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PostPosted: Sat Sep 07, 2013 3:24 pm 
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Posts: 31
Location: Alpharetta, GA
First off I'd like to give a huge thanks to John Sayer, all of the admins, moderators, and senior members of this message board. Lots of tried and tested knowledge. I wish I had discovered it a long time ago. You guys are awesome!
Welp, … here we go….
Greetings!!
My name is Jason. (*members- "Hello Jason").
I'm a musician, performer, instructor, engineer, and producer in Alpharetta, GA, outside of Atlanta. I've been running my studio in my home producing and engineering for the past 5 years. It is small and absolutely nothing special but its been getting the job done. Work has been steady but I've been losing business due to the fact that I don't have the space to live track a full band. Business is good and it is time to expand! I'm currently building a new studio from the ground up and I would greatly appreciate all posts, comments, suggestions, criticisms, and advice that anyone would care to share because I've never designed or constructed an acoustically sound structure before. I have a background in construction so I'm not completely green, and I have my father who is a construction guru as my partner that has been helping me get the ball rolling. This has always been a dream of ours and now we finally get to do it! We are making a facility that will be a recording studio and used as a place for small live performances and rehearsal space. Our plan was to erect the basic structure (slab/masonry, basic framing, roof siding, rough utilities, etc.) since we knew we could do it cheaply by GC'ing it ourselves, and then proceed to conquer the interior build out of the studio as we gathered more knowledge and decided on our build methods. The roughing in of the building is almost complete, I've gathered my thoughts, and I think I'm finally ready to post on this forum. All comments and verbal ass kickings are welcome and appreciated! I wasn't sure if I should post this in design or construction so please forgive me if I shouldn't have posted here.
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Studio-Floor Plan-Current.jpg

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LR-CR Wall.jpg

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Crawlspace.jpg

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CR front -Hall Wall.jpg

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CR Front Wall 2.jpg

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CR Front Wall 3.jpg

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CR Rear Wall.jpg

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CR-LR Window view.jpg

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Studio building1.jpg

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Current Floor Plan-CR Design 1.jpg

Overview:
The entire building (see pics) is about 2000 sqft (28'x64' with a 12x12' punch out on the back wall). 308sqft control room, 1180 sqft for live & iso space, and about 500 sqft for lounge/kitchen,bathroom/office. It is located on my property in Alpharetta near a somewhat noisy back road, but I have no neighbors to piss off!. Yay! I've done a complete drawing of it in Sketchup with my desired end design. I'm new to sketchup and got a little layer-crazy but the drawing is accurate to the current existing construction, -Also I cant figure out how to shrink the size of my sketchup file down to 500kb for sharing from its current size of 2.1mb... can anyone throw me a quick bone so I can resize and share?-- I haven't added the roof trusses to the drawing yet but will soon. My plan is to tackle this mammoth in sections because different parts of the building have different needs. I think I've formed a pretty good plan of action but am still indecisive and unsure on a few topics. After gluing myself to this board for the past month or so I've managed to answer a lot of my own questions, so thanks to all of you, but with so many ways to "skin the cat" its hard for me to decide what is right for my scenario. My budget for building out the interior of the studio is about $40-50K. My overall plan for the interior is to finish out the control room and lounge/bath area first so I can at least be mixing while the live half of the building is coming along. That being said, lets try to focus our posts on the control room for now. :)
CONTROL ROOM: L= 20' 6 1/2" W= 14' 3 3/4" H= 10' ceiling dropping down to 8' over the rear 4 feet of the room.
Current Status: The control room is on floor joists above a crawlspace with one layer of 3/4"plywood decking. The walls are double 2x4 walls with a 2" gap in-between. Unfortunately these walls are capped with a 2x10 due to certain structural needs of the building so they are not full decoupled from each other which totally sucks. When completed I will be outfitting the studio with a console/ workstation of some sort. Maybe an SSL AWS, but I've been toying with the Idea of making a modular tracking console out of miscellaneous outboard gear… thats a whole other post that will come out soon enough! As for monitoring I will have some NS10's, mixcubes, and dynaudio BM5a's to choose from for near-fields. As the studio grows I would like to add a pair of soffit mounted loudspeakers to the control room. Probably a pair of Augspruger GA115's with a single sub. I want to construct the soffits now but leave them covered and still working as traps until we get loudspeakers.
----- Areas of confusion: 1) acoustic design & components, 2) walls, 3) floors, 4)speaker soffits
1) Acoustic Design- When dimensioning this room, I knew how much space I needed to have a comfortable, decent sounding workspace but am still uneasy about choosing the different angles in the room and the treatment methods. After a bunch of research I think I'm close to what will work but could definitely use some help. Acoustics is a realm of the audio world that is still a bit over my head but im learning more every day. See the design pic below. On the sketchup drawing you can see that I made a rough footprint of the speaker soffits angled at 30. the front helmoltz absorbers angled at 12, and the rear absorbers angled at 6. Notice the bass trap across the back of the room that I plan to fill with hanger traps. If my calculations were correct my helmholtz's are about the size that they will need to be to help with the rooms frequency issues. I was also considering using clouds over the room and less absorption on the walls. There is a window looking into the live room on the right long wall of the CR. I know this window is in the RFZ which is a bad place for glass but am wondering if leaving it there would corrupt the sound in the mix position.
Questions for # 1 -A) is my design on the right track? Help me point out my flaws
B) Am I bat-shit Crazy? … Please take me to school on this one guys! any suggestions or comments would be a big help.

2) Walls - A few things are making my mind drift trying to settle on a wall method. Adjacent to the front wall of the CR is the hallway/air-lock leading into the live area, and adjacent to the right wall of the CR is the live area. When I'm tracking artists I'm not monitoring at high volume so the goal is more of keeping sound out rather than in. With the existing double walls of the control room being capped and coupled to each other and the floor decking (9' thick total frame) my plan was to put up another 2x4 wall from the slab to the roof trusses 6" outside the right control room wall that will be the resilient "spring" wall and barrier between the CR and Live area. With this in mind I figured I'd be fine if I constructed the inner CR walls using 4" of OC703 in-between the studs, 2 layers of 1/2" drywall glued with green glue and screwed directly to the studs, caulked and sealed accordingly. The outer spring/barrier wall will be constructed of 4"of OC703, 2 layers of 3/8" drywall, glued/caulked/sealed, screwed to resilient channel on clips. That will make out to be - Inner Leaf / 4"insulation / 12" air space \ 4" insulation \ Outer leaf on spring. If i studied correctly this will be a very effective sound barrier between the zones because its two differently constructed leafs with 12" of air in-between with one of them on a spring. I'm pretty sure that will stop any sound from the live area from getting into the control room if installed properly. If I end up turning the hallway/airlock into a vocal booth I was planning to do the leaf on the booth side with 3 layers of 3/8" drywall glued/caulked/sealed on a spring for better isolation being in closer proximity to the control room.
Questions for # 2- A) With my existing CR double walls being coupled to themselves by the 2x10 cap and coupled to the floor decking with no spring, do you think the way I intend to finish the walls will achieve my desired isolation? Am I doing to much? More/less wall mass? More/Less air space?
B) Any thoughts on working a mass loaded vinyl or audio mute material into this equation to improve it?

3) Floors - I'm gonna keep this one short since I'm pretty sure I know the answer. The 3/4" CR decking sits on 2x10 joists 2 feet above the slab below that is a crawlspace. I'm planning on adding an 1/8" layer of MLV and another layer 1/2" ply to the existing floor before the finish flooring to add mass.
I'm gonna say it…"Do I need to float my floor?" Honestly, I sure as Shit don't want to!!!
I figured that by building the barrier between the CR and live area the way I described it in #2 above that It would provide enough isolation between the sounds of the live room and the sounds of what is seeping through the floor into the crawlspace under CR. If I turn the hall into a vox booth, I would probably float the floor off of the existing decking to better isolate it from the CR if I absolutely had to.
Questions for # 3 - A) Given the crazy added costs and weight of floating floors and in my scenario. I really don't wanna float my floors.
Do I need to float my floors, and why? (please say no, please say no, please say no…)
B) Do I even need to bother adding MLV to the floor or will 2 layers of ply on some felt do the trick?
C) Would it be smart to plan on insulating the cavities between the floor joists to help with the leakage?
Again, while I'm recording clients I'm not monitoring them at 100 db. Trust me, I like to blast it just as loud as the next guy. But when I'm actually recording someone and am listening critically its not at high volume.

