Impedance measurement

[lorrain]

Hi,
In Impedance measurement, Rin (soundcard input impedance) is limited to 1Mohm but some soundcard have higher levels of impedance (more than 2Mohm for Focusrite Clarett in configuration Instrument Input for example) .
It would be nice to accept higher values
Eric

 

[John Mulcahy]

If you go through the calibration steps the input impedance value isn't used once the reference resistor measurement has been completed, in effect it is determined from the calibration results.

 

[lorrain]

Thank you very much for your answear, John.
I understand that if we calibrate in 2 steps only (without precison resistance) , the knowledge of Rin is useful and if we calibrate in 3 steps with the precision resistance, the knowledge Rin is not useful. Is it correct?

 

[John Mulcahy]

Yes, but the errors from not making a reference measurement will be far larger than the influence of such a high input impedance.

 

[lorrain]

Thanks
It's clear