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PostPosted: Fri Jun 16, 2017 5:23 pm 
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Location: Erfurt, Germany
Hey guys,

My name is Phil and I live in Erfurt, Middle Germany. So far I was, like most thread starters here, a silent viewer and follower in this forum over years, but finally I am going to build a middle sized recording studio by myself and may need some advice (or let’s say acknowledgement?) concerning some topics.

We’re going to record and mix pop, rock and metal music in the studio. I am also producing music and sounds for advertisements and films once in a while. The control room should also suit for mastering. The live room should also function as rehearsal room up to a certain point. I prefer one bigger room for everything than multiple small rooms for vocals, drums, etc. due to our given space and also regarding building costs.
The outer construction, water and electrics are going to be made by professional craftsmen. The inner rooms and the acoustic treatment inside these rooms, I want to build on my own.


Situation
After a very long search, me and my business partner just found and acquired a real estate with a ~10x10m solid concrete foundation slab. So the outer dimensions are already fixed.

Attachment:
1_concrete_foundation_slab.png

Next step is now planning and constructing the outer walls and roof (outer leaf) by an architect and a craftsman. The outer construction as well as the inner construction will be built with lumber. According to our structural engineer a roof spanning over a 10x10m slab has to be supported with a pillarin the middle of the building. A service entrance room (german: HAR), a toilette (WC) and also place for a small kitchenette are mandatory requirements. The position of the service entrance room and the toilette is more or less fixed due to the position of cables and connections in the foundation slab.

Attachment:
2_HAR+WC.png



Location
The area around the real estate is commercially used. Mostly offices and some trucks passing by once in a while. But also chances are high that there are going to be new buildings getting constructed next door, so we may even have to deal with construction noise. Despite this, the area is mostly pretty quiet. :lol: The building is going to be free-standing and is potentially accessible from all directions.


Layout
After some layouts I made and had to redo, I came up with this current one:

Attachment:
3_full_room_layout.png

The control room and the live room have windows facing each other. Also the live room has two windows to get some sun light into the room. The control room is fully symmetrical and has no windows, but two doors. The small room to the left of the control room may be used for cables and small stuff, maybe also as place for fresh air in/outlet silencers (or maybe even as cool chamber for AC). You could even place another door to the ouside here to have a second entrance.

Do you think there is a better way to layout the rooms to utilize the space more efficiently? I tried a corner control room layout, but it always gets in the way of the HAR/WC/entrance. Also the pillar (which can be moved from the center up to a certain point to fit into the room layout) seems to limit my possibilities.

The control room has partially splayed walls (20°). Due to being 561.6cm and 460.8cm the perfect matching height is 360cm according to Golden Ratio #2 (1; 1.28; 1.56). Adding a second ceiling and floor I assumed that 4m plus a little buffer/workspace in total were okay, so we are planning the outer construction with 4.1m height inside. Due to the room having partially splayed walls, room modes aren’t thaaat relevant for these wall pairs anyway, right? Still we have a fair amount of surfaces of parallel walls in the control room: 6.6qm in the width (5.616m resp. 61Hz) and 12.6qm in the length (4.608m resp. 74Hz).

Attachment:
4_control_room_RFZ.png

The circle in the middle should represent a head. Listening position is at about 39% of the rooms length. The reflection free zone is marked green, assuming the back end being absorptive and diffusive (no treatment in the sketch yet). The ceiling in the control room is going to be sloped by about 25° to transport early reflections to the back of the room in order to increase the reflection free zone also in vertical dimension (more details on this in a 3D model later). Also I want to hang a cloud above the mixing position.

In the current layout the live room does still have parallel walls. I’ve found, that you need at least a 12° angle in your walls (source: Soundman2020) to efficiently eliminate parallel wall effects like standing waves or flutter echo. But this would really take up a lot of space. I'd go for the maximum dimensions (like currently shown in the image) and deal with these problems with treatments later on. Is this a bad idea?
Anyway, I could not find a fitting room dimension ratio for the LR (Golden, Louden, Dolby Lab, etc.) for all three dimensions without losing a lot of space. The matching room height could be 3.15m (Golden Ratio #1: 1/1.14 of 3,59m width) or 3.39m (Golden Ratio #2: 1/1.39 of 9.39m/2 length) according to Golden Ratios when you leave out the third dimension. The latter would utilize the given space better. But this probably being inadequate, and drastically reducing one dimension just to fit into a given ratio being a waste of space, I’d just go for the maximum height of 3.6m again, like in the control room, to utilize the room to its maximum.

But therefore having 35qm of parallel surfaces (ceiling-floor, corresponding mode: 95Hz at given 3.6m height) the live room would really benefit from sloping its ceiling, wouldn’t it? Does that make sense to do or is there a better idea? A continuous 12° angle over the whole width would mean a ceiling height between 3.60m at its highest and 2.70m at its lowest point.


Construction
Is there anything that we need to keep in mind or look out for while planning and constructing the outer leaf concerning the acoustic sealing? Due to getting this part build by craftsmen, I would like to have this leaf rather simple (costs) compared to the inside rooms (which I am going to build on my own and therefore can pay more attention to details).

The room-in-room construction is going to follow John’s concepts. The floor is going to be floating. The walls are build on top of the new floor and are going be based on John’s inside out design. The ceiling rests on top of the walls. More details on this later. I’m going to make a way more detailed plan and model (3D, wall design, sloped ceiling, reflection paths) right after I am sure that there is no better way to layout the rooms.

Also I want to soffit-mount my speakers. I have Adam A8X (shown in the control room image above, in horizontal position). I want to have an exchangeable box with tight fit around them to upgrade the speakers at any time in the future.


