John Sayers' Recording Studio Design Forum

First off, thank you for all this great info!

My question is about insulating control rooms v. live rooms. Maybe there's no difference in treatment

So far I have built: 16' x 24' space with Reward Wall 11" blocks. That's 6" concrete core + 2.5" styrofoam on either side.

There is also a 4" poured slab with expansion on the sides and down the middle partition (to be wood + space). There will be two rooms, the control room being 9' x 11 7/8" x 13' 10". The live room side will have open cathedral ceiling and above the control room is a open loft.

For sound absorption insulation within the walls and ceiling, should I be using (in my case I use) Rockboard 60?

I also have made 6 traps...they are standard 6" x 24" x 48" with Rockboard. See this post. http://blog70.org/?p=1000

I'm sorry if this is incomplete, I'd be glad to show pics, floor plans etc. My plan now calls for 2x3 framing, RC-2, and a 1" cavity. NO insulation.

Construction is picking up speed now that my walls are poured and the slab is walkable...I'm just trying to get it right! Thanks so much.

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Chris Jones
www.circa70.org

Hi Chris, and welcome!



I'm not sure that I follow what you are saying: you seem to be confusing insulation, isolation, and treatment all in one. They are different things. Insulation can be used as part of your isolation, and also as part of your treatment, but isolation is not treatment, and treatment is not isolation.

So you are saying that you have a concrete slab on the ground, and you have built four walls around the perimeter with these blocks? Is that it? So you now have an empty space inside, measuring 16 x 24, and you want to build a two-room studio in there, with one live room and one control room?

I didn't get that at all. I think you are saying that your floor slab is divided in two down the middle of this 16x24 space, and there is expansion joint compound in the gap between the two pieces, but I don't get the "wood + space" comment. What does that mean?

OK, so it seems you don't actually need much isolation between the rooms: you are fine with sound bleeding between the rooms, and all you want to do is to treat the rooms?

Bow you confused me again! It seems like you DO want isolation between the rooms.... If not, then why do you need damping inside the wall cavities?

Yes, that would be useful. It's hard for us to imagine what the place looks like, just based on a brief description. You can see it, but we can't unless you show us!

Whoaaa!!!! You just said that you plan to use insulation in the wall cavity, but now you say you do NOT want to use insulation in the wall cavity So which is it? Do you need isolation, and therefor plan to damp the cavities with insulation, or do you not need isolation? And if you do not need isolation, then why use RC? Since you are using RC, it seems like you DO need isolation, but then you say you will not damp the cavity with insulation!!!! Sorry, but this is really confusing! And 2x3 framing will not take the huge weight of what you are trying to do, especially for ceiling joists. Depending on span and other factors, you might need 2x8 or even 2x10 for joists, and certainly at least 2x4 for walls.

Maybe you could post a more detailed description of what it is you are trying to accomplish first, then how you are planning to achieve it.

Also, a 1" cavity is way too small to be useful for isolation: The cavity should be at least 4", absolute minimum. But don't confuse the cavity with the gap between the studs: it's not the same thing, unless you are planning to build your walls inside-out.

Nice work! Those look pretty good, and should work fine, but you didn't label the graph! I'm guessing here: Red is "before" and green is "after"? Also, your placement of those devices seems rather strange: You only shoe three of them in the final position, but they don't seem to be in the places where they would be doing the most good. Is there a reason why you have them where you do? And where are the other three?

- Stuart -

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

Yes, I understand this now. It's my first time tackling all these aspects and I'm getting it straight.


Yes.


The partition wall is to be constructed with double framing and an air-space. If I can find a better design than that I'd do it.


The control room will have a 9' ceiling. On top of it is a storage loft. The other side is open. I'm looking to isolate both sides from each other.


Yes, I want isolation between the rooms. Does damping mean insulation? I'm doing that to stop wall cavity resonance.


