In 2008, I had Udo at MTG reskin an M7 capsule for me. Since then, it has sat unused in its airtight container that they shipped it back in. (...)This week, I happened to take a look at the MTG capsule, as well as the Thiersch, and they are already developing the familiar PVC cracks. (pics soon)
Neumann's K47 - when they are at their best*- are equal in emotional draw to a healthy Neumann or pre-2000 MTG M7 PVC, but they draw from a different sonic terrain: their authority rests on the superb rendering of the lower mid range octaves, and they don't quite have the pointed "liquid gold" high end of the M7, yet make up for that with their rich yet robust lower register.
The container itself can be the reason for problems, by outgasing destructive chemicals.And don't forget the electrolytic capacitors, ALL of the do outgas to a certain amount.
There was a bit where MG had just shifted over to mylar, were delivering mics with M7 that way (...)