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Should you include inductance (Le) in a WinISD model?


Distinguished Member
There seems to be some debate about the audibility of (high) inductance in a subwoofer. Some say it's irrelevant at sub bass frequencies, is a HF issue only & is only a problem if the Le varies as excursion increases (hence increasing non linear behaviour). Others disagree and think it is as issue as the stored energy results in ringing and hence reduces articulation & depresses both ULF performance and at higher frequencies (i.e. into the XO region). Essentially that it produces an effect much like a much higher Q system. There are never clear answers here :)

Anyway it appears to be typically set to 0 in WinISD driver files yet changing this value dramatically changes the response & hence changes the EQ that one should apply to hit a target anechoic response. It's not a commonly published value so perhaps that is why it is not generally included. Any views?

Here's a pic of an SP4 15 in a Q=0.707 enclosure with Le = 0 (yellow), Le = 3 (green) and Le = 6 (purple). For reference, the measured values of the Fi Q and SSD driver over on data-bass shows Le in the 6-9 range.


FWIW with the SP4 driver, I can see this sort of hump in a near field measurement but it is not remotely visibly in a measurement at the MLP. I'd need another driver to measure in the same room to determine if there was any difference in the step response.
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Distinguished Member
This is something I looked at the other day and there's very mixed views .

How is le measured and to what distortion level.


Distinguished Member
I don't know. The values I have seen are always at 1kHz. I have seen 200Hz mentioned as the point it is an issue when you have v high inductance. My interest is in determining the extent to which I should correct the system vs the room. Anyone got a car park to lend me to measure in :facepalm:

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