In audio interfaces (e.g. USB) you often find one input that can handle XLR and jack.
The jack input is usually used for an electric guitar input. For that, there is a "High-Z" switch to it.
It's clear for me why there is a need for a high-impedance input with pickups from electric guitars - the pickups themselves can have an impedance of a few 10k in some frequencies. To get the amplitude of the signal at the audio-interface input as independent as possible from the frequency, you want to use a high-impedance input stage (resistor-divider etc.)
- What is the disadvantage of a high-impedance input?
- Why do we need the possibility to make it a "not high impedance" input?
- Shouldn't microphones work with high-impedance inputs as well?
- Wouldn't it be more linear?
One idea that I have is, that high values of resistors are more noisy than lower values and of course you want to have as little noise in your signal as possible. But as far as I know, the high-impedance is done by using JFETs instead of BJT. Am I wrong?