If you need high isolation, then the only way to achieve that at a reasonable cost is with complete "room-in-a-room" construction, more technically known as fully-decoupled two-leaf MSM construction, for each room. In other words, you need to build one complete new structure for each of the rooms, inside the existing concrete shell, and each new room will consist of its walls and its own ceiling, built as a single unit that does not touch any part of the existing structure, or any of the other rooms. So for each room, you build your walls, then you put your ceiling across the top of just those walls, not touching any other ceilings or walls. The only thing in common between the rooms, is the floor.
Could this be placed say 500mm below the slab to conceal AC ducting, wiring etc?
Yes, but that sounds like a lot of wasted space. Unless you are planning to blow a hurricane through the rooms, I doubt that you'd need ducts 50cm thick! 8" flex duct, for example, takes up less that half of that height, and if you use a custom metal duct you could probably fit it into an even smaller space. The only real size issue would be the size of the silencers, but even those can be designed to be low profile. OK; so you do have 3.7m to play with, which is great, but there's no need to wast that unnecessarily!
:) Especially in the live room, height is a great asset, so waste as little as possible.
In any case, your final inner-leaf ceiling height for each will be determined by the room ratio more than anything else, in order to have good modal response, so you should decide on that first. What ratios did you have in mind? It is not at all clear from your rough sketch, since it does not show any dimensions, and you didn't mention what sizes you are planning for in your description.
All input greatly appreciated !
Have you considered other arrangements of your rooms? The one you show looks nice, but isn't very practical. It is usually better to try to have direct sight lines from the CR into the LR, which you don't have right now. The engineer is going to end up with whiplash from spinning around sideways all the time, to see what is going on in the other rooms!
There's also a huge amount of space wasted in that corridor between the control room and the vocal booth, and the corridor also puts the vocal booth far away from the mix position, behind four thick windows: Unless you have very careful lighting design, there won't be any visibility across there, due to glare.
CR2 seems to be awfully small, and probably unusable, acoustically. At only 7m2 floor area it is barely one third of the minimum recommended size in the specifications for control rooms, from organizations like the ITU, EBU, AES and others. Plus CR2 looks roughly square in shape, and the mix position seems to be in the exact center of the room.
CR1 has some acoustic issues as well: the windows are at your first reflection points! So either you'll have to suffer with all of the acoustic artifacts and inaccuracies that that implies, or you'll have to cover them with suitable treatment, which obviously defeats the purpose of the windows. There are also discontinuities in the lines where the soffit extensions meet the side walls (windows), and those will create diffraction artifacts, which is sort of defeats the purpose of the soffits: part of what they do is to prevent diffraction artifacts!
You also show skyline or QRD diffuers on the rear wall, but it is not clear that the room is big enough to be able to use diffraction like that. It might be OK for the mix position (impossible to tell without knowing the dimensions of the control room and the cut-off frequencies of the diffuser), but it is most definitely not OK for the sofa. Anyone sitting on that sofa will be smack in the middle of the worst and strongest lobing artifacts from those diffusers.
The rear doors in the control room (CR1) are too far back, and do not allow sufficient space for good bass trapping in those corners. I would move them forwards at least 50 cm.
It's nice to have lots of glass in a control room, but you also have to have enough walls space to allow for the correct acoustic treatment of the room, and it seems to me that you don't have any wall space at all, or very little. certainly not enough for good treatment.
You also show both a keyboard and a drum kit in your live room, and assuming that is representative of a typical recording session, then I'd really suggest using some of that extra space to split the LR in two, with one part being a separate booth for the drums.
Finally, the machine room is also unworkably small; there's no way you can get even a single rack in there while also having the necessary space around it and behind it to proved access for installation, reconfiguration, and maintenance.
So my number one suggestion would be to re-arrange the entire layout of all the rooms for better sight lines, better use of space, better sized rooms, better acoustics, and perhaps splitting the LR in two, to gain a drum booth.
Once I grasp the best way of getting the isolating ceilings in place I would welcome some advice on ceiling designs / solutions that can be placed below the isolating ceiling to achieve correct acoustic control and aesthetics in the various rooms.
That sounds to me like you are either considering a three-leaf ceiling, which would be a bad idea seeing that you need high levels of isolation for low frequencies, or you are confusing isolation with treatment. As I explained above, each room has its own individual ceiling, which is part of the two-leaf MSM isolation system, and there is no common "isolating ceiling". There is just the existing concrete slab above you, which is the common outer-leaf for all of the rooms, and then there is the inner-leaf ceiling for each room. Those ceilings are separate from each other, are not connected to each other, and are independent, isolated units.
THEN comes the treatment inside each room. Isolation and treatment are two different things. There is no "isolation ceiling" plus a "treatment ceiling that provide aesthetics". There is just ONE ceiling in each room that provides the isolation, and then the necessary treatment is hung from that ceiling, as indicated by the initial acoustic predictions and also by the actual acoustic analysis of the finished inner-leaf room, with suitable aesthetics included as part of the design. Yes, you might well need clouds in one or more of the rooms, but those are not ceilings: they are acoustic treatment devices hung from the ceiling, or attached to it. So each room has only one ceiling, which is the inner-leaf of the MSM isolation system, and then the treatment is added below that, as needed.
The actual design for the ceiling of each room depends on the design concepts, and the dimensions. For example, if you want one of your control rooms to be a true RFZ or CID design, then the front part of the ceiling must be angled accordingly. If you prefer to go with the (obsolete) true LEDE concept, then you don't need to do that. etc. So the ceiling design depends on the design criteria for the room as a whole. Each design concept has a set of implications for how the walls and ceiling are arranged, and also for how the acoustic treatment is arranged.
- Stuart -
