The woofer is a 12" driver of a Klipsch SW-12 that has its own internal amplifier in a closed enclosure with a passive 12" radiator.
I tested the whole subwoofer with the driver out of the enclosure a few times. Its spider is partially off the voice coil filler now.
I'm wondering if testing this way caused this damage or the amplifier caused it by sending abnormal signals.
In other words, do most closed enclosure provide damping effects significant enough to restrict overexcursion of the voice coil?