New Studio projet in France

Hello Everyone, My name is François, I’m french, 32 years old and I’m working as a freelance sound engineer for a couple of years now. First of all, excuse my english, I will do my best to be understandable... I’m in the process of buying a farm in France, Burgundy with some friends. I’m about to live here and guess what? I want to make a recording studio in the barn! So it would be a residential studio with a 160m2 (2 floors) apartment for the clients, and I’ve got a 180m2 surface for the studio. So I’m reading this forum for quite a long time, books by Rod Gervais, Bobby Owinsky and the Philipp Newell’s one is on this way from Amazon. I had spend countless hours on construction threads in many forums, so I think I can understand a little what I’m trying to do. I also already build little rooms in Paris in the past years, with my hands, some friends and very tight budget, which sound quite great in regards of the space. I’m in DIY stuff for a long time now and I plan to do the maximum of work by myself, with a little help of my friends, of course! Budget: The budget is not so high, I don’t have a clue on it and this is why I want to discuss here some solutions regarding isolation in order to estimate what I need. I wish I could stay below 30000E for the studio construction (not including acoustic treatment). I want to stick to the best price/quality I can get because this business is quite in a crisis here to... And I also need a console, and some mics, so the cheaper I can go, the best tools I can get after. But I don’t want to cut on the basis! The location: The farm is a great place near Paris in the countryside, the first neighbour is at 800m from the house, and the barn is 10m away from the building we will live in. the road is also at 500m, so there is really no traffic sound, the only thing that can disturb me is the dogs of my friends (which can be deal easily...) and the agricultural tractor from the guy who grows wheat in the fields all over the farm. And it will be my biggest thing to deal with, because the little road he use is next to the studio. He isn’t here everyday, not in the winter, but in the spring it can be annoying if I can’t record because of him. I will mostly record Folk, Rock, Pop and I’m not in the Heavy metal business, but I will certainly (and I want) be able to record full rock band Live. So I’m needing the best isolation I can afford, in order to deal with the tracor thing, and I would like my friends (even if they are aware of what I’m doing) to enjoy the peaceful place even if I’m recording heavy drums at night. The Barn: Here’s some pictures of the barn, in order you to see what it’s look like. The right part will be the apartment for the clients The wall are made of 50cm of stone, there are some holes in it I’ll have to deal with, the floor is “naked”, just hard-packed earth (?? I don’t know the correct words for that) on the half that will be the Studio and the is some concrete on the other half, which will be the control room and a lounge. This is an open top to the roof, which is a subject of many questions I will ask later. Dimension: 23m x 8,1m x 9m (to the top of the roof) The project: I’m spend my last two weeks trying to make some layout for the studio, this is the one i’m quite happy of: So the dimensions: (LxWxH) Control Room: 6,99m x 4,81 m x 3m, 33,6m2 Machine room: 5,34m2 (subject to change) The Studio will be a 12,76m x 7,55m x 4,80m room (96m2) Inside the studio there will be: - Drums booth: 12,75m2 - Mics Locker: 7m2 - 2 small iso booth: 3,7m2 - Live room (with all the height): 57,28m2 And there will be a mezzanine on the drums booth/mics locker, which will add 20m2 of recording space. Some pictures of my sketchup: From the CR Mezzanine I also need to fit my electronic lab (20m2) a little sound editing room (16m2) and an office in the space left. I’m planning to do a floor on this space, leaving the ground floor to be a loudge, and fit the lab above the CR, the editing room and the office above the lounge. this isn’t done yet and the main things is the studio. If we buy the house, we’ll be focusing first on our apartements, in order to live there as soon as possible and after that will come the studio, so I think I’ve got 2 years before I do any of this, it let me a lot of time to think about it, which is great, but we’ll need to do the concrete slab in the barn soon after we buy because it’ll be the place where we will keep our building materials. So I need to know about the layout in the 6 months coming so I can do it right the first time ;-) Ok, now you know most about what i want to do, so my concern are about the layout, I know there is great guys here with great comments, and I’ll love to hear them dismantling what i’d done! And I’ve got another concern, and this is “What’s the best way to obtain the best isolation in a place like that?”, In fact I wish I can use this big stone walls to be one layer of my MSM system, but can it work? And there is “no” ceiling, so what you think I must do here? This is my nightmare of the last week... I don’t know how to do this part, and it’s the one I don’t want to screw up! Any other comments are welcome! So I hope you guys, can help me! If everything is going as I want, I will try to make this thread a very nice and complete “building thread”! Thanks!

