I have tested and retested in several set-ups a recent sample of Thiersch's new "Blue Line" (PVC) M7 Neumann capsule copy.
First, this is a wholly-Thiersch-manufactured capsule, i.e. not only does it use Thiersch's diaphragms but also his brass backplate which is patterned after the "Berlin M7", the type that has a particular pattern of concentric rings at the edge of the backplate, and which features other peculiarities.
This effort is a whole step closer to the 'real thing' than his previous attempts, and he is certainly closer than his competitors in achieving the goal to emulate the Neumann M7. Here we have a balanced frequency response in general, with just a tiny bit too little high frequency sheen, reasonably good side-to-side performance, and a pleasant timbre, void of shrillness, lisp, sibilance, or dried up bass.
Considering the trend, I am optimistic that he may succeed in the one area this capsule still lacks- the magic of an M7 to get behind the note, of having a level of resolution and speed of response, from the very high frequencies through the lower mids, that allows the voice or the music come to you, without too much listening effort. A "pearling off" effect, if you will, where the apparatus- the capsule- helps you along.
None too scientific, and probably an annoying description for the pocket protector types among acoustic engineers; but such is the quest for emotional satisfaction through the ear- a decent scientific explanation for the link between hearing, absorbing and the mechanics of getting there is still beyond our reach.
I have some ideas how to maybe overcome what may still be missing in Thiersch's M7 effort. To that end, I have started discussions with him; so let's toast to a successful M7 year!