Firstly the secondary pair of speakers work for the ITDG (I've also seen ISD gap, apologies if that caused confusion). This is an example-
I'm not sure if you actually read and understood that thread on Gearslutz, but Bjorn summarizes the issue perfectly: "your room looks like a very dead environment with little energy. And it seems you're now trying to compensate for that by introducing more channels. Which again leads to more lobing and a chaotic response." to which he later adds: "More sources leads to superposition and lobing, thus a more chaotic response. It's quite basic knowledge. It can't necessarily be shown in a measurement." Very true.
He is creating the diffuse field by firing them into adjacent rooms,
... which is not what you claimed originally, to start with, and is exactly what I said: it cannot be done electronically, and must be done acoustically! You seem to be contradicting yourself without even realizing it. You said you were planning to do it with "secondary speakers and DSP". Jim is using a hell of a lot more than that (using a Lexicon effects box!), as well as additional physical rooms, and still not achieving it, even though his room is totally dead.
Bjorn later adds: "It seems you are trying to reintroduce something you have lost . And my recommendation is rather to go back and start over again. Your room is filled to the brim with treatment. So no, I don't understand why you can't get some nice looking diffusers. You have way too much absorption in this room". Yup. Spot on.
A few pages later, Bjorn once again adds words of wisdom: "The goal of LEDE was to get close as possible to large concert hall sound. That implied surgical use of absorption or better; redirection (RFZ design with splayed walls) and a late lateral arriving diffuse tail. Reverberation time wasn't (and isn't) considered valid for small rooms, thus never used. This is quite different from what you have done and experimented with."
After 21 pages, more than 5 years of experimenting, hundreds of REW tests, enormous amounts of absorption, numerous combinations of speakers, reverb boxes, PEQ, time delays, stacks of money, and a whole bunch of other things, he still didn't get a result that looks like a real control room:
best-case-fake-reverb-field.jpg
best-case-fake-reverb-field-RT.jpg
best-case-fake-reverb-field-IR.jpg
I took all of that from the "final" MDAT file he himself posted, in 727. That's his very best outcome, after all that effort.
There is no ITDG! The level NEVER returns to -20, or even -30, barely even -40, except for that huge specular reflection at 24ms. The overall decay time is well over 400 ms (over 700 at some points), and extremely uneven between adjacent bands...
I, for one, would find it extremely hard to mix in such a room, because it is not telling the truth at all.
I admire the OP's persistence, and tenacity, and perseverance, but I noted throughout that he's not even trying to make a room that is accurate for mixing! That never was his objective. he's trying to make a room that "sounds good". Many of his comments are about how nice the room sounds (and I'm sure it does sound nice! He's got some of the best reverb boxes on the market, so of course it will sound good!): But that's not the point at all of a control room. In reality the control room should have no sound of it's own at all! It should be neutral. It should neither add to nor subtract from the direct sound coming form the speakers. Period. If it does "add to" or "subtract from", then it is not a control room. His does both: first it completely subtracts everything, since he started by making the room as dead as it could possibly be then he added in "fake" room reverb by using speakers, other rooms, PEQ, and rather expensive effects boxes. The whole experiment was never about making a control room: it was about making a room that sounds nice.
In fact, he even states the purpose of his room himself. It is NOT a control room, and was never intended to be one! Here is what he says: "This is my living room as well as my listening room, " The big clue; Take a look at his speakers, and their location in the room. It's an AUDIOPHILE room! Not a control room. He was never intending it to be a control room, so accuracy never was a consideration. He wanted it to "sound nice", and that's all.
But all of that is totally besides the point, because NONE of it applies to your big room in any way! You said that your big room is primarily a live room, and that you also want to use it as a control room sometimes, in which case you would use your CD speakers and your fake reverb to create the ITDG and following sound field. As I already mentioned, the key here, the thing you seem to have missed, is that in order for you to be able to do that, your live room would have to NOT be a live room at all! It would have to be entirely dead, just like the OP's room: Packed out several feet in all directions with pure absorption, such that the room is practically anechoic.
I repeat: in order to achieve what you are saying you want to achieve, your live room would be totally dead. And therefore totally unusable as a performance space, rehearsal space, tracking room, jamming room, practice space, or any other form of music room.
So, once more time: What you claim is not physically possible. You cannot have a room that is both a LIVE room and also a DEAD room at the same time. Even the names contradict each other. If the room remains live enough to be worthy of the name "live room", then it will be massively too live to be able to use it as a dead room too: The natural sound of the room would overwhelm your attempt to "add" the ITDG electronically. It would be like trying to make your swimming pool wetter by adding a few teaspoons of extra water...
what I have played with in my current space is placing them above a cloud and firing towards the side walls into diffusers.
