- Nov 29, 2017
I think that is a function of the higher noise level of R&S measurement gear he is using.
In theory, that R&S should be pretty low noise - about 2uV by the specs http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/Rohde & Schwarz Audio Analyzer UPL (brochure).pdf which isn't too much higher than most AP's whose specs I've seen. Perhaps the THD+N plot is more flat in this case due to the dominant noise source being in the analog stage, meaning that relative digital level (and the DAC's nonlinearity) doesn't make an impact until high outputs?
Edit: Upon a moment's reflection, that would only make sense if the plot was referencing distortion products and noise to an absolute level, as Mindbomb says. If the THD+n is relative to the fundamental, all that would make sense would be that this is distortion, rather than noise, based, and the analyzer is simply low enough in noise (and the FX Audio high enough in distortion) that none of the distortion is hidden in the noise floor.
Just create a signature and put association/title/name of the company there as you see in mine.
Gotcha! That should be set up now. Just wanted to check, I know some places prefer to have members of trade or others with potential biases permanently flaired by admins.