I have added some acoustic foam tiles to the ceiling. Kept the two temporary acoustic absorber panels behind me (which are 1.25m x 0.45m x 180mm deep each not what I said earlier) and done some more measurements with the ECM8000 and a Rode NT2000 microphone which is set to omni to compare.
Used Behringer ECM8000 microphone
Used Rode NT2000 microphone
The graphs look quite different and to be honest I think it more likely that the NT2000 has produced a more accurate curve. I say this because the slight hump I am getting at 10KHz corresponds with the graph shown in the microphone manual. This can be seen
here.
Also Sonnie showed in the thread
Professional Mic Calibration where there is hump at 15KHz for the Behringer ECM8000 that was calibrated. So I suppose it looks a bit like that as well. I can see why getting a mic calibrated can help, just need to find someone in the UK.
So after all that, apart from the peaks around 50-60Hz it looks reasonably flat, would you agree or not.
I have not toed out the speakers very much as they would end up being too far off axis with my listening position which is very close.
Not sure how to remove those low peaks, any pointers appreciated.
Thanks,
Mike