4) Speaker Soffits - Never done this before! Definitely need some help!
As described above, as the studio grows I'd like to upgrade to a pair of soffit mounted loudspeakers. I'd like to construct the soffits framing now and just have them operating as hangar traps covered by a cloth finishing or solid piece of ply until I get loudspeakers. Once speakers are chosen I'll remove the cloth covers or cut into the ply and rework the cavity to properly house the speakers. Good idea? bad idea?
In the end, my speakers will have to be angled down at the mix position because they will need to be more than 4' 6" from the floor. I can't figure out exactly what angle to use for the slanting of the soffits because Im not exactly sure of a good ballpark distance for loudspeakers to be from the mix position. I've worked in studios with great loudspeaker systems but never thought about how far away they were from the mix position. I know it probably varies from speaker to speaker and room to room. Right now I have it designed where the face of the soffits will be about 7 feet away from the mix position, a little over 60 degrees from phantom center and slanted at 30 degree angles off of the front wall allowing for a 24" wide, and 16" +/- deep cavity at its lowest point. I'd like the speakers to be 6' +/- high and angled down to the mix position. I've sorted through lots of posts and reference material on the soffit subject but still cant put it together.
Questions for # 4 - A) Is the idea to "rough in" the soffits now a good idea, or should I wait until I actually have the speakers i'm going to mount and then construct the soffits in what will be an existing, working control room?
Wheeeewwwhhh!!!
I just scrolled up and realized how long this post is and how it spans over several discussion categories so I hope I don't get a lashing for posting this on the wrong board, and hope I didn't break too many rules. I hope I didn't go too overboard with this first post but I've just been bottled up with questions I've been waiting to ask! Thanks to all that have taken the time to read my post. Skimming all of your posts for the past months has been intriguing and educational. Any existing threads, links, or reference material that might answer some of my particular questions would be greatly appreciated. I'll be eternally grateful to anyone who downloads my sketchup file and helps me work with my design. I also am not opposed to hiring someone more experienced to work with me directly and consult the build. Any beacons of light in all of this himiny-ha are welcome. I'm open for all questions and suggestions..
Thanks again to John and all of the senior members for their free wisdom and the time and effort they put into their posts, and keeping this board alive!

Jason


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PostPosted: Sun Sep 08, 2013 2:22 am 
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Hi Jason, and welcome to the forum! :)

Great first post, by the way! That's refreshing. Way too many newcomers post things more like "Here's my square. How do I make it into a studio?". So it's great to see a first post like yours, with very complete, detailed information.

Quote:
I just scrolled up and realized how long this post is and how it spans over several discussion categories so I hope I don't get a lashing for posting this on the wrong board, and hope I didn't break too many rules. I hope I didn't go too overboard with this first post
On the contrary! You did it completely right. That's exactly the type of first post that we ask for. It shows that you have already put a lot of effort into thinking things through, explaining where you are, what you want to do, asking about things that you are concerned about, etc., which is great.

I'd really like to reply at length to your post, since there is so much to be said (on what you mentioned, and other aspects that you didn't mention), but unfortunately I'm totally tied up for the rest of the weekend with other commitments, so I probably won't be able to comment until Monday.

But I did want to at least say "hi", and welcome you to the forum.

- Stuart -

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PostPosted: Sun Sep 08, 2013 3:10 am 
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Location: Alpharetta, GA
Hello Stuart! ...Pleasure's Mine.

Thanks for responding and showing interest. It's literally taken me a month to gather my thoughts and work everything in to sketchup before posting anything. Glad to hear I did it right. I probably could've included more detail but felt myself getting carried away and writing a novel. :blah:
If I can add my sketchup drawing it'll probably answer most people's first typical questions. Did my best to make it dead nutz to existing scale.
Thanks for taking the time to form a response.. I don't mind waiting.
But quickly before you go... I'm sure theirs a way to shrink my sketchup down to postable size but im new to the program. Any quick tips on how to get the file up? Is it ok for me to post the file up on sendspace or other file sharing site and post the link to the download here?

Thanks!

Jason


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PostPosted: Sun Sep 08, 2013 10:10 am 
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Quote:
But quickly before you go... I'm sure theirs a way to shrink my sketchup down to postable size but im new to the program. Any quick tips on how to get the file up? Is it ok for me to post the file up on sendspace or other file sharing site and post the link to the download here?


There's a strange thing about SketchUp: when you delete something inside your model, it disappears from the screen, but the data is still stored inside the file, in case you want to then "undelete" something. So as you work on your model, creating and deleting things, the file grows much bigger than it should, due to all the unused "baggage". But you can remove that: On the "Window" pull-down menu, select "Model Info": That opens a new pop-up window. Select the "statistics" tab on the left. Click on "purge unused", and it will clear out all the deleted garbage. (Of course, you won't be able to "undelete" stuff earlier after doing that).

If the file is still too big to post after you purge it, then sure, it's fine to upload it to Dropbox or something like that, then post the link here. As long as you use a service that doesn't spew spam when you try to download the file!

- Stuart -

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PostPosted: Mon Sep 09, 2013 7:18 am 
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Didn't have much luck shrinking down the Sketchup file but

Here's the link to download the sketchup file for anyone that would like to take a look....

http://www.sendspace.com/file/c9bfpk

Notes about the drawing :

1. I went a bit layer crazy so I could make this drawing more accurate. The constructions in the drawing that currently exist are the slab, masonry, joists, decking, exterior walls, control room walls and ceiling trusses, and all interior walls that are on the joisted half of the building. The live area is still just a wide open space like it shows in the pictures above.

2. If you notice that the studs and such are not on exact 16" centers, its because they aren't in the existing construction.

3. Some of the pictures above show the CR windows. The window frames will be resized soon to match the window dimensions and placement in the drawing.

4. I would appreciate and encourage anyone who would like to download the drawing, make some changes or suggestions, and repost. If you do so, thanks for your time!

Hope the drawing helps to describe my scenario.

Thanks all!


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PostPosted: Thu Sep 19, 2013 9:40 am 
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So it's been a few weeks since I started this thread. It looks like about 100 people have seen it but no one's replied.

I'm trying to be patient but the suspense is killin' me folks!!
Can anyone post some thoughts or comments?

Thanks all.


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PostPosted: Mon Sep 23, 2013 8:22 am 
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Oooops! :oops: There I was saying I would get back in a couple of days, and then I went on vacations without ever bothering to reply! :oops: :oops: :oops: Sorry about that!

Quote:
308sqft control room, 1180 sqft for live & iso space,
That's a pretty good ratio, and a nice size for the CR. ITU specs call for a minimum of 215 ft2 floor area for a two-channel control room (2.0, 2.1), and 322 ft2 min for multichannel (5.1, 7.1, etc.), so at 308 you could go either way. Are you planning 2.0 or 5.1?

Also, it is generally recommended that the LR should be at least twice and preferably around five times the volume of the CR, so even if you have the same height ceiling in both, you'd be good there. And since your LR ceiling is higher, that's great!

Quote:
I'm new to sketchup and got a little layer-crazy
Layer crazy is good, in my book! You should see some of my studio designs: they can have over a hundred layers.... :shock: (I kid you not...) So as far as I'm concerned, you did great with that! Makes it MUCH easier.

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My plan is to tackle this mammoth in sections because different parts of the building have different needs.
Right! And it's also a lot of work to try to do all at once. Are you going to do all this work yourself, or hire contractors?

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My budget for building out the interior of the studio is about $40-50K.
That sounds reasonable.

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CONTROL ROOM: L= 20' 6 1/2" W= 14' 3 3/4" H= 10' ceiling dropping down to 8' over the rear 4 feet of the room.
Oops! That's a square profile. Your length is almost exactly double your height, so all the modes related to those two axes will line up, just one octave apart (the even harmonics of height will match the odd harmonics of length, all the way up the scale). In general, you should avoid dimensions that are within 5% of being double or triple each other. So your control room fails one of the three critical tests. Fortunately that can be fixed without too much pain, as you only have framing up so far. Not a big deal to move a wall or modify the ceiling.

