Discussing how to load a mic output to measure the -6dB point to determine output impedance...
On 12/18/24 20:12, kandoit7 via groups.io wrote:
If we consider it as a load on the output, I think it would be sufficient to connect a resistor between Pin 2 and ground to measure the output.
The difficulty is that there are several (at least three) types of microphone outputs to be aware of.
1. Classic dynamic mic.? No connection at all to ground (other than for shielding), the output is between pins 2 and 3.? In this case you would put the resistor between pins 2 and 3.
2.? Balanced active mic.? This is where an active output stage feeds pins 2 and 3 separately but equally (other than the two pins have opposite polarity).? You would probably put the resistor between pin 2 and pin 1.
3.? Unbalanced active mic.? This is where one pin gets all the audio output, the other is often "impedance balanced" so that a balanced input would get equal induced noise (noise picked up by the cable in between mic and preamp).? You'd have to figure out which pin has the audio, and connect the resistor between that pin and pin 1.? As an alternative, you could try to measure the resistance between the other pin and pin 1 to see what the mic designer thought would be the correct output impedance.
Sorry for making this even more complicated. That's a part of the process, I guess. :)
-Scott
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---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