HVAC
For fresh air supply I want to install a ‘classical’ inlet and a outlet in the CR and LR with silencer boxes (size not calculated yet) as most of you do in this forum.
For AC I want to buy a multi split with simple wall-mounted indoor units in the CR, LR and also one for the toilette (protection against freezing in the winter). I found a well-priced indoor unit by Panasonic (CS-Z7SKEW-M) which claims to be just 19dB(A) (in low mode).
Do you think a multi split is acoustically critical, because it’s connected to the same outdoor unit? Are three single mini splits better? Is this reasonable compared to the costs?

BTW: I saw some indoor units (Low Static Pressure Hide Away) which can be placed inside a false ceiling and could be integrated into a ducted air system. They aren’t cheap and even slightly louder, but I’m just curious: Did somebody here combine these units with fresh air in/outlets + silencer boxes or is this generally a bad idea?


Budget
25.000€ (without outer framing/water supply/electrics)
(But flexible up to some point, when it’s really necessary and reasonable, so don’t take that number too seriously, please)


Questions
Here I want to collect all questions for the sake of convenience (of course feel free to cite and comment anything in the text):
  • Do you think there is a better way to layout the rooms in order to utilize the space more efficiently?
  • I'd go for the maximum dimensions in the LR and deal with these problems with treatments later on. Is this a bad idea?
  • (...) The live room would really benefit from sloping its ceiling, wouldn’t it? Does that make sense to do or is there a better idea?
  • Do you think a multi split is acoustically critical, because it’s connected to the same outdoor unit? Are three single mini splits better? Is this reasonable compared to the costs?
  • BTW: Did somebody here combine these units (Low Static Pressure Hide Away) with fresh air in/outlets + silencer boxes or is this generally a bad idea?


Thank you very much in advance, and also thank you so much for even reading up to this point! :D I hope some of you guys could give me some feedback, advice or tips for improvements on this early stage plan. I would really appreciate your help!

Phil


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PostPosted: Sat Jun 17, 2017 2:53 am 
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Location: Santiago, Chile
Hi Phil, and Welcome! :)

Quote:
me and my business partner just found and acquired a real estate with a ~10x10m solid concrete foundation slab.
Just checking here: All that you have right now is the slab, with no walls, roof, or anything else, correct?

Quote:
Next step is now planning and constructing the outer walls and roof (outer leaf) by an architect and a craftsman.
Mistake! You should never allow an architect to do the primary design for any part of a studio, especially parts that are so critical for isolation (outer leaf), unless that architect has extensive experience in studio design. Most don't. Rather, you should design it yourself, or get it designed by an experienced designer, then just checked by the local architect for compliance with local building codes, regulations and by-laws. The architect can draw up the plans and file the paperwork with your local authorities, but should not be given the task of doing things that he has not bee trained to do, such as designing one half of the isolation system for your building.

Quote:
The outer construction as well as the inner construction will be built with lumber.
Lumber plus what? Lumber is just the framing: You also need sheathing and possibly separate cladding of some type on the outer-leaf. Defining that is far more important than defining the framing.

Quote:
According to our structural engineer a roof spanning over a 10x10m slab has to be supported with a pillar in the middle of the building
I don't see why! It is possible to design trusses that span much larger dimensions than that. So there must be an underlying reason why you do not want to do that. Cost? Complexity?

Quote:
The area around the real estate is commercially used.
How quiet do you have to be, legally, in decibels?

Quote:
After some layouts I made and had to redo, I came up with this current one:
Your isolation wall is incomplete. There's a missing section between the show room and the kitchenette area, and between the live room and that same kitchenette area.

Quote:
The control room and the live room have windows facing each other. Also the live room has two windows to get some sun light into the room.
:thu:

Quote:
The small room to the left of the control room may be used for cables and small stuff,
In that case, you are also missing an isolation wall there. Also, the door is unable to open much like that. Perhaps not even legal?

Quote:
I tried a corner control room layout, but it always gets in the way of the HAR/WC/entrance
Then put it in a different corner! :)

Quote:
The control room has partially splayed walls (20°).
... which use up a lot of space, and reduce the total volume of the room! You don't really need to have them splayed so far back into the room. As long as they are splayed about as far back as the mix position, you should be OK.

Did you ray-trace to ensure that the angle is correct?

Quote:
Due to being 561.6cm and 460.8cm the perfect matching height is 360cm according to Golden Ratio #2 (1; 1.28; 1.56).
Which "golden ratio #2" are you referring to? There are dozens of good ratios...

Besides, your room is not rectangular, and not even close to rectangular, plus it also has nine sides, not six, and calcualtors only work for six sides.... so simple ratios are not applicable, and you can't use a room mode calculator to predict anything.

Quote:
Adding a second ceiling and floor
Why would you want a second floor? :ahh:

Quote:
Due to the room having partially splayed walls, room modes aren’t thaaat relevant for these wall pairs anyway, right?
Wrong. Room modes are ALWAYS relevant, and the fewer you have in the low end, the worse it is. Modal support is what defines the overall acoustic response of the room. Splaying walls does not "get rid of" modes: it merely moves them to a different frequency, possible smears them (lower Q), and makes it harder to predict the outcome.

Quote:
width (5.616m resp. 61Hz) and 12.6qm in the length (4.608m
Why is the room wider than it is long? :shock: In general, the speakers should face down the LONG axis of the room, so that the back wall can be far behind your head. Unless the room is very large, it is better to orient it that way.

Quote:
The circle in the middle should represent a head. Listening position is at about 39% of the rooms length.
OK, but the speaker angle and/or and aim point is wrong. You show the speaker axes intersecting at the back of your head, but that point should be well behind your head, perhaps 30cm to 50 cm back in that room.

Quote:
The reflection free zone is marked green,
I'm not sure how you arrived at the green area, but that isn't where the RFZ is! I can see numerous reflections that will arrive into most of that area. You need to properly ray-trace your model, in 3D, to determine where the RFZ is, but I can guarantee you that the green area is not it!