I will show you plans. My architect has not designed a studio so I am trying to correct them by learning fast


I'm sorry for the confusion. My architect specified no insulation. I am correcting that by adding it. I do want isolation and I do want to pre-treat the room via insulating cavities. My architect has not designed a studio before and I'm trying to fill in the blanks.


Yes, the ceiling joists are 2x10.


I'm trying to create a control room based on a 9' ceiling using either a 1/1.14/1.39 ratio or 1/1.28/1.54. The entire space available is 14'3" x 22'3". I'm dividing the space into two (2) with a shared wall, effectively two (2) rooms, one live, one control.


I believe the gap is just to keep framing off styrofoam, not for any isolation attempt. It's less than 1" it's a 1/2" air gap.


Thanks. Yes red = before, green = after. You are seeing only three, there were two at the reflection points on the walls and one was not involved. The center one was probably a mistake as the back wall was very far away. It was not a good shape = basement with 7' ceiling. I will be making some traditional wedge corner traps to use in front corners.

Thanks very much for chiming in. I'm taking all these various hints in. I hope I cleared up any confusion with the initial post.

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Chris Jones
www.circa70.org

Please just go here:

viewtopic.php?f=2&t=17809

Mods can delete...I've also pm'd my responder. Thanks.

_________________
Chris Jones
www.circa70.org

The partition wall between the two rooms is only part of the isolation: you cannot isolate two rooms with a single partition wall: sound will simply flank around that wall through the rest of the structure. Isolation requires that BOTH rooms are constructed as fully-decoupled MSM "room-in-a-room" systems, with the existing wall that you already built being the common outer-leaf. So you don't just need a partition wall: you need to frame each room individually, put drywall on the framing, and put insulation in the cavity.

How will you get access to that storage space? That will have to be by external stairs. You cannot have any holes or access hatches in your inner-leaf ceilings if you want good isolation.

That's exactly what damping is: the fibers of the insulation act to damp the resonance in the wall and ceiling cavities.

That is a major problem. Designing a studio is nothing at all like designing a house, school, office or shop. There are major differences in basic concepts: you can't learn this stuff in a few hours. I would suggest that you also hire an acoustician to do the acoustically related parts of the design: your architect might be a great architect, but if he has never designed a studio then he's not the right guy to be doing that.

... which is why you need an acoustician involved! Your architect missed a major issue there: insulation in the wall cavity is a major factor in calculating the MSM resonance, which you must do in order to correctly design the isolation plan. Not putting isolation inside the wall cavities will cost you as much as 16 decibels of isolation: that is a MAJOR difference. It's the difference between good isolation and an unusable studio. That's how important it is.

... which suggest that 2x3 framing for the walls is inadequate. What live and dead loads did you consider, and what deflection, and what span, when you did the calculations to figure that you would need 2x10 joists?

The Styrofoam has no useful acoustic effects: styrofoam is closed-cell foam, which is good for thermal insulation, but lousy for acoustics. It does nothing for you, either in isolation or in treatment. So you will still need suitable insulation in the cavity, at least 4" of it. Either fiberglass or mineral wool will work fine.

Also, the 1" air gap is way too small: the equations for calculating MSM resonance are not linear, but exponential, so as the gap gets much smaller than about 4", the resonant frequency rises very fast, and it becomes impractical to compensate with more mass on the leaves.

OK, but those three at the front are still not in their optimal locations. You would still have been getting SBIR issues and comb filtering like that. It must have been hard to do a mix in that room that would translate well. The two panels that are above the speakers should have been placed directly behind the speakers, between the speakers and the front wall. Perhaps even rotated to be vertical, instead of horizontal. The center one is probably fine where it is, but would have been better if it were a bit lower down the wall. There are several other things that could have been done to improve that room, but with this new one you'll be able to do a lot more to get it right!

- Stuart -

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

_________________
Chris Jones
www.circa70.org

Please quote and reply here..

viewtopic.php?f=2&t=17809

_________________
Chris Jones
www.circa70.org