So you are ALSO not doing it the way you said you would!
But anyway, let's see how that works out in practice: Please follow the normal setup and calibration process that I recommend for REW, then run three tests with the mic in the mix position: One with only the left speaker running, one with only the right speaker running, and one with both speakers running. Do all of that with your "ITDG faking system" turned off (in other words, to capture just the natural acoustics of the room, no fakery), then repeat the same three tests with your system turned on. Do not change anything in between the tests. Upload that MDAT file to a file sharing service such as Dropbox, then post the link here. Also please provide an accurate diagram of the room, showing all dimensions, locations of the speakers and mix position, and post a few photos of the room.
That plus some artificial reverb produces a suitably diffuse ITDG and make is less susceptible to being blocked by the people sitting in the back of the room.
Ummm.... if it is possible to "block" the ITDG and diffuse field, then there's something drastically wrong! If it can be blocked, then it isn't a diffuse field. The very definition of a true diffuse reverberant field is that it is the same everywhere in the room. It might change slightly due to having people in the room, yes, but if people can "block" it, then there's a problem.
Also the room needs to be as anechoic as possible for the first ~20ms for any design criteria,
BINGO! Your honor, I rest my case. By his own claim, the defendant declares himself guilty as charged!
If the room is so dead that there's nothing after 20ms, then there's no way on the face of this planet that anyone would ever consider it to be a "live room"! I think you'd find very, very few musicians and bands that would want to come back to such a room and play/rehearse/track in there. The decay times in a good live room would be fifty times, a hundred times, or even more, longer than that.
if there is some return from the room that mixes with the speakers that only adds to the diffusion.
Ummmm... no it doesn't. As Bjorn so aptly points out: "More sources leads to superposition and lobing, thus a more chaotic response". Which is why it can be blocked by a person. Because there is lobing, superposition, and chaotic response. That would not be possible in a true diffuse reverberant field.
Additionally some synthetic reverb can be used to make the return more dense.
.... rephrase: "Additionally some synthetic reverb can be used to make the return
more chaotic, with
more lobing and
more superposition"....
I've tried it, and it works for me. If you have objectively collected data that shows this to be a poor system I'm interested in it...
I think the thread itself that you refer to is already a really good set of data that proves that point! There's a stack of objectively collected data there, and it clearly proves the point. And the tests that you will do, in your own room (as outlined above) should add to that. Once we have that data, we can compare it to ITU BS.1116-3, EBU TECH-3276, and other similar specs for the acoustic response of a critical listening room, and see how it stacks up. We',, be able to see if your room does, indeed, meet the conditions necessary for it to be usable as a high class control room.
You can then compare all of that to the data for this room:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 which is pure acoustic treatment plus some minor digital tweaking, and see how that stacks up.
I want the space to be ala carte, so that people don't have to pay for a big room when they don't need it.
Again, typical of many medium and large facilities.
Certainly this does mean having some compromises, but with Dante the signal wiring flexibility is MUCH more flexible.
I'd agree entirely with that! I love Dante. But I don't so how it would help to change a room from being a vocal booth to being a control room... that's a purely acoustic issue, nothing to do with wiring or signal flow.
Personally I know many artists that prefer not to be able to see anyone at all, and I like having a video camera because I can position it to *really* monitor their position relative to mics without having to stare at them. I have hunted down some studios using HD-SDI video and low latency quad viewers and everyone I talked to seems very pleased with those (including clients and freelance producers using those studios).
You are not answering the question: in fact, you are avoiding it! The question was not if some producers and clients are pleased with CCTV, but if most
artists, musicians and engineers prefer actual real sight-lines to CCTV. For those folks who like to play invisibly, curtains are a lot cheaper than than multi-cam multi-way HDTV CCTV systems! So if I understand you correctly, you are planning to have two or three HDTV cameras with zoom lenses on PTZ mounts in each room, with a couple of large HDTV screens in each room, plus some sort of routing switcher and distributed control system that only allows the people in each room to select a certain subset of cameras, or to block the cameras in their room if they prefer, and you think this is going to be cheaper/better than a few panes of laminated glass?
For just the cost of the routing switcher alone you could buy quite a few panes of nice thick glass...
I generally want the smaller control (room A) to be relatively small.
Fair enough. Many facilities have a large control room and a small control room, or simple edit station. But they don't try to turn their control rooms into drum rooms, amp chambers, or vocal booths! And they don't try to turn their main live rooms into control rooms either! Yes, you certainly can record some instruments and vocals in a control room, but that flies in the face of what you say you want to do. You said that you wanted to have some small cheap rooms to rent out to people on lower budgets, but by definition a control room is
not a cheap room! Renting that out as a vocal booth is not very productive: it's an expensive room!. It only makes sense if it could not be rented out as a control room at the same time, but if you schedule your facility usage properly, that won't happen very often. I'm pretty sure that if you had the choice, you'd rent out that room for it's intended usage as a control room at full price, rather than as a vocal booth at a quarter the rate....
