[Elecraft] K2 and K3 Microphone Input Impedance

[Jim Brown]

On 1/6/2011 2:55 PM, George & Jan wrote:
> It is not critical at all - should be at least 10 times the microphone
> impedance.

Actually, the current applicable IEC Standard DEFINES the impedance of a 
microphone as 5X its rated load impedance. And yes, a higher input Z is 
better -- the rated impedance is a minimum value.  Most professional 
mics have an impedance of 150-250 ohms, and most pro mic inputs have an 
input impedance of at least 1K-1.5K ohms, and there are excellent 
technical reasons for values of 5K ohms or greater.

73, Jim Brown K9YC
Member, AES Standards Committee and WG on Microphones