[Elecraft] K3 Yamaha CM500 vs Koss SB40

[Bob McGraw - K4TAX]

As a general rule, if you measure the DC resistance at the connector on 
the mike and it is less than 2K ohms, it is likely dynamic.  If it is 
10K or more, it is likely an electret element.    If it is near infinity 
then likely there is a DC blocking capacitor in the circuit.   The R 
values have nothing to do with impedance, as they are just DC resistance 
values.

The electret element requires bias.  They dynamic will likely distort 
when bias is turned on.

73
Bob, K4TAX