Signal to noise ratio LOW, even the "chek level " are OK

[grillotalpa]

Hello everybody,
it has been some years i'm a happy user of REW for measuring and tuning my audio set;
i have a behringer ECM8000 connected to UPHORIA UM2 usb external audio I/F,
no problems till a couple of days ago, while measuring it started to give me messages regarding
the quality of the audio recorded as in fig 1 and if i try to increase the output volume it warns me there was a clipping .
I always used to set mike input volume knob on the I/F at max and output volume of my AVR at -30dB,
and check levels before measure are OK.
I tried to uninstall and reinstall REW 5.20.14 (tried stable version 5.20.13 too),
and at last tried even with another laptop but the results are always the same.
The poor audio result are visible in fig 2 in STEP function of overlays:
in red the recent measure, in green the measure taken months ago.
Have you got any ideas about what could have happened?
Could be a broken mic or audio I/F fault?
Thank you in advance.

 

[AudiocRaver]

Assuming no other variables, I would guess the audio interface went bad. Perhaps an input device or a power filtering device. Do you have another you can try?

 

[grillotalpa]

unfortunately not.
do you think is more likely an I/F fault than mike problem?

 

[John Mulcahy]

Can you attach an example mdat file?

 

[grillotalpa]

Hello Mr Mulcahy,
here's the mdat file with measures taken in january and now.

 

[John Mulcahy]

You have set the IR windows very wide in the recent measurements. The left window is 1000 ms, which is a very odd choice since the region before the peak is noise and distortion, not signal, so you are adding a lot of noise there. The right window is 2000 ms, but your impulse is already in the noise floor at 400 ms so again you are adding a lot of noise. Try the default 125 ms left and 500 ms right window settings, as used in your earlier measurement.

 

[grillotalpa]

Here's the measurement 125/500.
Anyway it gives me the same warning signal to noise too LOW.

 

[John Mulcahy]

The warning is shown below 30 dB SNR and the measurement was 29.9. I'll look at relaxing the warning threshold since the measurement is fine.

Is there a reason you have the Analysis preferences set to retain the full IR? It means your measurements are much larger than they need to be as you are using a long sweep.

 

[grillotalpa]

No, there was not.
I thank you for your patience and your advices, and first of all for your excellent work.