It seems I had not read correctly the forum rules... And I apologize! I think I corrected my mistakes now!

So I started to find some solutions about sound isolation, Here what I think about the walls and floor: So, first of all,I assume I had filled all the holes in the existing stone wall, and make it the more airtight I can. Make a wall foundation, all around the studio, to support a 20cm width sand filled concrete block wall, on top of a deadsheet Make a concret slab inside the studio, decoupled with 5cm medium density rockwool from the walls Fill the 20cm air gap between existing wall and new wall with 10cm of medium density rockwool for damping and for ceilling: Make a concrete floor on the existing structure, 10cm slab Make a second ceilling on the new walls, with wood joist, filled with 20cm of medium density rockwool, and directly under a sandwich layer of plasterboard and deadsheet Ok all of this is theoretical, and I've got one question: I tried to make some calculation with the TL formula: TL@f=20(log(fm))-47 where: Tl@f is transmission loss at frequence f in dB m is density of the materials in kg/m2 So I find that: Density of 20cm sand filled concrete block is 280kg/m2 sandwich layer plasterborad with deadsheet: around 25kg/m2 Existing 50cm stone wall: 1150kg/m2 10 cm concrete slab: 230kg/m2 (I hope it's correct...) For 50Hz: Wall TL@50Hz=85dB Wall TL@100Hz=97dB Which is great if I don't make a mistake, But for the ceilling: Ceilling TL@50Hz=50dB Ceilling TL@100Hz=61dB Which seems not bad... BUT, is there really a point to achieve such an isolation in the walls if I can't go the same way with the ceilling? Is this waste of money? And do I have better option? Again, I know this is theoretical and I don't think I can achieve this figure in the real world... Thanks in advance for your help! François

I'm also thinking of an alternative solution, with a complete wood shell from floor to ceiling (more fitting the shape of the roof), with plasterboard/deadsheet/plasterboard sandwich I don't think I can reach the same amount of isolation than the previous one, but maybe it would be enough, easier to do and cheaper (I know I need to mesure my needs in , and I will in July) Any thoughts about this idea? I don't do any ketchup right now, I'm seeking for advice before! So please tell me, I'm feeling alone here! ;-)

Hi Mirouf, and Welcome to the Forum! :) :) Sorry about the delay, and thanks for being so patient! It's been crazy around here lately, and there aren't too many people responding to questions... Anyway,

So it would be a residential studio with a 160m2 (2 floors) apartment for the clients, and I’ve got a 180m2 surface for the studio.

Wow! That is NICE! Lucky you.

the only thing that can disturb me is the dogs of my friends (which can be deal easily...) and the agricultural tractor from the guy who grows wheat in the fields all over the farm.

... and maybe wind, rain, hail, thunder, aircraft flying over, sounds from the house, like radio, TV, telephones, vacuum cleaner, talking, .... also cars arriving and leaving, etc. There are numerous sources of sound that people don't think about, until it happens...

but in the spring it can be annoying if I can’t record because of him.

Maybe sabotage his tractor? :) Just kidding! Or maybe buy him a better silencer for the engine...

So I’m needing the best isolation I can afford, in order to deal with the tracor thing, and I would like my friends (even if they are aware of what I’m doing) to enjoy the peaceful place even if I’m recording heavy drums at night.

It would be good to put numbers to that: use a sound level meter to measure how loud you are, how loud the tractor is, and how quite the place is when there is nothing going on.