Quote:
assuming the back end being absorptive and diffusive
Absorptive yes, absolutely, but certainly not diffusive in that room. It is too small to be able to use diffusers on the rear wall, since the room is not long enough for that, and I don't see many places on the side walls either. I doubt that you'll be able to use most types of diffuser in there.

Quote:
The ceiling in the control room is going to be sloped by about 25°...
Careful! That implies compound angles for every single piece of wood in your splayed side walls and front ceiling section! It's REALLY hard to get that right, and your framing carpenters will be spending a lot of time carefully cutting and planing all sides of the framing members, to make them fit. The theory is OK, but the practical implementation is way harder than you think. Also, 25° is a very large angle, which would make the front end of the ceiling very low, and it wastes a lot of room volume.

Quote:
to transport early reflections to the back of the room
It would be far simpler to have a flat ceiling, then hang a hard-backed angled cloud from it. Same overall effect, but allows the room to have much more air volume.

Quote:
Also I want to hang a cloud above the mixing position.
:shock: You want a very steeply angled front ceiling, AND ALSO a cloud? WHY??? What do you plan to attach the cloud to? What angle would you have the cloud at? It would have to be VERY steep....

Quote:
In the current layout the live room does still have parallel walls.
:thu: Fine. Nothing wrong with that.

Quote:
I’ve found, that you need at least a 12° angle in your walls (source: Soundman2020) to efficiently eliminate parallel wall effects like standing waves or flutter echo.
Perhaps you misunderstood something I said: Yes, a 12° angle will reduce flutter echo, but it won't eliminate standing waves! Modes are a fact of life, due only to the distances between the walls. If you change the wall angles, you change the frequency at which the mode will appear, and that's all! If you splay it enough, you might broaden the Q of the mode, or perhaps even change it from an axial mode to one or mare tangential / oblique modes, but you cannot destroy a mode. In fact, you should not even try! You NEED modes. You need LOTS of them. The problem with a small room is NOT that it has too many modes: exactly the opposite. The problem is that it does not have enough!

Quote:
I'd go for the maximum dimensions (like currently shown in the image) and deal with these problems with treatments later on. Is this a bad idea?
No: it's exactly the correct idea!

Quote:
Anyway, I could not find a fitting room dimension ratio for the LR (Golden, Louden, Dolby Lab, etc.)
... good, because you don't really need one! It's a live room, not a control room, and it is much larger, so that's fine.

Quote:
according to Golden Ratios
There is no such thing as one single "golden ratio" in acoustics. Despite what you might have read on a certain website that promotes fictitious geometrical figures with zero independent and reputable experimental backing... There are simply a large set of good ratios, most of which fall within the Bolt area. As long as you are reasonably close to one of those, you are fine.

Quote:
according to Golden Ratios when you leave out the third dimension.
:?: :shock: If you leave out one of the dimensions, then you certainly don't have a room ratio! Rooms have three dimensions, so you MUST consider that in all of your modal calculations.

Quote:
the live room would really benefit from sloping its ceiling, wouldn’t it?
Nope! That would greatly reduce the volume of the room once again. Rather, it would be much better to just hang suitable treatment from the ceiling.

Quote:
A continuous 12° angle over the whole width would mean a ceiling height between 3.60m at its highest and 2.70m at its lowest point.
--- which would be a very bad thing, as you'd be wasting many, any cubic meters of room volume.

Quote:
Is there anything that we need to keep in mind or look out for while planning and constructing the outer leaf concerning the acoustic sealing? Due to getting this part build by craftsmen, I would like to have this leaf rather simple
Your building shell is one half of the acoustic isolation system. It MUST be designed together with the other half, as they work together as a SYSTEM. Imagine a jet plane where the wings are designed by someone who has no aeronautical experience, and the fuselage is designed by someone else, yet these two people never communicate with each other, and have no idea what the other one is doing...

So your entire building should be designed with acoustics and isolation in mind, THEN handed over to the architect so he can check for code compliance, and draw up the plans to present to the authorities.

The outer leaf can indeed be built by a contractor, as long as he understands the major differences as compared to building a normal house, office, shop, church, school, etc. But the design of the entire building must be done by one single person who understands the acoustic importance of each part, and the interrelationships between them.
Quote:
The floor is going to be floating.
:shock: :ahh: :?: :?: Why????? Your slab is on the ground, there's nothing you mentioned that might cause severe vibration in that slab, the building is free standing, and yo don't seem to need extreme levels of isolation.... so why on earth would you want to flat your floor?

You REALLY need to read this: viewtopic.php?f=2&t=8173
Quote:
going be based on John’s inside out design.
:thu:

Quote:
The ceiling rests on top of the walls.
CelingS Plural. You will have several ceilings, one in each room. The ceiling for each individual room rests on the inner-leaf walls f that room.


Quote:
Also I want to soffit-mount my speakers.
:thu: Very smart!

Quote:
I have Adam A8X
Nice!

Quote:
shown in the control room image above, in horizontal position
Ummm... WHY???? Why would you ever want to mount those speakers with the tweeter NOT above the woofer? Are you not aware of how that will totally trash your sweet spot? Here's the issue:

Attachment:
Speakers-mounted-vertically-and-horizontally-standing-up-laying-down-on-side.jpg


So set up your speakers vertically, the way they were designed to be used. If not, even a small movement of your head will change what you hear.

Quote:
I want to have an exchangeable box with tight fit around them to upgrade the speakers at any time in the future.
:thu: It can be done. I have a designed a few such speaker mounting systems for paying customers. You will need to work things out carefully, and think it through in detail, to ensure that it will actually work in the real world.

