John Sayers' Recording Studio Design Forum

Hi. My name is Reed Black and I am a recording and mix engineer located in New York City. I am doing a build-out in a ground-floor commercial space for a musician-friend as his writing/recording space. His budget is a maximum of $20k.

The object is to make a room or a pair of rooms for my friend to have his outboard gear, mics and instruments permanently set up (drums, gtr & bass, amps, vocals) as well as a Mac Pro & Pro Tools DAW w/o control surface, in order to write his band's next album. I am assuming I'll use a room-within-a-room design. We want this to be a robust, reasonably flat-response room where he can make high-quality, clear-sounding demos of his material, and be able to mix in a clear environment, as he's accustomed to doing for pre-production.

Occasionally, an engineer might come in to work with him on real tracking, so he wants a truly good-sounding space. However, since he is not a bonafide engineer himself, and is predominantly working on demo material, a one-room "writing room" design is not out of the question. He has already chosen a smaller space over a larger one to economize. Nevertheless, he & I wish to create a serious recording space that provides both a reasonably flat response for tracking/mixing and good isolation from the outside world. We want to make a one- or two-room writing environment where legitimate recording and mixing work can be done.

My friend is also concerned about getting as much natural light as possible. There is a pair of windows that each abut the northwestern glass door on either side, making a T-shape window looking out on the street. We want as much of this light to pass through to the inner room as possible, without risking noise contamination.

I have come up with two different designs, but I'm not sure if either one is the best use of space. Each is included in this post as a Sketchup document, and an overhead floorplan is provided for each as well.

In Version 1.0, I made one big room for both a mixing environment and tracking environment. In order to match the recommended ratios found in F. Alton Everest and Mike Shea's "How to Build a Small Budget Recording Studio... ," I thought of the "Modified L-Shape" as two intersecting rectangular rooms, made the ceilings an even 10', and then made each intersecting room 1 : 1.28 : 1.54 and 1: 1.3 : 1.9. The wasted room in the alcove to the south would be used as a machine room, but is a great, and possibly unnecessary, sacrifice.

In Version 2.0 I employed John's recently posted "Components.skp" room design as a control room, and then created a small live room on a separate floor platform in the southern alcove. This would house amps and a vocal mic with tie lines to the control room. Drums could also be placed in there, but I think it might make more sense to place drums directly behind the mix position in the mix room, somehow more or less where those two big rear absorptive panels are. The big problem with this little live room design is that the inner ceiling height will be very close to the length of the room, about 11'. That's in addition to only having a couple feet of width. Modal buildup might make these "doubled" dimensions unusable, in which case: divide in two and have an amp room in the back and a vocal booth in the front??? Ideas???

John & the gang, and others, do you have any thoughts on either of these designs? Or does a different design leap to mind?

I have been reading this forum, as well as all most of the classic design and theory books, for many years; and I have assisted in many aspects of building in friends' studios. And I'm an engineer who understands a lot about the behavior of sound. However: I know that that's not nearly the same as designing and building studios every day for a living.

This plan has come about very quickly for the usual reasons, and I begin work as early as next week. I know that's quite soon for a poster on this forum, and I know your time is very valuable; but any thoughts you have would be greatly appreciated.

DETAILED DESCRIPTION

This studio will be a room-within-a-room design in a newly rented commercial space. The outer-room is on the ground floor above a basement. It has two windows and two different glass doors looking north onto a New York City side street.

The room's floor is linoleum. The ceiling is drywall. The Certificate of Occupancy indicates that the floor can take 100 lbs per square foot of live weight.

There is an air duct from the adjacent businesses on the west side to the east side, including a restaurant two units over, which has been dry-walled into a soffit that goes down the center of the ceiling, dropping a ≈2-foot-wide and ≈2-foot-deep rectangular column down across the ceiling in one form, from the east wall to the west wall. This results in the 12-foot ceiling dropping to about 10 feet for this structure.

