John Sayers' Recording Studio Design Forum

Hey guys,

It's been a long time since my last project. I know this is the best place to go for some feedback.

I'd love for you to shoot some holes in this thing. I'm in the prelim stage. It's really a clean slate. It's going in an existing building for a profit/non-profit organization that teaches kids about music, recording, dance, technology. A very cool thing to be a part of.

Any and all feedback would be greatly appreciated.

Jason

Hi Jason, Welcome back!

A couple of quick comments:

The basic plan looks good, but you seem to be confusing the isolation and treatment! One of your side walls is marked "slats and fabric", but that wall should be the inner leaf or your isolation system! Yes, you can put slats on that wall if you build it inside-out, and thus combine isolation with treatment, but you still need to think of the two concepts separately: isolation is one thing, treatment is another. Those walls should be labeled "inner-leaf", and they should be built with drywall on stud frames, as a proper MSM system.

Another comment on your SketchUp model asks "Insulation bass trapping in these voids?". Wellllll, .... yes and no!!! Those "voids" are the "spring" part of your MSM system, and yes they do need to be filled with insulation. But they are not bass traps, and cannot be used as bass traps if you also want to isolate your room. Instead, they need to be designed correctly to work as an MSM system with a sufficiently low resonant frequency for isolating that room.

In other words, what you show in that diagram as a treatment plan should actually by the isolation plan! Treatment design comes later, once you have the isolation system properly designed.

Maybe you could also provide construction details of the rest of the building, plus your design goals for the room, in terms of how much isolation you actually need.


- Stuart -

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

Thanks for the reply Stuart. It's good to be back here.

The existing structure is basically an 18,000 sqft. space in a business park. It was previously a furniture store. 11' ceilings with the usual suspects like, fire sprinklers, conduit for lights, duct work, etc.

What I should have been more clear about in the drawing is that I'm coming down to 10' to allow for all of the afore mentioned spaghetti. I plan on using a metal stud framing with rigid fiberglass and sheetrock walls with acoustic caulk on the seams to frame out the "outside room".

Then, inside of that will be the other stucture that you see. This will be built the same way with metal framing and rigid insulation and sheetrock. Inside of those walls will be the treatment.

I hope this is more descriptive. Looking back on my post and pictures... it was ridiculously vague.

THX!

Jason

Hmmmm.... red flag?




That sounds a lot like a 3-leaf system to me. Maybe even a 4 leaf? Is that really necessary, considering the resulting loss in low-frequency isolation?


- Stuart -

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

When I say existing sturcture, I'm talking 18k sqft. of nothing but flooring. It's an empty shell of a building with 11' ceilings. The studio will be only one area of the total business. It's a school really. They will build classrooms in there, a runway/stage for modeling/live performance, the whole 9 yards.

Imagine a wide open floor plan and you need to build a studio smack dab in the middle of it and there's other stuff going on all around. It's not supposed to be completely isolated. The budget won't allow for it, plus it's a long-term lease.

Ahh! That makes more sense!

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

Here is the BASIC idea.

Walls = sheetrock > rigid fiberglass > sheetrock

Basic idea looks fine to me!

But I'm still not clear on some things about your diagrams. Are you planning to build the inner leaf inside-out?



Does that mean that you plan to have sheetrock on just one side of the outer leaf studs, and sheetrock on just one side of the inner leaf studs, with fiberglass insulation in the large cavity between them?


- Stuart

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

Well, if that would work better... I'm all for it.

My intial thought was to have a full two leaf system and then build another two leaf system inside of that. So, one room of sheetrock > rigid > sheetrock and then inside of that structure another room of sheetrock > rigid > sheetrock > acoustic treatment.

Basically, one room won't cut it being that the classrooms will be around. I figured the air gap between the two structures would be benificial as well.

Thoughts?

That goes right back to my original suspicion that you were planning on building a 4-leaf system: that is exactly what you are describing: a 4-leaf system, and that will, of course, severely compromise your low-frequency isolation, although it will be great for very high frequencies.

How much isolation do you actually need, and what frequency range do you want that isolation to cover? If you are planning to build a 4-leaf system, then I can only assume that you need all your isolation in the high frequencies, and very little in the low frequencies, so I assume you don't need to mix things like drums, bass, percussion instruments, and keyboards, and that there are no low-frequency sounds elsewhere in or around the building that you are concerned about getting into your room, such as HVAC systems, elevators, escalators, trucks arriving/leaving, etc. Either that, or you are planning on installing huge amounts of mass on all four leaves, with very large air gaps, to compensate for the large loss of isolation in the low frequencies.

I don't follow: Are we talking about walls or about rooms? I only see one room on your diagram. How can one room not cut it when you only show one room? Or did you mean to say that "one wall won't cut it"? If so, why would one wall not cut it, if that wall is a fully decoupled 2-leaf MSM system? What is the major high frequency problem that prevents a 2-leaf wall from "cutting it"?

