A bit later than i wanted, but I finally got the measurements.
This is a graph showing the Neo3 PDRW response curve for with and without the deep cup attached. (1/6th smoothing)
Red: Deep Cup Green: Open Back
% THD graph
Aside from the peak at 1.7K Hz, the mod's response is actually quite smooth, esp from 2K-20K Hz.
Open-backed, I'm a bit surprised by the 2dB dip in the response around 2-4K Hz, but it gets some pretty good extension, easily down to 600Hz
I'm actually the most surprised by the rise in THD, esp above 5K Hz..
But I'll see how the standard Neo3 fares, as well as testing the GRS-3, since it will be a more direct comparison to the PDRW model I have currently
Next time I get to do some testing, it will be with the standard Neo3.
It will also be a little more involved, since I'll need to mod it with both the cup, but also some thick yarn, to be the closest approxiation to Danny's GR Neo 3.