A door in the southeast of the building accesses a bathroom that was divided in the past, framed off and dry-walled.

Currently, a window-mount AC unit is installed above the northeastern egress.

There is a door in the floor that leads to the basement. I have been told that this can be sealed off and built-over.

Let me know if there's any more information I can provide. Thank you everyone! Respect due to all of you.

Hi Reed. Welcome!

Just a couple of random comments, for what they are worth:

First, you didn't mention how much isolation you need: it is very important to define that. Isolating a room for 70 dB is very different from isolating it for 40 dB. Isolating it for recording a heavy metal rock band with massive drums and bass is very different from isolating it for recording piccolo and violin, (even if the overall loudness is the same).

You can do that, but windows do make it a harder to isolate the room well. Isolation windows need thick laminate glass on both leaves, properly sealed into suitable frames. Try to find out what type of glass is in that existing window, to see if it needs replacing: It most likely does.

While that can work from a pure space-saving point of view, personally I find it very hard to track drums if I'm in the same room. I like to be able to hear each mic individually on the monitors in the control room, without also hearing the drums directly, so I can confirm that I'm getting a good sound form that mic. If the drums are in the control room, you can't do that. Not even headphones block enough sound to make that feasible. Maybe your friend doesn't mind, and can track drums just fine in the same room, but if you expect to have guest engineers coming in, then they might not like that setup. Just a thought.

Or tilt the ceiling...

I would not divide such a small room further. Small rooms = bad room, acoustically. Keep each room as large as it can possibly be.

It normally takes me a several months to design a room fully! I really, really doubt that you can come up with a workable design in one week.

It's "quite soon" even for the best studio designer on the planet! You might be able to get a rough layout done in a week, but there are just so many details that have to be taken into account that you'll need rather more than a week to come up with solutions for them. For example, you didn't mention HVAC in your post, but HVAC is critical. You didn't mention the electrical system, but ditto. same for signal cabling. Same for doors, windows, etc.

The glass doors will probably be a problem. We'll need a lot more details on those to see if they can be used as-is or not. Probably not.

Sounds noisy to me! Have you measured the normal ambient noise level just outside and just inside those glass doors? If not, then that should be your starting point: find out how much noise you are dealing with, and also at what frequencies.

Linoleum on top of what?

Drywall below what? What is above you, and how is it built?

That's great, but it's only about the average load on the floor. Your inner-leaf walls will be massively heavy, and will concentrate all their load along a line around the perimeter, not spread out evenly over the entire floor area, so you'll still need to get a structural engineer involved (once you have finished the entire design, and can tell him exactly how much each wall weighs), to check that you are OK to continue.

Might it be possible to use the basement for the studio, instead of this room? Basements have a huge advantage for isolation: they are usually underground (at least partially) and they have concrete "slab on grade" floors.

That's a problem. It limits your maximum ceiling height, and makes it hard to fit in the rooms. But the good thing is you still have 10 feet to play with, and you might even be able to use some of that extra space for bass trapping.

Regarding layout, I think personally I'd try rotating things 90°, so that both rooms run across the page, side by side, and splay the dividing wall to optimize both space and acoustics. Also, I would NOT have the door to the bathroom leading into the control room, and I would also have the main entrance leading into the live room, not the control room. That's purely for access reasons: when you have musicians loading in and loading out their equipment and instruments, or going to the bathroom, or going out for a smoke, or to answer the phone, or to take a break, you normally don't want them running backwards and forwards, through the control room. So I'd suggest putting the control room at the far end (against the wall marked " 20' "), then the live room next to that, and leave a little passage to get to the bathroom from the lobby, not from either of the rooms.

Those would be my suggestions, FWIW!


- Stuart -

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

Hi Stuart! Thanks for your enormously thoughtful and helpful reply.

I understand that the speed at which this is happening is almost impossible--I will try to squeeze in every last second of planning time I can. I know it always costs more to do things the wrong way twice than the right way once...

