U47 by Mic and mod noise problems

[alexgras]

Hi guys, I have a big problem. Big because I have to resolve it in short time because a singer that is recording in my studio wants only record with this microphone where I'm having problems.
I build the microphone with success... it worked till 2 month ago.... no problem.... only noise we know 408a in parallel. Now.... The problem is in the SAMPLE that you can hear here....  SINE NOISE at high frequency.... I'm thinking that I have to change the 408.... but it's really this the problem? can be also the capsule?
Please help me

https://www.dropbox.com/s/703hwh5ristuj5u/NOISE%20u47.wav?dl=0

 

[Majestic12]

Most likely the tubes, which ofter are / become noisy.

Mic & Mod doesn't have a good reputation here in the forum, I don't think you'll get much of help concerning their products.

 

[granger.frederic]

check the wiring on the output transformer ...

 

[ln76d]

Quality control of chinese overpriced microphone kits.