I have been reading older posts in this group regarding the inductance
of the voice coil, and I realize that the inductance is far from
ideal, that its inductance drops with frequency (in one way of looking
at it). I also read an article by Marshall Leach (JAES no 6 2002, p
442-) which describes this phenomenon quite nicely and presents a
model that I have succeded in fitting very well to a small number of
real speakers I have had at hand. I actually carved the cone and coil
away from one element and measured the impedance curve again, and
indeed the impedance was quite different. Apart from the obvoius (the
peak corresponding to the mechanical resonance disappeared) the
inductance now looked like an inductance normally would, ie with a 90
degree phase shift and a +6dB/oct slope above some frequency (for the
disected loudspeaker, nb).

This brings up the question what the manufacturers say in their data
sheets. They mostly specify an inductance. They rarely specify the
"lossiness" (the n value in the article above) of this inductance or
the frequency at which the inductance was measured.

So, what does the "voice coil inductance" figure that the
manufacturers supply us with mean, really?