Big room is too much room for people to hang out and chat.
Which is why it probably won't see much usage for it as a control room!
It's a large room, it needs to be billed out a a premium rate. By the way, who would pay for the downtime that you need to convert if from CR to LR and back again? Not the guy who just left after his session is complete, and not the guy who will be arriving in a while to start his session... neither of them is going to want to pay for the conversion... but somebody has to! ... It's going to take quite a while to cart in the truckloads of treatment, speakers, and gear that you'll need to convert it from a live room to an anechoic chamber... then quite a while to cart all that out again, and just put back the normal live-room treatment... Billable days lost on both sides....
Also I am aware that this layout does not detail the iso plan. It was meant just to look at the HVAC system
Fair enough, but it would be good to have a plan where both of those are shown together, since they are interlaced. My comment was mostly about the only mention of a double wall being: " a double wall and the space to the right ", as though that were something special, unusual. In reality,
all of the walls will have to be double-walls, especially it you might have different people doing different things in different rooms.
Hey Stuart I apologize if I have offended you-
Not at all! I'm not angry, or offended, or even annoyed! It's just my normal style for drawing people's attention to things that don't make a lot of sense, or issues they seem to have missed. I don't do PC at all, and I don't go off on gentle, soft, flowery, feathery explanations that will slowly reveal the issue to you, in cotton-coated words and pastel shades... that won't get your attention at all! But dumping it all in your face certainly does. It worked here, for sure!
So don't get me wrong: There might well be a case that could be made for enhancing diffuse fields in audiophile listening rooms, to make them sound nicer, but it cannot replace the natural sound of the room itself. But I can't even see a reason why you would want to do that for a professional control room, when it isn't even necessary. There's no need to chase magical ITDGs and specific shapes and extensions of diffuse fields just because the room can't provide it naturally. If your room is too small to be able to produce a certain decay shape, then so be it! Why would you want to fake it? Just because the written specs for a specific design concept of a larger room say that it is desirable in that larger room, does NOT also mean that it is desirable in the smaller room! Your brain is not dumb: when the sound it hears does not match the room you are in, your brain pretty much tells you that there's something unnatural going on. It knows that your ears are not hearing the same room that your eyes are seeing, and that's confusing, and fatiguing. That's fine if all you want is a room that sounds nice, to listen to music! But it's NOT so fine if the purpose of the room is to tell you the truth, so that you can make accurate mix decisions and turn out mixes that translate well. I don't understand why anyone would want to try to mix in a room that is lying to them. The entire purpose of a control room is to tell the cold hard ugly truth. (Sort of like I do!
)
I have designed small control rooms, and I have designed large control rooms, and they are
supposed to sound different! Why would you even want to make one sound like another? You can make a large room sound smaller to a certain extent by killing it with treatment, but it certainly does not sound natural like that, and it does not sound like a truly small room either. But you can never make a small room sound large and natural. The room must actually sound natural, and neutral, in order to be usable as a control room. As you can see from the "final" graphs for the room you admire, it could never be used as a control room. The decay times are way, way too long for that, and extremely uneven, the reverb tails do not match the room frequency response, there are at least four different decay "spaces" visible in there, the Schreder integral looks like a noodle that hit a brick wall, and the spectrogram, looks like a jigsaw puzzle!. If you go back to the start of the thread, you'll see that his early attempts at treatment actually did good things for the room, and evened it out quiet well. It would have been usable as a control room at some points in that progression. A one point, early on, Rod even comments on that, saying it would be great as a control room. But then the OP got sidetracked onto his quest for the impossible, became obsessed with the ITDG which is not even applicable at all to that room, and he killed the room in order to fake it. Which basically trashed what he had already accomplished, and made it totally useless as control room.
In the end he did get sort of what he wanted, an audiophile listening room. But it most certainly would not be any use as a control room. And certainly nothing he did after page 7 has any bearing at all on what you need to do.
- Stuart -
What makes your place so totally unlike any other studio that has ever been built on this planet? Are you saying that nobody has ever recorded any of the instruments you plan to record? That nobody has ever had the latent heat load and sensible that load that you plan to have? That nobody has every built a studio in an area such as where you plan to build yours? That nobody has ever dealt with the type of artists that you plan to deal with? In order for your claim to be true, you'd have to convince me that you have invented an entirely new and unprecedented genre of music, played by an entirely new and unprecedented type of musician that the world has never seen before ( 
), and that you have also invented an entirely new set of musical instruments, the likes of which have never been heard any place on the face of the planet! 
Smart move!