Quote:
HVAC
For fresh air supply I want to install a ‘classical’ inlet and a outlet in the CR and LR with silencer boxes (size not calculated yet) as most of you do in this forum.
For AC I want to buy a multi split with simple wall-mounted indoor units in the CR, LR
:thu:

Quote:
I found a well-priced indoor unit by Panasonic (CS-Z7SKEW-M) which claims to be just 19dB(A) (in low mode).
Ummm... yuo first need to do all the calculations for EACH INDIVIDUAL ROOM, to find out what heating, cooling, and airflow capacity you will need for that specific room. Only then can you look for units that can supply that, and THEN compare the sound levels... Starting with sound levels when choosing the HAVC, is like starting with the color of the floor mats when choosing a car: not very relevant.

Quote:
Do you think a multi split is acoustically critical, because it’s connected to the same outdoor unit?
No. Not a problem.

Quote:
Are three single mini splits better? Is this reasonable compared to the costs?
Since you need four units (CR, LR, lobby, bathroom), it would probably be much better to look into getting a single ducted AHU that can handle all of that from just one unit, then do the ductwork and dampers accordingly. Since you already have a utility room, you could put the AHU in there, and have totally silent HVAC operation in your actual studio rooms.

Quote:
BTW: I saw some indoor units (Low Static Pressure Hide Away) which can be placed inside a false ceiling and could be integrated into a ducted air system. They aren’t cheap and even slightly louder, but I’m just curious: Did somebody here combine these units with fresh air in/outlets + silencer boxes
That's what I do pretty much all the time, with studios I design, but using a DUCTED unit, and NOT with a low static model. There's considerable static pressure in a typical studio duct system, so you would need a high static unit, and since that unit will be recirculating air through a proper duct system, it must be a ducted unit, not a ceiling cassette unit.

Quote:
25.000€ (without outer framing/water supply/electrics)
Probably a bit tight. You might want to consider adjusting that.

Quote:
Do you think there is a better way to layout the rooms in order to utilize the space more efficiently?
Possibly, yes. For example, Right now, you have very poor sight lines between the CR and LR: most of the LR is invisible from the mix position.

Quote:
I'd go for the maximum dimensions in the LR and deal with these problems with treatments later on. Is this a bad idea?
:thu:

Quote:
(...) The live room would really benefit from sloping its ceiling, wouldn’t it?
No. Take a look at this thread, from yesterday: viewtopic.php?f=1&t=21110

Quote:
Do you think a multi split is acoustically critical, because it’s connected to the same outdoor unit? Are three single mini splits better? Is this reasonable compared to the costs?
I would go with a single ducted mini-split AHU system, with the AHU located either in the utility room or above the ceiling in the lobby. That would be able to serve all five rooms (the above four, plus the utility room). The cost of one such system should be much less that than the cost of four mini-split units.

Quote:
BTW: Did somebody here combine these units (Low Static Pressure Hide Away) with fresh air in/outlets + silencer boxes
Yes, but high-static, not low static, and a proper ducted AHU unit.

- Stuart -


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PostPosted: Thu Jul 13, 2017 5:53 am 
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Location: Erfurt, Germany
Soundman2020 wrote:
Hi Phil, and Welcome! :)

Hi Stuard. :)
You have an amazing response time! Thank you a lot for going through my post and revealing some major issues with my plan! This really does help a lot.

Quote:
All that you have right now is the slab, with no walls, roof, or anything else, correct?

Correct.

Quote:
You should never allow an architect to do the primary design for any part of a studio, especially parts that are so critical for isolation (outer leaf), unless that architect has extensive experience in studio design. Most don't. Rather, you should design it yourself, or get it designed by an experienced designer, then just checked by the local architect for compliance with local building codes, regulations and by-laws. The architect can draw up the plans and file the paperwork with your local authorities, but should not be given the task of doing things that he has not bee trained to do, such as designing one half of the isolation system for your building.

I may explained that wrong. He is exactly for what you described: Drawing up the plans, filing the paperwork and advising concerning building codes.

Quote:
Lumber plus what? Lumber is just the framing: You also need sheathing and possibly separate cladding of some type on the outer-leaf. Defining that is far more important than defining the framing.

Correct. But at the point in time I wrote the post there was no determined material yet other than the frame being build with lumber. ;) But there are news on this topic: More on this see wall design chapter later.

Quote:
It is possible to design trusses that span much larger dimensions than that. So there must be an underlying reason why you do not want to do that. Cost? Complexity?

I missed to point that out. My partner insists on having a flat roof (solar panels, outer appearence, possible second floor extensibility, etc.). So yes, I guess this, combined with lumber as framing material lead to the need of a support pillar due to statics.

Quote:
How quiet do you have to be, legally, in decibels?

The local guidelines for this particular area are:
daytime (6:00 - 22:00): 65 dB(A)
nighttime (22:00 - 6:00): 50 dB(A)

Quote:
Your isolation wall is incomplete. There's a missing section between the show room and the kitchenette area, and between the live room and that same kitchenette area.

Quote:
In that case, you are also missing an isolation wall there. Also, the door is unable to open much like that. Perhaps not even legal?

I corrected that. Also I left out the small room in the new layout, because it was getting too small to use it reasonable.

Quote:
Quote:
The control room has partially splayed walls
... which use up a lot of space, and reduce the total volume of the room! You don't really need to have them splayed so far back into the room. As long as they are splayed about as far back as the mix position, you should be OK.

This will be considered in the next layout.

Quote:
Quote:
Due to being 561.6cm and 460.8cm the perfect matching height is 360cm according to Golden Ratio #2 (1; 1.28; 1.56).
Which "golden ratio #2" are you referring to? There are dozens of good ratios...

Actually the 1, 1.28, 1.56 Golden Ratio, as I said, or what do you mean? But … nevermind. Due to not being rectangular, this doesn’t even apply.