The wall are made of 50cm of stone,

Excellent, but the mortar needs to be sealed properly. It is porous.

the floor is “naked”, just hard-packed earth (?? I don’t know the correct words for that) on the half that will be the Studio and the is some concrete on the other half,

I would consider pouring a separate, isolated slab for the live room and drum booth at least, and maybe even for other rooms, if you have the budget. That will maximize your isolation.

I’m spend my last two weeks trying to make some layout for the studio, this is the one i’m quite happy of:

with that amount of space, I would really, really turn the control room to face the live room, so you have direct line-of-sight to everyone. There's plenty of space to do that, and it is a bigger thing than many people think. Sight lines are very important.

Machine room: 5,34m2 (subject to change)

Make sure you leave space around the racks for installation, cabling an maintenance! That's a problem that I often see in badly designed post-production houses: racks with no access to the rear, or no way of sliding equipment out for calibration, cleaning, repair, etc. How many racks are you planning to put in there? What size?

Inside the studio there will be:

Wellll... not really "inside". Each room is built independently, self-supporting, not touching any other room. So it is not that the drum booth is "inside" the live room, but rather that both the drum booth and the live room are "inside" the outer shell of the entire building. This is fully decoupled 2-leaf MSM construction.

Some pictures of my sketchup:

Your rooms are not decoupled! You won't get good isolation like that. see above....

so I think I’ve got 2 years before I do any of this,

Excellent! Honestly, that is about correct. It will take that long to properly design all of the details, and check everything over, and do all the calculations, and figure out all of your costs, and your construction sequences, etc. So you are being very realistic about this.

but we’ll need to do the concrete slab in the barn soon after we buy because it’ll be the place where we will keep our building materials.

I mentioned this above, but if that were my place, I would do one slab per room, all independent from each other. Or a the very least, one for the drum booth, one for the live room, and one for everything else.

Ok, now you know most about what i want to do, so my concern are about the layout

Probably the only real change I would make is, as I mentioned before, to rotate the CR 90° left, so you get a direct view into the LR and all the other rooms.

And I’ve got another concern, and this is “What’s the best way to obtain the best isolation in a place like that?”, In fact I wish I can use this big stone walls to be one layer of my MSM system, but can it work?

Yes! Exactly.

And there is “no” ceiling, so what you think I must do here? This is my nightmare of the last week... I don’t know how to do this part, and it’s the one I don’t want to screw up!

For the live room, I would try to use as much height as possible, so I would hang the inner leaf up near the roof. You already said you want a mezzanine level over the drum booth, so that needs to have it's own two-leaf ceiling. The others would probably be lower.

Here what I think about the walls and floor:

You could do it that way, or you could build the walls on top of the individual floors, so each room is a single monolithic "block". That would make construction easier.

Make a wall foundation, all around the studio, to support a 20cm width sand filled concrete block wall, on top of a deadsheet

Not one wall for the entire studio, no: one for each room.

Make a concret slab inside the studio, decoupled with 5cm medium density rockwool from the walls

Yes, but one slab for each room, and no need to decouple form the walls.

Fill the 20cm air gap between existing wall and new wall with 10cm of medium density rockwool for damping

Yes. But filling the entire cavity is better: more isolation. For mineral wool, the density should be 50 kg/m3 (or if you use fiberglass, it should be 30 kg/m3).

and for ceilling:

Not enough mass, by far! You are putting up thick, masonry walls to get good isolation, so a thing drywall ceiling is not going to be enough to keep the surface density consistent. I'm not sure what you mean by "deadsheet", but I'm assuming it is some form of MLV? If so, forget it: there are much cheaper ways of adding mass to your inner-leaf ceiling.

I tried to make some calculation with the TL formula: TL@f=20(log(fm))-47

That is for mass law, but you are using 2-leaf MSM, which is different. The equation is: (Not sure which text book that comes from, so apologies for not providing the credit. If anyone knows, please tell me so I can fix that). The simplified version is: F0=c[(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 C=43 for imperial, 1897 for metric m1, m2 = surface density of leaf #1, leaf #2 d=depth of air gap That gives you the resonant frequency. Isolation rises at 18 dB per octave from that point, very roughly (not considering coincidence dip and other possible resonant dips).

