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PostPosted: Sat Apr 16, 2016 1:55 am 
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Joined: Sun Apr 10, 2016 3:16 pm
Posts: 4
Location: France, Bretagne
Hello,

my name is Fred, I'm from France. I plan to build my own studio.

I record, mix, produce and master for 25 years near full time. In these domains, I've got experience and still learn everyday with passion, but in acoustics I'm far less experimented. Well...just have modestly build experimentally 2 recording studios from scratch in every home I lived in -- but also worked professionally regularly in high class acoustic environnements, so I know how it is supposed to "sound" when studios are very well made. Have read about acoustics few books, and experimented at home to fix some issues, constructed absorbers and diffusers, made measurements, saw and heard the differences. So I perhaps only know the fundamentals that a sound engineer must know, but I am absolutely not skilled at all for designing and calculate sizes, angles and so on to achieve the best results. In fact, this is my first serious attempt to create a studio, I mean, not from scratch, but conceived and calculated the best I'll can. I've just bought recently my own house, which is big, and hope to get for the first time a quite decent studio. This is my wish. It won't be perfect, since ceilings are already limited to 3m height most of the time inside. But this will be whatever far better than what I had at home before.

Unfortunately, as this is a house, the biggest rooms are already surrounded and made in heavy material so I have to manage with (don't have the budget to break and reconstruct heavy walls, and for some of them, no way to do so technically even with budget because some are bearing walls). I have to deal with what I have in terms of heavy structure. For instance the inclined roof on the 40m2 room, which is intended to be my mastering room. I want it constructed as a RFZ mixing room because I always found them to be more accurate, more analytic acoustically (less comb filtering) than so-called "mastering rooms" which are often too live for me). Notice that I will have also to mix (digitally) there. So RFZ control-room is my first goal.

The rest of the building is 3m height, and it will be the recording part with another control room (a bit smaller in terms of X & Y but 3m ceilings and less natural light).

Well, anyway, my priority is to create first of all the mastering / mixing room inside the room with angled ceiling.
And I need to understand number of things as you see before drawing something good !!

so this topic will be centered mainly on this Mastering / mixing room.

To begin with,

THE SIZE : 8m (Lenght) x 5m (Width) x 2,30m to 3,20m (Height)
Size are external measurements. Knowing that concrete walls are made of 20cm thick concrete.

Here are two pictures I took very quickly in order to show you the room.

Image

Image

The windows will be replaced with brand new higher ones (220 cm x 150 cm) with highest sound isolation properties. Of course, I plan to covered them with translucend acoustic treatment. It can be absorber type (tissue), it can also be translucent diffusors made of plexiglass.
This will depend of the needs in acoustical domain.

Just for information, this house is in the country, so outside noise level is not a problem (except some farm animals sometimes, but this is quite negligible), and the studio noise won't be a problem for neighbours since they are very far away from my home.

I'm working on drawings now..Not easy, I'm learning.

But I have several questions in which I can't find answers, this is why I write to you here.

First question :

As far I searched, I did not find room mode calculator which can take account of inclined roofs such mine. Can you help me to find one if by fortune, it exists ?

Second question : concerning thermal insulating in recording studios.

In acoustic books that I have, I never saw anything about thermal insulation. It is perhaps supposed that thermal insulation is always made on the outside, so there is no need to build insulation walls inside.

in France, most of the houses and buildings were and still are isolated inside because of the price (3x espansive for external technologies). Also, the current standards of thermal insulations inside building impose to place everywhere on the fiberwool a thick microporous plastic leaf (vapour barrier) which allows the moisture to escape but blocking the air leaking (to avoid air currents, I don't know if it is the right expression). and the we put plasterboards. This is for ordinary buildings. For recording studios I don't really know.
But I can't affort external insulation so I have to manage with this factor.

