Although I really really don't want to be one of those guys that asks for advice and then doesn't take it, I'm having to make an executive decision and for now I'm going to leave the flush mount speaker option
No problem! We'll always try to give you the best advice, but often there are overriding reasons why you can't take it. "No money" is a very valid reason. If you can't do the soffits now, then by all means postpone them until you can.
So, I've done a REW test to get the ball rolling, hopefully I followed the instructions carefully, I tried to read some other forum posts to see what mistakes us newbies were likely to make and hopefully avoid them (mains hum etc). On first look, to my novice eyes, the results look a little bizarre....
It's a bit unusual, but nothing way out of the ordinary. It looks valid, and clearly the room was absolutely empty when you did that test, correct? Not one single shred of treatment of any kind in there?
Test was with an Avenson Audio STO-2 mic (flattest in my collection)
That's fine. Good choice for a measurement mic. They don't come much flatter than that!
A couple of things about the way you did the test: first, you followed the REW instructions and did them at a level of 70 dB for each individual speaker, but I prefer to do calibrate and test at 80 dB for each speaker, which automatically gives you 86 dB with both of them on, and 85 dB just happens to be the "standard" level for calibrating studios and cinemas. It's also the level that many engineers like to mix at. And at that level, you are pretty much guaranteed of triggering all the modes that want to be triggered. So for all your tests from here on, please re-calibrate to get 80 dB for the "L" and "R" speakers individually. After you do that, do not adjust anything when you do the "LR" test.
Second: You don't need to save each test as an individual file: you can save a whole bunch of tests inside one single MDAT file. Each time you hit "Start Measure", it adds a new measurement set to another tab down the left hand side of the screen. Just make sure to re-name each test as soon as it is done (text box at the top of each tab), so you don't forget which is which. You can get something like 20 or so tests into a single MDAT file, which makes it easy to compare things when you are analyzing.
and I put one at each side of the room against to wall to be as unobtrusive as possible. Perhaps they may have affected the results?
Probably having some effect, but very minor compared to the huge undamped room response,which is thousands of times bigger. Sort of like comparing a speed-bump to Mount Everest...
. At this point in the game, that just isn't relevant.
OK, about the actual data: You need new speakers! Or at least a sub. Those things have no low end at all. Below about 38 Hz, they die real fast. Amazingly fast: by 33 Hz, there's nothing left at all!
As long as you don't need low bass, you'd probably be sort of OK with that, but if you ever need to mix a 6-string bass, grand piano, church organ, 10-octave keyboards, or anything else that hits the bottom octave of the musical scale, then you really do need something to fill in a bit down there.
Second, your modal response is crystal clear: 67.9, 73.2, 94.4, 104.9, 117.4, 132.3, 137.4, 151, 169, 191, 206. I bet if you plug your room dimensions into a mode calculator, that graph would match your data very handily.
I also bet your room is close to square... several of those seem to be occur in pairs that are very close together...
What are the final interior dimensions of your room?
The other thing that is crystal clear is the SBIR dip at around 79 Hz, and other smaller ones at around 96, 121, 158 and 213. I could do the math and figure out which dimension each of those relates to, but I'm lazy right now, and in a bit of a hurry, as I have deadlines to meet on a couple of projects I'm working on. But you can do the math: the 1/4 of each of those will be directly related to the distance between the speaker and one of the walls, referenced to the location of the mic. I'm betting that the huge dips around 79 Hz are related to the rear wall...
So what does all this mean?
1. Major treatment on the rear wall! Superchunks or hangers, for sure, plus whatever else you can throw at that wall. It needs to be killed. But you will also need something in front of those bass traps to keep the highs in the room: probably plastic will do the trick.
2. Large bass traps in several other corners. The front vertical corners, definitely, but perhaps also the wall-ceiling corners? I'd go for superchunks there too, at at least corner absorbers.
3. Cloud: It definitely needs to be hard-backed, and hung at as steep an angle as you can get within reason. And it needs thick insulation both below and above the hardback. I'd go for OC-703 below, and maybe on top as well, or at least thick "pink fluffy" on top. Here too I'd put thin plastic below the bottom absorber before you put the fabric on. Not so much for returning highs here, but more for preventing the insulation fibers from sifting down all over your gear over time... nasty stuff...
4. More treatment! But let's get to that later.
First do the above, in any order you like, but do another set of three REW tests at each stage, as soon as you have it finished, so you can check that it is working as planned. Do the test BEFORE you put the final covering on, if you can, so that do any modifications that might be needed before covering.
Why all this treatment? The target RT-60 time (or more accurately "decay time") for a room that size is probably around 200 ms (I'll figure it more accurately once I know the dimensions). Right now it is well over 1200 ms!
It's a boomy, screamy, clangy, shrill, roaring, hellish monster in there right now! And that's putting it mildly. It's BIG monster, so it's gonna need some serious taming. You have to get it down to a soft, dull whimper... That needs a lot of taming.
The GOOD news here, is that the overall frequency response isn't that bad at all, and there's definitely hope that it can become a really good room. But you have your work cut out for you!
- Stuart -
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Not sure why it did that.