(Dick Pierce) wrote in message ...
(Svante) wrote in message news:n3Idb.619108$uu5.100398@sccrnsc04...
(Dick Pierce) wrote in message ...
(Svante) wrote in message news:hO3db.435049$Oz4.241458@rwcrnsc54...
The phenomenon we observe is that as we go higher in frequency, we
see an increase in eddy current coupling in the metal parts, which
have a fairly high ohmic loss. The result is a decrease in inductance
and an increase in resistance that pretty reliably follows a 1/sqrt(f)
for inductance and sqrt(f) for resistance.

Pardon me for responding twice, but I thought you may be interested in
seeing the actual curves. The curves are available at
http://www.tolvan.com/disected_lsp.jpg
As I said I observe the same as you do, the red line is from the
disected loudspeaker, without any iron or magnet present, the black
curve is the impedance of a normal element of the same brand and
model, and the green dashed line is modelled data with a "n" value of
0.67. The model also includes the mechanical resonance, as you may
see. I think we agree that there is a huge difference between the
black and the red curves.

Now that I have read it more carefully, your data is entirely consistent
with the current knowledge of the behavior, including my own measurements
and models.

So, what about the 1 kHz? Have you actually seen in datasheets that
manufacturers specify that they use this frequency when they measure
the inductance? What about tweeters, shouldn't there be be a great
interference from the mechanical resonance at 1kHz?

The reason that I ask is that I am writing a simulation software, and
I would like to use the inductance figure that one can find in the
datasheets. This is why its usefulness is of interest for me.