What I meant was that I have a lot of experience recording piano.
Ahhh! OK, got it. Then I take off my hat to you, because in my opinion, piano is one of the hardest instruments to record. Especially concert grand piano. I'd rather mic and track a large drum kit in a lousy room, than try to track a grand!
Wishful thinking about mixing in the same room, perhaps, and I was aware of the problems but hoping to get some ideas about how to accomplish that....
Wellll..... it IS possible using variable acoustic treatment. For example, here's a variable thingy I designed for a vocal/instrument room, for one of my customers:
Variable-acoustic-01--panels--construction--half-open-SML.jpg
There you can see the basic concept, with the device under construction: A central "slot wedge" device that does a number of things at once, with two absorber panels on each side, and swinging "wings" that can either fold back over the absorbers, our out over the wedge.
Another view, with the wings fully out, over the wedge:
Variable-acoustic-02--panels--construction--fully-open--SML-ENH.JPG
A similar view, but with part of the actual treatment installed in the wings:
Variable-acoustic-03--partly-completed--SML-ENH.jpg
And the completed device in the fully competed room:
Variable-acoustic-04--room--completed--SML-ENH.jpg
So what did this device accomplish? Well, here's the results, from an actual acoustic test we did in the finished room
variable-acoustic-05--acoustic-rt60-plots-all-positions-t20.jpg
That shows how the decay times change over the entire spectrum as the wings are opened and closed to various angles. That set of measurement was taken with the test speaker and test mic set up as though it were recording the ambient sound of an acoustic guitar session, or something like that. You can clearly see how the low end of the spectrum gets tighter and deader while the high end gets brighter and more live, while the mid range only changes slightly.
You would need devices that work something like this, to be able to change the room acoustics from "live and warm enough for piano and concerts", to "smooth and neutral and even enough for mixing".
It can be done, but you'd need a LOT of such devices, all over your walls, and probably something in the ceiling too (I designed some similar "flip over" panels for another customer, for the ceiling of his live room, but I don't have photos of that). Each device would need to be placed carefully, and designed to deal with the specific acoustic issues at that location in the room. The room where the above device is, isn't very big: it's meant mainly for vocal tracking and instruments such as acoustic guitar, and there are TWO identical devices in that room. The graph you see above shows the changes as BOTH of them are adjusted together, because that's the amount of wall area that I needed to get these changes. They are useful, yes, but not dramatically huge. The decay times in the high end change from about 370 ms to about 270 ms, and in the low end, from about 330 ms to about 150 ms. So that's nice, and useful, and infinitely variable, but not enough to turn a piano room into a control room. You'd need considerably more devices, designed a bit different, since your room will be much larger.
Anyway, my point is that it CAN be done, but it isn't easy, and it's going to be expensive, in both design and also in building and mounting and testing all those devices.
putting mix space in a corner,
Not a good location! Corners are great for treatment, but a lousy place to mix. All room modes terminate in corners, so if you are looking for the location in the room that has the absolute worst set of modal problems tat you can imagine, you'll find that in the corners. In fact, one acoustic test I often do in rooms to understand them better, is to place a speaker in one corner and the acoustic test mic in the diagonally opposite corner, because that setup is guaranteed to trigger and detect all the room modes... ever last one of them. It looks ugly on a graph...
building false roof
Not necessarily a full roof, but certainly you will need a ceiling cloud over the mix position. It might even be feasible to make it in such a way that it can be folded, slid, rotated, or some such to get our of the way when not needed. You can see what I mean by "ceiling cloud over the mix position" in this thread:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 There are several clouds up there. Or rather, one cloud made up of several parts. That cloud is key to getting this room as good as it is. So yes, you'll need something like that, for sure.
with a lot of panels to control reflections,
That's the right concept, yes, but you need more than just panels. You can see in the thread above that the entire front of the room is carefully shaped with angled walls and things that control reflections, and the cloud is a part of that too. There's a geometric design involved to ensure that all reflections go only where they need to go, and do NOT go where they are not wanted. This design concept is sometimes referred to as "RFZ", since it creates a reflection free zone around the mix position.
recording using good closed headphones.
Meeehhhhh.... tracking on headphones is not something I recommend!
You never get the real sound of what you are tracking, especially for something as complex as a grand piano.
The idea occured because I'm a one man operation, mostly, and dislike having to push open two heavy doors to get back into the CR,
Then don't have heavy doors that you need to push open and closed!
Instead, have sliding glass doors that you can leave open when you are setting things up, or playing, or practicing, or whatever, and you only close them when you need to mix...
Like this:
John-Sayers-Sliding-Doors.jpg
That's one of John Sayers studios, and you can see how those sliding glass doors between the CR and LR make it so easy and simple. You can also leave them open to talk to the musicians while tracking, if you want, just as you wood with a single large room, then just close them when you need to mix, or to check mic setup without hearing the sound from the other room (only the speakers).
Seems like building a separate mix room would be just as expensive.
Probably, yes. Both options would be expensive. It's hard to say which would be less expensive.
This will be a big room,
If you could post some photos of the actual space, and some diagrams of the dimensions, then we'd get a better idea of what you are facing, and maybe come up with some ideas to hep you get it right.
- Stuart -