I've been meaning to get back to this thread several times, but also put it off several times because what I have to say is not what you want to hear, and I hate to be a wet blanket.
But to be very honest (perhaps too brutally honest) there's just so much wrong in there that I really don't know where to start. I just don't know how to say this kindly, so I guess I'll just dive right in and blurt it all out.
The control room is basically no use at all the way it is right now: there is no symmetry (which is critical for control rooms), the geometry of the speaker/mix position is wrong, the shape of the room itself is no use and will need to be modified to be usable, the arrangement of all the rooms is nowhere near optimal, and there's just so much clutter in there that even if it had a perfect shape, perfect geometry, and perfect symmetry, it still wouldn't be very good. You very literally have absolutely everything in there, including the kitchen sink! There no way that room can work as a control room, as it is right now.
Please take the above in the spirit it was intended: I'd really, really like to help you get that room usable, since there is potential there, and I see from your own explanations that you are suffering, and you know just how bad it is. So I'll do you a favor, and tell you straight: you will never be able to mix well in that room, until you rebuild it right. It can be fixed, but the task is daunting.
I'm not sure how much you are prepared to invest in this (both time and money), or how badly you need it, or how far you want to go, but to get it decent is a pretty big task.
I know I have a problem a big problem the low end, and have just had to leave things alone in that freq region when mixing and mastering, ... and I feel like I am always wrestling with balancing.
Those problems (and many others evident in the REW data) cannot be fixed without a major overhaul of the room itself. There is no treatment that can fix the problems. Sorry. The room itself has to be fixed first, then the treatment can be added to tweak the room response. There's no way on earth that you could ever hope to mix well in there, and mastering is totally out of the question.
I wish I had better news for you, but that's the sad truth.
The room is already over-damped in the highs, yet the decay time is way long in the low end: evidently, there's no bass trapping at all, or if there is, then it is not working, and is way insufficient. There are at least three different acoustic environments evident in the impulse response, all rolled into one, and they all have different decay times. I'd hazard a wild guess and say those are probably the front area of the room, the rear area, and the kitchenette area, but there's other stuff going on too. The room itself is bad, and cannot be used as a professional control room like it is
I do have some corrective narrow band eq, but as well all know that can not make up for room nulls (bad idea)
Right! In fact, there are precious few acoustic issues that
can be "fixed" with EQ. And even then it should be used only as a last resort, for the final tweaking. It should never be used as the first approach.
so I would really-really like to tame the room's problems, but I doubt it will be an easy task
You are spot on there: it won't be easy, and it likely won't be cheap either. Do you have a budget in mind for this? Are you willing to whatever is necessary to fix it?
and I have kind of dreaded even trying.
Probably somewhat similar to my dread of even responding!
But the good news is that it can be fixed, and turned into a decent room. However, the bad news is the amount of effort and cost involved.
If I sweep that region manually it goes up and down from strong to almost gone at 65Hz and 85Hz. . . it sounds even worse that it looks.
And it looks pretty bad! It must sound awful.
As I said in my first reply, the frequency response isn't too bad: the issues are with the
time
-domain response, modal issues, reflections, and symmetry (among others), and there's no easy fix for any of that without fixing the entire room first.
The level of the file may have been low, but the audio volume in the studio was loud enough that I thought it best to put on my hearing protection, and I felt it was as loud as I wanted to drive my monitors. I would have thought there was plenty of digital resolution to do meaningful calculations. No?
Right, but you still haven't calibrate REW to tell it how loud that was! Like I mentioned before, you do need to get a good sound level meter (not a cell phone!), measure the real level in the room, then tell REW what that level is using the "SPL Meter" tool, and the "Calibrate" option. In other words, set both the hand held sound level meter and REW to "C" weighting, slow response, use REW to play pink noise on all three speakers at once (L,R, sub), adjust the speaker volume so that it is showing 86 dB on the hand held meter, then tell REW that the level it is hearing is 86 dB. After that, do not change any of the controls, no matter what! If you change the mic gain, or the speaker levels, or the sound card settings, or anything else, then you will need to recalibrate. After you calibrate, don't touch any levels at all: just run the tests.
If you don't do that, then REW has no idea what level you actually have in the room. It just uses the default values, which clearly do not match your sound card and mic setup.
