest just using the concrete floor already there then?

Yup! If it is good thick concrete poured on the ground ("slab on grade"), then that's excellent. It means you have the entire planet as the damping material behind your slab.... hard to beat that! :)

We don't really have a set budget in mind, from a guesstimate i'm hoping sub £20,000 to get started

That sounds a little on the low side. 20k for 600 m2 = £33 per m2. You might want to re-think that. To get an idea of what it will really cost, call a couple of local building contractors, and ask for their flat rate per square meter for renovating an existing house, or for converting an existing unfinished garage or basement to an up-scale guest room with bathroom. The rate per square meter is roughly what it will cost you for your studio, give or take 20%.

I just finished working at a studio and it had so many imperfections and bugbears with the building and construction that i don't want any of that to come into play here.

Cool! You are in the right place to avoid that, for sure!

Stuart, thank you again for your help, I'm sure you'll prove to be worth your weight in gold!

Gold is fine! But even silver and emeralds are acceptable forms of payment! :) (Also Visa, MasterCard, American Express, PayPal... :) )

Do you think the "inside out" design would be better for the teaching and rehearsal rooms? I've seen it mentioned quite a bit and thought it looked interesting!

"Inside out" is more of a construction method than a design. It has its uses, but makes it harder to build (and perhaps more expensive). You might need to use it in some places, but that's getting ahead of yourself. The places where it could be used will more or less suggest themselves once you get into the actual design process. - Stuart -