The secrets of Neumann U47 part 2

This is rewriting the old post possibly with some additions


1. Heater voltage reduced. The heater voltage used is less than the specs of the VF14 tube. See next post in advantages of reduced heater voltage or cathode temperature.


2. Cathode connected to a very snall resistor, It is possible For it to be small as Georg Neumann passed the heater current thought it too. V=IxR (Comment by studio technician Boby).


3. Rectification effect at large signals. The tube gain is reduced. The release constant of the variable gain or compressing action is dictated by the discharge of the grid through the grid leak resistor?


Reference:


Neumann U47 schematic


Altec or RCA BA6A compressor schematic