When a measurement doesn't match, we need to see why. Either the measurement is wrong, or the published info is wrong. In this case, the difference in Le measurement has been discussed many times over the past 15 years. Most programs like the WT3, Sound Easy, and others, will try to fit the very bottom of the curve. The curve fit points are all within the first few octaves above FS. They are designed to fit a VC acting as an iron core inductor with the solid steel pole inside. The copper sleeve forces the VC to act like an air core, removing the interaction with the pole. What results is the software being unable to fit the curve. The measurements at DriverVault stated:
"SE's curve fitting did not like the weird impedance profile of this driver due to the full copper sleeve on the pole piece, so measured Le is a bit higher than actual."
What happens is the same in all the TD woofers. The copper sleeve flattens the curve making the VC become like an air core inductor. In the case of the TD6M there is a very slight rise below 500hz and the WT3 will fit to that portion of the curve. However, you can see that is really not accurate as the rest of that curve doesn't follow the small bump. Here is an actual measurement of the impedance curve of the TD6M:
Even at 20KHz there is still barely any increase to the impedance curve. Now if we look at the modeled curve putting in .15mH and 1.13mH we see why it is incorrect. The green curve shows the .15mH inductance and the blue curve shows the 1.13mH inductance.
You can see that the .15mH measurement is closer to what is really seen. In reality though, even the green curve shows far more predicted increase by 20KHz than the actual measurement of the driver.