I believe the theory behind PC microphone connections is that the same
connector will work for both dynamic and electret microphones. Dynamic
microphones use mono plugs, which short the "bias". That isn't a
problem as the bias is not a voltage source - it is actually the
drain(?) load on the pre-amplifier in the electret microphone - so quite
a high resistance source. Any DC blocking is assumed to be in the PC.
Electret microphones connect the "bias" by having ring and tipped
connected together.
Electret microphones don't need any real bias, as the electret provides
a permanent electrostatic field.
--
David Woolley
Owner K2 06123.
On 29/10/13 15:22, MontyS wrote:
The rear mic jack is a mono, not stereo, jack. It will short the ring
and sleeve together. Audio is on the tip, as is the voltage. The mic
should have a blocking capacitor to isolate the audio from the voltage.
This is standard for every radio I have owned. If a stereo jack is
used, it would be for PTT, not a separate bias connection.
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