Quote:
Current Status: The control room is on floor joists above a crawlspace with one layer of 3/4"plywood decking.
:shock: OOOPS! And a big one! To put it bluntly: you have built your control room on top of a very large kick drum :!: There's no easier way of saying it. That crawlspace is nothing but a large resonant cavity, and it will cause you endless problems. The floor is a resonant membrane stretched across a resonant cavity: ie. a drum. This is a major problem. Every time your speakers play a note that happens to be related to either the floor itself or the cavity under it, or both, then the note will either be enhanced or sucked dry by the resonance. Your frequency response in that room will be all over the place, and there is no way of fixing that later with acoustic treatment in the room. In essence, the entire floor IS acoustic treatment, but doing random unknown (and unwanted) things at unknown frequencies.

What you have done, in effect, is to float your floor, but in the wrong way. This thread should help to guide you to the only sane conclusion, but it's a conclusion that I'm sure you don't want to get to:

viewtopic.php?f=2&t=8173

Quote:
The walls are double 2x4 walls with a 2" gap in-between.
You mean a 2" gap between frames, right? Not a 2" air gap?

Quote:
Unfortunately these walls are capped with a 2x10 due to certain structural needs of the building so they are not full decoupled from each other which totally sucks.
Then there's a major design issue here! The inner-leaf of the control room must be self-supporting, and must NEVER touch the outer leaf. The inner-leaf walls can structurally support only the inner leaf ceiling, not the outer leaf. If you are relying on the inner leaf walls to support the outer-leaf roof, then you have a major structural design problem that needs correcting.

However, your SketchUp model does not show any inner leaf at all! It only shows the outer-leaf, which is confusing. Or rather, it shows part of what could be an inner leaf in some places, but not in others, and even then those parts are firmly coupled, instead of being separate.

In summary, there's a big problem with the concept of the framing: It is not correct structurally, and it is not correct acoustically. It is not doing either correctly.

Quote:
As for monitoring I will have some NS10's, mixcubes, and dynaudio BM5a's to choose from for near-fields.
Personally, I would go with the BM5A's for the actual speakers, but still put the NS-10s in the room for show... without actually connecting them! :) :mrgreen: 8) )

Quote:
As the studio grows I would like to add a pair of soffit mounted loudspeakers to the control room. Probably a pair of Augspruger GA115's with a single sub. I want to construct the soffits now but leave them covered and still working as traps until we get loudspeakers.
Smart move! Yes, build them now completely, designed for the exact speaker you plan to install later.

Quote:
1) Acoustic Design- When dimensioning this room, I knew how much space I needed to have a comfortable, decent sounding workspace but am still uneasy about choosing the different angles in the room and the treatment methods. After a bunch of research I think I'm close to what will work but could definitely use some help.
What is your basic design concept for the room? Are you going with LEDE, RFZ, CID, MR, or something entirely different? That's the starting point.

Quote:
See the design pic below.
Where? Looking, but not seeing.... :)

Quote:
On the sketchup drawing you can see that I made a rough footprint of the speaker soffits angled at 30.
Looks about right.

Quote:
the front helmoltz absorbers angled at 12,
:shock: "Helmoltz absorbers"? :?: Are you sure about that? Maybe you mean "slot wall"? Pure Helmholtz resonators are notoriously difficult to tune to the correct frequency that you are trying to target, and even then they need to be positioned at a point in the room where the pressure node for that mode is at its peak, or close to peak. Then they also need to be rather large to have a useful effect on the room. So I guess you are talking about using broadband slot walls there?

Quote:
and the rear absorbers angled at 6. Notice the bass trap across the back of the room that I plan to fill with hanger traps.
To be honest, I think it would make more sense to just put Superchunks in the two rear corners, with hangers next to them, or even hangers in the corners ranging to larger and larger sizes as you get closer to the side walls.

Quote:
If my calculations were correct my helmholtz's are about the size that they will need to be to help with the rooms frequency issues.
You need to have a cavity that is about 1% of the room volume for each of the frequencies you plan to target. So if you plan to target ten frequencies, you'd need to use up 10% of your room volume for that.... :shock:

What frequencies are you planning to target, and how are you planning to do that? Helmholtz resonators for very low frequencies are really hard to do, so you should make them tunable in some manner, such that you can adjust them as needed to hit the actual mode that you are after. This isn't easy to do, and is going to take a lot of time and care, with no guarantee of success. I would seriously consider dropping the idea of using tuned bass traps, and just go for broadband treatment, such as Superchunks and/or hangers, which will cover all your modes with no tuning required.

Quote:
I was also considering using clouds over the room and less absorption on the walls.
Yup. Smart move! And also keep the floor solid, hard, massive and reflective...

Quote:
I know this window is in the RFZ which is a bad place for glass but am wondering if leaving it there would corrupt the sound in the mix position.
It looks to be far enough back that it won't be a problem, but the only way to tell for sure is to ray-trace.

Quote:
B) Am I bat-shit Crazy? … Please take me to school on this one guys! any suggestions or comments would be a big help.
:lol: :shock: :!: :D Yup! If you weren't crazy, you wouldn't even be here on the forum, taking about building your own studio! :) Insanity is a key requirement in all studio builders....

So far, your biggest issue (and it IS a biggie) is that floor under your control room. That has to be fixed. Without rectifying that, your chances of having a great control room are very low. The next "biggie" is the framing. There's a conceptual issue there that needs to be fixed: The outer leaf (building shell) ONLY supports the outer leaf, and the inner leaf ONLY supports the inner leaf. There can be no mixing of the two. If you cannot support the outer leaf without resorting to connecting it to the inner leaf, then you are using undersized lumber, of the wrong type, spaced too far apart. Or you need to switch part of the structure to steel.

Those are the two major issues so far.

And to add another rock to the pile for beating yourself over the head... :) I would seriously consider rotating the control room 90° right, so it faces the LR. Then you can have a clear view of what is going on in there, without ending up with whiplash from cranking your neck back and forth every few seconds. To my way of thinking, sight lines are very important to the smooth flow of a tracking session: you need to be able to see the musicians and they need to be able to see you, almost as much as they need to be able to see each other.

Quote:
With the existing double walls of the control room being capped and coupled to each other and the floor decking (9' thick total frame) my plan was to put up another 2x4 wall from the slab to the roof trusses 6" outside the right control room wall that will be the resilient "spring" wall and barrier between the CR and Live area.
If the walls are fully coupled through the ceiling and also through the resonant drum head floor, then there isn't much point talking about isolation here: there wont be much. I doubt you'd get more than 40 dB, if you are lucky. Hardly better than a typical house wall. It matters not how big you make the air gap, or how much insulation you put in, since that isn't the path that sound will take: it will take all the flanking paths through the structure of the building, totally bypassing the insulation and air.

Quote:
With this in mind I figured I'd be fine if I constructed the inner CR walls using 4" of OC703 in-between the studs, 2 layers of 1/2" drywall glued with green glue and screwed directly to the studs, caulked and sealed accordingly.
You'd be wasting your money. Green Glue is great stuff, but only useful if the wall is already well isolated. It can't do anything about flanking paths.

Also, 1/2" drywall is too thin. 5/8" is what you need.

Quote:
The outer spring/barrier wall will be constructed of 4"of OC703, 2 layers of 3/8" drywall, glued/caulked/sealed, screwed to resilient channel on clips. That will make out to be - Inner Leaf / 4"insulation / 12" air space \ 4" insulation \ Outer leaf on spring.
Forget the clips and the RC. You don't need both anyway, ever: RC decouples, and clips decouple, so one or the other, but not both. And you can't even use RC with clips: it wont fit. For clips, you need hat channel, not RC. But if you have a proper decoupled two-leaf wall, then you don't need RC or clips!