But the band begins tracking for eir album in August, so time is of the essence... And unfortunately, it's what I have to work with. Just finding a space that is useable and affordable has taken my friend almost 6 months! New York is a shit-show.

STC: This is Manhattan, where outside noise is inevitably a significant factor, and neighbors are prone to being disagreeable about drum leakage. But this is a side-street, where there are no buses that come through, and not a full through-street, so trucks will only pass by if they're lost, which is unlikely in these days of GPS. The location is far from underground subways--Score! But airplanes DO fly overhead everywhere in this town. I have not measured the sound with an SPL meter yet, let alone a spectrum analyzer; but my general thought is that the class of sound transmission attenuation I'm going for is chiefly to avoid neighbor complaints from audible drums or amps, and that that should be a sufficient STC to keep out any relevant noise from the outside world. That may be the assumption that paves my road to hell... Yikes. The one chance I had to spend an afternoon in the unit, during the middle of the day, the street sound was quite low. I know that's not a number. Let's see if I can get in there sometime today or tomorrow and do a proper reading.

What is underneath the linoleum, what is above the drywall ceiling, what is inside the walls: I do not know, and have the sense that I won't know until we bring in a sledgehammer. Dept of Buildings was no help. Landlord doesn't know. Let me do some sleuthing and see what I can find.

Regarding your ergonomic suggestions, I hear ya... But this is truly meant as a writing space with "color-by-numbers" mic setups. My usual method for finding drum sounds is to use my shure in-ear monitors (custom molds) as I place mics, listen for places that seem to pack in great resonance with lowest voltage, and tweak from their. With a control-room-less design, like having the drums in the monitoring room, I would then go back and forth recording test strips and tweaking until the drums sound DECENT. Then leave the mics set up that way for him to demo ALL SONGS. That's obviously not how I engineer in my own studio, but it works for this particular situation.

Finally, yes, we will probably have to replace all glass and doors. These are typical NYC ghetto POS's.

HUGE question, that is so obvious to most readers here that I don't believe anyone has ever asked it explicitly on this forum: in creating my double leaf, are the existent outer room walls leaf number 1? Or Leaf number 0, inside which I build leaf numbers 1 AND 2. It seems to me that the former is correct, since building two full walls inside this structure would bring them extremely close to the existent walls, which would (in this line of thinking) create a 3-leaf effect. But somehow I have trouble thinking of walls that are essentially shared with neighbors constitute a real, functional part of the studio design. Am I just thinking about this all wrong?

Phew. Stuart, thank you again. I can't tell you how helpful your insights and questions are. I am very grateful.

All the Best, to you and everyone here,
Reed

Meeting the RE Agent this afternoon, and will run some tests. I'll post material and SPL info later this afternoon. Stay tuned.

OK, this is more of a "nit pick" on terminology to some people, but terminology is rather important in acoustics. STC is not a good way of talking about studio isolation. It does not take into account the low frequency end of the spectrum at all (bottom two and a half octaves!), so it tells you zip about how well a wall will isolate drums, bass, keyboards, and such like. STC was designed mostly for speech, not music. It also isn't really a number that you can relate to decibels easily, since the method for measuring STC is all about fiddling with readings in several frequency bands, looking for "deficiencies" then making "adjustments" until you come up with a curve that is just below one of the STC curves, then you can claim that your isolation is the same as the number on that specific curve. In reality, I can build two walls that give the exact same STC rating, yet one of them will isolate music a hell of a lot better than the other. Or I can also build two walls that isolate music to about the same level, but their STC numbers would be wildly different. So it's a mistake to base your isolation on STC. Instead, you should use Transmissions Loss (TL), which is far more useful for studios.

