The Bottom graph shows the original 305 measured by Harman. The difference between treble and low-mid is about 1 to 2 dB.
The top graph shows the new 305P mkII measured by Amir. The difference between treble and low-mid is around 4 dB !
What happened between the two versions of this speaker ?
A few hypotheses come to mind:
- A reference axis issue similar to the Neumann KH 80 snafu
- Sample-to-sample variation and Amir measured a particularly bad sample (not unlikely given the price range, I wouldn't expect quality control to be amazing)
- Actual differences between Mk I and MkII. Seems unlikely given the waveguide looks exactly the same.