I'm also thinking of an alternative solution, with a complete wood shell from floor to ceiling (more fitting the shape of the roof), with plasterboard/deadsheet/plasterboard sandwich

That would work too, but once again, you probably don't need the "deadsheet". What product did you have in mind for that? Do you have a link?

I don't think I can reach the same amount of isolation than the previous one, but maybe it would be enough, easier to do and cheaper (I know I need to mesure my needs in , and I will in July) Any thoughts about this idea?

How much isolation do you need? That's the key to it all. Once you have that number, then you can start looking at alternative methods of construction that will give you that amount of isolation, on your budget.

So please tell me, I'm feeling alone here! ;-)

I hope you are less lonely now! :) :shot: - Stuart -

Sorry about the delay, and thanks for being so patient! It's been crazy around here lately, and there aren't too many people responding to questions...

Don't worry! Many thanks for helping me!

but in the spring it can be annoying if I can’t record because of him.

Maybe sabotage his tractor? :) Just kidding! Or maybe buy him a better silencer for the engine...

I will meet the guy in July, and I already discuss his schedule, he isn't there in winter, and during spring, appart from the harvest, some trucks will come to load the wheat. I will stay 4 days in he house to see contractors about the "living" part of the house, and with some chance, I can catch this with a sound level meter. By the way, I try to figured out which settings is relevent, dBA, C? Slow, fast??

The wall are made of 50cm of stone,

Excellent, but the mortar needs to be sealed properly. It is porous.

Is the cement roughcast on the outside is good with it?

the floor is “naked”, just hard-packed earth (?? I don’t know the correct words for that) on the half that will be the Studio and the is some concrete on the other half,

I would consider pouring a separate, isolated slab for the live room and drum booth at least, and maybe even for other rooms, if you have the budget. That will maximize your isolation.

Ok sorry, I try to simplify some things at the beginning, and I forget to mention I've got this in mind too..

I’m spend my last two weeks trying to make some layout for the studio, this is the one i’m quite happy of:

with that amount of space, I would really, really turn the control room to face the live room, so you have direct line-of-sight to everyone. There's plenty of space to do that, and it is a bigger thing than many people think. Sight lines are very important.

I'm aware of that, but I didnt find a good way to rotate the CR, I think I'm loosing myself with the ratios I choosed for it, and maybe I must rethink this with a bigger CR (50sq.meter maybe) facing the Live room, or maybe keep the same but rotate the console in front of the windows, is it ok to have a widder than longer CR? The only thing is that the musiciens will be closer to my back, and hell they're noisy! (most of all ;-))

Machine room: 5,34m2 (subject to change)

Make sure you leave space around the racks for installation, cabling an maintenance! That's a problem that I often see in badly designed post-production houses: racks with no access to the rear, or no way of sliding equipment out for calibration, cleaning, repair, etc. How many racks are you planning to put in there? What size?

You're right, I need some place inside, i'll rethink this too!

Inside the studio there will be:

Wellll... not really "inside". Each room is built independently, self-supporting, not touching any other room. So it is not that the drum booth is "inside" the live room, but rather that both the drum booth and the live room are "inside" the outer shell of the entire building. This is fully decoupled 2-leaf MSM construction.

Some pictures of my sketchup:

Your rooms are not decoupled! You won't get good isolation like that. see above....

You're right, I need to make a better schematics, this one was for fun, and brainstorming, so I don't try to do all the walls, but I was wrong and I'll take some times to do it again right

And I’ve got another concern, and this is “What’s the best way to obtain the best isolation in a place like that?”, In fact I wish I can use this big stone walls to be one layer of my MSM system, but can it work?

Yes! Exactly.

Great!

And there is “no” ceiling, so what you think I must do here? This is my nightmare of the last week... I don’t know how to do this part, and it’s the one I don’t want to screw up!

