amp input levels?

[Neil Groves]

This is all technology that as yet i don't understand, i will brush up when i get my projects finished, actually i am learning all the time while i am constructing thanks to you people.

Neil.

 

[4pyros]

oh, how do i go about measuring output impedance of a circuit? or input impedance for that matter?

Neil.

The best way may be using spec sheets. The impedance of a circuit will generaly change with frequency and so is usually graphed.

 

[audioguru]

oh, how do i go about measuring output impedance of a circuit? or input impedance for that matter?

Impedance uses an AC signal. An ohm-meter uses DC.
You can feed a very low impedance AC signal (from the output of an opamp) through an adjustable resistor (Pot) to the input or output of a powered amplifier. While measuring the load AC voltage turn the resistance until the amount of signal across the load is half of the maximum. Then the resistance of the pot is the impedance.