Mic used the first time where just the cheap behringer ECM8000. I have a lot of great and expensive mics for recording, but only other mics that are candidates for this are my Earthworks TC25 omnis. . . although not really analyzer mics, they should be a good reference.
The ECM8000 is fine, if you have a good one:

some of them are not so good... I have one of the "not so good" ones. I also have a PreSonus, which I find is much better. But you can indeed use any decent omni mic that has flat response down to under 20 Hz. Or if the response is not that flat, then you need a mic calibration file to load into REW
However, the issues seen in the REW data are not from the mic: they are the room. The mic might not be totally accurate in frequency response, but there's no way on earth it can be inventing time-domain issues such as those seen in the data.
I will look at that. . . so calibration files can be cascaded (one for the interface, one for the mic)?
Correct. There's a "Change Cal" button under each reading you take with REW: if you hit that, it brings up a window where you can load in different files for the mic and sound card. REW sorts out how to handle them both.
Speakers - used were Blue Sky Monitor One; i) wo/Sub and then ii) w/Sub.
Those are fine. No problem there.
Mic was at mix position, where my head usually is...
OK, but it wasn't centered, and you only tested with both speakers at once. You should test with each speaker individually (left, right, sub) then with all three together. That way you can spot the issues with symmetry, and figure out what to do about them.
I am not completely opposed to rearrangement of the equipment, if there is a huge benefit to how the room sounds, as long as it still flows for the people etc. . .
The main issue isn't re-arranging thins in the room (although that clutter really has to go!). The big issue is the room itself. The shape is no use, and there is no place you can get symmetry. Symmetry is absolutely, totally critical for a control room. The left half of the room has to be a mirror-image of the right half, at least as far back as the mix position, and hopefully all the way back to the rear wall. There just is no way of doing that with the current shape of the room: the solution involves either building walls, or tearing down walls. Or more likely, both. That's the question here: Are you prepared to do that? If you want the room to ever be usable for mixing, that's what you are looking at. If you don't want to invest in doing that for whatever reason, then to be very brutally honest (yet again) K really wouldn't bother doing anything much to the room, since the issues can't be fixed by treatment with the current shape and layout: Yes, yo could throw in a couple of big bass traps and get a noticeable difference, but it will not cure the sickness. It would be like putting a band aid on severed artery: it stops the blood flowing a bit, and gives the satisfying sensation that you accomplished something, but the patient is still dying....
I look forward to hearing ideas on the best way to improve this room for mixing without reducing the space to such a degree that I can no longer have tracking sessions, such as outlined above.
OK, this is the part that I've been dreading writing, and you've been dreading reading. If that were my room and I were 100% committed to making it the best it could be, and I had the budget, I would start by ripping everything out, back to the bare walls of the basement, and start again. I would re-design the entire thing from scratch, making sure that I make the control room symmetrical and a decent shape and size, with two live rooms arranged around it, and forget the vocal booth. The control room would be JUST a control room: No sink, bar, fridge, counter, stools, or general clutter, with the bare minimum of equipment racks, better arranged at the mix position (not behind it), and it would be treated properly, with soffit-mounted speakers. The two live rooms would be one for drums and bass, and the other for everything else (kbds, guitars, etc.). Vocals would be recorded in the CR. You can't afford the space for a booth in the available area you have there. Two live rooms would give you plenty of space to split up the band nicely, and do the vocals in the CR itself. The kitchenette, hanging guitars, extra gear, and general clutter would all find a new home in the area marked "Lounge Area".
That would be my approach to fixing that studio, and making it useable.
That's not what you wanted to hear, I'm sure, and it's no fun saying it either, because I know just how disheartening it is to figure out that what you have is no use in its current form, and needs a large investment to make it work. Been there, done that, cried the tears, and then bit the bullet and did it right. More than once. It hurts. But the question is: do you want to have a room that is very usable for mixing? Or do you want to carry on suffering?
Sorry I can't sugar-coat this any, but the sad reality is that what you have can't be fixed by just dumping in some superchunks and throw rugs. There are major underlying issues that have to be addressed, and doing so does not mean re-arranging the furniture: means re-arranging the walls, windows, doors, ceilings, HVAC and everything else.
- Stuart -