The first measurements came from Neumann's development manager "Markus Wolff", as stated in the article. Only later, with image no. 11, the magazine refers to "their own" measurements.
It however is interesting that those seem to be exactly the same as found on Neumann's website, as well as in "Sound & Recording" - just different excerpts of the graphs seem to have been published at different resolutions. (Why?) // The reason
might be a commonly delegated external laboratory; as the FIDELITY website states an excursion to the measurement facility in Aachen (a German city) - in their
'B&W 800 D3' review. Both the magazines do also state the exact same measurement hardware and limitations, mainly due to floor reflections, of their measurement chamber.
The important take-away is, that the measurements are
inaccurate below 100 Hz, due to the measurement chamber's nature (it is
not fully anechoic).
A 'Klippel NFS' would provide much more reliable data even <100 Hz, as their proprietary algorithms have proven to accurately remove reflections for analysis purposes in the whole measurement spectrum. This is also why Klippel states a higher accuracy than common measurements in an anechoic chamber could provide: even fully anechoic chambers often suffer from interferences of the outside world [<50 Hz].