Quote:
Besides, your room is not rectangular, and not even close to rectangular, plus it also has nine sides, not six, and calcualtors only work for six sides.... so simple ratios are not applicable, and you can't use a room mode calculator to predict anything.

Exactly. But I needed a height to start with. And why not choose one that is far away of being a multiple of the other parallel wall distances in the room instead of a random number. I was not saying I chose this to handle modes.

Quote:
Room modes are ALWAYS relevant, and the fewer you have in the low end, the worse it is. Modal support is what defines the overall acoustic response of the room. Splaying walls does not "get rid of" modes: it merely moves them to a different frequency, possible smears them (lower Q), and makes it harder to predict the outcome.

You are absolutely right. And again: An imprecise formulation for my part.

Quote:
Why is the room wider than it is long? :shock: In general, the speakers should face down the LONG axis of the room, so that the back wall can be far behind your head. Unless the room is very large, it is better to orient it that way.

This seems to make sense, yes. I saw a lot of small control room layouts by John and others, which were orientated this way, so I adapted that. I’m gonna try a long layout in the next layout. Maybe it even fits better.

Quote:
I'm not sure how you arrived at the green area, but that isn't where the RFZ is! I can see numerous reflections that will arrive into most of that area. You need to properly ray-trace your model, in 3D, to determine where the RFZ is, but I can guarantee you that the green area is not it!

Oh. Yes, you are right. The displayed RFZ is wrong. I just wanted to get a rough impression and drew it quickly, but I have to redo a correct and precise version of this. And this is just in 2D for now to determine the 2D wall layout. Dealing with a full 3D version follows later on. More on this topic, see below.

Quote:
It would be far simpler to have a flat ceiling, then hang a hard-backed angled cloud from it. Same overall effect, but allows the room to have much more air volume.

Sounds reasonable. Good advice, I’ll do that. Thank you!

Quote:
Quote:
The floor is going to be floating.

Your slab is on the ground, there's nothing you mentioned that might cause severe vibration in that slab, the building is free standing, and yo don't seem to need extreme levels of isolation.... so why on earth would you want to flat your floor?

If you believe it or not, but I was so convinced having my floor floating, that I assumed this is a must for any proper sound isolation plan. But well, it isn’t. And that’s good. It saves a lot of complex calculations, money and time. Thanks a lot for pointing this out! But after reading a lot of threads regarding not to float your floor I see I wasn’t the first one with this wrong assumption. :D
So I have to have a rigid firm connection between the walls and the concrete slab, and there is no need to decouple or float the walls in any form, right?

Quote:
Why would you ever want to mount those speakers with the tweeter NOT above the woofer? Are you not aware of how that will totally trash your sweet spot?

Well, ADAM even suggests the possible horizontal positioning in the instructions manual, so I assumed this would be ok. But you’re right. I tested it A/B. Never thought that would be such a difference… :D I feel a little ashamed, I must admit. I tested it, when I bought them some years ago. But I guess my hearing got way better since them, so I can now tell that you are absolutely right. Thanks again, Stuard!

(just slightly off topic: There are many horizontal mid field speaker designs out there like the Adam A77X or Dynaudio LYD-48. Is this rather relating 2-way systems than 3-way systems, because 3-way-systems have a phantom sound source placed in the middle, due to its 2 woofers? Aren't the sound waves still overlapping unevenly like shown in your attached picture?)

Quote:
yuo first need to do all the calculations for EACH INDIVIDUAL ROOM, to find out what heating, cooling, and airflow capacity you will need for that specific room. Only then can you look for units that can supply that, and THEN compare the sound levels... Starting with sound levels when choosing the HAVC, is like starting with the color of the floor mats when choosing a car: not very relevant.

Well, somehow, yes. But the reason I was researching this was that all the devices recommended in this forum are actually rarely available in my region, because having an AC is pretty uncommon in Germany, you know. So I was looking for possible suitable products regarding availability, costs and sound level first. Actually deciding for a system is not possible at this point, because I am still designing the room layouts. So I don’t know the actual room volumes yet. But having a quick thought about AC in early planning stage, even when you haven’t determine your room dimensions, can not be thaaat bad, can it? ;)

Quote:
Since you need four units (CR, LR, lobby, bathroom), it would probably be much better to look into getting a single ducted AHU that can handle all of that from just one unit, then do the ductwork and dampers accordingly. Since you already have a utility room, you could put the AHU in there, and have totally silent HVAC operation in your actual studio rooms.

Quote:
I would go with a single ducted mini-split AHU system, with the AHU located either in the utility room or above the ceiling in the lobby. That would be able to serve all five rooms (the above four, plus the utility room). The cost of one such system should be much less that than the cost of four mini-split units.

Again: Thank you for this advice! I am going to research this topic.

Quote:
Right now, you have very poor sight lines between the CR and LR: most of the LR is invisible from the mix position.

Yes this is a good point. I consider this in the next layout.




Layout Version 2
The CR is now rotated 90° and has shorter splayed walls (just up to the listening position).
The speakers are facing down the long axis of the room and are rotated correctly.
The ceiling is build straight (+ hanging a hard-backed cloud later).
Due to the 90° rotation of the CR the door to the lobby is now located at the front between the speakers.
The right side has now a large glass sliding door to provide better sight into the live room.
A missing wall section between CR/LR and lobby was added.
Also the layout now has exact values for framing and walls.

