about measuring impedance

[xiao]

Why is the high frequency band like this ? "In the picture, a resistor is being measured., but the same situation can occur when measuring loudspeakers."

 

[John Mulcahy]

A little noise pickup, or phase noise in the interface reference clock. Might clean up with the impedance measurement noise filter options.

 

[xiao]

A little noise pickup, or phase noise in the interface reference clock. Might clean up with the impedance measurement noise filter options.

Thank you for your answer.I tried it, but it didn't work.
Is it because the input is too high? As pictured -40 dBFS?

 

[Brian Steele]

Last time that happened to me, it was because of the choice I made for sampling frequency.

 

[Andyung]

Hi, could you givme some advice ? I can only use Notebook (now HP 8570p) and I have to buy an external USB audio interface, to create the proper setting to measure the speaker impedance result. Coud you please advice to me a best compatible audio USB card that you have already tested with good results? I was thinking to M-Audio 194/4 or any other advice?

 

[dcibel]

Pretty much any 2in/2out interface will be fine, just stay away from Behringer UCA202. Cheap option could be Behringer UMC202, or can look at Steinberg UR22, for more high end unit look at Motu M2.