For the live room, I would try to use as much height as possible, so I would hang the inner leaf up near the roof. You already said you want a mezzanine level over the drum booth, so that needs to have it's own two-leaf ceiling. The others would probably be lower.

I don't follow here, what is my "outer" leaf, the roof? You mean I need to cover all the roof with on leaf and do another ceiling in top of the inner wall? And I also don't get the mezzanine things... I will try to figured it out.

Make a wall foundation, all around the studio, to support a 20cm width sand filled concrete block wall, on top of a deadsheet

Not one wall for the entire studio, no: one for each room.

Make a concret slab inside the studio, decoupled with 5cm medium density rockwool from the walls

Yes, but one slab for each room, and no need to decouple form the walls.

Fill the 20cm air gap between existing wall and new wall with 10cm of medium density rockwool for damping

Yes. But filling the entire cavity is better: more isolation. For mineral wool, the density should be 50 kg/m3 (or if you use fiberglass, it should be 30 kg/m3).

Ok good things to know

and for ceilling:

Not enough mass, by far! You are putting up thick, masonry walls to get good isolation, so a thing drywall ceiling is not going to be enough to keep the surface density consistent. I'm not sure what you mean by "deadsheet", but I'm assuming it is some form of MLV? If so, forget it: there are much cheaper ways of adding mass to your inner-leaf ceiling.

I'm also thinking of an alternative solution, with a complete wood shell from floor to ceiling (more fitting the shape of the roof), with plasterboard/deadsheet/plasterboard sandwich

That would work too, but once again, you probably don't need the "deadsheet". What product did you have in mind for that? Do you have a link?

I assume it's the same thing: http://www.solutions-elastomeres.com/en/30-bitumen-heavy-masses/380-masses-lourdes-standard.html I'm reading the Philipp Newell book, and he use this term a lot By the way, which cheaper ways? I'm interested!

I tried to make some calculation with the TL formula: TL@f=20(log(fm))-47

That is for mass law, but you are using 2-leaf MSM, which is different. The equation is:

Not preserved: MSM-equation.jpg

(Not sure which text book that comes from, so apologies for not providing the credit. If anyone knows, please tell me so I can fix that). The simplified version is: F0=c[(m1 + m2)]^.5 / [(m1 x m2 x d)]^.5 C=43 for imperial, 1897 for metric m1, m2 = surface density of leaf #1, leaf #2 d=depth of air gap That gives you the resonant frequency. Isolation rises at 18 dB per octave from that point, very roughly (not considering coincidence dip and other possible resonant dips).

Ok, I try to do again the math, but I'm a little confused, If I say: m1 is my wall stone: 1150kg/m2 m2 is my sand filled block: 280kg/m2 d is 0,2m (20cm) I found F=280Hz, it seems quite high? No? If this is true, how can I know the TL@280Hz? and below? which is my main concern. Maybe I screw up something in the process... Is there a topic with all the formulas?, it would be a great thing!

I don't think I can reach the same amount of isolation than the previous one, but maybe it would be enough, easier to do and cheaper (I know I need to mesure my needs in , and I will in July) Any thoughts about this idea?

How much isolation do you need? That's the key to it all. Once you have that number, then you can start looking at alternative methods of construction that will give you that amount of isolation, on your budget.

I will definitively do this!

So please tell me, I'm feeling alone here! ;-)

I hope you are less lonely now! :) :shot: - Stuart -

[/quote] And I thank you again for that! François

I try to figured out which settings is relevent, dBA, C? Slow, fast??

"C" weighting, and "Slow" response. "A" weighting is more used for measuring low level sounds, and usually what legal regulations mention, which is good because it is less sensitive to low frequencies! "C" is closer to the way the human ear perceives loud sounds. "Fast" shows more peaky measurements, "Slow" averages over a bit longer time periods.

Is the cement roughcast on the outside is good with it?

I would still paint the outside with a good quality masonry sealant, just to be sure, and also the inside. A porous wall means that air can move in and out, which changes the acoustic properties, and can potentially reduce isolation.

is it ok to have a widder than longer CR?