Attachment:
full_room_layout_2.png


Attachment:
wall construction layers3.png


Wall design concept

Outer walls
Layers from outside to inside:
  • 2 mm textured plaster (3.2 kg/m²)
  • 120 mm styrofoam (thermal insulation, 30 kg/m³, 0.17 kg/m³)
  • 12.5 mm gypsum fibreboard* (15 kg/m²) **
  • 12.5 mm gypsum fibreboard* (15 kg/m²) **
  • 160 mm wooden frame with 160 mm fiber glass insulation (5 kPa*s/m², but looking for a better one at about 15kPa*s/m²)
  • Vapor barrier
307 mm total

*note: gypsum fibreboard, not drywall/plasterboard. It’s stiffer and has a much higher density. It is also recommended for outer application
**note: maybe be replaced with wood fibreboard with equivalent weight

Inner walls
Layers from outside to inside:
• 18 mm plasterboard (15.2 kg/m²) ***
• 18 mm plasterboard (15.2 kg/m²)

[i]***note: may be switching to OSB with equivalent weight here

Wooden framings of the outer wall and inner wall are 12 cm away from each other.
This leads to an air gap of 28 cm between these both leaves.




MSM system calculation
Based on this.
m1 (outside wall): 15+15+0.17+3.2 = 33,4
m2 (inside wall): 15.2+15.2 = 30,4
d (depth of cavity): 0.28m

[i](I hope I am right when I assume that the cavity is everything that is between the two leaves (fiberboard on the outer leaf and plasterboard on the inner leaf) including the wooden studs/framing.)

So f0 is ~20.4 Hz. The wall system starts isolating at ~40.7 Hz.
This is slightly below the low E of a bass guitar, which is pretty good so far I think.
Assuming having a 110dB rock band playing inside, this would meet the local decibel guideline of 50dB at night (assuming the bass player does not use a 5-String bass guitar… :D )

RFZ
Here is an updated version of the “2D-RFZ”. Please note that this is just the sectional view for the height of the speakers. This is not the full RFZ for the room in 3D. I know this is not sufficient. This is just to see how the splayed walls work together with the listening position, room length and speaker placement. A 3D version follows.

First, here is the pure ray tracing for one speaker. The back wall of the room is assumed to be treaten absorptive, so sound (rays) doesn’t continue to travel when it hits this surface.

Attachment:
raytracing_2D_leftspeaker.png

Here is the ray tracing for both speakers. This leads to a “2D-RFZ” as shown:

Attachment:
raytracing_2D_bothspeakers.png

To increase the RFZ by adding another 0.6 m absorptive section at the sides, it could look like this:

Attachment:
raytracing_2D_treated_sides.png

Next step is now to do a full 3D model of this. Unless there aren’t any issues in the 2D model of this anymore… (I think it's not very smart to make a whole 3D model when the 2D version still has remaining issues)

But nevertheless I have one issue/question:
The distance between inner and outer leaf is not equal to all sides. There are four sections that caught my attention regarding the MSM resonant frequency. I marked them with colors in the next picture:

Attachment:
problems2.png

Section red, yellow:
The distances between inner and outer mass is different (greater) here. Does this ruin my isolation plan from above? Increasing the distance isn't a problem, because f_0 increases, and so does the isolation, right? Is there anything I have to look out for?

Section blue:
Because CR and LR both have the inside-out-design their walls are facing each other here. To keep up my isolation plan, I should keep the 28 cm gap here, too, but that would mean a great loss of space. Currently the distance is 12cm. This would increase the wall system’s resonant frequency to 31.8 Hz, so it starts isolating at 63.7 Hz. That’s 23 Hz higher than the isolation plan from above…
Should I really increase the gap up to 28 cm or are there any other thoughts on that?

Ceiling
The air gap there is at least 43cm. Probably a little more. Which is not problematic, but good, I guess.

And yes, I am fully aware of putting as much insulation material in the air cavities without overcompressing it. :)

Phil


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Last edited by SchwertPhil on Sat Jul 29, 2017 12:26 am, edited 4 times in total.

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PostPosted: Sat Jul 22, 2017 5:36 am 
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Hey, I have some news.

Our structural engineer said we are going to need an additional new layer of concrete on top of our foundation slab because the pillar in the middle is going to produce a force onto the slab, which can not be handled by the slab the way it is build right now. Well… ok. But after we said that leaving out the inner sheathing of the outer walls would be essential (to ensure we have a true 2-leaf-system in combination with our inner walls and not a 3-leaf-system) he said he does not want to continue working on our project anymore. He said our project would become way too complex and so he left. :roll:

Meanwhile we looked out for a new one and found one, who is finally open enough for such an unusual project like ours. He said building the outer walls, like we have planned, is no problem at all. And having an additional layer on top of our slab is probably also not necessary, but he first has to calculate everything. He will be finished in about a week he said.
Also he suggested to check with our architect if we can leave out the thermal insulation (styrofoam) on the outside. This might not be based on a local building code (like I assumed) and may be an optional thing. Due to our room-in-room-system keeping the heat will most likely not be issue, this might not be necessary for us. Except for the other rooms (WC, HAR, Lobby) maybe. News on this coming soon.

And because this post/news does not add anything essential new to this thread, I want to enhance it by giving you an impression on our location by attaching two pictures of the slab. And don't get confused: The houses around are no real homes people are living in. These are just show houses, since our slab is located inside a show house park with different companies showcasing their houses.

Phil

Attachment:
IMG_20170718_201250.jpg


Attachment:
IMG_20170718_123910.jpg


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PostPosted: Sun Jul 23, 2017 12:36 am 
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Quote:
But after we said that leaving out the inner sheathing of the outer walls would be essential (to ensure we have a true 2-leaf-system in combination with our inner walls and not a 3-leaf-system) he said he does not want to continue working on our project anymore. He said our project would become way too complex and so he left.
That's good news! :thu: It seems like that guy was totally out of his depth, didn't know what he was doing in this situation, so you are definitely better off without him.

Quote:
He said building the outer walls, like we have planned, is no problem at all.
Yup. This guy sounds a lot smarter than the other one.

Quote:
And having an additional layer on top of our slab is probably also not necessary,
Yup! Second point in his favor!