But you also posted photos showing that the building already exists, with siding and all, yet you are now talking about putting the outer leaf on RC: that means you'd have to take off the siding from the outside of the building, put the RC on, then re-hang the siding from the RC... I'm not even sure that code would allow you to do that. So I guess you are talking about only doing that on the other three sides of CR, not the side that faces the building outer leaf? Even so, it makes no sense to do it that way around with the mixed framing design you have right now.

Quote:
I'm pretty sure that will stop any sound from the live area from getting into the control room if installed properly.
IT would if done properly, but not in your case, since you are not planning to decouple your walls, and you also have that resonant monster growling under the CR floor.

Quote:
A) With my existing CR double walls being coupled to themselves by the 2x10 cap and coupled to the floor decking with no spring, do you think the way I intend to finish the walls will achieve my desired isolation?
Simple answer, plain truth? No. Not even close.

You didn't say how much isolation you want, in terms of dB, but you'd basically be limited to mass law like that, minus the flaking, minus the resonant monster: I'd hazard a guess at about 40 dB isolation, with luck. I doubt that is anywhere near enough.

Quote:
B) Any thoughts on working a mass loaded vinyl or audio mute material into this equation to improve it?
Adding MLV would improve one thing only: the balance sheet of the MLV manufacturer! :) It won't to anything for your isolation that could not be accomplished much cheaper in other ways. To stop sound you need mass. MLV is very expensive mass. Drywall is very cheap mass. Which do you prefer? :) Sound waves don't care about price tags: all the react to is mass, regardless of how much it cost you to put there. So go with the least expensive mass that will do the job. MLV is only useful in a few specific cases that drywall can't handle, such as wrapping noisy pipes. Apart from that, the only benefit is to the guy who sells it.

Despite the claims of some manufactures and dealers, there are no magical materials. ALL building materials obey the laws of physics, and those laws are crystal clear about how sound can be stopped and controlled. Magic and snake oil do not come into the equations at all.

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3) Floors - I'm gonna keep this one short since I'm pretty sure I know the answer. The 3/4" CR decking sits on 2x10 joists 2 feet above the slab below that is a crawlspace. I'm planning on adding an 1/8" layer of MLV and another layer 1/2" ply to the existing floor before the finish flooring to add mass.
I'm gonna say it…"Do I need to float my floor?" Honestly, I sure as Shit don't want to!!!
Actually you already DID float it, and that is the entire problem! You might not think that you floated it, but you did.... sort of. And it desperately needs to be "un-floated", brought back down to earth, so to speak: Your CR floor needs to be solid concrete, nothing more, thing less. It does NOT need to be a drum, which it is right now.

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I figured that by building the barrier between the CR and live area the way I described it in #2 above that It would provide enough isolation between the sounds of the live room and the sounds of what is seeping through the floor into the crawlspace under CR.
Not really, since you are greatly underestimating the power of resonance. It's a good tool that you can use to your advantage in studio design, but it is also a wild beast that can destroy things in ways you never imagined if you don't control it. And one way to unleash the beast is to give him a wonderful dungeon to roar and rumble in, right under your CR.... (I'm feeling a bit poetic today! sorry....)

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Questions for # 3 - A) Given the crazy added costs and weight of floating floors and in my scenario. I really don't wanna float my floors.
Good! Then you need to "un-float" the one you already half-floated! You are totally correct that you do NOT need to float your floors! Not any of them. So you just need to undo the floating that you already did unintentionally.

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Do I need to float my floors, and why? (please say no, please say no, please say no…)
OK: "NO!" But that "NO" probably doesn't make you happy, since it implies something that I'm sure you don't want to do...

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B) Do I even need to bother adding MLV to the floor or will 2 layers of ply on some felt do the trick?
See above for my opinion of MLV (not just mine: it's the general consensus of studio designers). Needless cost. Very expensive mass. Very few legitimate uses in acoustics. Can easily be forgotten entirely.

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Again, while I'm recording clients I'm not monitoring them at 100 db.
You might have to, if you don't fix your isolation! Let's say you are tracking a typical rock band. The drums are putting out around 115 dB. Your walls are stopping 40 with luck. so you have 75 of drums in the CR.... so your monitors need to be much louder than that: You'd better turn those puppies up to about 95 dB at least, if you hope to be able to hear the drums on the monitors above the drums bleeding through the walls, floor and ceiling. And even then, it won't do much for the pumping vibration under your feet, with each and every thump of the kick drum...

Then there's the bass player, proudly slapping away on his beautiful six-string bass, with his amp turned up to eleven, and your chair, floor, desk and console happily rumbling and humming to the tune of the bass line, as they bounce and float around the room....

OK, so I'm exaggerating just a little, but not much. There's a major issue with resonance, and a major issue with isolation. They need to be addressed urgently, before you carry on building. Right now you are just at the framing stage, so the modifications can be done without too much pain (but still a lot of pain, nevertheless).


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4) Speaker Soffits - Never done this before! Definitely need some help!
As described above, as the studio grows I'd like to upgrade to a pair of soffit mounted loudspeakers. I'd like to construct the soffits framing now and just have them operating as hangar traps covered by a cloth finishing or solid piece of ply until I get loudspeakers. Once speakers are chosen I'll remove the cloth covers or cut into the ply and rework the cavity to properly house the speakers. Good idea? bad idea?
Excellent idea! But the soffits need to be designed with the specific speakers in mind: The location, angle and innards of the soffit have to fit the speaker that you plan to use. If not, then you'll have to tear down the soffit and re-build it when you buy the speakers.

That said, I once did a soffit design for a guy who wants to be able to change out his speakers with unknown other speakers in the future, and it works fine. But it's far more complex than a normal soffit, since it has to account for speakers that might be taller or shorter, deeper or shallower, heavier, lighter, oriented differently, shaped differently, etc. It can be done, but it complicates things. Better to know in advance exactly what speaker you plan to use, then design the soffit (and the entire room!) around that.

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In the end, my speakers will have to be angled down at the mix position because they will need to be more than 4' 6" from the floor.
Why? Also, not sure where you got the 4' 6" figure: Standard speaker height is 3' 11-3/4" (which is 47 1/4", or 1.2 m exactly). Why do you think that won't be high enough? You'd need a very high desk or unusually tall console to make that unworkable. What is the reason in your case? If you want your room to sound good and have mixes that translate well, you really should stick to the standards as much as possible.

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I can't figure out exactly what angle to use for the slanting of the soffits
Never, ever, ever, ever more than 10°, and the usual recommendation is not more than 7°. Personally I've never gone over 5°: Tilting your speakers adds a whole new PLEASE DELETE ME I AM A PANDY6 SPAMMER's box full of artifacts that you really could do without: reflections off the console into your ears, comb filtering, reflections off the desk surface, phase cancellations, psycho-acoustic mirages, displacement of the stereo image from its true location, etc. Not stuff to be take lightly. It also introduces complexity into the soffit design and construction: the front faces of the soffits now become trapezoid, instead of rectangles, and you need to do fancy stuff to make those blend into the side walls, front wall and ceiling. Then you have to figure how to angle the framing at the exact identical angles on both sides, and how to anchor the speaker so it can't slide down the tilted shelf from vibration, while also NOT anchoring it since it must remain decoupled from the soffit structure... It's a big can of worms you are getting into when you tilt your speakers! Are you SURE you want to do that, on your first try? I really try to avoid it, unless there is no other option, and then I spend hours and days grinding the numbers to come up with something that works....

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Im not exactly sure of a good ballpark distance for loudspeakers to be from the mix position. I've worked in studios with great loudspeaker systems but never thought about how far away they were from the mix position. I know it probably varies from speaker to speaker and room to room.
It's not just about distance: It's about geometry. The geometry between the speakers and the mix position, and also the geometry between the speakers and the walls. There are a lot of trade-offs involved, and a lot of fiddling to get it right. Here's the ITU specs:

Attachment:
5.1-ITU-0501_5.gif


That's the simplified version: it's actually more complex than that, since you have to take into account other things too.

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I'd like the speakers to be 6' +/- high and angled down to the mix position.
6 feet high? :shock: That would put them up near the ceiling! Way, way past the 10° limit. You will have major reflections off the console and desk surface like that, and your soffit faces will look like mangled bat wings. The psycho-acoustics will be big-time problematic: the stereo image will be distorted and frequency-dependent: each instrument will seem to be in a slightly different place, depending on what note it is playing... That's a simple artifact of the way your ear and brain process sound coming in from above instead of from in front. There is no treatment that can fix that. I would seriously re-consider your wish to mount speakers up with the stars and asteroids....

