Hi there "civvie", and Welcome!
Cement floor and ceiling. Drywall/rockwool the rest.
Not sure I understand you there: Where is the rockwool? Inside the wall cavity, behind the drywall? Then it is not in the room: it is isolation, not treatment. Inside the room? Then it really is treatment, but does not count when measuring your room dimensions.
Room dimensions are measured form the hard, solid, rigid, massive surface of the walls the define the room itself. What you see as you stand inside the totally empty room, without any furniture, treatment, gear, or anything else. Just the bare inner-leaf walls.
I want a balanced and deadish mixing and overdub room (no booth just one great sounding room)
OK, but that's only partly about modal response (room ratios). Yes, having a good room ratio is important, but there are many other aspects of the room that need attention to get it sounding good.
Also, if it is "balanced" then it isn't "deadish"! That's a contradiction in terms. If it is balanced, then it will have the right decay time for the room volume and room purpose. If it is dead, then it isn't balanced!
Now I know that having basically the same height and width is bad.
Oh yes! For sure. And you are preyy much identical there. But I'm not clear if we are talking about the dimensions of the empty space where the room will be built, or the final dimensions of the inner-leaf after the room is finished. Those are probably two different things, unless you don't need any isolation....
I notice if I 'lower' the height to 221cm I am 'almost' in the BOLT area.
Studio design is all about trade-offs: Less of this to get more of that, nudge here to improve over there, etc. The Bolt area is a good place to be, but if it means bringing your ceiling down very low then it might NOT be such a good place to be. It might be better to sacrifice a bit of width or length instead (or both. Or all 3). Then again, making the room smaller overall isn't a good idea either: you really should aim for the most possible volume you can get...
In other words, you should fiddle around with all of the dimensions until you get a reasonable compromise. You do have a lot of height to play with, which is rare in home studios, so don't waste that just to hit a good ratio! You do need to reduce it a bit,, but only by about 15cm or so. As long as there's more than about 5% difference between dimension, you are reasonably OK. 10% would be better. So bringing your ceiling down to 280cm or maybe even 270 would be a possibility, but I wouldn't go lower than that. 280 sounds reasonable.
THEN with that done, yes, by all means build a hard-backed angled cloud over the mix position, and tilt it to whatever angle you need to get optimum performance. Probably something like 10° to 20°, but that would depend on the rest of the room as well, and also how the cloud is designed.
The cloud does not need to cover the entire ceiling: just the front section of the room, in the area over the desk/console/mix position/speakers, roughly.
I'd suggest designing your room in SketchUp, then posting the design here so we can take a look and see if there are ways it might be improved.
It would also help if you post photos of the room as it is right now, and provide as much detail as possible on what you plan to do in there.
- Stuart -