There's another option here that is far simpler, presuming that you do indeed need a support post at some location: It would be much easier, and cheaper, to simply cut a small hole through the slab, dig a hole deep enough (with an auger), and pour a concrete footing for JUST the new post. You do not need to reinforce the entire slab when you only need support for a single point load.

I have done this a couple of times, in similar situations, and with good structural engineers on board both times. It's fast, simple, very effective, and a lot cheaper than trying o reinforce a 100m2 slab! Run that idea by your new engineer.

Quote:
Also he suggested to check with our architect if we can leave out the thermal insulation (styrofoam) on the outside.
Third point in his favor! He sounds like a much smarter, better informed engineer.

Quote:
Due to our room-in-room-system keeping the heat will most likely not be issue,
Exactly. You will have a lot of thermal mass in both leaves, a lot of insulation between them, and no thermal bridging at all, since the leaves will be entirely independent with no mechanical connections at all.

Quote:
Except for the other rooms (WC, HAR, Lobby) maybe.
True. Since those are not built sa fully decoupled two-leaf rooms, they might need better insulation.

Quote:
And because this post/news does not add anything essential new to this thread,
To be honest, I think it adds a LOT! It adds the fact that your first choice of structural engineer was not competent for this job, and your second one seems to be a lot smarter! That's big news, and very important.

Quote:
... by attaching two pictures of the slab
It might just be the photo angle, but it seems to me that there is cracking in the path leading up to the slab. It looks like there's a crack opening up in the brickwork of the path. It might not be important, but it does indicate that the ground has moved or settled. Better bring that to the attention of your engineer, and see if he thinks it is important or not. It's probably nothing, but worth getting it checked. It might just be that the pathway brickwork was improperly laid directly on the ground, without proper preparation of the underlying surface, and that would explain it. Hopefully that's all it is.



- Stuart -

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PostPosted: Sun Jul 23, 2017 12:57 am 
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Location: Erfurt, Germany
Soundman2020 wrote:
It would be much easier, and cheaper, to simply cut a small hole through the slab, dig a hole deep enough (with an auger), and pour a concrete footing for JUST the new post. You do not need to reinforce the entire slab when you only need support for a single point load.

If you believe it or not, he suggested and explained exactly this method! :D In case we have to support the pillar.

Quote:
It might just be the photo angle, but it seems to me that there is cracking in the path leading up to the slab. It looks like there's a crack opening up in the brickwork of the path. It might not be important, but it does indicate that the ground has moved or settled. Better bring that to the attention of your engineer, and see if he thinks it is important or not.

He checked the slab yesterday and said everything's fine. :thu:


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PostPosted: Sat Jul 29, 2017 12:28 am 
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Location: Erfurt, Germany
Stuard, just checking here: Did you see/read my long post above concerning my wall design plan?


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PostPosted: Tue Aug 08, 2017 7:36 am 
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Update!

Our structural engineer finished his calculations. The pillar remains. But no new slab slayer. :) Our wooden framing is now 200 mm thick (increased by 40 mm). Our outer wall now fulfills local thermal insulation requirements without any styrofoam on the outside. Also it is stable enough to handle the roof and not to be sheeted from the inside.
He also recommended that we use wood fibreboard instead of OSB or gypsum fibreboard for the outside sheating, which is permeable to moisture and should prevent any damage from moisture in or between our walls. To finally get enough mass he recommended that we do not double-sheet, but increase our plastering on the outside to reach equivalent mass (about 12 mm).
The wood fibreboard we want to use isolates (thermal) and stabilizes the wall. But because of laws (... *sigh* ...) a wall material is not allowed to be used for thermal AND stabilizing purpose at the same time in its final construction. So we further need diagonal stabilizer bars from the inside to ensure stiffness. :roll:

New outer walls now look like this:

Outer walls
Layers from outside to inside:
  • 12 mm plastering (15 kg/m²)
  • 60 mm wood fibreboard* (16.2 kg/m²) *
  • 200 mm wooden frame with 200 mm insulation (15-20 kPa*s/m²) **
  • Vapor barrier
  • (Diagonal stabilizer bars)

*note: STEICOuniversal (data sheet)
**note: ISOVER ULTIMATE Holzbauplatte 035 (data sheet (german)): I contacted the manufacturer for products regarding suitable flow resistivity and he suggested this among others and assured this has 15-20 kPa*s/m² (actual measurements) and not just ">= 5 kPa*s/m²" like in the data sheet)


Outer ceiling
Layers from outside to inside:
  • 22 mm OSB (14.1 kg/m²)
  • 22 mm OSB (14.1 kg/m²)
  • 220 mm wooden beams with insulation (15-20 kPa*s/m²) **
  • Vapor barrier


Inner walls, inner ceiling
Inner walls remain the same as before:
Layers from outside to inside:
  • 18 mm plasterboard (15.2 kg/m²)
  • 18 mm plasterboard (15.2 kg/m²) ***
  • 160 mm wooden frame with 160 mm insulation (15-20 kPa*s/m²) **
  • Vapor barrier and cloth covering

***note: may be switching to OSB with equivalent weight here

Wooden framings of the outer wall and inner wall are 10 cm away from each other. Both inner and outer walls are inside-out (sheeted from the outside, open from the inside). This leads to an air gap of 30 cm between these both leaves.


MSM system calculation
Based on this.
Hasn't changed much:
m1 (outside wall): 15+16.2 = 31.2 kg/m²
m2 (inside wall): 15.2+15.2 = 30.4 kg/m²
d (depth of cavity): 0.30m

So f0 is ~20.0 Hz. The wall system starts isolating at ~40.1 Hz. This should meet the local guideline of 50dB at night.