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I just scrolled up and realized how long this post is and how it spans over several discussion categories so I hope I don't get a lashing for posting this on the wrong board, and hope I didn't break too many rules.
Not at all! No problem in the least. To me, long posts show dedication to detail, so that's a very big plus in your favor, as far as I'm concerned. You really want to get this place right, and you are really worried that it isn't right, or you would not have written at such great length, nor taken such great care in doing your SketchUp model. So please don't worry at all about long posts are adding too many details! On the contrary, it's the folks who post too little detail and tiny posts, who get the least help around here! I normally try to put as much effort into answering as the poster puts into posting. The guy who just posts a picture of a square and text saying "This is my room. How should I design it?" gets zero help from me, since he put zero effort into that. But you put a lot of effort into yours, so I hope I've done likewise, and managed to help you somewhat to get on the right path! But if not, then let me know what I missed, or what I didn't explain clearly, and I'll give it another shot.

Also, I hope I haven't bummed you out to much with all the negative stuff about things that are wrong with your design: I kind of have this habit of just blurting it out straight, no sugar-coating, no beating around the bush. Some folks don't like that direct "in your face" response, so I hope it hasn't rained on your parade! You have a REALLY nice space there, with major possibilities for making it into an excellent studio. You have the budget to do it right, and you clearly have the desire to do it right, so all of that bodes very very well. Don't let my harsh attitude discourage you! Your place can be fantastic, but it does need some pretty big changes to get it there. The path you are on right now is not going to get you there....

- Stuart -


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PostPosted: Tue Sep 24, 2013 2:43 am 
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Stuart,

Thank you for your response! Hope I didn't sour the vibe on your vacation by asking you about my post before you made it back to "reality" . :oops:

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I hope I haven't bummed you out to much with all the negative stuff about things that are wrong with your design: I kind of have this habit of just blurting it out straight, no sugar-coating, no beating around the bush. Some folks don't like that direct "in your face" response, so I hope it hasn't rained on your parade!

Not at all bummed! I actually think I'll sleep a little easier tonight. Your responses to my questions backed up all of the "voices in my head" in the decision making process on this build, and the "no sugar coating" is exactly the type of response that I wanted and respect. I'm a musician and an engineer. I'll be the first to admit that studio construction is over my head which is why I'm trying to reach out to others around the world that would be willing to offer guidance. Again, thanks to all who reply.. :)
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I want this studio to amaze people. "That'll do" doesn't amaze people.

That says it all!
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Are you planning 2.0 or 5.1?

I'm planning to go with a 2.0 system for nearfields, and 2.1 for loudspeakers. I currently work on the BM5a's and like'em just fine. I wanted to add some ns10's along side them for "industry standard"s for incoming engineers, and because I like them just the same! I'd like to have a loudspeaker system that is 2.1 using possibly some 1x15" tops and an 18" single sub. Being undecided on the exact is why I wanted to frame my soffits now to dimensions that could easily be fitted with speakers of that generic size when the time comes to install them.
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Are you going to do all this work yourself, or hire contractors?

I plan to do as much of the work myself as humanly possible. Given the jobs that may need to be done, I'll hire contractors for elements of the build that would be more cost effective and time saving. To be honest, at this point I don't exactly trust contractors to give the attention to detail that I think is needed for this application. I want to have my hands on as much of this as possible. It's just personal like that... 8) I will be hiring an HVAC contractor that I trust, and already have an electrical contractor to finish out utilities. Plumbing and electricity are roughed in. No HVAC contracted yet because I wanted to have my entire finish plan decided before taking that step.
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You mean a 2" gap between frames, right? Not a 2" air gap?

Yes.

Perhaps it would be wise to get to the nitty gritty of this post and address it with a "ground up" priority pecking order instead of bouncing from subject to subject. Your reply has really helped to hone my plan of action from the current status.
The Control Room half of the building (the side of the structure that is up on joists, not on concrete) is the first completion priority to me. You confirmed the biggest fear I've had regarding the control room and the Hall/Booth. Having them up on joists over a crawl space was going to be the biggest demon and most crucial fix of them all :twisted: Standing in the currently constructed space and stomping my foot on the floor told me this loudly! It actually had such a good sub bass thump that I wanted to record a sample of it, :shot:, before realizing how much of a problem it would cause. I feared it acting as a "drum" that would not only resonate the control room but also resonate what bleed might come from the live room. Along with the floors, there's issue of walls not being true inner and outer leafs since they are capped with 2x10"s and coupled to the existing floors.
I'd consider these the two mother#%&#@'s that have to be dealt with before this studio can thrive.
First, the floors.
In my mind there are 2 options...
1)Remove the existing floors of the CR and hall/booth and lower them down 2' onto the slab below.
2) Build and float another floor on top of the existing floor deck.
On #1, I think doing this would definitely increase integrity on all fronts. The major downside is the cost of reconstruction to make it happen.
On #2, Would floating a new floor system on top of the existing one that could support the entire inner leaf be a solution? Build a new decoupled room inside of the existing frame to isolate the control room from the structure around it? Working within the existing boundaries would definitely cost less and is what I'd rather do so I'm not eating the cost of the current build. But at the end of the day, it has to work. Do you think it is possible to work within to get good isolation between rooms?

I guess that's a good place to start. Please reply when you have a minute.
Thanks Stuart !!

Jason


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PostPosted: Tue Sep 24, 2013 4:12 am 
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I'm planning to go with a 2.0 system for nearfields, and 2.1 for loudspeakers.
So no 5.1? Great. That's one decision out of the way. 5.1 calls for some changes to the design that are easy to do now, but hard (and expensive) to do later, so if you wont ever be doing 5.1, that simplifies things.

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Being undecided on the exact is why I wanted to frame my soffits now to dimensions that could easily be fitted with speakers of that generic size when the time comes to install them.
It can be done. When the time comes to talk about soffits, I'll PM you some info on that.

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To be honest, at this point I don't exactly trust contractors to give the attention to detail that I think is needed for this application.
Smart move! Unless the contractor has already done a couple of studios successfully, he'll need very close supervision all the time. So if you have to be there all the time watching and correcting, you might just as well do it yourself, or as much as you can.

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I will be hiring an HVAC contractor that I trust,
Great, but does he have studio experience too? If not, there's some stuff he'll have to do different from what he is used to doing. It's not as big a deal as a non-studio-experienced building contractor, but still important. Things like oversized ducts to reduce flow velocity, ducts lined on the inside with proper duct liner, silencer boxes on all wall penetrations, decoupling ducts from equipment with canvas or rubber sleeves, low-noise diffusers and registers, etc. HVAC implies chopping huge holes in your beautiful soundproof walls, so it's rather important to get it right!

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have an electrical contractor to finish out utilities
Again, does he have studio experience? There are many things he must do different, such as star-grounding for all outlets, running the electrical stuff very far from the signal stuff, only crossing at 90° (never parallel), having only one single wall penetration into each room, then internal surface-mount distribution within the room, etc. Many things will be different for him too.

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The Control Room half of the building (the side of the structure that is up on joists, not on concrete) is the first completion priority to me. ... there's issue of walls not being true inner and outer leafs since they are capped with 2x10"s and coupled to the existing floors.
Right. Those are the biggies.

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In my mind there are 2 options...
1)Remove the existing floors of the CR and hall/booth and lower them down 2' onto the slab below.
2) Build and float another floor on top of the existing floor deck.
Both are options, but if it were my room I'd probably go with #1. Overall, it would be easier and cheaper, and probably a lot of the materials that you demo can be re-used in the rebuild.

If you prefer #2, that's also possible, but complex and expensive. I'm not sure if you saw that link I gave you yesterday to the thread on floating floors, but here it is again. Required reading:

viewtopic.php?f=2&t=8173

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On #1, I think doing this would definitely increase integrity on all fronts. The major downside is the cost of reconstruction to make it happen.
My guess is that it would be substantially cheaper than #2.