But in any case, regardless of what name you put on the isolation rating, in order "avoid neighbor complaints from audible drums or amps," you are looking at some fairly hefty isolation. Drums can easily put out 115 dB(SPL), and you need to get that down to whatever the legal requirement is, so a good starting point would be to get hold of the noise regulations for your area, and find out what your legal level is. That's how quiet you have to be. Assuming that the legal level is 45 dB (might be lower at night), then you need 70 dB of isolation. That's a tall order. Do-able, but not easily.

To get an idea of what all that means, consider this: An ordinary wall made of a 2x4 stud frame with 1/2" drywall on each side will get you about 30 dB of isolation. Getting 70 dB of isolation means that the wall must block ten thousand times as much energy as that normal wall. No, I'm not just pulling a number out of a hat: it really does have to block ten thousand times as much energy. Each time you go up by 10 dB, you increase the amount of energy tenfold, and the subjective level is double (or half). In other words, a 70 dB wall sounds like it is about 16 times better than a 40 dB wall, subjectively, but in reality it is 10,000 times better.

To get that level of isolation, you need plenty of mass on each leaf, and a large air gap between them.

Yes, but you did say "Occasionally, an engineer might come in to work with him on real tracking, so he wants a truly good-sounding space", so that should be the factor you are shooting for: If the guest engineer can't track like you do, what are you going to do? Would it not be better to take that into account up front? You seem to have enough space to build a good size control room and reasonably decent drum booth. so why not do that? The drum booth would be your live room the rest of the time, and you can have the drums set up in the control room if that's the way YOU prefer it, but it sure would be useful to have a room where you can move the drums if you get a pro engineer in there that doesn't track the way you do.

Just a thought.

Exactly. The existing shell is the outer leaf.

However, if those are party walls (shared with your neighbors), then they already have one leaf too many on them! Party walls are already two leaf walls: there's one leaf on your side, and one leaf on the neighbor's side, with a frame in between. If you are lucky, the frame is staggered stud, and if you are incredibly luck, it is two separate frames, but most likely it is just a single stud frame with drywall on both sides. And no matter how it is built (any of the three above methods) it is already a two-leaf system. To make it into one leaf (which is what you need), you have to take the drywall off your side, and beef up the other side from within the wall. And in your case, you'll need to REALLY beef it up. That's the normal way of doing things.

So the existing wall will end up as a single leaf. You then add the other leaf, which will become the surface that you see when looking around inside your completed room. Those are your two leaves.

Can you do it another way? Well, yes you can. You can build a three leaf wall if you really want to (EG: not taking the drywall off "your" side of the party wall), but they you'd need much larger air gaps on your final leaf, and much more mass. Or you could even build a 4-leaf wall (EG adding a two-leaf room inside what is already there) but then you need even more mass, and even larger air gaps.

They wouldn't be "full" walls in the sense of a normal wall: they would just be a stud frame with drywall on one side only, not both sides. But yes, you would take up a lot of room like that!

Yup!

But there's another issue that might be big problem: if the walls are party walls, then the floor and ceiling might also be shared with your neighbors. In other words, your floor is probably just a continuation of their floor: both are built on the same beams and joists. If so, then you have a solid mechanical connection, a "flanking path". Impact noise and all other sounds that get in to the walls, floor or ceiling will be easily transferred though the build structure itself, and will be audible on the other side, no matter how well you build your wall. You could build your wall for 80 dB of isolation, but if the floor is flanking and only giving you 40 dB, then your room has 40 dB of isolation, regardless of the walls. sound just takes the easiest path out. So if the walls are the hard path and the floor is the easy path, then the sound goes through the floor and ignores your wall. As you can see, designing the isolation system is an "all or nothing" proposition. All sides of the room, and the HVAC, and the windows, and the doors, and the electrical system, must all be done to the same level. If not, then whichever one you skimped on is going to be the path that the sound takes out. Even a tiny crack under the wall, or a single electrical outlet box, or a stray nail that went the wrong way and joined to bits of wood that are supposed to be decoupled, can seriously degrade your isolation.

