I am thoroughly enjoying using my QA401 - great hardware!
I would like to know what are the best parameters for measuring/quantifying amplifier noise? I prefer unweighted measurements and use a 20-20 000Hz bandwidth - I am presuming that because bandwidth is digitally derived this 20-20kHz is genuine noise bandwidth and i do not have to take into account any filter slopes used to define the bandwidth like in an analogue analyser.
Should I use averaging? I am not looking for repetitive phenomena just noise quantification, so it would seem averaging should be off…or does averaging simply affect the display of the noise and not its power/amplitude?
Should I use any windowing? It seems to me that any window (except rectangular of course) will bias the measurement.
What does the N+D Level actually measure?
On a separate note was reading your notch filter post and wondered would it be possible to export FR measurements in the same way so as to use them as self-correcting weighting files? My QA401 is 0.2dB at 20kHz and I would like to get it flat to 50kHz for measuring phono preamps.