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On #2, Would floating a new floor system on top of the existing one that could support the entire inner leaf be a solution?
It is possible, yes, but a properly floated floor needs huge amounts of mass (read: "concrete"), and hefty isolation mounts, such as these:

Attachment:
mason-floating-floor-isolation-springs.jpg


Attachment:
mason-floating-floor-isolation-jacks.jpg


Two different types there: one is a spring, the other is rubber. They both do the same basic thing. The concept is that you lay thick insulation on your sub floor, cover it with plastic, set these gadgets in several key places, pour concrete around them up to almost flush with the top, wait for the concrete to cure, then use the gadgets to jack the entire slab up, so only the springs (or rubber bases) are supporting it. That gives you the mass and resilience you need to get the resonant frequency down low enough that it is no longer a problem.

The fun comes in calculating your mass and other loads correctly, then locating the correct number of isolation jacks in the correct locations to get the floor to float... :)

If you want to get into the theory and real-world lab tests of various types of floating floor, then this is the best paper I'm aware of for that:

http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir802.pdf

Some of the graphs are scary, and show why this is not something to be taken on lightly. Many graphs show a REDUCTION in isolation at low frequencies for floor assemblies done with low mass or incorrect resilient materials... IN other words, getting the float wrong means that you have LESS isolation than you would have had if you would have just done nothing at all! Not a happy scenario...

Check out the Mason Industries and Kinetics web sites for more info if you are interested in going this route.

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Working within the existing boundaries would definitely cost less ...
I'm not so sure about that! A few cubic yards of concrete, half a dozen isolation jacks, ... :)

What I would do if that were my place, is first bang my head on the wall for a few minutes, sigh deeply, then start taking it all down while trying to save as much lumber as possible to re-use. Then I'd carefully re-design the place, starting with the concrete slab as the basic floor, and work up from there.

This also has the advantage of making it dead easy to fix your inner-leaf framing issues, and also giving you a lot of space for a high ceiling, excellent treatment, and more room above the ceiling for HVAC. The ducts and silencers you need for those rooms are going to be rather sizable. You didn't show the roof trusses and deck on the SketchUp model, so I'm not 100% certain, but my guess is that there was very little space up there between the CR ceiling and the roof trusses for running HVAC. Realistically, you need at least a foot, preferably two feet up there for your ducts. They have to be much larger than would be normal for a non-studio installation of the same size rooms, since the flow rate has to be kept the same, but the speed has to be lower, meaning the volume has to be higher, meaning large ducts. They also have to be lined on the inside with 1" duct liner all around, so they need to be 2" bigger in both dimensions, just to account for the lining, plus the extra size for the larger volume / lower speeds... I'm getting a bit sidetracked here: HVAC is another issue that we didn't get to yet, but it does need to be considered in the initial CR and LR design, since it just takes up so much darn space! Silencer boxes for a room that big can be huge...

I did notice some consideration for HVAC on your SketchUp, but not enough....

So that would be my plan: take it down, working carefully to save as much as possible of the materials, then re-design and re-build.


- Stuart -


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PostPosted: Tue Sep 24, 2013 7:09 am 
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I'm not sure if you saw that link I gave you yesterday to the thread on floating floors, but here it is again. Required reading:

I've read this one a few times. I knew immediately that the CR floor was going to be trouble so I've been trying to explore all potential solution options of working within the existing construction.
Quote:
If you prefer #2, that's also possible, but complex and expensive. A few cubic yards of concrete, half a dozen isolation jacks, .

Agreed. As opposed to floating a concrete floor, which probably wouldn't be a smarter solution than just cutting out the existing floor and setting up flat on the slab, I was wondering if a timber "raft" on neoprene blocks on top of the existing floor with a good massive deck and insulation in the cavity be an option? I know it comes with the complexities of calculating loads amongst other things. Or would doing so just end up making another resonant "drum" on top of the existing one?
I read thru the lab test pdf you attached.thanks. Pretty informative and pretty scary.
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What I would do if that were my place, is first bang my head on the wall for a few minutes

BANG! BANG! BANG ! BANG ! :cen:
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Then I'd carefully re-design the place, starting with the concrete slab as the basic floor, and work up from there. This also has the advantage of making it dead easy to fix your inner-leaf framing issues, and also giving you a lot of space for a high ceiling, excellent treatment, and more room above the ceiling for HVAC.

If this ended up happening, would using the slab as the floor be possible? probably not directly on the concrete, maybe some tile. Or put down a vapor barrier, thin sand cavity, and hardwood flooring on top?
Or would you suggest having the concrete be the subfloor and then floating a new floor on top of it?
I realize that if I had to cut out the floor and start over that I have the advantage of revamping the entire design, and reusing as much material as possible. It's funny how you said " I'd strongly recommend rotating the CR 90* ". I've been thinking the exact same thing and already made a full second design implementing that. :D I found that it makes the whole space function better. If the floor has to come out, then the redesign will be easy to construct. But before taking that massive plunge I have to eliminate all options of building within what exists first just to be thorough. :horse:

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You have a REALLY nice space there, with major possibilities for making it into an excellent studio.

:lol: thanks. I know its going to take a lot of blood and sweat to get this place on par, but I'm up for the challenge and that's why I'm here!
Thanks again for your time and interest.


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PostPosted: Tue Sep 24, 2013 12:17 pm 
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I was wondering if a timber "raft" on neoprene blocks on top of the existing floor with a good massive deck and insulation in the cavity be an option?
It's another option, yes, but the key words here are "a good massive deck". As in majorly massive.

Isolation in a two leaf system comes from using resonance in your favor (instead of against you, which is what you have now). The basic concept is that a two-leaf wall is a "Mass - Spring - Mass" system, and follows the equations of physics that govern such systems. If you hang a spring from something rigid, then hang a weight on the bottom of the spring and give that weight a tug, it will bob up and down on the end o the spring for a very long time: it is resonating. It will only do that at one specif frequency, which is set by the amount of mass and the "bounciness" of the spring, also called "resilience". If you try to make it bounce at another rate, either faster or slowly, it will actively resist your efforts, and as soon as you stop trying it will instantly go back to the same rate as before. It does NOT want to resonate at any other frequency. Pushing a child on a swing is another example of the same principle: it's really hard to make the child swing faster or slower than than that natural resonant frequency of that system.

A two-leaf studio wall, or floor, or ceiling works on the exact same principle: the massive leaves on each side are Mass #1 and Mass #2, and the air trapped between is the spring. We don't normally think of air as being "springy", but to a sound wave it sure is! So the wall/floor/ceiling is also a Mass-Spring-Mass ("MSM") system, and just like the weight bouncing up and down, it also wants to resonate at one single frequency, and "fights back" against all other frequencies. At its resonant frequency it does not isolate at all, and in fact it amplifies the sound, making it louder. But at all other frequencies, it isolates. So if you can set the conditions right so that its natural resonant frequency is outside of the audio spectrum, then bingo! It isolates ALL frequencies that you can hear!

Simple! so how do you "tune" the wall to get it to resonate at the correct frequency? There are only two factors in the MSM resonance equations for walls and floors: the mass on each leaf, and the resilience of the spring. For a wall, the spring is the air between the two leaves. For a floor, it is the steel springs or rubber pads (and also the air, to a certain extent). As you increase the mass on both leaves, the resonant frequency goes down. As you increase the size of the air gap (or the resilience of the spring/rubber), the resonant frequency goes down too. So with a bigger gap or more mass, you get a lower frequency. In reality, the system amplifies at resonance, is neutral at 1.414 times resonance (neither amplifying nor isolating), and isolates above that. So you need to get the resonant frequency down to about half of the lowest frequency that you want to isolate. In other words, if you want to isolate down to 50 Hz, you need to get resonance below 25 Hz. If you want to isolate down to 20 Hz, you need to get resonance below 10 Hz. Etc.

Of course, Murphy steps in here: the lower you go, the harder it is to go further... There's a "square root" operator in the equation, so the effect is exponential. Don't you just love acoustics? Just when you think you see light at the end of the tunnel, it turns out to be the headlight of an express train coming at you...