In other words, the entire room needs to be designed to the same level of isolation, all around, all at once. If the floor cannot be made any better than 40 dB, then just do walls for 40 dB as well: any more would be a waste of money.

Here's what I'd do: Order right now form Amazon.com, with overnight delivery, these two books:

"Master Handbook of Acoustics" by F. Alton Everest.
"Home Recording Studio: Build It Like The Pros" by Rod Gervais. As soon as they arrive tomorrow morning, read them both from cover to cover. (I hope you took a speed-reading course in college! ) Those are the best two books for you right now. The first gives you all the background theory on how acoustics works, but in a simple and very readable manner, without going into heavy equations and things: just logical, clear, well thought out explanations. The other book is more about the practicality of how to actually build studios, in terms of 2x4s and drywall, air handlers and distribution panels, door seals and window glass. Together they'll give you enough background to get a handle on what you are trying to do.

By the way, you never did answer about the basement: would that be a viable possibility? Basements are MUCH better when you need good isolation.

Looking forward to the photos!


- Stuart -

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

Wow, Stuart, you just clarified a hell of a lot in short order. My sincere thanks.

FWIW, I actually do own and have read both those books -- and each more than once. Which probably doesn't demonstrate a good absorption rate on my part, so bear with me...



My careless mistake on terminology, but a good "teaching moment." I know that low frequency is far more troublesome than higher frequencies, due both to its greater relative power and also to its tendency to modally couple with the room-size humans like to occupy... But I did not quite understand how VERY important it is. That sounds like a contradiction. BUT: your examples of the two walls with same or different STC's brings me much closer to full understanding about just HOW important this is to good design. It's not a detail, it's the subject. Ok.



There we go. Not a detail, it's the subject.



I understand. I guess I was arranging my priorities differently: I am used to recording drums in large rooms, and therefore think of every cubic foot as far more precious than it may warrant. I was thinking that getting the largest possible single room, in cubic feet, trumped any concerns about workflow for an outside engineer. (Workflow for my friend on his own is important -- but that's not what we're talking about.) That said, maybe I'm wrong in being so tied to big spaces. You seem to be putting it (slightly) lower on the priority list, not worthy of the same level of sacrifice. Likewise, Tchad Blake records drums in as small a room as he can find and I LOVE his drum sounds. But my own professional experience has driven me to demand large rooms, which may be more personal taste and experience than I realize. What do you think?



Ok, this entire paragraph of your response is the deal-sealing clarification that I never found in any of the foundational literature about the effect of "leafing." For anyone confused about how leaves work, and what constitutes a leaf, this paragraph is mandatory reading.

I guess everyone's gonna have their blind-spots... So thank you for making this completely clear (in spite of all the caveats physics includes!)



Oh shit.

But wait--if I'm building a room-within-a-room, with ample space between the two leaves (adjusting the design to my new understanding), isn't this just NOT my problem? I may be overestimating the degree of isolation that provides. I've been assuming that a well-constructed R-W-A-R design would provide such lack of conduction that I wouldn't have to be worried about any normal sound-pressure level being transmitted, either by air or by structure. But of course I trust your judgement here. So how much space, and what type of inner floor construction, gets us to the point of not caring? Of approaching that "70 dB" of reduction that you mention as an ultimate? Is it beyond reach?



Unfortunately, very unfortunately, we can't use the basement. I understand that that would fix so many of the problems we've gone over; but for my friend, natural light is an absolute must. It's a big part of how he selected the space. It's just a fixed parameter for this design: he must have big windows. He knows it's a tall order, and knows it's gonna cost him -- but in his dirty thirties, he's just come to the realization that he can't make art without seeing the sky. And, IMHO, fair enough. You can be picky about a couple things, as long as you're flexible about most others. And he is.



Ok, today's visit to the space provided me with the following data:

Using an SPL meter with A-weighting:
1) The maximum level of sound pressure inside the space was 48-50dB.
2) The maximum level of sound pressure on the street outside was 61dB.

