Okay... more news.
The good:
* Laying down an entire tube of epoxy around the perimeter of the spider landing does seem to keep it attached. I put down epoxy all around the perimeter AND added more on top of the top spider.
* Tested @ 1400 watts measured free-air in my lap @ 50 Hz for about 10 minutes... no spider landing failure with the "pre-fixed" woofer (not the one that I fixed after I blew the landing).
The bad:
* Discovered a serious design flaw with the spiders. The bottom set of spiders are not set up correctly, likely they should be faced the opposite direction (mirrored). Saw this same flaw w/ the 15s my customer brought by -- thought it was a triple joint failure due to the noise it made.
* The problem is actually that the inner roll on the bottom spider will invert itself on rearward stroke and it sounds like the sub is blown or badly damaged.
* The sound it makes is quite loud and noticeable due to how stiff the spider is.
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So... looks like they may be fairly promising for SPL after all with some seriously amounts of epoxy applied to them. But, the spider inversion problem would render them totally unlistenable for me... at least at high volume levels when the woofer reached over ~12-15mm of x-max and the roll inverts itself.
I will be testing the more long-term as "dummy loads" on my test bench... will be using them to power test amps before shipment.
