One of my JBL SR4722x boxes lost the 12" woofer. I tore it apart and battery tested the speaker (2206hpl is 8 ohm). It made a noise, so I suspected the crossover. Checked the solder joints and all looked well. I touched them up anyway, still no low end. So I chesked the resistance of the driver...1.9 ohms. I think the vc is shorted.
I ran sound for a too loud Metal band a couple of weeks ago and I think that did it. I run 2 of these a side powered by PLX 3602's over 2 SR4718x Subs per side powered by IPR3000's. I gotta quit doing other bands. When my band plays thru it, this system kicks loud and clean.