I can't send you the MDAT file right now, but all I can say is that we were all surprised by the curve and what we heard. In reality, looking closer to the data it's more like 3 dB's and in the highs it's more. Between 4 and 20k it is way more uneven.
Then there's something wrong, either with the way you did the test, or with the way you are interpreting the results. It's really, really hard to believe that you got the low end flat but the high end has large swings in it. That makes no sense, and I can't even think of any acoustic situation where that could happen. Something is wrong here. I suspect a flawed testing procedure. I'd really suggest that you should repeat the testing procedure, carefully Here's how to do it right:
http://www.johnlsayers.com/phpBB2/viewt ... =3&t=21122
there is no real room treatment nor soffit mounting, just a few foams and vinyl shelfs with foam covering the vinyls.
Then the
highs should be reasonably flat, and the
lows should be uneven! It makes no sense at all that you could get flat lows and messed up highs with that type of treatment. I suspect there was either an error in the test procedure, or in the equipment, or in the interpretation of the results.
Room sounds surprisingly good with so little treatment. Not utterly good, nor gorgeous.
That's a major indication that there's something wrong with your test results: A room that has flat response does not "sound" like anything at all! It certainly does not sound "good", and even less "gorgeous". Many people don't like the way a flat-tuned room sounds, because it is absolutely neutral, and has NO sound of its own. It sounds like "nothing". So if you feel that the room sounds nice, then that's a sure sign it is not flat.
What is the overall RT-60?
Sizes are: 5.26m x 3.51m X 2.11m.
It's a small room with a low ceiling, the floor area is less than the minimum recommended for critical listening, and even though the ratio is reasonable, it's not really that good. In a room that size with minimal treatment, there would still be modal issues at around 82 Hz, where your 0,0,1 axial and 2,1,0 tangential modes line up nearly perfectly, plus another modal issue at around 98 Hz, where your 0,2,0 and 3,0,0 modes are right on top of each other, less than 1/10th of 1 Hz apart. I would also expect to see the typical floor-bounce dip at somewhere above 100 Hz., SBIR from the front wall, plus various other issues. None of those can be fixed by the treatment you have in there right now.
So please repeat the test, carefully, following those instructions. It's real easy, and only takes a few minutes to do. Then post the MDAT file, and I'd be happy to analyze it for you.
nor soffit mounting
Then why does your diagram show soffit mounting?
Listening position would be between yellow and green triangle.
That would not be optimal for that room. There's a process for arriving at the optimal position, and it won't be where you are wanting to put it.
between something like 3.5 to 4.5m back from the front wall there was some phase and comb filtering
That doesn't make much sense! If you have a phase problem at
one point in the room, then you have it at
all points in the room! The phase relationship might change as you move about the room, but it will still be there, at all locations in the room.
I'm also glad that my friend considers investing in acoustics, aka his room, instead of gear
Very much! However, if you try to treat his room based on incorrect acoustic analysis data, you could end up making things worse, not better. You really need to do the testing properly, and make sure it is correct, before proceeding to the treatment stage.
- Stuart -