RTF Schoeps CMT30F hiss

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Gachet

Well-known member
Joined
Feb 15, 2006
Messages
144
Location
Bordeaux France
Hi;

I recently put my hands on some kind of schoeps CMT30F with cardiod capsule that works.
The capsule is in great shape but the preamp has a lot of hiss. It's manageable on loud sources but it's not on vocals and quiet accoustic instruments.
I think the preamp has been modified to accomodate +48 instead of -10.
NPN transistors have been replaced with PNP except for the FET. 
the 5.6v zener along with the polarized caps are reversed.

My question is:
is that ok to replace polarized caps and transistors to reduce hiss?
What is common practice in that case?
I saw that cleaning the board was important regarding noise.

Thanks
public

 

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