In the old days, plasterboard, outside the fact it acts a rigid wall in the houses, had the role of blocking air leaking from the outside.
Nowadays, with plastic vapour barrier everywhere, if it is properly done, we can avoid putting plasterboard if needed. For instance, we can put directly stretched fabric, or anything else. So, in a recording studio, there is no longer need to have after thermal insulation wall, a second layer of glassfiber for acoustic treatment. I don't know if I'm very clear but this is difficult for me to explain in english. I never really saw how old recording studios were build in france (never opened a wall...) but I think they solved the problem with no separate thermal insulation, but more heating in winter. Now energy costs are constantly and dramatically increasing, so we have to take in account. Here in winter we can reach -15°C sometimes. Not often but this happens. Whatever -5°C in the night is the rule several months per year.

So if we avoid plasterboard second wall, we will have plastic vapour barrier on the surface. This won't prevent LF absorption, which is good, but of course this will act as a reflector in the HF domain. And of course this is optically ugly. This can be covered of course with stretched fabric or whatever else needed for acoustic purposes.

Question (maybe a bit obvious, but just to confirm my thoughts) : is it a problem to have [excepting the windows and the door] absolutely everywhere around the studio at least 160 mm thick fiberglass and on the roof 280 mm all long ? Of course we can put more fiberglass locally where it is needed and advised (corners, front wall). But where it is no needed, the only possibility is to put plasterboard, if something rigid is needed, or any kind of diffusor or abfusor.
If I well understood, will it be right so ?

I have already other questions, but let's begin with the basic or "newbiest" ones, after I will go further in details.

Hope those questions won't be too "newbie" levelled...

Thanks so much in advance for your answers and advises.

Best regards from France,

Fred


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PostPosted: Sat May 21, 2016 10:43 am 
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Joined: Thu Aug 21, 2008 10:17 am
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Location: Santiago, Chile
Hi there Fred, and Welcome! :)

Quote:
Unfortunately, as this is a house, the biggest rooms are already surrounded and made in heavy material so I have to manage with (don't have the budget to break and reconstruct heavy walls, and for some of them, no way to do so technically even with budget because some are bearing walls).
That probably will not be a problem. What is roof made of?

Quote:
I want it constructed as a RFZ mixing room because I always found them to be more accurate, more analytic acoustically (less comb filtering) than so-called "mastering rooms" which are often too live for me)
:yahoo: Yes yes yes! Absolutely!

Quote:
THE SIZE : 8m (Lenght) x 5m (Width) x 2,30m to 3,20m (Height)
Size are external measurements. Knowing that concrete walls are made of 20cm thick concrete.
Nice size. That can be made into a good mastering studio.

Quote:
The windows will be replaced with brand new higher ones (220 cm x 150 cm) with highest sound isolation properties.
Careful! Don't replace anything yet. Windows work as a system. You can't replace the outer-leaf windows until you have the inner-leaf designed, and know what the propeties of that will be.

Quote:
Of course, I plan to covered them with translucend acoustic treatment. It can be absorber type (tissue), it can also be translucent diffusors made of plexiglass.
Plexiglass is not much use in acoustics: it is light weight (not very massive), and flexible (not very rigid). Your inner-leaf window should be glass, just liek the outer-leaf one. They work together as a pair.


Quote:
Just for information, this house is in the country, so outside noise level is not a problem
No wind? No rain? No hail? No thunder? No aircraft flying over? No cars arriving/leaving? No people talking outside? No radios, TV, lawnmower, or anything else? ...

Quote:
As far I searched, I did not find room mode calculator which can take account of inclined roofs such mine. Can you help me to find one if by fortune, it exists ?
No. Because there aren't any... ! :) Simple room mode calculators on work for rectangular rooms with six sides. As soon as you angle one side, or have more than six sides, the results are no longer valid, and you would have to switch over to hiring an expert FEM/FEA operator to model your room in FEM, then analyze it, then interpret the results. There is no other simple way of doing that, if you want accuracy.

Plus, you cannot leave the roof like that in any case! A mastering room must be perfectly symmetrical, and must be oriented along the longer axis. You cannot achieve that with the angled roof. You will have to build an inner-leaf that creates both symmetry and a good room ratio. If you try to build a master room without doing that, you will not get an accurate stereo image, and the sound stage will be skewed to one side: the frequency response will be different on each side. That MUST be fixed if you want an accurate mastering room.

