Correcting Joe's typo, Mic audio is present between pins 2 and 3, NOT
between 2 and 1.
73, Jim K9YC
On 6/9/2020 2:54 PM, Joe Subich, W4TV wrote:
> So which is correct?
They are electrically equivalent.
Pin 2 of the XLR connection is Mic+
Pin 3 of the XLR connection is Mic-
Pin 1 of the XLR connection is the cable shield (ground).
Mic audio is present between pins 2 and 1.
Pin 1 is nothing more than a shield and should be independently
connected to the *chassis at the jack*.
Good quality XLR cables use a *TWISTED PAIR* for pins 1 and 2.
That twisted pair is shelf shielding - particularly good for
rejecting hum. Connecting a shield in parallel with the wire
for pin 3 "unbalances" the twisted pair and makes it much
more susceptible to hum and RFI - particularly when the shell
of the 3.5mm plug/jack is not tied to the chassis/case of the
transceiver.
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