Inside: Using an Avenson STO pressure transducer microphone (small diaphragm omni) through an MBOX2's internal preamp and converter:
3) The frequency spectrum of the noise was heavily weighted towards the low end, ( ) as seen below.

Using my eyeballs:
4) The windows and glass doors are thin, unlamenated glass that we will have to replace.
5) I am waiting to hear back about what is below the linoleum floors and what is above the drywall ceiling. What I did realize is that the western and southern walls are ENTIRELY brick or concrete -- I hadn't looked close enough to see that what I called "drywall" on the southern wall was actually concrete painted white. The eastern wall, however, is indeed drywall. Ehat's behind it, I don't yet know. But more soon.

Using my ears:
6) The sound of the air being forced through the existent air duct is audible in the room. That is not good news. But it is encased in some sort of drywall-casing-structure, which I imagine I can replace with a more effective structure. But I would guess that that "air right-of-way" is another noise-radiating fact of life in this space.

Reed

Ok, re-reading the part of Gervais' book on floors. He extols the virtues of concrete, and makes a great, in depth case for it -- but then doesn't go on to describe a good floor build for a room above dirt-level. I'll bet he didn't bother because building a studio in a city probably sounded like suicide -- but here i am. And my under-floor is providing easy access to flanking from the sounds of outside chaos AND it's behaving like a sympathetic, selective drum... What can I possibly do?

Reed

Glad to help!

Oj, I absolutely prefer to track drums in large spaces, if I have the option! No doubt about it. Getting a small space to sound good for drums (or drums to sound good in a small space) is not easy, and the smaller the space is, the harder it is. No argument there. That's why I was suggesting splitting the available space roughly in two, with them being approximately the same size. That would give a decent drum room and also a decent control room. I think there's enough space for both...

Well you sure can get great walls if you put plenty of mass on them and have large air gaps. But the problem here is the floors, not the walls. Since your walls will be resting on the floor, and your floor has a hard mechanical tie to your neighbor's floor, then there's a point at which the walls will be better than the floor. After you pass that point, it doesn't matter how good you make the walls, they simply won't do anything more to help your isolation, since sound will now be taking the easy path out of the room: the floor. Your entire isolation is only as good as the weakest link.

Think of it this way: you are standing outside the world's best isolated drum booth, looking in through the glass door, and there's a crazy gorilla drummer in there, hammering like mad, but you can't hear a thing, since the isolation is so fantastic. There are no weak links. But then you open the door.... now what do you hear? REALLY LOUD DRUMS! But why? The walls, floor, ceiling and windows are still isolating just as well as they were before! So why can you hear the drums now? You created a weak link, so that's the path the sound is taking: the easy way out.

Same in your case: if you build 70dB walls but the floor is only giving you 40 dB, then your total isolation is 40 dB, not 70.

So what do you do? Well, then, you have to isolate the floor! It seems obvious and logical, actually. But sometimes we forget the obvious things!

However, isolating a floor is no easy matter....

It is possible, but getting there ain't easy. You probably won't like what you are going to hear...

Yup. There's a reason for that: isolating a concrete floor above an air spaces (such as a basement) is not so easy. That's just a drum, on a different scale. In simple terms, a drum is a membrane stretched tight over a resonant cavity. Sort of like a floor over a basement. Maybe the helps to get the picture? That's why the general recommendation is to always build studios on the ground floor, wherever possible. Concrete slab on grade is excellent isolation. Concrete slab on air: not so great.

Not suicide, and if it was on the ground floor even in a city, it still could be done. I have a customer here in Santiago whose studio is right on one of the busiest roads, with heavy trucks and buses, and kazillions of cars, roaring by all day and night. It's a six lane road, and their studio is no more than 30 meters from that. And it is dead silent inside. Because they built it right, and built it on the ground floor. But before they moved to this facility, they had another one where the studio was on the second floor of another building, across town, and that one was also dead silent. But it cost them several TIMES more to isolate that old one, than it did the newer one.

