Incorrect impedance measurement

[DELAMOTTE]

I performed a calibration (photo 1) of my sound card on my PC thanks to the recommended mounting to measure the impedance of a speaker. I then made a measurement of impedance of a 3 "speaker and I obtain the following result (photo 2). I have no bump but a hollow at the level of the resonance frequency and all the curve is abnormally too low, less than 1 ohm in the middle of the curve.
Where does the problem comes from?
Merci pour l'aide thanks for the help

 

[EarlK]

I performed a calibration (photo 1) of my sound card on my PC thanks to the recommended mounting to measure the impedance of a speaker. I then made a measurement of impedance of a 3 "speaker and I obtain the following result (photo 2). I have no bump but a hollow at the level of the resonance frequency and all the curve is abnormally too low, less than 1 ohm in the middle of the curve.
Where does the problem comes from?
Merci pour l'aide View attachment 31205 View attachment 31206 thanks for the help

It seems that you did an acoustic ( spl level ) calibration instead of an electrical ( using resistors ) calibration.

As far as I can tell you did not actually do the impedance calibration setup properly.

That's my guess.