John Sayers' Recording Studio Design Forum

Hello to you all,

I'm Mic from Holland and this is my first time at this great forum.
I've designed a new studio for myself and was wondering if I did the right thing.

Dimensions are: DxWxH 850cm x 510cm x 290cm
The room is made soundproof by a box in box construction from Acousticon. The inner walls are made of double drywall.

I was planning to cover the walls with a light weight carpet and place some absorbers.
The sweat-spot is at 38% of the room.
In the back corners I planned hangers for bass-trapping and a diffusor.

I have some pics attached.

Can someone take a look at it and give me some comments.

Thanks

Hi Mic, and welcome!



What is the purpose of the carpet? Is it proper acoustically transparent carpet and only intended for decoration? If so, then that's fine. But if you are talking about just hanging ordinary carpet, I'm not so sure that would work. My guess is that it will give the room a "honky" sound, since it will absorb some highs but not lows, and you want the opposite.

Are those big blue things in the corner bass traps? If so, good! Make them big.


What ratio is that based on?


Is the inner leaf totally decoupled form the outer leaf? You have a 5 meter ceiling span, so you must be using some pretty large beams for the joists for your inner leaf ceiling. What are the construction details of the rest of the room? What is the floor made of, and what about the outer leaf? How about doors and windows? And have you considered HVAC?

38% is just a guideline, a starting point: You might find that once the room is built, you can move that around a bit, to find the REAL sweat spot.

I see all your speakers are free-standing on stands: Have you considered flush-mounting (soffit mounting) for the front speakers.

Just a couple of comments.


- Stuart -

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

Stuart. Hi and thanks for your welcome and reaction .

The carpet is just for decoration.
The blue things are indeed the bass traps, I planed hangers in it.
Or do you have other suggestions?

The room dimensions are not in ratio it's just the space I have.
Is it wrong?

The whole inner construction(walls, ceiling and floors is Fermacel. (Kind of drywall)
The ceiling hangs on the existing ceiling with a special construction made of pieces of fibreboard with some kind of foam/rubber between it. (Sorry I'm Dutch I can't translate everything into English.)
There comes a final ceiling under need it. But hat's not on the pictures
Must the ceiling be a symmetrical with the floor?

The floor becomes a wooden floor.

They are two doors. They are made out of 5cm wood.(Plywood?)
One window with two panes.

The speakers are just for the picture. The real speakers are B&W Nautules. I like them standing on the floor. They are made for that.

There comes a professional split HVAC in it. Anything special I must no about this?

Thanks so far.

So then it should not be normal carpet (the type you put on your floor). It must be proper acoustic carpet, which is transparent to sound, and has almost no effect on it.


How about these?

http://www.johnlsayers.com/HR/index1.htm
http://forum.studiotips.com/viewtopic.php?f=8&t=535
http://forum.studiotips.com/viewtopic.php?f=8&t=534
http://www.bobgolds.com/TrapHarder/home.htm

Search the forum for "bass trap", and read, read, read....


It might be! Or it might not be. Calculate what your ratio actually is, then compare it to some of the graphs and charts that you will find here if you search for "room ratio". A poor room ration means that you will probably have very uneven low-frequency response. A good room ration means that the response will be more even.


Do you have photos of that? I have not heard of that method before. Normally, you want to disconnect your inner ceiling from the outer ceiling, to avoid "flanking".


So you have THREE different ceilings in there? That is probably not good. If so, it means you have three-leaf construction. That means that your isolation at high frequencies will be better than for normal two-leaf construction, but for low frequencies (drums, bass, etc.) the isolation will be worse. So if you really do have three leaves, then the sound of your drums, bass guitar, and any other low-frequency will get through your ceiling very well, and well be heard up above.

I'm not sure if that is actually what you are describing. Could you make a detailed SketchUp model of your ceiling, showing exactly how it is built?


It can be, but many people angle the ceiling at 12 degrees, so it is lower at the front (over the speakers) and higher at the back. The control room must be symmetrical to the left and right, so that you get good stereo imaging, but it is not necessary to have it symmetrical from top to bottom.


And what is underneath the wood? Is it wood laid directly on top of concrete? That would be good. Can you show a detail of how the floor is built, starting with the ground underneath and showing everything from there up to the finish floor?


That sounds OK. The doors are sealed well, all around the edges?

What kind of glass is in the window panes, how thick is it, and what is the size of the gap between the panes? For best results, the glass should be thick laminate glass (not normal float glass), and there should be 8 inches of air gap between the two panes.