If you are interested, the equation for MSM using air as the spring is this:

Attachment:
MSM-equation.jpg


That's the full equation: it can be simplified by making some assumptions and combining the fixed values into a single constant:

F = 60 * [(m1 + m2)/(m1 * m2 * d)]^.5

Where m1 and m2 are the two masses (surface density, in kg/m2), and d is the distance between them (in meters). The constant of 60 is for an empty cavity, but if you fill the cavity with suitable insulation, then you can change that to 43. Insulation acts as a damper, like putting a shock absorber inside your car suspension springs. It damps the resonance, which further reduces the resonant frequency and greatly improves isolation.

If one of the masses is extremely large with respect to the other (eg, you have a 10 inch reinforced concrete wall as the outer leaf, but only a single sheet of 5/8" drywall for the inner leaf), then you can simplify the equation even further:

F = 60 / [(m * d)]^.5]

Where m is the mass of the drywall, and d is the size of the air gap.

OK, that's for using air as the spring. If you use a physical spring, then the equations are a bit more complex, since you have to take into account the resilient properties of the rubber or spring, which are likely non-linear, but the same basic principles apply. But no you only have one variable: you cannot change the resilience of the rubber (unless you rip it out and put in another type of rubber), so your sole remaining method for tuning the floor to the resonant frequency that you want, is mass.

The lower mass in your two-leaf MSM floor is the concrete slab on grade, and that is extremely massive: you have the entire planet down there! That's hard to adjust. So you are left with only the other mass, on the top leaf. That's all you can change.

OK, so far so good. so you get some rubber pucks, and you put some mass on them, and bingo! Resonant system! Floated floor! Weeellll..... not so fast. There's the issue that rubber is not compressible, like air is, so it acts a bit different. Rubber doesn't compress when you load it: it squishes down and spreads out. The amount of "squish down" is called "deflection", and that's the key to making your floor float. Air is a spring all the time, compressed or uncompressed, but rubber has to be loaded to the right deflection or it wont "spring". If you put too much load on it, then it "bottoms out" and is no longer resilient: your floor won't float. And also if you don't put enough mass on it, then it "tops out" and is not resilient: your floor won't float. So you have to get just the right amount of deflection in the rubber to get it to its optimum loading for peak resilience. With air, it doesn't matter: it is always "bouncy", so you just set the right size gap for the frequency you want, but with rubber you also have to get the deflection just right so the rubber is bouncy at all! Get it wrong, and there's no bounce. And you wasted an awful lot of time, money and effort, all for nothing. With air, it doesn't matter if you accidentally put too much mass on a leaf, and in fact that's a god thing! But with rubber, putting too much mass on by accident will totally kill your isolation.

All that to say that floating a floor is a complicated issue: getting just the right load to get the rubber to optimum deflection and resilience is a big deal. Lots of calculations involved. And then there's the additional issue of the variable load on the floor! It will be much heavier in some places (eg, where the desk and console are, or where the sofa is), and much lighter in other places, where there is just bare floor: so you need to take that into account by have a larger area of rubber at the heavily loaded locations to keep them floating, and smaller pads at lightly loaded places. But then there's the issue of variable loading: what happens when a musician drags in his huge 400 pound speaker and amp stack, and leaves that sitting on the floor? Or what happens when you have four "well built ( :!: :shock: )" folks sitting on the sofa, as compared to nobody at all? What will that extra thousand pound load do to the rubber under the sofa? Does it overload it into bottoming out? How do you account for that?

Etc.

Designing a floating floor system is fun and games!

The only real way of dealing with all those variables is to make the floor so massive that none of them make any real difference, and make it so rigid that the load is spread evenly, regardless of where you place it. I think you see where this is going: you cannot do that with just wood. Wood is flexible and low mass. But concrete is rigid and high mass. To put numbers on it, the density of plywood comes in at around 500 kg/m3, so a deck of 3/4" plywood weighs about 10 kg/m2. For concrete, the density is about 2300 kg/m3, so a 4" slab weighs about 230 kg/m2. Just a slight difference! To get the same mass with wood, you'd need twenty three layers of 3/4" plywood. Now I'm not sure how much wood costs in your area, but I'm betting that a 4" concrete slab is going to work out somewhat cheaper than 23 layers of plywood! :) Not to mention that 23 layers of 3/4" plywood is over seventeen inches thick...

OK, that's my long and rather convoluted way of answering your question: "I was wondering if a timber "raft" on neoprene blocks on top of the existing floor with a good massive deck and insulation in the cavity be an option?" Simple answer: no, using a wood deck is not a feasible method of floating your floor, despite what some manufacturers of rubber pucks want you to believe! The amount of mass you need to solve the variability issue just makes it totally impractical, even assuming you could figure out the math. In theory their products will work, but in practice.... Not so easy to do!

If you take a look on YouTube, you'll see numerous videos of people happily and proudly showing how they are floating their 1/2" OSB floors 2x4s and rubber pucks. But strangely enough, they never seem to post a video about the final outcome, nor show actual objective test measurements of the isolation they achieved with their "floated" floors .... I wonder why? :)

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know it comes with the complexities of calculating loads amongst other things.
Yup!

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I read thru the lab test pdf you attached.thanks. Pretty informative and pretty scary.
Exactly. Scary is the word. Do it wrong, and you can easily end up with 10 dB WORSE isolation than having no floor at all! That's what I call scary...


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If this ended up happening, would using the slab as the floor be possible?
Yup! In fact, there really is no better floor for a studio than plain old concrete. Surprising, but true. If you look over some of the threads here of people who have already completed their studios, you'll see some really cool examples of what can be accomplished with concrete: it can be polished, buffed, stained, lined, etched and treated in other ways to look fantastic, and it makes an excellent acoustic surface. However, some people just don't like the look of concrete, or maybe your concrete is in bad shape to start with, so there are other options. One of those, as you suggested, is ceramic tiles. They can look really nice too, and also provide a great acoustic floor. Another option, which is cheaper and easier to install than tile, is laminate flooring: It goes in fast, and looks fantastic, and is also really good acoustically. Linoleum is another option. Anything that is solid, hard, and reflective is good. The wall framing goes directly on the concrete, of course, then the floor is laid right at the end, after the room is practically finished.

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and hardwood flooring on top?
I'm not too knowledgeable about hardwood flooring, but I understand that it cannot be laid directly on concrete: it needs a sub floor with an air gap, and that is a Big Bad Thing, of course. Any flooring that requires air under it is a no-no for studios. Flexible underlay is fine (such as the thin underlay that goes under laminate flooring), but nothing with entrained air.

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Or would you suggest having the concrete be the subfloor and then floating a new floor on top of it?
Not worth the money or effort, unless you need extreme isolation.

That's a good point, actually: How much isolation do you need, in terms of decibels? Both between rooms and also from each room to the outside world. Those are key numbers! Your entire design should be based around those numbers, so it's important to get them right.

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I realize that if I had to cut out the floor and start over that I have the advantage of revamping the entire design, and reusing as much material as possible.
:thu:

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It's funny how you said " I'd strongly recommend rotating the CR 90* ". I've been thinking the exact same thing and already made a full second design implementing that. :D I found that it makes the whole space function better. If the floor has to come out, then the redesign will be easy to construct.
Exactly!

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have to eliminate all options of building within what exists first just to be thorough.
Not only is that horse thoroughly dead, it is no beaten to a mushy pulp, I think! :)

Decision time....

