Input Impedance

[nagster]

Audio Science Review people
I look closely. It's interesting. Thank you.

I also want to know the measured values of the input impedance characteristics of amplifiers, etc.
The impedance analyzer is excellent, but isn't it okay to measure with an LCR meter?
I usually check with an LCR meter.

 

[Vini darko]

Hi welcome to ASR.
Have you found much variance from manufacturers specs? It is annoying when audio electronics don't supply this usful information for input and output.
As to your question about the LCR meter , if it's in close enough agreement with that fancy bench tester then I dont see to much issue.
Poor Amirm we keep piling more tests to do on him

 

[nagster]

Mr. Vini darko
You were the first to reply. Thank you.

The measured values displayed on the screen are not helpful.
The above post is not intended for measurements.
As you can see, due to the poor connection, there is no reliability to show the performance of DUT.

My post is an additional request for input impedance measurement.
And one suggestion is to measure with an LCR meter.
The image is a reference example of the tool or means.
Thank you.

 

[solderdude]

The cheapest way would be to simply use a 10k resistor and measure the response of the amp once with and once without the 10k.
Then it is just a matter of some calculus to arrive at the input R and you can even see the influence of input capacitance.

 

[nagster]

Thank you.
Sorry. There was a lack of explanation.
As you said, you can find out by calculating by hand, but I thought that it would be more persuasive if you could see it in the output image of the measuring instrument like the output impedance graph.
It seems that the APx500 cannot output the input impedance measurement result, so I wanted an alternative method.
Thank you.