2406H blown?

[Rippinr]

I recently had (2) jbl 2406h1 comp drivers fail. They still show continuity and read 4.6 ohms like they are supposed to but do not work. What causes this? I've used these drivers about 5 years now and never lost even one. These are from mp412 cabs on monitor duty. Were not overpowered. The coils dont really look burnt. I have never experienced this before with them beeping out good but definitley dont work. The two "sonic guard" bulbs in both these boxes did not blow.....wonder why the diaphragms did?

[grumpy]

This dia?:

46222

measuring diaphragm out of the driver?
no shorts to case from either terminal?
coil still attached to plastic dia?
no one stole your magnet(s) :) ?

[JBL 4645]

That is rather odd you’d think those (bulb fuses) would be the first thing to go, not the other way around.

A few FAQ on this JBL link regarding the issue
http://www.jblproservice.com/general_faq.htm

Should I fuse my speakers? JBL does not recommend fusing loudspeakers. A fuse may blow with a signal that would not damage the speaker, but it can also pass a signal that can damage the speaker. To protect your system, JBL advises using adequate, clean amplifier power and watch for amplifier clipping. Add a limiter to your system to electronically limit any potentially damaging transients. Some JBL Professional speaker systems include SonicGuard™, a system that actively protects drivers from excess power.

Well I use a DCX2496 as grumpy knows, and audio limiters on all fronts LCR LF/HF for maximum protection of the Control 5. I lost a few JBL control 5 tweeters in the past and the sodden fuse did sod all to protect the tweeters from being burnt to a crisp.