I'm seeing some strange things in the images of graphs you posted, but it might just be the settings you chose. I'd like to have a look at your MDAT files directly, but for some reason your upload service in New Zealand won't let me download them.
You can upload your MDAT files directly to the forum: there's no problems with capacity or bandwidth, and the forum will happily accept MDAT files, as well as many other file types. That also means that your files will always be accessible, and not subject to the vagaries of upload services.
So please upload your MDAT files here, and I'll take a look.
I also noticed that your overall decay times are very low: around 100 ms. That's a little too dead for a room that size. I'd suggest that you do something to return some life to the room: diffusive reflective surfaces, in front of the deep absorption, for example.
Also, an answer to an earlier question you had brought up:
I am aware about the invalidity of rt60 in small spaces but rew actually measures rt30 but it still names it rt60. Do all these designers mean t30 also?
This is more of a semantics issue: For small rooms, the measurements should more correctly be called "decay times", rather than "Reverberation Times". Even though small rooms do not have reverberant fields that decay over time, they still do exhibit just plain old "decay". In other words, the sound levels for each frequency band diminish over time, just as they do in a large room. The issue isn't that decay doesn't occur: clearly, it does! The issue is that, technically, it cannot be called "RT" (Reveberation Time), because there is no statistical reverberation time in small rooms. So what is "decaying" in small rooms is not a true reverberant field: just the sound level. In fact, the final outcome is the same: sound levels decay over time, at different rates! So the issue is really about what to call it, from a technical point of view. The only real difference, from a pure acoustics point of view, is that you can't validly use the statistical analysis tools to analyze what is going on... but you can still use the rest of acosutic theory to understand the issues, and to design treatment for them.
Bottom line? For most home studio builders, it doesn't really matter what you call it! RT is technically not correct, but it's a lot easier to write "RT60" than "non-statistical sound level decay times".... so pretty much everyone still refers to it as "RT60", even though it really isn't, from a pure technical point of view.
Also, "RT30" means basically the same thing as well. This is a different issue, but worth mentioning too: Since it is pretty hard to have a loud enough sound field to accurately measure a true decay of 60 dB, "RT30" measures the decay time over a range of just 30 dB, and extrapolates that to 60 dB. That's the issue. In practical terms, it's the same thing just measured a different and slightly less accurate way. The reason is simply this: The noise floor for the low end of the spectrum in a typical home studio might be 35 dBC. To get a good measurement, you'd want your lowest level about 10 dB above that, so call it 45 dB. Therefore, to measure "RT60", you would have to have to start with a level of 105 dB or more. That's LOUD! Your speaker might have trouble dong that, it's harmful for your ears, and even then it STILL isn't loud enough, strictly speaking: To get a true "RT60" measurement, you should start with an extremely loud, extremely short "impulse", such as a gunshot, or a large balloon bursting. Since you probably don't want to be firing guns or popping hundreds of large balloons in your room, that's not the way it is measured. REW uses an entirely different method, which is just as valid, but doesn't need any gunfire.l¿ And it can also do it at lower levels: around 30 dB lower than would be needed for a true 60 dB decay. Thus, it can estimate RT60 rather will by only measuring 30 dB of decaty, then using mathematical methods to extrapolate that to 60 db.
Hopefully, these explanations help to clarify the issues a bit!
- Stuart -