That's the key: you CAN isolate upper floors in buildings: it just takes a lot of money to do that.

What you are talking about, is "floating" your floor. Or in your case, floating the entire room, which is what that customer did in their first place. Floating your room means suspending the entire room on something resilient, so that there is no mechanical path for sound to take out of the room. That means springs. And once again, that floor is a two-leaf system. You have the outer leaf of the floor, which is normally a concrete slab that is totally connected to the rest of the building, mechanically. On top of that you have some springs, that are carefully designed to float that specific room correctly. And on top of the springs you have your inner-leaf floor, which is another concrete slab. You build your new inner-leaf walls on that slab, and your inner-leaf ceiling on the inner-leaf walls. So the entire room rests on the springs. Those springs are the ONLY contact between the room and the rest of the word, and they are designed to "float" the room. They are compressed ("deflected") just enough that the room is only connected mechanically at very low frequencies, at least an octave below the lowest frequency that you want to isolate. At all other frequencies they isolate the entire room.

So that's what you'd need to do if it turns out that there are hard flanking paths from your floor into the rest of the building. Yes, it can be done, but it isn't cheap, and it isn't easy. Most rooms don't need it. Rooms built on the ground floor seldom need it. But rooms built above ground where there is a need for high levels of isolation and there are hard flanking paths, well those rooms are prime candidates for floating.

So this is the part you won't like: What you'd need to do is to replace the existing floor with a thick reinforced concrete slab, which implies also beefing up the structure below to support the huge weight. Then you set up your springs on top of that, lay a deck of some kind (metal or wood) and pour a second concrete slab on that deck. Then you build your room.

The trick, of course, is in calculating the springs correctly. You have to figure out the entire weight of the complete room: walls, floor, ceiling, windows, doors, equipment, people, HAVC, etc.: everything. Then you find spring systems that can support that much weight. Then you look at how much they need to deflect to float the room. They you figure out how much weight you need to put on each spring to cause the optimum deflection. Then you spread enough springs around at the right locations to make the room float. And you hop you didn't screw up the calculations! If you put too much weight on the springs, then they bottom out and don't float. If you don't put enough weight on the springs then they are not deflected at all (they "top out) and don't float.

That's the theory. It can be done, but needs a bit extra money, and some careful calculations, and careful construction.

OK, so before you go out and jump in front of a bus, there's a second solution that MIGHT work, if you don't need extreme isolation. Instead of completely floating the floor, you might be able to get away with just decoupling it a bit. That's normally done with a layer of fiberglass insulation spread across the existing floor, and a heavy wooden deck built on top of that, out of several layers of thick plywood. The deck does not touch the walls: it just rests on the fiberglass, with a small gap around the edge. You fill that gap with some type of flexible expansion joint compound or other similar sealant. Done! That's not technically floated, but it is decoupled from impact noise, which might be the issue in your case.

I hope I'm not depressing you!

Here's some more light reading on floating floors and floated rooms, in case you are interested:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173
http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf


OK, I understand "vibe", so if that's what he needs, then fair enough: gotta get natural light in there, with windows on the outside world. So no basements.

That's not too bad, I guess, but not fantastic either. 50 dB A weighted is rather too much: for a top studio you should be looking at an NR-15 curve, or maybe you could relax that a bit, to NR-20 or even-25.

Also, you seem to be getting only about 10 dB of isolation from the existing structure, although that might not be so accurate at low levels, close to ambient.

Is there any way you can set up the software and calibrate the system so that the vertical scale reads actual dB(SPL)? That would make it easier to match against the NR curves.

That's to be expected. You'll see that on the NR curves anyway, and you are in a big city! The interesting part is the area from about 1k to 6k: that's higher than you'd expect. But more of a curiosity than a problem. What is the frequency response of that mic? I'm guessing that the flattening off below 100 Hz is probably more due to the limitations of the system than being a realistic measurement.