Yes... provided that the room is deep enough behind you. So the rear wall should be at least 3.5m behind your head, and that means the room needs to be about 5m (or more) from front wall to back wall. I think you have enough space to do that? That's why the normal recommendation for very small rooms is to have the speakers firing down the long axis of the room, since most home studios are not 5m wide. Many aren't even 5m long! But you have the space, so you can do your room either way.

I don't follow here, what is my "outer" leaf, the roof? You mean I need to cover all the roof with on leaf and do another ceiling in top of the inner wall?

The roof IS your outer leaf: How is it made? It might be possible to "beef it up" with more mass and a better seal. If not then this might be one of those cases where you have to have a three-leaf ceiling. Fortunately, you have plenty of height to do that properly.

I assume it's the same thing:

Similar, but not the same. That stuff is hard to work with, and may also be a fire hazard. Green Glue would give you similar results, and probably even better for low frequencies.

I'm reading the Philipp Newell book, and he use this term a lot

I'm not a huge fan of Newell. Some of the stuff he suggests doesn't seem to fit in too well with acoustic theory. On the other hand, he does build good rooms!

By the way, which cheaper ways? I'm interested!

As you can see from the equations for MSM resonance and mass law, the ONLY thing that really stops sound is mass. Lots of mass. The sound waves do not care how much you pay for the mass! They cannot read the price tag, and they are not "snobbish" anyway, so the really don't care. :) They just react to the mass, plain and simple. There's nothing in the equations that says one type of mass is better than another. So obviously, the most sensible thing to do is to use the cheapest mass that will accomplish the task. In most places in the world, that turns out to be plain old fire-rated drywall. OK, to be fair, there are some other factors that affect different parts of the spectrum, such as stiffness and damping, but the biggest factor is mass. MSM is mostly about low frequency isolation, but low frequencies is the most important part. So go with the cheapest mass that will work. Check your local pricing on the following: 16mm drywall, 16mm plywood, 16mm OSB, 16 mm MDF, 8mm fibercement board. Whichever is cheaper for the same size panel, is the best for you.

I found F=280Hz, it seems quite high? No?

:shock: I get 8.9 Hz, which is excellent! That wall will isolate extremely well, even down to very low frequencies. So there's something wrong with the math. :) - Stuart -

Soundman2020 wrote:

I try to figured out which settings is relevent, dBA, C? Slow, fast??

"C" weighting, and "Slow" response. "A" weighting is more used for measuring low level sounds, and usually what legal regulations mention, which is good because it is less sensitive to low frequencies! "C" is closer to the way the human ear perceives loud sounds. "Fast" shows more peaky measurements, "Slow" averages over a bit longer time periods.

Ok thanks, much more clear!

Is the cement roughcast on the outside is good with it?

I would still paint the outside with a good quality masonry sealant, just to be sure, and also the inside. A porous wall means that air can move in and out, which changes the acoustic properties, and can potentially reduce isolation.

Alright, I'm a little concern about humidity in the wall, as covering as stone wall with cement isn't a good thing, I understand this is because it can't "breath" anymore... And I also understand that I don't want him to breath for isolation... Any alternative here? I think i'll do the right things but it's disturbing for me ;-)

is it ok to have a widder than longer CR?

Yes... provided that the room is deep enough behind you. So the rear wall should be at least 3.5m behind your head, and that means the room needs to be about 5m (or more) from front wall to back wall. I think you have enough space to do that? That's why the normal recommendation for very small rooms is to have the speakers firing down the long axis of the room, since most home studios are not 5m wide. Many aren't even 5m long! But you have the space, so you can do your room either way.

I think I can achieve a 7,36m * 5m * 3m (W,L,H) CR, but I check the ratio, and they're not great, so maybe 6,75m*5m*3m, with is in the "Bolt Area", Is it relevant?

I don't follow here, what is my "outer" leaf, the roof? You mean I need to cover all the roof with on leaf and do another ceiling in top of the inner wall?

