Measured Le wrong?

[Vikash]

XLS 10" has been run-in and measured. The SW measurements are very close to the Peerless spec sheet, except for Le. Any ideas?

		Fs	Re	Vas	Qms	Qes	Qts	Le
Peerless T/S	18.9	3.4	89.70	2.63	0.18	0.17	4.30
Measured	18.52	3.4	89.25	3.27	0.18	0.17	0.79
Difference	0.38	0	0.45	-0.64	0.00	0.00	3.51

[Svante]

I am not surprised and I have actually never understood how the manufacturers can specify a voice coil inductance. The inductance of a voice coil is *not* like a ordinary coil, it is very lossy and the impedance does *not* vary as w*L with frequency.

Below I have overlaid two response and impedance simulations on the Peerless XLS10 responses on Peerless' home page. The red simulation are with a normal inductance of 4.3 mH as specified in the data sheet. In the green simulation, the inductance is modelled as lossy. The match is so good that the modelled and simulated curves are hardly separable. The absolute value of this voice coil inductance impedance goes as w^0.67 * 2.3e-3.

Having realised this odd behaviour of most voice coils, it is a mystery to me how the inductance specs in the data sheets are derived.

[Svante]

Originally posted by Svante
The absolute value of this voice coil inductance impedance goes as w^0.67 * 2.3e-3.

Sorry, should be w^0.67 * 1.77e-3.