Inductance (Le) for Altec 416-8b??

[longdrive55]

Has anyone measured the inductance of their Altec 416-8b's? I'd sure like to know the Le to help with my box/zobel design.

Thanks,

Erik

[GM]

You'll have to measure yours for best accuracy, but according to my notes, the few 416 series I measured way back when were in the 1.2-1.3mh range.

GM

[Richard C.]

Erik,
I have a pair of un-mounted 416-8b's so I can measure Le easily. I took them outside (away from reflections) and used a "B&K Precision" Model 875B digital LCR bridge on the 2mH scale - which measures @1kHz. One was slightly over 1.5 mH (about 1.52 on average) and the 2nd one was slightly under 1.5 mH (about 1.48 on average).
Hope this helps,
Richard C.

[analogman]

Voice coil inductance is measured by blocking the cone, preventing it from moving using special jigs.

[Richard C.]

Analogman,
I see where this would make a large measurement error when my measurement freq. (1kHz) is close to the driver resonant freq., as with a compression driver. I can't get any kind of reasonable reading on my four 902 drivers when I measure L at 1kHz. The cone is hardly moving at all when I measure a woofer at 1kHz - with the very small amount of current that my meter can produce. I will first turn them down tight against a flat surface, take a measurement, see what I get, and then try to block the cone in the relaxed - centered position.

Richard C.

[longdrive55]

GM and Richard,

Thanks very much for the information. Richard thanks for taking the time to do the measurments. I don't have the means to measure Le myself right now, but these figures will get me in the ballpark.

Thanks Again,

Erik