Projet Micro Neumann U47 Fet i Clone DIY !

Here is the asnswer I got from Brian Sowter ,

1303 (U47 FET). Ratio 9:1 Impedance ratio 16200/200 Ohms.

1304 (U67). Ratio 7:1 Impedance ratio 9800/200 Ohms. Feedback winding 22:1

Both cores are 100% Mumetal. Expected LF cut off frequency less than 10 Hz for both transformers.
Total Harmonic Distortion better than 0.05% at 50Hz.


I am just not sure about the core size , he is expecting some spec sheets soon , will keep ya posted ,

Dany,


Other info from B.Sowter,

I have released these transformers to the works and Ruth will be in contact with a quote.
Type 1303 U47FET
Type 1304 U67
Both will be in 34 mm dia x 24 high cans.


I am sure there is a possibility to have them outside the can if you ask for it ,
this is gonna be fun ,
Dan,

This is a dual-diaphragm, large diaphragm (34mm OD) capsule with a single, shared backplate and center-terminated 6-micron Mylar diaphragms. Because the U47 Fet was a fixed Cardioid microphone, Neumann used K47 capsules (designed “K47Fet”) whose rear sides did not meet specifications for use in multipattern mics. Therefore, unlike a multipattern K47 mic, a dirty or abused U47Fet capsule cannot be rotated 180°.