Sean B wrote:
http://www.sdiy.org/oid/mics/Schoeps.gif
So it's a cathodyne-style phase inverter realized with a jfet.
** Aka "concertina circuit" and other titles PLUS a pair of emitter followers with common collectors producing a 6.2V DC supply for the RF oscillator that boosts 60VDC. At least one of the Rode FET condenser mics ( the NT-2) use a near identical circuit - strange about that.
Are they just dumping one phase to AC ground to get a sensitivity
reduction?
** Nope.
I don't get the connection coming off the DC-DC converter going back
to the jfet's drain. Can anyone shed some light?
** In standard connection (B), inverted audio signal from the FET drain is coupled to the +60V supply feeding the capsule producing a 5dB gain loss through negative feedback.
In the (A) position, that link is simply removed and C1 is used as a final noise filter.
..... Phil