Hi all, nice forum.
I have a pair of JBL 4312 control monitors that when I crank up, I get a popping noise from one side. I have examined the spider and voice coil for any signs of separation but its good. As I manually exend the cone I notice on the white coating of the 2213h woofer a circular crack about midway of the cone. When I release, the crack disappears. Examining the cone from the back I see a permanant circular crease in the cone and it is now apparent that the cone does not maintain uniform stifness and flexes under moderate power. can this woofer be repaired with a mesh and glue/resin procedure or will the added mass affect the sound. Reconing it is very expensive.
I also see alot of 123a woffers on ebay pretty cheap. these were used in 4310 monitors and look identical from the front. Is there a difference between these 2 models?