Split system is good! It should be very quite, of course, if possible.

But what about fresh air? In addition to the cooling, you also need to get clean air into the room, and exhaust stale air outside. Split system air conditioners don't do that: you need a ventilation system to do that.

Did you actually BUILD this room already, or are you only in the process of DESIGNING it?


- Stuart -

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

Special carpet...ok...I hope I can find that.
Maybe just paint the room?

The ceiling, walls and floor are the same contrsuction.
Akoestiekregel(The MDF with foam in between, see picture) on the outer walls, insulation(rock wool)between them and double 12mm gypsum plasterboard on it. (On the floor it's fermacel)




BTW it's not me on the picture

The floor and ceiling are the same construction as the walls but the 'Akoestiektregels' are more heavy.
This is the way I created a box in box construction.
And this is where I am right know. Now I have place the wooden floor, absorbers diffusors etc.

The original outer walls are heavy mass white stone blocks(I realy don't know how you call them)They are 18 cm thick.

The original ceiling and floor whereupon the box in box is created is concrete.

I'm planning to hang a extra ceiling in the room witch is asymmetrical with the floor.
The 12 degrees should be ok then?
I can put the lights, AC and fresh air outlets in it.
Here's a example of the ceiling tiles:



I hope it's more clear now?

Thanks for the additional info. I've never seen those "Akoestiektregels' things before! Do you have any information on their acoustic isolation properties? Technical specifications from the manufacturer, for example? It looks like they just have some type of foam in between two layers of MDF, and I'm not sure how well that will isolate acoustic vibrations. They are not very thick, either, from what I can see on the photo: The air gap is just going to be a couple of centimeters. That doesn't sound like enough to get good isolation. The recommendation for good isolation is 20 cm air gap, down to about 10 cm, but it looks like those will only give you maybe 4 or 5 cm.

The good thing is that you have thick stone block walls, and concrete ceiling / floor, so you have plenty of mass in there. So probably the lack of a good air gap and good decoupling is not that important, I think.


Then you definitely are creating a three-leaf ceiling! This is not good in general, as it REDUCES isolation. Low frequencies will get through that much easier than if it was just two layers: I know that does not sound logical, but acoustics is not logical in general! That's the way it is. Three leaves will give you WORSE isolation at low frequencies. The second ceiling (the one that is attached to the "Akoestiektregels") is the one that should have been angled at 12 degrees.

But it's not a bog deal: Many people build studios with flat ceilings, and some even recommend doing that. Personally, I think that if you already have your two leaves in place, then forget the third angled ceiling, and just go with the flat ceiling that you already have. Maybe Rod or John or André or Ro could offer you better advice on that.


- Stuart -

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

Hoi Mic, welkom op dit forum
(another Dutch dude enters the forum, hurray!)

Akoestiekregels are 2 pieces of wood with bonded foam in between. The foam is supposed to act as a spring. does it work? dunno, it all depends on your mass. The spring has to be active or it'll just flank.
Recilient channel (you can get'm from Auralex, there's a dealer here in the Netherlands) have the same function. Do they work? same answer: depends on the mass that makes the spring active.

Hallo Ro, dank je. Het is een geweldig forum.
(Translation: Hello Ro, thanks it's a great forum)

I can't find any technical detail on the 'Akoestiekregels', but the company in Holland who sells them guarantees 60 to 70 dB sound reduction from the outside if you build it the way they say.
Wich I did.
Next week, when the doors are sealed and the windows pains are placed, I'm going to measure the sound reduction.

-Stuart-
I've used the 10cm 'Akoestiekregels' that should better then the one on the picture.

I have to place an extra ceiling because of the lights and AC. I know I should have give it thought before I started but the company who delivered the 'Akoestiekregels' told me to build it this way.
Maybe it helps that between the concrete ceiling and the 'Akoestiekregels' ceiling is also 10 cm of rock wool.

I hope that Ro, John, André or Rod can give me some advise here? Please.

Another question: When I want to place extra speakers(big ones) for the 2.0 mix, is it best to place them in the corners? There is then app. 5 meters between them.

it is!!

Akoestikon, the dealer in question, does provide universal info. Calculating the actual active spring in such products is tricky work. Too much mass (overload) or to little mass (underload) and it'll just end up as a flanking path. Tricky? yeah, sort of.

How did you figure?

What's your current ceiling/roof construction look like? Only concrete? Imagen the same Akoestiekregels on the wall and ceiling. Imagen how the same mass (say, 2x12,5mm GB) would act on the "regels". There's a big difference between the forces pulled on the material. Ask the supplier (akoestikon) how much mass is supposed to make it work and how much distance space between each "regel".