Quote:
In acoustic books that I have, I never saw anything about thermal insulation.
Right. Because you do not need any additional thermal insulation in a properly designed studio. You will have two massive leaves around you, on all sides, and there will be very thick insulation in the cavity between them. Both leaves will be sealed perfectly air-tight, and the HVAC system will be designed to keep the conditions constant inside. You do not need any additional insulation, unless you live in a very extreme climate.

Quote:
Also, the current standards of thermal insulations inside building impose to place everywhere on the fiberwool a thick microporous plastic leaf (vapour barrier) which allows the moisture to escape but blocking the air leak
Yes you will need a vapor barrier: that always goes on the warmer side of the wall cavity, which in your case will be the inner-leaf. But the vapor barrier has nothing to do with thermal isolation: it is there to control humidity inside the wall cavity, and to prevent condensation occurring in there. Maybe you are confusing that with an air barrier, or a moisture barrier? They are different hings, for different purposes. And they go at different places inside your wall.

Quote:
Nowadays, with plastic vapour barrier everywhere, if it is properly done, we can avoid putting plasterboard if needed.
No you cannot. The vapor barrier is vor a very different purpose than the plasterboard. As I mentioned above, the vapor barrier is a plastic film that prevents water vapor from moving through the wall into the wall cavity, from either side. It is placed against the warmest leaf of the wall, inside the cavity, and thus it also prevents the water vapor from condensing on the surface of that leaf,which would cause mold, and damage to the framing and insulation, over time. The vapor barrier does not and cannot replace the leaf, and the leaf does not and cannot replace the vapor barrier. They are two entirely different things, and serve entirely different purposes.

Also, since this is a studio that you are building, it has acoustic requirements, which means that your inner-leaf needs to be massive, rigid, solid, and suitable for attaching the acoustic treatment. A vapor barrier is useless for all of those. You would not be able to nail or screw anything to a vapor barrier, as that would puncture it, and therefore negate the entire purpose. It must be a complete sealed surface, with no holes. if you nail a hole in it, then it is no longer a "barrier" to "vapor", because the vapor can now get through the hole....

You seem to be misunderstanding the purpose of the various parts of a studio wall... You cannot change that.

Quote:
there is no longer need to have after thermal insulation wall,
The inner-leaf of a studio is NOT there for thermal insulation! Why would you think that? It is there for ACOUSTIC reasons. Nothing at all to do with heat.

Quote:
So if we avoid plasterboard second wall, we will have plastic vapour barrier on the surface.
No, you cannot do that. You CAN NOT use the vapor barrier as a leaf. You are completely misunderstanding how a wall works.

Quote:
This won't prevent LF absorption, which is good,
Actually, it isn't good, and studio walls are not there to provide LF absorption anyway. That is not the purpose.

Quote:
is it a problem to have absolutely everywhere around the studio at least 160 mm thick fiberglass and on the roof 280 mm all long
Yes it is. A big problem. You say you want a mastering studio, which means it must meet the ITU BS.1116-2 specification (or the similar EBU-3276 specification). You cannot achieve that by putting the same treatment everywhere. You need to put the correct treatment for each place in the room. There are methods and procedures for doing that. The goal is to that the room must be completely neutral, acoustically: It must not add anything to the pure sound from the speakers, and it must not take anything away. It must be "transparent".

Quote:
Of course we can put more fiberglass locally where it is needed and advised (corners, front wall). But where it is no needed, the only possibility is to put plasterboard, if something rigid is needed, or any kind of diffusor or abfusor.
It's a lot more complicated than that, for a mastering studio! The entire studio must be designed carefully, and tuned carefully, with specific treatment installed at each point that is needed, as indicated by careful acoustic testing. Such as this room: viewtopic.php?f=2&t=20471 That room has perfect acoustic response, as you can see from the graphs. It took a lot of work to make that happen, and there are many different types of treatment and tuning in there.

I would suggest that you buy two books: "Master Handbook of Acoustics" by F. Alton Everest (that's sort of the Bible for acoustics), and "Home Recording Studio: Build it Like the Pros", by Rod Gervais. they will give you the basics of understanding acoustics and studio design. Or maybe you should hire a studio designer to do it for you.

- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.


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