Well, if you figured it with the correct equations, then I'd like to see that! 4-leaf structures are pretty darn hard to calculate: I only know how to do 2-leaf and 3-leaf. I can estimate 4-leaf rougly, but the math is just too complex for my simple brain. What size air gaps and how much mass do you need on each of those leaves in that 4-leaf structure to get f+ and f- and f0 down low enough that the entire structure isolates down to 20 Hz?

Sorry, I guess I'm just a little confused still, and having a hard time following the logic here: Why do you need a 4-leaf system, when they are so lousy at isolating low frequencies? Why do you want to do that when it is so much easier, cheaper and more effective to just build a normal 2-leaf MSM? What is the extremely noise very high-frequency "thing" that has you so concerned that you need a 4-leaf wall? It must be that, right? There is something in the building that puts out a huge amount of noise at some mid-high or high frequency? Some kind of turbine, maybe? I can't think of any other good reason for going to all that major expense and hassle of wanting to build a 4-leaf wall instead of a 2-leaf.


- Stuart -

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

How about a two leaf system.


From the inside out, as follows:

Acoustic Treatment > Sheetrock > Rigid Fiberglass Between Light Gauge Metal Studs > Air Gap Filled with Fluffy Insulation > Rigid Fiberglass Between Light Gauge Metal Studs > 2nd Outside Layer of Sheetrock

That makes more sense, yes. A proper decoupled 2-leaf MSM wall. So there isn't actually any real need for a 4-leaf? No high frequency noises that you need to block?

But you still need to answer the question "How much isolation do you need" in order to determine how many layers of sheetrock to put on each leaf, and how big the air gap needs to be: In other words, you need to answer "How loud are you?" in terms of decibels that you'll be pumping out at your very loudest, and also "How quite do I need to be?", in terms of the level you need to drop down to on the other side of your wall. Or if the problem is something noisy outside your room, then you ask the other way: "How loud is that noisy thing outside?" in terms of decibels, and "How quite do you need it to be inside your room when the noisy thing is making noise?". Either way, subtract the "quiet" answer from the "loud" answer, and the result is a single number which tells you how much isolation (transmission loss) you need. Do those measurements with a sound level meter set to C weighting, slow response, and let us know what the result is. Based on that and your music styles, you can calculate the resonant frequency that you need for the wall, and the transmission loss: Adjust the wall mass and air-gap depth parameters until you get a good match.

- Stuart -

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

Yes, I need to figure that out. First reaction says full rock band would be 110 db maybe more. 20 feet away there will be classrooms with people learning. Still cost is a major factor. Obviously, the distance and the fact they classrooms will have their own walls will help that out a lot.

Is it crazy to think that this 2 leaf system in the pictures would get it down to 30-40 db?

Getting down from 110 dB to 30 dB means a reduction of 80 dB. That is a tall order! It can be done, but it ain't easy, and ain't cheap. 70 dB is attainable, but also not easy. 60 dB is within the realms of possibility. 50 dB is certainly do-able.

It is also unlikely that you need to get down to 30 dB: That's about the sound level you'd hear in the middle of the desert at midnight. 40 dB is a roughly the level of very soft whisper at a distance of a couple of meters. Fifty-something dB is roughly the noise level in an average home of office during the day, so that would be a reasonable goal. So if you are starting with a level of 110 dB inside and aiming for 50 dB outside, you are talking about roughly 60 dB of isolation. Do-able.

But on the other hand, you show only a control room: why do you expect to have levels of 110 dB in a control room? Standard mixing level is 85 dB. You might want to push it to 90 or even 100 to check the final mix, but 110 shouldn't be necessary: that's about the level of a full rock band, playing normally!

But anyway, to answer your question: With 2-leaf MSM construction you should be able to get 60 dB of isolation, if you put enough layers of drywall in each of your two leaves, and leave a large enough air gap.


- Stuart -

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

Awesome. I like do-able.

Your responses make me laugh, literally, outloud. I can understand your frustration given the explanations I've given.


I'm accounting for a 1' air gap. Whether or not that's necessary is another question, but defintely "do-able".

No, I usually only mix, at most, around 80 db. I could occasionaly go louder to see what low end stuff (ie. kick and bass) will do to the speakers. The "real-deal-Holifield" is in the tracking environment. These guys plann to run the gamut on genre. Would I expect most of the studio time monopolized by full rock bands? I do not. Although, I would like to be prepared.

I have enough Green Glue left over from my last project to do a double layer on the inside of the tracking room (all other things being equal to the previous game-plan). Seams staggered, of course (8' vertical first layer, and horizontal second layer with acoustic caulk in the seams). That's what I did in my first project and it turned out great.

What do you think, Stuart?