Dear Claus.
I am very grateful to you for your help.
Your advices help me a lot.
I want to ask you a question about the problem with my microphone U67. I'm familiar with a skilled craftsman. He is known as one of the best masters in musical audio equipment. For example, it can parse and compile SSL 4000. But he is not a specialist in microphones. Now to the point. I feel my microphone is losing the low end. The master tells me that the capacitor C9 is responsible for this. When we extracted it from the microphone, the capacity was normal(Capacitance is OK). But the master does not have a stand in order to test this capacitor. If we did not have a capacitor of a suitable size, we put two capacitors with a superior capacity of 4 times. These capacitors have a voltage of 200 volts. Master said that this is dangerous for the microphone. With the audio test, the microphone received a low end, but the sound turned out to be harsh. Please advise which film capacitor should be placed in the microphone?
At the second edition of U67, Neumann used film capacitors.
I see such suggestions on Ebay:
MKC 1860 250V 0.47uF 474 10% HV Non-polar Film Capacitor:
https://www.ebay.com/itm/1lot-6PCS-ERO-MKC-1860-250V-0-47uF-474-10-HV-Non-polar-Film-Capacitor/181834945143?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649 CAP, FILM, PET, 470NF, 250V, AXIAL MKT1813447255G By VISHAY
https://www.ebay.com/itm/1-X-CAP-FILM-PET-470NF-250V-AXIAL-MKT1813447255G-By-VISHAY/192229054155?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l26491. Could you advise me how to act?
2. Why is the U67 Schematic talking about 250 volts, but in reality I saw in several microphones 350 volts?
3. Maybe it's not a condenser?
PS: Any advice is welcome.
Second edition of U67: & My capacitor: