Telefunken 251 Clone finished

How are you simulating the transformer? The capacitor interacts with the inductance of the transformer, I think.

Since I don't have the specs on the T14 I ignored it in my simulation.  I'm simulating up to and including the output cap.  If my model for the 5840 is "close", I do believe the 400pF I have installed now could even be increased based on the resistances in my circuit.  The purpose is to roll off high frequency starting about 16kHz (in the original mic) so changing to the 100pF would actually move that point upward.  The mic is not overly bright and I haven't experienced any RF noise issues (I've scoped the output). It was an error on my part using the 400pF but it looks like its not really an issue in my current circuit.  I'll leave it alone for now.

Regards,
Jeff

Could you please post the schematic for the AC701 251? All I can seem to find is the E 6072 version. Thanks!

its 100pf