In the time period of 1946 to 1956 the radio station, that was set up by the british occupying forces, the NWDR (North West German Radio) developed many of the audio jewels we call classics today.
Due to the restriction of the Allied forces after WWII german engineers were not allowed to developed, research or build/manufacture, any other aspect of electronic than what we call today consumer electronic.
Many of the brilliant minds that thought up the guidance systems for rockets, the german version of the radar and radar deflecting systems, were now back to the drawing boards developing, either radios receivers or transmitters and related items...
With manufacturing equipment of the former R&D center of the german navy and the former Imperial Broadcasting Agency (Reichsrundfunk) the now called "Technische Werkstaeten/Zentral Technik" (central technology) started to develop an entire new standard and the equipment for audio/recording equipment that was use in the new german broadcast network.
About 20 engineers worked under the technical supervision of Prof. Nestler the former Head of R&D of Telefunken ELA (Electro Acoustic) Lab.
Aside 90% of all V /U and W-series modules, they also developed and build the M49, the KK47 capsule and the MSC series of tubes, the first SD nickel capsule microphones, the 140 Hall plate and several test/measuring instruments. Later licensed to companies such as Neuman, Hiller, Telefunken, Siemens, the historic TAB, EMT, etc. etc.
In 1956 everything was over, the german government split up the NWDR into several smaller radiostations now called NDR/WDR/SWF/SDR, etc.
The Zentral Technik became the IRT (Institute for broadcast technology) and moved from Hamburg to Munich.
All V-Series pre amplifier were based upon the pre war/war times V40 series, V72 and V76 where developed about the same time on the V41 preamp, etc.
The resistors are Rosenthal metal oxide.... relabeled for the different companies; grey Telefunken, red TAB and Neumann and green Siemens.
Best regards,