Phil


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PostPosted: Thu Aug 10, 2017 7:43 am 
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Location: Santiago, Chile
Quote:
Our structural engineer finished his calculations. The pillar remains. But no new slab slayer
That is good news! Less complications, and less expense

Quote:
Our wooden framing is now 200 mm thick (increased by 40 mm). Our outer wall now fulfills local thermal insulation requirements without any styrofoam on the outside. Also it is stable enough to handle the roof and not to be sheeted from the inside.
More good news!

Quote:
He also recommended that we use wood fibreboard instead of OSB or gypsum fibreboard for the outside sheating, which is permeable to moisture and should prevent any damage from moisture in or between our walls.
I'm not familiar with that method, nor why he wants it to be permeable, but if that's the way studio outer-leaf walls are done in Germany, then I guess it is OK.

Quote:
To finally get enough mass he recommended that we do not double-sheet, but increase our plastering on the outside to reach equivalent mass (about 12 mm).
We are still talking about the outer leaf, right? And we are talking about having sheathing ONLY on the outside of that wall, facing the world, right? If so, this is a little confusing: He wants to start out with a permeable board base, and then coat it with an impermeable layer of thick plaster? That seems to be contradictory...

Quote:
So we further need diagonal stabilizer bars from the inside to ensure stiffness
... unless you use OSB on the outside instead, which will provide the stability in sheer ... OSB is very, very commonly used for this very purpose. It has the necessary structural characteristics. So if you make your first layer OSB, then put your "fiberboard" on top of that, as the second layer, you would be complying with code. You could then add your layer of plaster, for extra mass.

Quote:
Layers from outside to inside:
12 mm plastering (15 kg/m²)
60 mm wood fibreboard* (16.2 kg/m²) *
200 mm wooden frame with 200 mm insulation (15-20 kPa*s/m²) **
Vapor barrier
Question: Why is the vapor barrier on the OUTER leaf? And why is it in the MIDDLE of the wall? They normal recommendation is that it should go on the surface that will be warmest in winter, and up against the sheathing with no air space, to prevent condensation from forming and causing mold and other problems. Doing it like you are talking about leaves it in the middle of the air cavity, with only air on both sides: it will get cold, and moisture will condense on it...

Quote:
Inner walls, inner ceiling
Inner walls remain the same as before:
Layers from outside to inside:
18 mm plasterboard (15.2 kg/m²)
18 mm plasterboard (15.2 kg/m²) ***
160 mm wooden frame with 160 mm insulation (15-20 kPa*s/m²) **
Vapor barrier and cloth covering
TWO vapor barriers????? :shock: Ummmm... please explain why you would want to purposefully trap moisture inside your walls. That does not seem to be a good idea at all! Walls should have only ONE vapor barrier, and it should be against the surface that will be warmer in winter.

Quote:
Wooden framings of the outer wall and inner wall are 10 cm away from each other. Both inner and outer walls are inside-out (sheeted from the outside, open from the inside).
Ummmm Nope! Your outer-leaf wall is built conventionally. Only your inner-leaf wall is inside out! You seem to be misunderstanding the term. An "inside out" leaf is one where the sheathing faces the wall cavity, and the studs face outwards. In other words, when you look at the completed wall, you see studs. With your outer-leaf, that is NOT the case. When you look at the wall, you will see sheathing, not studs. The studs will not be visible, as they will be covered by the sheathing.

So your outer leaf is conventional, and your inner leaf is inside-out.


Quote:
This leads to an air gap of 30 cm between these both leaves
Nope! Your air gap for MSM calculations is 200 + 100 - 22 - 22 = 256 mm. You have 20mm depth from the studs on the outer leaf, plus 100mm between the frames, less the space taken up by your two layers of drywall.

Quote:
MSM system calculation
m1 (outside wall): 15+16.2 = 31.2 kg/m²
m2 (inside wall): 15.2+15.2 = 30.4 kg/m²
d (depth of cavity): 0.30m

So f0 is ~20.0 Hz.
Nope. I'm not seeing that. Here's what I see:

f0=c[(m1+m2)/(m1 x m2 x d)]^0.5
= 43 ( (31.2 + 30.4 ) / (31.2 * 30.4 * 0.256) ) ^0.5
= 43 ( (61.6) / (242.81) ) ^0.5
= 43 ( 0.25369 ) ^0.5
= 21.65 Hz

Not a huge difference, but it's important to be accurate. But round it up to 22 to be safe.

Now for the actual isolation calculations:

R = 20log(f (m1 + m2)) - 47 [for the region where f < f0]
= 20log(22 (31.2 + 30.4)) - 47
= 20log(22 (61.6)) - 47
= 20log(22 (61.6)) - 47
= 62.5 - 47
= 15.64 dB

So your isolation below resonance is about 16 dB.


Now for the region between resonance and coincidence:

R1 = 14.5 log (31.2 * 0.205) + 23 dB
R2 = 14.5 log (30.4 * 0.205) + 23 dB

R1= 34.67
R2= 34.55

R = R1 + R2 + 20log(fd) - 29 [for the region where f0 < f < f1]

R = 34.67+ 34.55 + 20log( 22 * 0.256) - 29
= 34.67+ 34.55 + 0.896 - 29
= 55.23 dB

And for the high end:

R = R1 + R2 + 6 [for the region where f > f1]
= 34.67 + 34.55 +6
= 61.6 + 6
= 67.6

So, rough estimate: 16 dB below MSM, 55 in the mid range, and 67 at the top. That's pretty decent. The overall isolation will be around 55 dB

Quote:
This should meet the local guideline of 50dB at night.
That's a little more complex to figure out: You'd need to know the spectrum of the actual sounds you'll be producing, compare it to the isolation at several frequencies, take into account the decibel weighting required by your regulations (probably "A"), and see where you get! But assuming that your level inside is around 110, the level just outside the wall will be around 55, and a few m away it will be below 50.

It sounds like you have a plan!


- Stuart -

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