I've been doing some work with interstage impedance and I keep getting confused and I can't seem to get the correct answer myself. I know Input Impedance should be 10x the amount of the previous output stage, but I'm not sure where measurements should be taken from.
In the attached image, I’ve got 10 Ω coming out of the previous stage, 100 MΩ into the next input stage and an equivalent resistance (pot at 50%, linear taper) of 2.5k || 1M = 2.93k.
Now the query is, does the 2.93k get factored into both input and output impedance or only for the output calculation?
Zout = 10 + 2.93k
Zin = 2.93k || 100M
or
Zout = 10
Zin = 2.93k || 100M
I've seen the source impedance also calculated from the output of the potentiometer. I can't seem to work out where one calculation ends and another begins.