But yes, the graphs sure does show that you need now frequency isolation.

That's good news, at least!

I'm hoping to hear about large slabs of massively reinforced concrete... fingers crossed!

That's probably not a major issue, unless YOU need to tap into that HVAC. Do you need to do that, or do you have alternative plans for HVAC?

Float it, and/or isolate it, and/or add mass to it, and/or decouple it. Those are your only options. The good news is that you do have possible solutions. The bad news is the price tag. But before getting depressed again, let's at least wait until you got confirmation about the way things are built right now.

- Stuart -

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

Ok, another huge spoonful for thought!

I'm going in there with a crowbar and a mean attitude this afternoon. Will report back with my findings.

Reed

And a camera! Don't forget that. Take pics of everything as you work, then post the best ones here. A tape measure would be good, too, so you can get accurate dimensions of whatever you find. Post those as well.

- Stuart -

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

Amazing news, Stuart! Underneath the linoleum I found the following, from lowest to highest:

-Concrete floor in basement. 
-Brick and Concrete basement walls
-Some hung piping (hot water)
-10 1/2" concrete ceiling/studio floor!!!!!
-2" (nominal) real lumber
-1" lumber sub-flooring (not particle board)
-thin subflooring mat of some kind (black.)
-The linoleum.

The basement height is 6' 4 1/2". 

Except for a locked metal door that must lead to the basement of the adjoining unit on the southern wall, it is entirely ours, and sealed off from the neighbors.

The street side of the basement has two alcoves that go under the sidewalk with open-air grates on top -- don't know if that's worrisome, but somehow I suspect it's not. Air-borne sound underneath the slab can't be nearly as interesting to us as structure-borne vibrations conducting from the entire city, can it? Or else I'm about to learn a new lesson.

Caveat: the southern wall of the basement only goes as far as the northern walls of the bathroom. RE Agent didn't have keys to the metal door, so I'm hoping that on the other side of the supporting wall, the 10.5" slab continues, supporting the southern quarter of the room. But that basement may or may not be shared w/ the neighbors.

Does this bring us into the dawn of a new, less critical, non-float era???

I'll throw up the best photos when I can get to my computer.

Woo-hoo! (I hope)

Reed

Oh yeah! Now we be talkin' !!! That's a nice bit of good news.


Time to call for a big dumpster, and get that crowbar out again: You won't be needing any of the above. And More good news: you just gained an extra 3-and-a-bit inches of headroom!

In other words, get yourself down to nice bare concrete: That makes a great studio floor, just as it is. Or if you don't like the aesthetics of concrete then lay laminate flooring (not now! At the end, when everything else is done.)


- Stuart -

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

Here come the visuals. Browse from the bottom up -- I entered them backwards by mistake.

*By the way, Stuart and other admins, feel free to delete a couple of these if you think they're redundant. Just trying to give the most thorough impression possible.

So for all intents and purposes, does the concrete slab essentially act as an ideal an isolator for anything above a few Hertz, even though it's over a 6+foot basement? I can literally couple my inner wall structure with it, and have an isolation factor of whatever the wall-ceiling unit provides??? And is that especially due to the depth (and the mass) of the slab?

And could/would there be joists inside the slab? I'm just having trouble getting how it bears its own weight. Or are we sure that it's just a 10.5" mass of concrete, maybe with support bars or whatever, suspended across a 27' span???

And am I off the hook for reviewing my plans with a structural engineer??? Or do I have to do that regardless for a single leaf inner wall + ceiling load?

This has turned out to be a really good day.

Ok, Stuart, you really got me thinking about re-orienting the rooms. So here's a sketch of what the control room would look like. It looks like it could be awesome! As long as the front door and bathroom door don't compromise the isolation of the live room. It even lets us elegantly avoid the duct chase by having that be part of the sloped front of the room, I believe!

Good one!