Yes, fill it with wool.

no, corners is where bass builds up.

Do they mean "STC 60 to 70"?, or are they talking about transmission loss? Either way, that figure sounds very optimistic! And like Ro mentioned, in order for that stuff to work, you have to load it correctly. If you don't put enough mass on it, then it won't be stretched to the point where it starts working, so it will flank. If you put too much mass on it, then it will be overstretched, and will flank. Also as Ro mentioned, loading on the ceiling is very different from loading on the walls: With the ceiling, the entire weight of the drywall is suspended from those things, but with the walls there is practically no weight at all actually stretching them. Al of the weight is downwards, creating a shear across the face of those supports, not stretching it out, perpendicular to the face, which is what you need. I can see how they might work for ceilings, but I don't get the principle of operation for walls.

I
Well, that will give you a bigger air gap, but does the 10cm support have the correct specifications for the load you are hanging on it?


If you add another ceiling, that introduces a third leaf. The laws of physics say that this will REDUCE the isolation of your entire ceiling across a range of frequencies at the low end of the spectrum, roughly where instruments like drums and bass guitars put out a lot of energy. The exact frequency range where this will happen depends on a number of factors, including the masses of the leaves and the dimensions of the air gaps.


They told you to build a THREE LEAF ceiling? Did they explain to you that it will make the isolation WORSE at low frequencies? Did they know that you are building a recording studio? Perhaps this stuff and their three-leaf recommendation is only meant for office and residential construction, where there usually isn't much low frequency energy. so the reduction in transmission loss would not be too much of a problem.

But as long as you are aware that adding a third leaf will reduce your low frequency isolation, and you are OK with that, then I guess you have no choice but to go ahead.

Once again like Ro said, corners are not a good place for your speakers. Room corners are where all the room modes meet, so your speakers will probably excite all or most of those modes if you put them there, and especially they will excite low frequencies more than high. 5m apart is also a large distance. That would mean that your mix position would also have to be nearly 5 meters away from the speakers, which implies that you'd need a room over 13 meters long. Your is only 8.5. You'd also have to treat the room heavily if you wanted to make sure that you are not beyond the critical distance.

Normal recommendation is to have your speakers between one and two meters apart, with the acoustic center of the speakers at the height of your ears when seated at the mix position (which usually turns out to be about 1.2 m above the floor). They should be angled towards the mix position, so that the axes intersect about 25 cm behind the middle of your head at an angle of 60 degrees. You can move them further apart if you have to, and you can increase that angle to as much as 90 degrees if you need to, but try to not get too far away form the speakers, and do keep them out of the corners.


- Stuart -

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

Hi to all.

It's bin I while but now I can go further with finishing the studio.
The AC builders needed four weeks for all of the studio's.

My question is, what should I place for acoustical treatment.
If you look at the drawings, I planned to place absorbers at the side walls.
Big bass-traps in the rear wall corners and a broadband diffuser in centre rear wall.
On the empty spaces on the walls I planned thin wooden panels and maybe I cover it with acoustical transparent fabric just for cosmetics.(Acoustipro)

But I am a little concerned about a place on the wall that's the opposite of the window.
Should a place a diffuser there?

Any idea's here?
PS I try to place some pictures of the progress here at the end of the week.

It's about time you posted pictures!

General rule is: hard surface against soft surface. So on the opposite wall of the window you might wanna place an absorber.
Is that window a view into your tracking room? If not, my advice is to put a (portable) absorber there for your first reflections.

Yes I Now

Thanks Ro, but what about symmetry! I mean isn't that important for the stereo image when mixing? So isn't it better to place a hard surface or a diffuser in opposite of the window?

That window is for looking into two rooms which are multi purpose rooms. They are tracking rooms and edit suits. So when mixing It's possible to place a portable absorber in front of the window.

If it were my room I'd probably start with a known room ratio. 1/1.4/1.9 would make the room 406cm x 551cm.

Also, it looks like your window is right at the first reflection point of your speakers. I have mixed many times in aroom like that and while it doesn't completely suck I sure wouldn't design it that way.

I certainly don't want to hi-jack the thread but I have a quick question. Do you consider room ratios BEFORE or AFTER treatment? For example, John has an 8" DIY wall absorber on the front and back of the room in the DIY wall units tutorials. Is the room to spec before or after this?

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Myriad Rocker