The roof IS your outer leaf: How is it made? It might be possible to "beef it up" with more mass and a better seal. If not then this might be one of those cases where you have to have a three-leaf ceiling. Fortunately, you have plenty of height to do that properly.

A good picture is better than loosy explaination ;-) So this is what I mean with "no ceiling", and I'm a little concerned about adding lots of weight directly on the roof, It might collapse... I need to think about that. And that why I was thinking in the first place in making a concrete ceiling in between, I know I will have a three leaf, but a leaf with just the weight of the not really sealed tiled roof is really a leaf? I'm sure there is a good solution, and there is plenty of time to figured it out!

I'm reading the Philipp Newell book, and he use this term a lot

I'm not a huge fan of Newell. Some of the stuff he suggests doesn't seem to fit in too well with acoustic theory. On the other hand, he does build good rooms!

So it is the reason why I was a little confused about what I read in his book and what I read in the other books! Ok, but I think it's a great book, with quite interesting things, but I will keep in mind to double check!

By the way, which cheaper ways? I'm interested!

As you can see from the equations for MSM resonance and mass law, the ONLY thing that really stops sound is mass. Lots of mass. The sound waves do not care how much you pay for the mass! They cannot read the price tag, and they are not "snobbish" anyway, so the really don't care. :) They just react to the mass, plain and simple. There's nothing in the equations that says one type of mass is better than another. So obviously, the most sensible thing to do is to use the cheapest mass that will accomplish the task. In most places in the world, that turns out to be plain old fire-rated drywall. OK, to be fair, there are some other factors that affect different parts of the spectrum, such as stiffness and damping, but the biggest factor is mass. MSM is mostly about low frequency isolation, but low frequencies is the most important part. So go with the cheapest mass that will work. Check your local pricing on the following: 16mm drywall, 16mm plywood, 16mm OSB, 16 mm MDF, 8mm fibercement board. Whichever is cheaper for the same size panel, is the best for you.

Ok, I get the point, Mass, mass, mass!

I found F=280Hz, it seems quite high? No?

:shock: I get 8.9 Hz, which is excellent! That wall will isolate extremely well, even down to very low frequencies. So there's something wrong with the math. :)

Ok, I'm glad I screw up! But I can't figured out my mistake, I find the same again and again... I do this: Where m1+m2=1100+280=1380 But I prefer your version, So I was reading the73' Wyle Laboratories report I found on another thread, and if I understand correctly, the Mass law is OK for frequencies below F, so 8,9Hz in this case, and it's +18db per Octave above. In this paper they use TL=20log(Mf)-33,5 (M=m1+m2) and you use -47 instead of -33,5, why? (Sorry I need to understand things like that to sleep at night...) So if I use the paper formula: I've got Tl@8,9=20log(1384*8,9)-33,5=48,3dB And at 18Hz I should have 66,3dB, 84,3dB at 36Hz... And I will stop there because it seems strange, either I'm building Galaxy studio again, either I misunderstand something ;-) So I will work this, Thanks a lot, you're very helpful for me!!! François

Hello! I made a break today in the maths to try another layout for the studio, with a new CR, and decoupled walls, If anyone has any thougths, you're welcome! I tried a different shape for the CR, which became bigger (40 meter.square!) The blue things are windows, or windowed doors, and the brown things are plain doors

Looks good, actually! To avoid the need to have the rear surround speakers in the middle of the room like that, you could consider moving them to the walls (on the same angles, of course), then compensate for the time differences with delay on the other speakers. It makes the room look cleaner (visually) without affecting the acoustics too much. Also, you need another wall to complete the entrance "soundlock": as it is right now, the entire soundlock is in your wall cavity, between the two leaves... - Stuart -

Hello! I just realize my last post was 5 month ago... Just a word to say i'm not done with this! I've been very busy with work and the process of buying the house this last months. Lot of thing to think about, so I made a break in the studio design, waiting the barn to be mine (which is almost done!) i've got an architect who will working with me, in order to not do something stupid with the law ;-) and I will return to the drawing board the sooner I can, and I can't wait! Thank for your help Stuart, I'll come back soon with more questions! François