- Stuart -


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PostPosted: Tue Oct 08, 2013 10:48 am 
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Stuart,

After thinking on it constantly for days now, the horse has come back as a ZOMBIE horse!
I have a few more theories to bounce off of you before this subject has been thoroughly beaten and shot. In the head. With a silver bullet. :horse:
I appreciate you taking the time to reply as you have been so I hope I don't get on your shit list for bringing this back up. I swear I'll change the subject soon. lol

To quickly recap on the floor conversation... the layers of my existing floor surfaces from the ground up are...
EARTH
1.Concrete Slab
2. 2' crawlspace
3. 2x10" joist system sitting on cinder block walls
4. 3/4" ply floor decking.
CONTROL ROOM
The main threat discussed in this thread so far is that having my floor above this 2' space will cause the dreaded "drum" effect. Bad. Most obvious solutions - 1) demo the floors and setup on the concrete, 2) make the existing deck much more massive and build a new floated system inside.
OK... We both know solution 1 is the best solution. But, just for now, lets say it wasn't an option. Lets say there was a basement below or this CR was on the 2nd floor of a structure where the area below wasn't occupied so it could be modified or disturbed, but not deleted. If that were the case how would you handle it if you were stuck with it and had no other option?
This is what I was thinking......
First, I would go into the crawlspace underneath and reinforce the floors with 4x4" beams on jacks (like i did in my existing home studio) adequately spaced to take the "bounce" out of the existing joist system that currently "half-floats" on the cinder block walls, and to make it more rigid and able to support more mass above. Then fill all the cavities in between the 2x10's with thick insulation bats.
Second, I would pour a 1/4"-1/2" of self leveling concrete on top of the existing 3/4" decking adding about (2 lbs per sqft @1/4" thick x 300 sqft = ) 600-1200 pounds of mass to the floor depending on the thickness I end up going with.
Third, I would finish the floor with a porcelain or stone tile. Tile ranges from 4-8 lb/sqft depending on the item used so that would be (4 lb x 300sqft = ) 1200 lbs. If I did the light side of this arrangement it would add almost a TON to the mass of my floor. After all that, I'd like to think its safe to call that floor massive and rigid.
The final step would be going back into the crawlspace and filling the 2' air space between the bottom of the joists and the concrete slab with insulation to dampen whats left of the "drum" effect. I've heard of people in similar situations that just bought rolls of R-13 or higher insulation, cut the sides off of the wrap to expose the insulation, and fill the entire crawlspace with the still intact rolls instead of actually opening the rolls and laying it out in sheets. The major issue is the drum issue caused by the air space but we all know what happens when you stuff a blanket in a kick drum. it doesn't terminate the sound, of course, but greatly decreases its ability to resonate.
I know the theory I described above won't totally solve the problem like dropping the whole thing down to the slab, but I like to think it would get the problem down to a not-so-awful, tolerable level.

Could you please give me your opinion on this theory?
If you think it's a totally bunk idea, what would you do to fix things the best you could if you had no other choice but to proceed without removing the floor joisting system?

Again, I really appreciate you beating me over the head with a bag of bricks and helping me come to a decision.

" Thank you Sir, may I have another!!!" :horse:


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PostPosted: Tue Oct 08, 2013 11:33 am 
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To add to my previous post...
What about adding drywall to the underside of the 2x10s making the floor be from bottom to top-
Concrete / 2' crawl / drywall-sealed / 2x10 cavities filled with bats / floor ply / 1/4-1/2" concrete / tile-mortar-grout / CR ?
Would this have a positive, negative, or no effect on the situation?

Also, in the above post when I was describing filling the 2' crawl cavity with insulation, I was trying to think of ways to eliminate or minimize the cavity below instead of occupying it.
Stupid thought?

Thanks

Jc


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PostPosted: Wed Oct 09, 2013 4:25 pm 
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I think I'm gonna be haunted by the ghost of a mangled zombie horse for the next few days! :)

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before this subject has been thoroughly beaten and shot. In the head. With a silver bullet.
Can we also do a wooden stake to the heart? Just in case?

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Most obvious solutions - 1) demo the floors and setup on the concrete,
Yup! Which would also allow you to rotate the CR orientation for better sigh lines and acoustics, and also to fix your coupled framing problems.... Just sayin'...

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2) make the existing deck much more massive and build a new floated system inside.
Also possible, but does NOT allow you to rotate the CR orientation for better sigh lines and acoustics, or to fix your coupled framing problems.... You'd still be stuck with those issues.

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Lets say there was a basement below or this CR was on the 2nd floor of a structure where the area below wasn't occupied so it could be modified or disturbed, but not deleted.
If that were the case, then the recommendation would be to NOT build the CR in that location, but rather to find a slab on grade some place to do it. People do occasionally come to the forum with problems like that, and discover that building a CR on a wood-framed floor is a problem. Either they have to invest in beefing up the floor structure greatly, or they have to accept that they won't be getting much isolation.

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If that were the case how would you handle it if you were stuck with it and had no other option?
Depends on how big the budget is! If money is no problem, then I'd go ahead and beef up the structure sufficiently to float the floor correctly.

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First, I would go into the crawlspace underneath and reinforce the floors with 4x4" beams on jacks ...
Then fill all the cavities in between the 2x10's with thick insulation bats ...
I would pour a 1/4"-1/2" of self leveling concrete on top of the existing 3/4" decking ...
I would finish the floor with a porcelain or stone tile. ...
The final step would be going back into the crawlspace and filling the 2' air space between the bottom of the joists and the concrete slab with insulation to dampen whats left of the "drum" effect....


This might seem like an insulting comment, but it's intended to be constructive criticism: That sounds really complex and expensive. How exactly would that be easier, faster, or cheaper then taking out a few dozen bits of wood and putting the back in again differently?

I mean, what you propose might work, but there's the issue o cost, complexity, and the rather important "YBYOGP" factor. YBYOGO stands for "You'd Be Your Own Guinea Pig". Since the structure you mention is not described in any of the literature that I'm aware of, you'd become your very own test lab, doing tests that nobody else ever did before....

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I know the theory I described above won't totally solve the problem like dropping the whole thing down to the slab,
Or re-orienting the CR, or fixing the framing issues.... :)

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If you think it's a totally bunk idea, what would you do to fix things the best you could if you had no other choice but to proceed without removing the floor joisting system?
OK, I'll answer that question with another question: Why can you not proceed with removing the floor joist system? What dreadful thing will happen if you do that?

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Again, I really appreciate you beating me over the head with a bag of bricks and helping me come to a decision.
Can I add some chunks of broken concrete, some lead shot, and a few steel balls, into the bag? :)


OK, bottom line: Your plan is feasible and just might work, but you won't know for sure until you are finished. If it doesn't work, then you are very much "up the creek without a paddle". Is it worth running the risk of finding out that it doesn't work, after spending all that time and money?

Tough decision to make!

- Stuart -

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PostPosted: Thu Oct 10, 2013 10:43 am 
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Thanks again for a speedy reply. You're awesome!

Ok. Horse has been beaten, killed, buried, dug back up, shot with silver bullets, wood stake thru the heart, crucified, burned at the stake, and buried again. Done. DONE! :twisted:

You're gonna hate me and think I'm an idiot. I know I didn't describe the construction enough for you to understand why removing the floors is a bit bigger deal than you may think it is, in this particular case. I could go into why and everything that would involved in fixing it. After weighing it out, I've decided that I have to move forward with the existing floors and the theory that I have.
Damn! I heard you say "Aww man, what the f@&$?!" All the way over here in the states! :oops:
It's just what I have to do to meet my budget and deadline. I absolutely accept all blame and responsibility for what might happen by doing so and you are absolutely allowed to call me "dumbshit"
from here on out if it makes it easier to respond to me. All of the advice you've given me has been invaluable and 1050% respected and appreciated. I can't thank you enough for that and I hope you don't take it personally that I'm going against one of your rules of thumb. But when you've already given yourself lemons, you gotta make lemonade!
I know of several studios here in Atlanta that have great studios with similar flooring scenarios that are making killer recordings and don't have crazy isolation issues. I've been making great tracks in my current studio and my isolation is horrible! I know I majorly screwed up, but this build will still be light years ahead of my current setup. Luckily, the live half of the building is still a blank canvas, and none of the inner framework of the CR is up yet so maybe measures can be taken there to compensate for the short-comings of the control side. (I hear you still sighing)
Keep in mind that I'm not a pro like you are and this is my first time building a studio. I've been kicking myself since day 1 for not doing more research before breaking ground, but now I bask in my ignorance and have to deal with the hand I dealt myself. I hope you're still willing to lend your ninja knowledge through the rest of my build.
I'm preparing my next post and refining drawings to address the next phase, walls.
Any guidance you'd be willing to give would be great.
Thanks again for everything and trying to tolerate my stupidity.

-Dumbshit


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